Thread: Is the age of the universe the same in all frames?

When Special Relativity was invented the age of universe was not known, and the topic question was as far as I know not adressed in advance. So what is the answer? It seems obvious that the speed which the universe gets older by (Edit: as you perceive it), is a function of the speed of your frame relative to the universe. The faster your speed, the faster the universe seems to grow old. And it takes you a longer time to discover how old the universe was at a certain moment in your local time. But still the universe may perhaps have the same age everywhere independently of our speed.

Perhaps its a problem there because if it is so then it seems you can define simultanity without using light rays and middle points:
If the age of the universe is the same for two events then they are simultaneous.

Measuring the age of the universe directly seems an unpractical method but cant we use a clock
(Edit: and this is the sWclock.) that alters its speed depending on what changes of speed it happens to experience? Accelerate and the clock will speed up so its speed always is the same as the speed the universe ages with. Then comparisation of speeds with an ordinary clock showing local time will reveal your actual speed through space!

Is this possible or is something wrong?

It seems obvious that the speed which the universe gets older by, is a function of the speed of your frame relative to the universe.

The universe is not a reference frame.

Is this possible or is something wrong?

As AlexG has rightly pointed out the universe is not a valid frame of reference in SR, because it is not in a state of constant motion in relation to anything else.

The closest thing to a universal reference frame is the CMBR.

I dont think I mentioned a "universal frame"...

So what are we doing when we are ,say: travelling to the next star... arent we changing our position in the universe? Arent we in a local frame doing that? Hasnt the frame a speed relative to either the universe, our galactic supercluster or our galaxy? Will that speed not effect the passing of local time?
Whats your problem here?

What im asking is:

1 If the age of the universe is the same to all observers!

2 If that is of any consequence for Special Relativity?

Any comments on that?

Originally Posted by sigurdW

1 If the age of the universe is the same to all observers!

No, because the universe is not a frame of reference, therefore the measured age of the universe need not be the same for all observers, if they use their own clocks to measure it.

2 If that is of any consequence for Special Relativity?

No, for the same reason.

SR is only applicable in situations where a difference in gravitational potential is negligible, and as such can never be applied across those sorts of scales (galaxies, clusters or the universe as a whole), where differences in gravity are large between one area and another. For the answer to your questions you have to look to General Relativity, rather than Special Relativity.

Without knowing it, you are invoking a "universal frame" when you ask if we have a speed relative to "the universe".

Originally Posted by sigurdW

I dont think I mentioned a "universal frame"...

You didn't mention it explicitly, but you nonetheless invoked the existence of a universal frame. You do it again in the following:

Hasnt the frame a speed relative to either the universe,

By talking about "a speed relative to ...the universe," you are indeed assuming the existence of a universal frame, to which some other frame has a relative speed.

Now as to your two questions, there is a difficulty. First the easy part: Given the assumptions of relativity, we say that any experiment you perform in one place will yield the same outcome as if you were to perform it somewhere else (the laws of physics are everywhere the same). So an observer would compute the same age of the universe no matter where the observer was situated.

The difficult part arises in trying to compare the results of experiments run by two different observers. You would have to tell me how you propose to impose a synchronization protocol by which the comparison would be performed. There's no unique choice, so different answers would be possible. That's why, for example, there is a seeming violation of energy conservation by redshifted light; the source and destination frames are not the same so I can't readily compute the energy difference. It's precisely the absence of a universal frame that creates the complication.

Like SF and MH says, special relativity is only valid under special circumstances and is useful (I gather?), because the calculations are much simplified under those ideal conditions. In other words, SR is an approximation of GR where gravitational effects are mostly negligible.

Originally Posted by KALSTER

The closest thing to a universal reference frame is the CMBR.

Is that the cosmic microwave back ground? Thats what was used to determine the age of the universe as I recall?
Sounds good. If we can measure our movement relative that then there is something we can refere to.

Lets imagine were on a ship accelerating from earth and that we are moving close to the speed of light.
We have two clocks that at earth were synchronised but now they no longer are because the "earth" clock can sense changes in speed and adjust its own speed accordingly. It stays synchronised with time on earth and at present it moves with a much higher speed than the "ship" clock showing local shiptime. This is because the speed of the ship has significantly slowed local time.

By comparing the speeds of the clocks we should be able to determine the speed of the ship relative to earth...
Im not sure of the formula but hopefully I have got things right this far. Any objections?

Hi all! Im surprised theres so many visitors!
As to this "shit" with a universal frame: I mean no more than
that is possible to change ones position in the universe
and that it takes a certain time and that the speed then can be calculated.
Layman as I am I see the speed as relative to the beginning and end point
and since those are in the universe then the speed is relative the universe.
Hopefully you are able to translate layman lingo to physics.

Originally Posted by tk421

Originally Posted by sigurdW

I dont think I mentioned a "universal frame"...

You didn't mention it explicitly, but you nonetheless invoked the existence of a universal frame. You do it again in the following:

Hasnt the frame a speed relative to either the universe,

By talking about "a speed relative to ...the universe," you are indeed assuming the existence of a universal frame, to which some other frame has a relative speed.

Now as to your two questions, there is a difficulty. First the easy part: Given the assumptions of relativity, we say that any experiment you perform in one place will yield the same outcome as if you were to perform it somewhere else (the laws of physics are everywhere the same). So an observer would compute the same age of the universe no matter where the observer was situated.

The difficult part arises in trying to compare the results of experiments run by two different observers. You would have to tell me how you propose to impose a synchronization protocol by which the comparison would be performed. There's no unique choice, so different answers would be possible. That's why, for example, there is a seeming violation of energy conservation by redshifted light; the source and destination frames are not the same so I can't readily compute the energy difference. It's precisely the absence of a universal frame that creates the complication.

That is why I try to introduce a clock synchronised to earth time. What I really want is to have it synchronised with the aging of the universe. That it shows how much older the universe is compared to when the clock left earth. I suppose this must be done by measuring the age of the U at two different points of time. But how exact can we measure? And how much time must pass between the two measures to get a significant result? Damn! Theres difficulties everywhere I think. I hope they already have been thought of and the difficulties settled? Where can I read about it?

Meanwhile I want to make sure that nothing is wrong with my thought experiment so far:

By comparing the speed of the clocks, the speed of the ship can be measured. If we let the ship decelerate then eventually the clocks will have the same speed showing the ship to be at rest relative to earth.
Since our solar system probably moves relative to the universe (dont remind me theres no universal frame unless necessary!) the ship should also move.

A question is what it should indicate if the ship clock begins to move faster than the earth clock?
Does it mean that we are moving slower than the earth relative the universe?

Now let us meet a ship travelling with constant speed towards earth.

Let that ship also have an earth synchronised clock...
Is it now true that we cannot tell what ship is at rest and what ship moves?

Im a bit tired now and I dont feel sure about anything (except that)
but isnt this a classic situation (with a difference) often discussed in studying Special Relativity?

There is no beginning and no end point. There is no fixed or preferred frame of reference, and speed relative to the universe is a meaningless phrase.

Originally Posted by AlexG

There is no beginning and no end point. There is no fixed or preferred frame of reference, and speed relative to the universe is a meaningless phrase.

Please stop misinterpreting and stop repeating dogma. Of course there is a starting point and an end point to any journey! And Im pretty sure you dont know what you mean by "meaningless"...Share your definition please.

And Im pretty sure you dont know what you mean by "meaningless"...Share your definition please.

Does not relate to the physical universe. Meaningless.

Cranks, especially the ignorant ones, like to use the word 'dogma' to mean any actual knowledge on the subject.

Originally Posted by AlexG

And Im pretty sure you dont know what you mean by "meaningless"...Share your definition please.

Does not relate to the physical universe. Meaningless.

Cranks, especially the ignorant ones, like to use the word 'dogma' to mean any actual knowledge on the subject.

You dont understand what I write andyou imply im an ignorant crank...Ok ...youre on my ignore list.

Originally Posted by sigurdW

We have two clocks that at earth were synchronised but now they no longer are because the "earth" clock can sense changes in speed and adjust its own speed accordingly.

I do not think that this is possible, because I see no realistic way for the clock on earth to "sense" changes in velocity and acceleration of the moving ship. At best you would get some form of "pseudo-synchronisation" with an increasing lag between the two as the ship moves further and further away. My point is that the comparison between the clocks becomes meaningless, because any attempt at comparing them is subject to the speed of light restriction, and thus the notion of "same instant" is not easily definable.

By comparing the speeds of the clocks we should be able to determine the speed of the ship relative to earth...

In principle ( given purely inertial frames ) you could determine relative velocity by comparing clocks, that this correct.

Layman as I am I see the speed as relative to the beginning and end point and since those are in the universe then the speed is relative the universe.

Speed always means relative speed between two observers. There is no absolute frame against which speed can be defined.

That it shows how much older the universe is compared to when the clock left earth.

You get the right answer in all frames, regardless of whether they are moving or not; it is just that, using this method, not everyone gets the same answer.
That's the fun of relativity !

Damn! Theres difficulties everywhere I think. I hope they already have been thought of and the difficulties settled? Where can I read about it?

Any textbook of Special and General Relativity will explain the concepts involved. Wikipedia is also a good starting point, for a layman's introduction :

Special relativity - Wikipedia, the free encyclopedia
General relativity - Wikipedia, the free encyclopedia
Relativity of simultaneity - Wikipedia, the free encyclopedia

A question is what it should indicate if the ship clock begins to move faster than the earth clock? Does it mean that we are moving slower than the earth relative the universe?

No, all it means is that there is a non-zero relative velocity between the two clocks ( which you can calculate easily ). You cannot tell, however, which clock moves fast and which clock moves slow, because that depends on which frame of reference you are in when you compare the clocks. In other words, in the absence of a third frame, you can't tell which of the two clocks in moving and which one is at rest - you only know that they are moving relative to each other.

Is it now true that we cannot tell what ship is at rest and what ship moves?

Precisely. We cannot tell simply based on the comparison of their clocks.

Kinematic time-dilation (as described by SR) is not a factor in ascertaining the age of the universe. What is a factor, however, is gravitational time dilation (as described by GR).

The clock belonging to an observer close to a massive gravitational source will "run slow" in relation to the clock of an observer out in deep space, as far from any gravitational influence as possible.

Cosmologists understand this.

What they do is to assume a "cosmological" clock, positioned in a region where gravity is at its smallest, measured between the present and the Big-Bang.

Cosmological time (the age of the universe) is calculated relative to a theoretical clock that has existed since the Big-Bang, in a region with the least gravitational influence. A clock on Earth would run a little slower than a cosmological clock, due to the gravity around here, but this is calculated out.

Hi all you who are interested in Cosmology!
Ill begin by restating my thought experiment so you dont have to puzzle it together from different posts:

Lets imagine were on a ship accelerating from earth and that we are now moving close to the speed of light.
We have two clocks aboard ship that at earth were synchronised but now they no longer are
because the "earth" clock can sense changes in speed and (by an internal computer cleverly programmed)
can adjust its own speed accordingly.

It stays synchronised with time on earth
(in practice it takes us too long to synchronize it with the aging of the universe)
and at present it moves with a much higher speed than the clock showing local shiptime.
This is because the speed of the ship has significantly slowed local time.

By comparing the speeds of the clocks we should be able to determine the speed of the ship relative to earth...(Id like to see the formula used.)
Let the ship decelerate until the clocks tick by the same speed,
showing the ship to be at rest relative to earth.
Since our solar system moves through space the ship should also move.

A cool question is what it should indicate if the local clock begins to move faster than the earth clock?
Does it mean that we are moving slower than the earth relative to what?

Now let us meet a ship travelling with constant speed towards earth.
Let that ship also have an earth synchronised clock...
Is it now true that we cannot tell what ship is at rest and what ship moves?

Isnt this a classic situation (with a difference) discussed in studying Special Relativity?

Im no "ignorant crank", I dont advance preposterous claims (Im not really sure I know what is meant by that)
I dont claim there is a universal rest frame, but I claim that it is meaningful to say we change position in space and that that is in some sense a movement relative the universe...
What else than all that is contained in the universe is there to move relative to?
But it is more a manner of speaking than a claim of a universal restframe.

Its been noted that also General Relativity needs to be taken into consideration
since gravity effects the ships clocks...
Very true, also when the ship accelerates and decelerates, but im not excluding anything.

I "invent" a clock that can be synchronized with the aging of the universe
and I describe an experiment where such clocks seem to violate Special Relativity.
The rest really is up to you!

Ever since news of the age of the universe reached me
I wondered if this would effect the Theory of Relativity in any way...
Ive been waiting patiently for the matter to show up somewhere,
but it seems Im alone in raising the question.
So folks: How about you understanding and answering it?
This time (I believe) you cant look up and repeat the answer, you may have to think it out for yourselves!

Have fun! sigurdV

Originally Posted by Markus Hanke

Originally Posted by sigurdW

We have two clocks that at earth were synchronised but now they no longer are because the "earth" clock can sense changes in speed and adjust its own speed accordingly.

I do not think that this is possible, because I see no realistic way for the clock on earth to "sense" changes in velocity and acceleration of the moving ship.

Heh! I made a bad choice in naming the clock! What I refere to as the "earth" clock resides within the ship!

In the ship theres TWO clocks, one shows the local ship time, the other Earth Swedish Time.

Every ship in space is to be equipped with this Swedish Speedometer.
( Patent is already applied for... Just kidding.)

Originally Posted by sigurdW

Does it mean that we are moving slower than the earth relative to what?

You can only determine the relative velocity, but you cannot tell who is moving faster or slower.

Now let us meet a ship travelling with constant speed towards earth.
Let that ship also have an earth synchronised clock...
Is it now true that we cannot tell what ship is at rest and what ship moves?

Of course it still true, because all you can determine is the gamma factor between the two, you still can't tell which one is at rest and which one is moving.
Btw, you cannot synchronise those clocks. Or how would you suppose that should be done, exactly ?

I dont claim there is a universal rest frame, but I claim that it is meaningful to say we change position in space and that that is in some sense a movement relative the universe...

That would make the universe a universal rest frame by default. You don't move relative to the universe, you move in the universe.

I "invent" a clock that can be synchronized with the aging of the universe

And how, exactly would you do such a thing ?

I wondered if this would effect the Theory of Relativity in any way...

No, because that age is calculated using the FLRW metric of General Relativity. The age is actually a result of the laws of GR - so how would the result effect the theory ?

but it seems Im alone in raising the question.

That's because - see above - the age of the universe does not have anything to do with SR. SR is only a locally valid theory, but cannot be applied to the universe as a whole.

Originally Posted by sigurdW

A cool question is what it should indicate if the local clock begins to move faster than the earth clock?
Does it mean that we are moving slower than the earth relative to what?

This might be a good place to start from. I would suggest you look into the findings of the Hafele-Keating experiment.

Here, we have the atomic clock at the U.S. Naval Observatory, and two other atomic clocks that are synchronised with it. One of those other clocks was then flown around the world in an eastwards direction, whilst the other was flown in a westwards direction. Can you guess the results, when those two clocks were brought back and compared with the clock at the U.S. Naval Observatory?

Have a look at the link below, and see if the result surprises you, or not!
Hafele-Keating Experiment

Whoa! A load of questions/statements, and none of them stupid!
​I guess Ill be busy for a while.

Originally Posted by Markus Hanke

Originally Posted by sigurdW

Does it mean that we are moving slower than the earth relative to what?

You can only determine the relative velocity, but you cannot tell who is moving faster or slower.

Remember Im asking, not claiming things. Im only a layman on Physics,
worried by not understanding properly the Scientific consequences
the discovery of the age of the universe may have.

In trying to analyse whats worrying me a I have raised a topic question (actually two.) and I describe a situation I want analysed by professionals. (The topic question has been answered in two opposing ways and I cant help siding with the argument that the laws of physics are the same for all observers and that therefore the Age of the Universe is the same for all observers!)

Now lets look at your answer on the anomalious behaviour (!)
when the localclock starts to move faster than the earthclock:

You can only determine the relative velocity, but you cannot tell who is moving faster or slower

I dont find your answer illuminating, when the clocks were moving with the same speed,
the ship was at rest relative to Earth...
Meaning the relative velocity was zero.

And the question now is: What is the physical situation if local time then speeds up relative earth time?
(Or alternatively put: earth time slows relative ship local time.)

What is happening? Are we standing more still now? Can we? Is the situation an anomaly?
Is there perhaps something wrong with the the concept of the "Swedish Speedometer"?

Originally Posted by sigurdW

I dont find your answer illuminating, when the clocks were moving with the same speed,
the ship was at rest relative to Earth...
Meaning the relative velocity was zero.

Ok, I am officially confused now - where are the clocks, how are they moving, and who measures what ?
I don't think I am talking about the same state of affairs as you do.

Originally Posted by Markus Hanke

Originally Posted by sigurdW

I dont find your answer illuminating, when the clocks were moving with the same speed,
the ship was at rest relative to Earth...
Meaning the relative velocity was zero.

Ok, I am officially confused now - where are the clocks, how are they moving, and who measures what ?
I don't think I am talking about the same state of affairs as you do.

I like your cautious behaviour. Its good to be sure we really communicate!

I dont mind repeating a few times , your responce is commendable!
The story begins with a clock able to sense how it moves
and able to compensate for the movement
so it stays synchronised to the time frame its originally set to.

I refer to it as the "earth clock". A bad name you made me realise,
since its easy to believe I mean any clock on earth.
The earthclock then is put on a spaceship directed to a place
where the effects of gravity is as low as possible.

Act two

On our way we check into the Captains Cabin. We see two clocks beside each other.
This is the "Swedish Speedometer": By comparing the speed time passes on the clocks
it is rumored that the captain can calculate the speed of the ship relative planet Earth.

The ship is accelerating all the time so we notice that the shipwatch (to the left)
is moving slower and slower compared to the earthclock (to the right).
The ships engine is strong so at a speed close to the speed of light
we see the earthclock move incredibly fast (were we AT the speed of light,
our statues would not see how the efficient earthclock tries to move infinitely fast.)

Act three

Now the ship decelerates until the clocks tick with the same speed,
and the Captain declares that the ship is at rest relative earth,
and this was made possible by the Swedish Speedometer invented by sigurdV.
Suddenly the earthclock starts moving slower than the shipclock!
The Captains face gets white... WTF! is happening here he says...

There we let things rest for a while... any objections so far?

Define a clock for Earth. Is it at (rest in relation to) the centre of the planet and not rotating with the Earth (an inertial frame where the postulates of SR all apply - see Hafele-Keating as I already mentioned) or on the surface of the Earth (which is not an inertial frame)?

Originally Posted by sigurdW

The story begins with a clock able to sense how it moves
and able to compensate for the movement
so it stays synchronised to the time frame its originally set to.

This is not possible.
Or how would you propose to construct such a device ?

Originally Posted by Markus Hanke

Originally Posted by sigurdW

The story begins with a clock able to sense how it moves
and able to compensate for the movement
so it stays synchronised to the time frame its originally set to.

This is not possible.
Or how would you propose to construct such a device ?

At last: somebody starts from the beginning. At the moment it is only an assumption:

It is assumed such a clock can be made and if this assumption leads to a contradiction
then such a clock is impossible. But so far I havent been able to produce a contradiction
so its still an open question.

So what makes you think it is impossible?
Perhaps you fear no contradiction will follow from the assumption?
And without sufficient reason claims it is impossible to make such a clock.

I see nothing to stop such a clock from being produced with current technology:
But in Einsteins time it was nothing but a dream, so he didnt bother think of it.
(And no one after him it seems.)

1 The clock need sensors giving it information:
Theres already systems for navigation depending on gyroscopes and wtf I dunno what...
I know next to nothing of them but if something is moved then that could be detected
by having a small mass in its center and springs that should return the small mass to the center
when no force is experienced. By observing the behaviour of said small mass and the springs,
one should be able to deduce what is happening to the clock.

2 The clock needs a computer to handle the information from its sensors: So its a programming question...
I know nothing of that but it must be a clever program. Written by somebody with a deep understanding of physics since the computing speed of the computer is depending on the speed of the clock (or rather of the frame clock is in).
But this seems only technical difficulties...time, money and technological competence is all thats needed.
There seems to be no principle violated in building such a clock. Perhaps you can find one?

This is hilarious. As you seem to be ignoring my (very relevant) posts I will just sit back and watch. I have even made popcorn!

Please continue...

Originally Posted by SpeedFreek

This is hilarious. As you seem to be ignoring my (very relevant) posts I will just sit back and watch. I have even made popcorn!

Please continue...

Im NOT ignoring you! Im just overworked.
Take this quote:

"Define a clock for Earth. Is it at (rest in relation to) the centre of the planet and not rotating with the Earth (an inertial frame where the postulates of SR all apply - see Hafele-Keating as I already mentioned) or on the surface of the Earth (which is not an inertial frame)?"

Honestly: I try to do only necessary (or fun) things. Defining Earth Time surely may wait?

My immediate reaction is that "Earth time" is needed only before the spaceship sent out to test my invention
the"Swedish Speedometer" has found the place where my so called "earthclock"
ticks with "lowest possible pace".Then we make that pace our tentative "Universal Aging speed"
and set all earthclocks to tick at that tempo.

Please accept that you are a welcome contributor in this thread!


Edit: PS Now I checked out Hafele-Keating. It is, as I suspected, a proof that the tempo of time is a direct function of speed ... I didnt read that far, but the speed in this case was a function of distance from the center of the earth wasnt it?

The same goes for all ye Cosmologicians:
You are welcome! Just relax,post and wait.
The longer it takes, the safer your argument is

Originally Posted by sigurdW

Defining Earth Time surely may wait?

No.

You have to define the basis for the time your "Swedish clock" is supposed to relate to, before you can work out how one might achieve a synchronisation with it.

Originally Posted by sigurdW

My immediate reaction is that "Earth time" is needed only before the spaceship sent out to test my invention
the"Swedish Speedometer" has found the place where my so called "earthclock"
ticks with "lowest possible pace".Then we make that pace our tentative "Universal Aging speed"
and set all earthclocks to tick at that tempo.

No.

No clock on Earth ticks at "universal aging speed", due to the gravity of the Earth.
The "lowest possible pace" is the furthest from "universal aging speed! It is where time passes the fastest, not the slowest. Anywhere in the universe where there is more gravity than the least possible will measure time to be "running slower" than the cosmological clock, not faster.

Originally Posted by sigurdW

Edit: PS Now I checked out Hafele-Keating. It is, as I suspected, a proof that the tempo of time is a direct function of speed ... I didnt read that far, but the speed in this case was a function of distance from the center of the earth wasnt it?

No.

Speed was not a function of distance from the centre of the Earth, but time dilation was a function of the speed at which the clock made an orbit around the centre of the Earth, and the clock on the ground was neither the slowest nor the fastest of the three clocks, due to the Earths rotation...

Speed was relative to a theoretical frame at rest in relation to the centre of the Earth, where the Earth rotates around that frame. But this frame moves around the Sun, of course...

Is it starting to click yet?

Hi!

Originally Posted by SpeedFreek

Originally Posted by sigurdW

Defining Earth Time surely may wait?

No.

You have to define the basis for the time your "Swedish clock" is supposed to relate to, before you can work out how one might achieve a synchronisation with it.

Answer: You mean the "earthclock" of course, im reluctant to change given names...I prefere to suffer. I simply dont believe (yet) that I cant use Swedish official time to set the time on the earthclock. The point is that wherever it is transported it shows correct swedish time!

Originally Posted by sigurdW

My immediate reaction is that "Earth time" is needed only before the spaceship sent out to test my invention
the"Swedish Speedometer" has found the place where my so called "earthclock"
ticks with "lowest possible pace".Then we make that pace our tentative "Universal Aging speed"
and set all earthclocks to tick at that tempo.

No.

No clock on Earth ticks at "universal aging speed", due to the gravity of the Earth.
The "lowest possible pace" is the furthest from "universal aging speed! It is where time passes the fastest, not the slowest. Anywhere in the universe where there is more gravity than the least possible will measure time to be "running slower" than the cosmological clock, not faster.

Answer: Yes all clocks on earth are effected by earths gravity.
And gravity slows local time making it appear as if the universe ages faster...
BTW do you accept to assume that earthclocks can be made and synchronized with swedish time so we can
jump to our spaceship somewhere in intergalactical space where we according to the swedish speedometer are at rest with respect to earth? Hey, you speak of cosmological clocks! Is that an earthclock synchronized with the aging of the universe? Im not yet discussing how that is done.

Originally Posted by sigurdW

Edit: PS Now I checked out Hafele-Keating. It is, as I suspected, a proof that the tempo of time is a direct function of speed ... I didnt read that far, but the speed in this case was a function of distance from the center of the earth wasnt it?

No.

Speed was not a function of distance from the centre of the Earth, but time dilation was a function of the speed at which the clock made an orbit around the centre of the Earth, and the clock on the ground was neither the slowest nor the fastest of the three clocks, due to the Earths rotation...

Answer: I didnt read that closely. And its basically the distance from center that together with rotation determines speed...Why this nitpicking?

Speed was relative to a theoretical frame at rest in relation to the centre of the Earth, where the Earth rotates around that frame. But this frame moves around the Sun, of course...

Yes and the solar systems rotates around our galactic center and our galaxy ...Probably moves slightly more intricately and so on ad univ.

Is it starting to click yet?

No I dont understand acceleration and its effect on the clocks aboard ship.
Can we adress the situation described in #25? Or are there more preliminaries to do?
Ill reprint it in here:

The story of the Swedish Clock

Begins with a clock able to sense how it moves
and able to compensate for the movement
so it stays synchronised to the time frame its originally set to.
The swedish clock then is put on a spaceship directed to a place
where the effects of gravity is as low as possible.

Act two

On our way we check into the Captains Cabin. We see two clocks beside each other.
This is the "Swedish Speedometer": By comparing the pace of the clocks
it is rumored that the captain can calculate the speed (and distance?)
of the ship relative to planet Earth.

The ship is accelerating all the time so we notice that the shipclock (to the left)
is moving slower and slower compared to the swedish clock (to the right).
The ships engine is strong so at a speed close to the speed of light
we see the swedish clock move incredibly fast (were we AT the speed of light,
our statues would not see how the efficient earthclock tries to move infinitely fast.)

Act three

Now the ship decelerates until the clocks tick with the same speed,
and the Captain declares that the ship is at rest relative earth,
Suddenly the swedish clock starts moving slower than the shipclock!
The Captains face gets white... WTF! is happening here he says...

Well then friends: What is happening? Can it be happening?

Okay, I'll play along...

Originally Posted by sigurdW

BTW do you accept to assume that earthclocks can be made and synchronized with swedish time so we can jump to our spaceship somewhere in intergalactical space where we according to the swedish speedometer are at rest with respect to earth?

Not without constantly accelerating to maintain the instantaneous rotation of the Earth at the latitude of Sweden, whilst also maintaining the instantaneous orbit of the Earth around the Sun and also maintaining the Suns instantaneous motion around the galaxy and the galaxies motion within the local group, relative to wherever we are, now. No.

Originally Posted by sigurdW

Hey, you speak of cosmological clocks! Is that an earthclock synchronized with the aging of the universe? Im not yet discussing how that is done.

No, the earthclock runs slower than the cosmological clock.

Originally Posted by sigurdW

Suddenly the swedish clock starts moving slower than the shipclock!
The Captains face gets white... WTF! is happening here he says...

Well then friends: What is happening? Can it be happening?

Aside from the fact that you cannot instantaneously remain at rest in relation to the Earth anyway, It could be many things. You are now out of the galaxy, so the swedish clock is now gravitationally time-dilated to a large degree. If you are far enough out of the local group the gravitational time-dilation would be even greater, and the expansion of the universe might be taking the solar system away from you too... but you are getting far closer to the cosmological clock than the Earth is.

Perhaps Ill begin using the name "Swedish clock" (="sWclock") instead of "earthclock"? Its no big thing.
Yesterday I was beginning to doubt, but my confidence is now restored. Since you play along with me,
Ill play along with you and I now think it is a good idea to repeat the Hurley experiment using my device of a sWspeedometer consisting of an ordinary clock combined with an sWclock:

After the first sWclock is produced at the factory it is set to official Swedish time. Then we combine it with an ordinary clock and verify that they work with the same speed...that they show the same time. I dont expect you to deny that they can.

We have now constructed the sigurdW Speedometer and we will repeat the Hurley experiment... We move the speedometer one floor up in the factory building and now we have three clocks to check: clock one at the birthplace of the swclock, and clock two: an ordinary clock one floor up in the factory stuck together with the sWclock. (Those last two clocks constituting the sWspeedometer.)

I think the sWclock and clock one still will show the same time...that they are synchronized (both showing official swedish time). But the sWclock and clock two no longer tick with the same speed. Dont you agree?

I think its easy to see that it is so: Clock two and clock one is proved by the Hurley experiment to now tick with different speeds and if the sWclock has adjusted itself in the way its supposed to, according its construction specifications, then it ticks with the speed of clock one and cant therefore tick with the same speed as clock two. (quod erat demonstrandum)

My tentative explanation of the effect in act three is that the reason the sWclock ticks slower than clock two is that the gravitational effects on the speedometer is weaker than the gravitational effects on clock one. That means that the sWclock now ticks with approximately the same speed as cosmological time. And i read you as if you agree with this!

If we now tell the sWclock to stay synchronised with its new frame, then if we return it to the factory it will no longer tick with the speed of official swedish time. It will, to a better approximation than swedish official time, show the "true" aging of the universe (i.e. how much older the universe is measured from its latest synchronisation).

This is complicated so Im very happy to get some help in thinking this out!

Hello all new readers!

This talk about clocks is perhaps boring?
I try now (for your sake) to put what worries me in its simplest form.

Suppose we at time t1 measure the age of the universe and get u1.
Then we let some time pass, and repeat: at time t2 the age is u2:

If (u2 - u1) = (t2 - t1) then we are at absolute rest!

Since there is no place inside the universe free from gravitational effects,

(u2-u1) will always differ from (t2-t1) and the actual difference determines our speed.

So either we cant measure the age of the universe, or Relativity is perhaps slightly wrong.

Which is it?

Theres already systems for navigation depending on gyroscopes and wtf I dunno what...

Yes, but it isn't possible for such systems to distinguish between acceleration due to movement, and acceleration due to the presence of a gravitational field. You simply couldn't tell whether the probe is actually moving or not, much less still its velocity.
That's really my main point - you cannot keep two clocks synchronous, in fact the notion of synchronicity in GR, particularly for two spatially separated clocks, is highly problematic. How do you even tell whether they are sychronized or not after you separate them ? As SpeedFreek has pointed out to you already, relativity of simultaneity comes into play, and increasingly so as the distance grows larger.

Why is this relevant ? Because the thought experiment is meaningless if its basic premise ( i.e. a clock which changes according to its own speed ) cannot be realized.

Originally Posted by sigurdW

Suppose we at time t1 measure the age of the universe and get u1.
Then we let some time pass, and repeat: at time t2 the age is u2:

If (u2 - u1) = (t2 - t1) then we are at absolute rest!

No, because you would get the same result if you have been moving uniformly ( without acceleration ) between the two times. You can never distinguish between uniform motion and rest by comparing clock readings.

Since there is no place inside the universe free from gravitational effects,

(u2-u1) will always differ from (t2-t1) and the actual difference determines our speed.

No, you can't distinguish between speed and gravitational potential by comparing clocks.

Originally Posted by Markus Hanke

Theres already systems for navigation depending on gyroscopes and wtf I dunno what...

Yes, but it isn't possible for such systems to distinguish between acceleration due to movement, and acceleration due to the presence of a gravitational field. You simply couldn't tell whether the probe is actually moving or not, much less still its velocity.

This is a good objection but you havent yet shown the clock is impossible.
Perhaps it need sensors like radar to examine its surroundings
detecting objects that can influence it gravitionally

Originally Posted by Markus Hanke

That's really my main point - you cannot keep two clocks synchronous, in fact the notion of synchronicity in GR, particularly for two spatially separated clocks, is highly problematic. How do you even tell whether they are sychronized or not after you separate them ? As SpeedFreek has pointed out to you already, relativity of simultaneity comes into play, and increasingly so as the distance grows larger.

One way of telling is to return to the factory to check if the sWclock still is synchronized to clock one.
In reality there would be many such clocks keeping contact with each other by conventional means
spotting if some clock deviates... Clocks need maintenance and repair.

Originally Posted by Markus Hanke

Why is this relevant ? Because the thought experiment is meaningless if its basic premise ( i.e. a clock which changes according to its own speed ) cannot be realized.

I have realised that the whole time, rest assured on that. But its not obvious that the clock cannot be realized. One way of proving it impossible is to assume the clock exists (something you seem reluctant to do)
and then prove that this assumption leads to a contradiction!
That may be easier than proving that technical difficulties involved makes the clock impossible.

Coming to think of it, the thought experiment hasnt got that far yet! At the moment the interpretation of the possibility that the sWclock moves at a slower rate than clock two is examined...It seems to be possible to explain.

Dont you see that the thought experiment also is a way of explaining things for laymen?
Why resist it and try to kill it from the start? Dont you want laymen to understand the finer points of relativity?

Originally Posted by Markus Hanke

Originally Posted by sigurdW

Suppose we at time t1 measure the age of the universe and get u1.
Then we let some time pass, and repeat: at time t2 the age is u2:

If (u2 - u1) = (t2 - t1) then we are at absolute rest!

No, because you would get the same result if you have been moving uniformly ( without acceleration ) between the two times. You can never distinguish between uniform motion and rest by comparing clock readings.

How do you mean? How does the argument assumes any movement?
Cannot the age of the universe be measured twice from earth?

Originally Posted by sigurdW

Since there is no place inside the universe free from gravitational effects,

(u2-u1) will always differ from (t2-t1) and the actual difference determines our speed.

Originally Posted by Markus Hanke

No, you can't distinguish between speed and gravitational potential by comparing clocks.

Im not sure I understand you here either: According to theory any point in the universe moves in the fourdimensional universe. The difference is how much of the traveling is done at the conventional axises and how much is spent on time. A point "rests" if all its movement is on the time axis.

It would be cool if you tried explaining things instead of denying things.

Can you explain (better than I do) what different values
means physically in the formula:(u2 - u1) is equal to,or larger than (t2 - t1)

While youre at it you could also explain to us laymen why the left side cant be smaller than the right side.

Originally Posted by Markus Hanke

You can never distinguish between uniform motion and rest by comparing clock readings.

IF that is what I claim to be possible, THEN isnt an insult to me if you just deny it without proof?

How do you mean? How does the argument assumes any movement?

What I mean is that under the rules of relativity you cannot distinguish between rest and uniform movement by comparing clock readings in the same reference frame.
That is why the difference in clock readings does not allow one to conclude that one is at rest.

Im not sure I understand you here either: According to theory any point in the universe moves in the fourdimensional universe. The difference is how much of the traveling is done at the conventional axises and how much is spent on time. A point "rests" if all its movement is on the time axis.

Acceleration and the presence of a gravitational field are equivalent under the rules of relativity. What that means is you cannot distinguish between a clock running slow due to gravity, and a clock running slow due to acceleration and movement, while staying in the same frame.

IF that is what I claim to be possible, THEN isnt an insult to me if you just deny it without proof?

I don't know where you see an insult. There certainly was none intended.
This is just the basic principle of relativity, i.e. all inertial frames are equivalent, and you can't tell who is moving and who is at rest without any outside point of reference. If we don't even agree on the basic principles, then that would mean for me that you are not in agreement with the entire theory of relativity. Is that the case ?

Originally Posted by Markus Hanke

How do you mean? How does the argument assumes any movement?

What I mean is that under the rules of relativity you cannot distinguish between rest and uniform movement by comparing clock readings in the same reference frame.
That is why the difference in clock readings does not allow one to conclude that one is at rest.

One can measure the age of the universe twice in the same frame: suppose were on a ship travelling with constant speed close to the speed of light then (u2-u1) is a very high number compared to (t2-t1). This tells us our speed is also very high. Dont you agree?
Had (u2-u1) been close to (t2-t1) then our speed must have been low. If we have two clocks, one of them ticking with the same (or approximately the same) speed as the aging of the universe then the same result could be reached by comparing the rate of change of the clocks​ , contrary to your claim! Perhaps you dont distinguish between clock readings and the rate of change of clockreadings?

Originally Posted by Markus Hanke

Im not sure I understand you here either: According to theory any point in the universe moves in the fourdimensional universe. The difference is how much of the traveling is done at the conventional axises and how much is spent on time. A point "rests" if all its movement is on the time axis.

Acceleration and the presence of a gravitational field are equivalent under the rules of relativity. What that means is you cannot distinguish between a clock running slow due to gravity, and a clock running slow due to acceleration and movement, while staying in the same frame.

So if we, in the middle of intergalactic space, find our clock running slow
then it isnt caused by acceleration rather than gravity?

Originally Posted by Markus Hanke

IF that is what I claim to be possible, THEN isnt an insult to me if you just deny it without proof?

I don't know where you see an insult. There certainly was none intended.
This is just the basic principle of relativity, i.e. all inertial frames are equivalent, and you can't tell who is moving and who is at rest without any outside point of reference. If we don't even agree on the basic principles, then that would mean for me that you are not in agreement with the entire theory of relativity. Is that the case ?

That is definitely not the case! I assume that the theory of Relativity is correct and that the age of the universe can be measured (down to the Planck limit)... Then I want to be assured no contradiction can be derived. from the two assumptions. Should a contradiction arise
then its my conviction that some minor adjustments will suffice to straighten things out.

Your statement in blue is interesting: Maybe Im trying to use the difference between the ages of the universe at two different points in local time as a substitute for your outside point of reference?

PS Of course you dont have to agree with what I say, but reading comments always beginning with "No!"
is annoying. You did not write in that style this time, thank you!

Originally Posted by sigurdW

This tells us our speed is also very high. Dont you agree?

It only tells you that the relative speed between the two clocks used is very high, but you don't know which clocks are moving, and at what speed. All you can measure is relative speeds.

So if we, in the middle of intergalactic space, find our clock running slow then it isnt caused by acceleration rather than gravity?

Firstly, you would need a reference point to compare your clock to, or else you wouldn't know that it runs slow.
Secondly, you could not distinguish between the dilation being the result of gravity and being the result of acceleration ( without reference to some other external frame ).

I assume that the theory of Relativity is correct and that the age of the universe can be measured

Yes, very much so - but don't forget that the calculations for the age of universe are based on GR rather than SR, and that the metric which is used is only valid globally. It is quite possible that you could come up with scenarios which create paradoxes locally where the FLRW metric is not valid, but globally within the FLRW domain all observers will agree on the age.

Then I want to be assured no contradiction can be derived.

That is fair enough. See above with regards to global and local metrics.

Maybe Im trying to use the difference between the ages of the universe at two different points in local time as a substitute for your outside point of reference?

I am not certain what you mean by this; however, locally one can always introduce frames which are inertial to a good aproximation.

We have a communication problem: You keep saying the same things over and over.
Perhaps I also do so? Whats the use?
If we cant get a common ground to base our statements and conclusions on, the communication is a failure!

From my point of view, you dont understand what Im saying, and I dont doubt you share the feeling, so I suggest we somehow returns to a common understanding and carefully work from there...

Perhaps here:
Suppose we at time t1 measure the age of the universe and get u1.
Then we let some time pass, and repeat: at time t2 the age is u2:

Now let us analyze the formula: (u2 - u1) is equal to or larger than (t2 - t1)

Question 1: Is it a true statement? If so why?

I think its a good place to start since my assumptions are not objectionable,
We actually have measured the age of the universe once, so we should be able to repeat
and evaluate! And I present a formula that has to be interpreted... accepted or rejected.

Originally Posted by sigurdW

We actually have measured the age of the universe once, so we should be able to repeat
and evaluate! And I present a formula that has to be interpreted... accepted or rejected.

You do know that our actual estimate for the age of the universe has a margin of error that spans hundreds of millions of years, don't you? And that there is every reason to think that this will always be the case, due the complexity involved in coming up with that estimate. The calculation involves things like the Hubble constant, which has a huge error margin all of its own, but based on the assumption of a certain Hubble constant, we get a certain estimate for the age of the universe. Plus or minus a few hundred million years. Based on a Hubble constant of ~70 km/s/mpc (when that figure might be nearer 60 or closer to 80, for instance).

There is no practical way to ascertain an accurate enough age for the universe for us to be able to use it for a clock we can compare our own proper time with. Your formula might give you a rough approximation if there are a few hundred million years between t1 and t2.

If, on the other hand, you want to compare your own proper time with the clock of anything in the universe, rather than the clock of the universe itself, you will run into all the problems we have already talked about.

​

Originally Posted by SpeedFreek

Originally Posted by sigurdW

We actually have measured the age of the universe once, so we should be able to repeat
and evaluate! And I present a formula that has to be interpreted... accepted or rejected.

You do know that our actual estimate for the age of the universe has a margin of error that spans hundreds of millions of years, don't you? And that there is every reason to think that this will always be the case, due the complexity involved in coming up with that estimate. The calculation involves things like the Hubble constant, which has a huge error margin all of its own, but based on the assumption of a certain Hubble constant, we get a certain estimate for the age of the universe. Plus or minus a few hundred million years. Based on a Hubble constant of ~70 km/s/mpc (when that figure might be nearer 60 or closer to 80, for instance).

There is no practical way to ascertain an accurate enough age for the universe for us to be able to use it for a clock we can compare our own proper time with. Your formula(What are you saying!? isnt it an already known formula?) might give you a rough approximation if there are a few hundred million years between t1 and t2.

If, on the other hand, you want to compare your own proper time with the clock of anything in the universe, rather than the clock of the universe itself, you will run into all the problems we have already talked about.

Of course I know...why do you think I invented the sWclock?
On the other hand Whats a few hundred million years between t1 and t2, compared to the age of life?

The important aspect of the "impractical" time comparisation is to determine if it is possible in principle!

And if it is, then that is evidence for the sWclock being possible (again in principle).
And if so, then in practise the annoying time problem may get solved.
Are you getting the total picture now?
Thank you for your qualified interest.
Its been a pleasure discussing this wit you

What are you saying!? isnt it an already known formula?)

No, you just made it up.

Of course I know...why do you think I invented the sWclock?

So your 'sWclock' is simply using the earth as it's inertial (which ist isn't) frame of reference?

Originally Posted by AlexG

What are you saying!? isnt it an already known formula?)

No, you just made it up.

Of course I know...why do you think I invented the sWclock?

So your 'sWclock' is simply using the earth as it's inertial (which ist isn't) frame of reference?

GREAT NEWS!
Do you understand the formula?
Is there someting wrong with this formula originally derived by me?
Mind you, you cant say that since the well known ignoramus sW derived it then it MUST be incorrect.
THAT may be so, but "proof" it aint!

There is nothing wrong with your formula, and it is theoretically valid in a highly idealised and grossly simplified toy universe model, but in practical terms it is useless, due to the error margins in any estimate for the age of the universe.

No observer can ever remain in the region of least gravitational influence in the universe, due to their inevitably being perturbed by the closest gravitational influence. This means, in reality, you would have to accelerate to remain "at rest"...

Originally Posted by sigurdW

Suppose we at time t1 measure the age of the universe and get u1.
Then we let some time pass, and repeat: at time t2 the age is u2:

Now let us analyze the formula: (u2 - u1) is equal to or larger than (t2 - t1)

Question 1: Is it a true statement? If so why?

Is the clock used to perform the two measurements at rest, in constant motion, or accelerated ?
Is there a gravitational field present ?

Originally Posted by Markus Hanke

Originally Posted by sigurdW

Suppose we at time t1 measure the age of the universe and get u1.
Then we let some time pass, and repeat: at time t2 the age is u2:

Now let us analyze the formula: (u2 - u1) is equal to or larger than (t2 - t1)

Question 1: Is it a true statement? If so why?

1 Is the clock used to perform the two measurements at rest, in constant motion, or accelerated ?
2 Is there a gravitational field present ?

1 The formula does not tell, that means theres a better formula incorporating all necessary circumstances.
(Feel free to publish it!) If the circumstances vary then the values we put into the formula varies.
So to understand the formula and its consequences we must check the result for various inputs.
(The writing of a single formula for all this is left as an exercise for experts.)

Suppose its done in constant motion close to the speed of light then we will find U much larger than T.
And the physical meaning is that time has passed much slower within the experiment than outside the experiment, verifying the demands of special relativity.

In your second question you ask how the formula is effected in gravity...Well...
I dont really feel Im qualified thinking in terms of General Relativity but my GUESS is that U will be larger than T. Here youd better ask SpeedFreek,he seems informed on such matters.

Im not sure he gets all points of my argument but Im impressed anyway: He correctly tells us that T will be an inconveniently large number which simply means its impractical to wait for the result unless were close to immortality... My answer is that human culture perhaps IS immortal,and can wait for the result of the experiment if theres a good reason. (Why does nature take such pains to prevent us from getting the answer quickly?)

Im more interested in the principle than in the practise. Its fun to see what the consequence would be if,
to make a minor adjustment to the formula: U/T could be estimated with exact inputs (down to the planck limit) and the duration of measurements compressed to microseconds.

Question 2: Please explain what the physical significance of "U/T" is...

If I understand myself correctly then my purpose in inventing sWclocks
was to make instant approximations of U/T possible in the frame the sWclock happens to be.

Can that be useful if it can be done ?

Originally Posted by SpeedFreek

There is nothing wrong with your formula, and it is theoretically valid in a highly idealised and grossly simplified toy universe model, but in practical terms it is useless, due to the error margins in any estimate for the age of the universe.

No observer can ever remain in the region of least gravitational influence in the universe, due to their inevitably being perturbed by the closest gravitational influence. This means, in reality, you would have to accelerate to remain "at rest"...

Hi! Its a pleasure to read your posts...
I cant understand how I could ignore your first post?
Luckily you stayed interested, deciding to play along.

Question 3: Do you accept existence (Mathematically that is.) of sWclocks?
So their properties (Were they to exist.) can be analyzed?

PS What your saing is that U/T never will be equal to 1?
(Its "dangerous" telling me something is impossible...
My instincts might force me to prove you wrong )

Originally Posted by sigurdW

In your second question you ask how the formula is effected in gravity...Well...
I dont really feel Im qualified thinking in terms of General Relativity but my GUESS is that U will be larger than T. Here youd better ask SpeedFreek,he seems informed on such matters.

I can assure you that, when it comes to General Relativity, Markus is far better informed than I.

Originally Posted by sigurdW

Question 3: Do you accept existence (Mathematically that is.) of sWclocks?
So their properties (Were they to exist.) can be analyzed?

I accept the mathematical definition of cosmological time, based on an idealised theoretical clock in the region of least gravitational influence, comoving with the expansion of the universe, between the Big-Bang and "now". No such clock could really exist (even theoretically!) such that its properties can be analysed, no.

If such a clock were to start out in the region of least gravitational influence, there is no way it could remain in the region of least gravitational influence and no way for it to know it is not in the region of the least gravitational influence any more. You cannot tell whether gravity is influencing your motion, or not. You do not feel the "pull" of gravity.

Originally Posted by sigurdW

PS What your saing is that U/T never will be equal to 1?
(Its "dangerous" telling me something is impossible...
My instincts might force me to prove you wrong )

U/T will never be equal to 1, in a universe that contains matter or energy, no. Gravity extends to infinity.

1 The formula does not tell, that means theres a better formula incorporating all necessary circumstances.

Like SpeedFreek said, the formula is fine ( at least locally ), but what is problematic is the interpretation of it. The reason is the equivalence principle - in the absence of an outside frame of reference we cannot distinguish between time dilation due to acceleration, and time dilation due to the presence of a gravitational field, and thus there is no way to tell our state of motion by comparing clock readings.

Can that be useful if it can be done ?

This ratio would be a purely local value, and will vary from one point in space to another.
I am not certain what the use of this would really be.

PS What your saing is that U/T never will be equal to 1?

Correct, because a point without gravitational potentials does not exist in our universe, thus this ratio can never be 1.

I can assure you that, when it comes to General Relativity, Markus is far better informed than I.

Ha ha !
Thank you, but somehow I doubt that

It seems to me as if you have not proved it, but believe that:
Either there cant be an sWclock or the theory of Relativity is inconsistent!

I would like to see a formal proof of that conclusion.
Because it expresses, rather exact,
what began to worry me when the age of the universe was estimated.

What is impossible with an sWclock?
Cant we adjust the clock in the higher position
so it is synchronized with the clock in the lower position?
We dont have to make a PERFECT sWclock, cant we use approximations?

Is it so that all someone has to do to prove Relativity to be inconsistent
is to build an sWclock?

Perhaps functioning with very low efficiency...but still...functioning?

PS Of course you have noticed that I nowhere claim that U/T =1 anywhere?
(But just for checking the limits of the argument:
Suppose we define a miniuniverse
containg nothing but an observer
and a clock...what then about U/T?)

Originally Posted by sigurdW

It seems to me as if you have not proved it, but believe that:
Either there cant be an sWclock or the theory of Relativity is inconsistent!

Both SpeedFreek and myself have explained to you over the last few posts why such a clock cannot be constructed - the reason comes down to the fact that it would violate the equivalence principle ( which, btw, is well verified ) :

Equivalence principle - Wikipedia, the free encyclopedia

Furthermore, I think you are completely missing the point of comparing local clock readings - the age of the universe can only be determined globally, because it is based on the FLRW metric of General Relativity, which is a global solution of the Einstein Field Equations :

Friedmann

One would determine the global age by estimating the Hubble parameter through observational measurements of how fast space expands, and then extrapolate backwards via the Friedman equation, which is itself a result of aforementioned metric. All of these are global measurements, refer here :

Age of the universe - Wikipedia, the free encyclopedia

What you are arguing is that someone who takes local clock readings can either tell different ages of the universe, or determine whether he is at rest or not. This is not possible, because local clock readings cannot be compared to the global age of the universe - your relation between u/t is valid only for a local point in space, but not for the universe as a whole. In essence you are comparing an SR relation to a GR field equation solution - that is much like trying to compare apples and oranges. The full and correct treatment of the age of the universe can only be done via GR alone, as referenced above. As you can read there for yourself if you don't believe my explanations, there are no internal inconsistencies.

Originally Posted by sigurdW

Is it so that all someone has to do to prove Relativity to be inconsistent
is to build an sWclock?

No, because such a clock would only allow a local observation. It cannot be related to the global age of the universe, see previous post.

I have no wish of "trolling"
so maybe I should stop communicating on this issue?

But I think progress is going on. The expression:
Either there cant be an sWclock or the theory of Relativity is inconsistent!
Is now more precisely put as:
Either there cant be an sWclock or the equivalence principle is violated !

Being nothing but a layman on Relativistic Theory, im not yet assured everything here is safe and sound:
Can it without assuming the equivalence principle be shown that there in principle can be no sWclock?
It appears to me that the assumption of the equivalence principle is equivalent to the assumption that there can be no sWclock!?

Originally Posted by sigurdW

It appears to me that the assumption of the equivalence principle

Assumption? Did you miss the bit about it being well tested?

Originally Posted by Strange

Originally Posted by sigurdW

It appears to me that the assumption of the equivalence principle

Assumption? Did you miss the bit about it being well tested?

No I did not!

Originally Posted by sigurdW

Originally Posted by Strange

Originally Posted by sigurdW

It appears to me that the assumption of the equivalence principle

Assumption? Did you miss the bit about it being well tested?

No I did not!

Therefore it is not an assumption.

Originally Posted by sigurdW

Can it without assuming the equivalence principle be shown that there in principle can be no sWclock?

I am afraid that despite repeated explanations you are still missing the point - even if you were able to built such a clock ( which you aren't ), you would still not be able to make any meaningful conclusion as to the age of the universe. That is because the clock reading is always a local event, whereas the age of the universe can only be determined globally.

I would advise you at this point to thoroughly study the principles involved, particularly General Relativity and the Einstein Field Equations together with their cosmological solutions; without at least some basic knowledge of these areas it will be very difficult for you to put forward meaningful points.

It seems you are alluding to "violations" and "inconsistencies" of the theory of relativity as it relates to time and the age of the universe - I can assure you that no such inconsistencies exist. If you are in doubt or don't wish to believe my word on this, then please at least have a thorough read through the articles I referenced.

Originally Posted by KALSTER

The closest thing to a universal reference frame is the CMBR.

It certainly seems like a universal reference frame to me, being the remnant echo of the first transition of energy into matter (0.00001 seconds after the Big Bang). It is associated with the beginning of the Universe, and not with any particular object in the Universe. And since the stretching of space caused by the expansion of the Universe creates the redshift observed in the CMBR, it would appear that the age of the universe is indeed dependent on the value of CMBR redshift at any point of expansion. According to Peebles:

It is standard practice to label an epoch of the universe by the expansion factor [the ratio of stretched radiation wavelength as it is observed relative to the unstretched wavelength as it was emitted. This is] defined by redshift, z, even when an epoch is so early the redshift cannot be observed in detected radiation… The standard interpretation of the redshift as an effect of expansion of the universe predicts that the same redshift factor applies to observed rates of occurrence of distant events. (P.J.E. Peebles, Principles of Physical Cosmology, Princeton University Press, Princeton, 1993, pp.91, 96)

So, the rate of occurance of events as measured by the CMBR, and as viewed here at our location, would seem to be different than the rate of occurance of those same events at a location where/when the universe was only half as large as it is now? For example, when the Universe was about the size of our Solar System, the wavelength of the CMBR was "x", after the universe expanded to twice this size, the wavelength of the CMBR would have been redshifted to "2x". The rate of occurance of events at this boundary of the universe would be one-half that of the original rate. Similarly, now that the CMBR is stretched by a factor of 10^12, the rate of occurance of events for us is stretched out by this same factor, i.e., one second at the moment CMBR was emmitted = one trillion seconds here and now.

Hmmm, what was your source for those figures you used?

The CMBR has a redshift of z=1089, and the change in scale factor is expressed in the form 1+z, so the universe is now 1090 times larger than it was when the CMBR was released, which was ~380,000 years after the Big-Bang.

Therefore, an event that had a duration of 1 second at the time of recombination, when the CMBR was released, would today be seen to have a duration of 1090 seconds.

If a supernova has a peak luminosity duration of 20 days locally, it will be seen to have a duration of 40 days at z=1, 60 days at z=2 and so on.

Originally Posted by Strange

Originally Posted by sigurdW

Originally Posted by Strange

Originally Posted by sigurdW

It appears to me that the assumption of the equivalence principle

Assumption? Did you miss the bit about it being well tested?

No I did not!

Therefore it is not an assumption.

The theory of relativity is a well tested theory resting on the assumption that the equivalence principle is true...

But no empirical theory can be proven to be absolutely true! Its always possible that some experiment may prove it is not valid in some case. And revision must then be done.

An example is Newtons theory...It was very well tested but it was nevertheless superseded by Relativity.

Are you saying that there is no, nor never will be, a reason to test the Theory of Relativity by a new experiment? Is that what you mean by:"Therefore it is not an assumption."? Please explain.

When I read about the measuring of the Age of the Universe I wondered:
Can this affect relativity in any way? Is it possible that another test is needed?
How do we know such things? Im not sure how you answer that question.

If I hear that the equivalence principle has been tested AFTER the discovery of the age of the universe,
and that that test was designed to reveal any conflict between the concepts then I will be happy.

But discussing with the respectable posters in here has not given me confidence,
they seem somewhat surprised of the thought that there could be any such conflict.
Thereby implying no such test was ever done.

Originally Posted by Markus Hanke

Originally Posted by sigurdW

Can it without assuming the equivalence principle be shown that there in principle can be no sWclock?

I am afraid that despite repeated explanations you are still missing the point - even if you were able to built such a clock ( which you aren't ), you would still not be able to make any meaningful conclusion as to the age of the universe. That is because the clock reading is always a local event, whereas the age of the universe can only be determined globally.

I would advise you at this point to thoroughly study the principles involved, particularly General Relativity and the Einstein Field Equations together with their cosmological solutions; without at least some basic knowledge of these areas it will be very difficult for you to put forward meaningful points.

It seems you are alluding to "violations" and "inconsistencies" of the theory of relativity as it relates to time and the age of the universe - I can assure you that no such inconsistencies exist. If you are in doubt or don't wish to believe my word on this, then please at least have a thorough read through the articles I referenced.

I am afraid that despite repeated explanations you are still missing the point,
If you check you will NOT find me claiming that an sWclock is showing the age of universe:
The defining characteristic of an sWclock is that it stays synchronized
with the frame its speed was set in, unless you intentionally reset it in a new frame.
Perhaps you have understood sWclocks to be something else than what I intended them to be?

The sWclock,
Is a clock able to sense how it moves
and able to compensate for the movement
so it stays synchronised with the frame it was originally set in.
(Let it also have memory and let it produce a map of its movements.)

May I now ask if your concept of an sWclock was as I define above?
PS Hi, and welcome to the forum, rickstones ​

What you are suggesting is akin to trying to measure your own motion across the Earths surface in, say, 1 hour, against your motion due to plate tectonics, using a perfectly elastic ruler you can never be sure you aren't stretching, whose increments are too large to measure the motion of plate tectonics!

And as for the CMBR "rest frame", it is a convenient frame to use in cosmology, when dealing with distances and ages the span billions of years, but a real clock can never actually remain in that frame (gravity again).

The Solar System is moving at something around 600 km/s or so relative to the CMBR rest frame (the error bars for this estimate are quite large and it took years of analysis of the WMAP data to get this figure), but there is also a lot of gravity in these here parts. These are not calculations that can be done "on the fly", and even if they could they would still be subject to the other problems we have mentioned.

Originally Posted by sigurdW

But no empirical theory can be proven to be absolutely true!

Of course not. So what?. You seem to think that if something isn't proved to be "absolutely true" then anything goes. Which is obviously nonsense.

Many experiments to test relativity have been done, to incredibly high levels of accuracy, and more will continue to be done, to even higher levels of accuracy. That is what science does: always testing to try and disprove the current theories. That is where the excitement and rewards are.

Are you saying that there is no, nor never will be, a reason to test the Theory of Relativity by a new experiment? Is that what you mean by:"Therefore it is not an assumption."? Please explain.

No, of course not. Why would saying that something is not an assumption imply that there is no reason to do new experiments?

Does "not an assumption" mean "proven fact" to you?

If so I have to ask if English is not your first language? Or do you have some sort of cognitive deficit that affects language processing? If you don't have any such reasonable excuse for misunderstanding fairly straightforward language, can you see why people might assume you are deliberately misinterpreting and twistign words to create an argument (ie. trolling)?

Anyway, to explain:

An assumption is something like "I assume sigurdW has blond hair" or "I assume sigurdW has green skin"; i.e. something based on no evidence whatsoever and which has not been tested.

We could turn these assumptions into hypotheses by suggesting experiments or observations that could be performed to test them.

For example, we could look at how many people have blond hair or green skin. This allows us to eliminate the "green skin" hypothesis with a reasonable amount of confidence. But we cannot prove it absolutely wrong until we get a sample of sigurdW in the lab.

However, the "blond" hypothesis cannot be easily disproved yet. We don't have enough data.

Now, if we are able to capture a sample from a wild sigurdW, we can run some tests and establish a much higher level of confidence and develop the "blond hair theory". Perhaps not "absolute proof" because we might get a blond hair that belonged to the subjects girlfriend or that has been bleached for a jest, etc.

If someone says "you are just assuming sigurdW has blond hair" we can respond, "no it is not an assumption, we have some evidence". That does not mean that we have absolute proof, it means we don't know for sure but it is not just a random guess pulled out of thin air.

We can always continue to do more research to get better data.

So, an assumption is a guess, a supposition, something baseless. The opposite of assumption (if that makes sense) is not "proven fact".

So, if I say that something is "not an assumption" I simply mean that we have tested the idea, we have some supporting evidence (maybe a lot, maybe a little), or maybe that it is derived from well-tested theory. Or both. Either way, it does not mean that we do not need to do further testing.

Do you need me to provide any further explanation of what the word "assumption" means? Or do you think you will be able to grasp it now? Perhaps I should set some practical exercises in the use of the word to make sure you have got it.

If I hear that the equivalence principle has been tested AFTER the discovery of the age of the universe,
and that that test was designed to reveal any conflict between the concepts then I will be happy.

You were provided with a link to some of the many tests of the equivalence principle. Did you check those to see if they met your requirements?

Originally Posted by sigurdW

If you check you will NOT find me claiming that an sWclock is showing the age of universe:

Well, you should stop messing about with your definitions and names then. You keep talking about the age of the universe, for... what reason again?

Originally Posted by sigurdW

The defining characteristic of an sWclock is that it stays synchronized
with the frame its speed was set in, unless you intentionally reset it in a new frame.

Which, as I have already explained a lot earlier in this thread, is impossible. It would also have to sense how the frame is was set in has moved, and as distance is involved the relativity of simultaneity also rears its ugly head.

Originally Posted by SpeedFreek

Hmmm, what was your source for those figures you used?

The CMBR has a redshift of z=1089, and the change in scale factor is expressed in the form 1+z, so the universe is now 1090 times larger than it was when the CMBR was released, which was ~380,000 years after the Big-Bang.

Therefore, an event that had a duration of 1 second at the time of recombination, when the CMBR was released, would today be seen to have a duration of 1090 seconds.

If a supernova has a peak luminosity duration of 20 days locally, it will be seen to have a duration of 40 days at z=1, 60 days at z=2 and so on.

I can't find the exact reference right now, but it was from Joseph Silk's The Big Bang. He compared the current temp of CMBR to estimates of original temperature to determine an expansion factor of the universe 10^12.

Well as far as I know Joseph Silk is reliable source (I have used him as a source on a number of occasions), but that expansion factor is unlike anything I can recall, except perhaps in relation to cosmic inflation, in which case we aren't talking about the observable universe or events within our particle horizon. It certainly doesnt reflect the cosmological time-dilation of an event from the era of recombination, when the CMBR was released.

The particle horizon is the edge of the observable universe and is estimated to have a current radial distance of ~46 billion light-years. It is the distance to the place where the CMB we detect was originally released, if that place has receded with the expansion of the universe. That particle horizon had a radial distance of ~42 million light-years when the CMB was released, which equates to a scale factor of a little under 1100. This is the standard Lambda-CDM cosmology, and means a 1 second event when the CMBR was released would equate to an ~1100 second event today.

The CMBR is thought to have had an original temperature of ~3000K, and is at 2.7K today.

Oh, and welcome to the forum!

(I wasn't arguing with any of the principles involved in your post, which was very good by the way, it is just the figures in the last paragraph)

Originally Posted by SpeedFreek

Well as far as I know Joseph Silk is reliable source (I have used him as a source on a number of occasions), but that expansion factor is unlike anything I can recall, except perhaps in relation to cosmic inflation, in which case we aren't talking about the observable universe or events within our particle horizon. It certainly doesnt reflect the cosmological time-dilation of an event from the era of recombination, when the CMBR was released.

The particle horizon is the edge of the observable universe and is estimated to have a current radial distance of ~46 billion light-years. It is the distance to the place where the CMB we detect was originally released, if that place has receded with the expansion of the universe. That particle horizon had a radial distance of ~42 million light-years when the CMB was released, which equates to a scale factor of a little under 1100. This is the standard Lambda-CDM cosmology, and means a 1 second event when the CMBR was released would equate to an ~1100 second event today.

The CMBR is thought to have had an original temperature of ~3000K, and is at 2.7K today.

Oh, and welcome to the forum!

(I wasn't arguing with any of the principles involved in your post, which was very good by the way, it is just the figures in the last paragraph)

Thank you. Do you have any suggestions for a good "Lambda-CDM" standard model reference source? In particular, one a semi-literate layman could be able to read and understand?

Well, for the figures I would recommend you use the ones in Table 8 from the paper below.

http://lambda.gsfc.nasa.gov/product/...ic_results.pdf

As to a layman's guide to the model itself, I'm not sure what to suggest, but (strange as it might seem) wikipedia is a pretty good place to start. The physical cosmology section of wikipedia is pretty well written, edited, and referenced.

Lambda-CDM model - Wikipedia, the free encyclopedia

Originally Posted by SpeedFreek

What you are suggesting is akin to trying to measure your own motion across the Earths surface in, say, 1 hour, against your motion due to plate tectonics, using a perfectly elastic ruler you can never be sure you aren't stretching, whose increments are too large to measure the motion of plate tectonics!

And as for the CMBR "rest frame", it is a convenient frame to use in cosmology, when dealing with distances and ages the span billions of years, but a real clock can never actually remain in that frame (gravity again).

The Solar System is moving at something around 600 km/s or so relative to the CMBR rest frame (the error bars for this estimate are quite large and it took years of analysis of the WMAP data to get this figure), but there is also a lot of gravity in these here parts. These are not calculations that can be done "on the fly", and even if they could they would still be subject to the other problems we have mentioned.

Would you please tell me what the statement in red refers to? The measuring of the age of the universe twice? Are you trying to be obscure or funny?

Originally Posted by SpeedFreek

Originally Posted by sigurdW

If you check you will NOT find me claiming that an sWclock is showing the age of universe:

Well, you should stop messing about with your definitions and names then. You keep talking about the age of the universe, for... what reason again?

Originally Posted by sigurdW

The defining characteristic of an sWclock is that it stays synchronized
with the frame its speed was set in, unless you intentionally reset it in a new frame.

Which, as I have already explained a lot earlier in this thread, is impossible. It would also have to sense how the frame is was set in has moved, and as distance is involved the relativity of simultaneity also rears its ugly head.

"Messing about" give an example please!
I keep talking of the age of the universe BECAUSE I suspect that measuring its age twice if (t2-t1) is large enough may be an experiment showing the the equivalence principle being invalidated.

And since it takes too long time (ignoring other difficulties for the moment) to do the experiment,
I try design an experiment that can be done in a resonable amount of time.

How about someone answering some question of mine for a change?

You say, for example:"Which, as I have already explained a lot earlier in this thread, is impossible"

IF the reason its impossible is because the sWclock violates the "you know what" principle
THEN Im satisfied.

Next step is then to consider approximations of the sWclock,
and see if they also are violations...
simplifying them until we actually CAN make one and check
( by using some experiment like the hurley) IF they violate as well!

I dont mind if Im PROVEN wrong in my suspicion but it irritates me that Im opposed and deliberately misunderstood every step on the way! Why dont you wait until my argument is concluded??

Arguing with a troll is useless, except for entertainment.

Originally Posted by AlexG

Arguing with a troll is useless, except for entertainment.

Yeah! I agree. He He.

Originally Posted by Strange

I have to ask if English is not your first language?
Or do you have some sort of cognitive deficit that affects language processing?

I decided your polite question deserves an honest answer . Heres some facts:

The bastard sigurdW was born and raised in 1945 by Swedish mother and Russian prisoner of war.
He is extremely prejudiced against prejudice of any kind and despite being totally committed to truth he wont admit to prejudice. Discovering at the age of four what the curiously looking "ants" were doing in the newspaper and happening to find a book in english by the author Enid Blyton a few years later then discovered written english. Trying to tell the first englishman he met a harmless joke nearly got him killed, so since then he has had no further feedback from english "people". (stay away from them is his adwise) He admits of endurance and tenacity above the norm. He might of course flee if (ever) facing too many attackers at once but he probably will teach himself the noble art of snipeshooting as a result. He also thinks he is intuitive but that is all, he does not believe himself to be exceptional in ANY other way.(What other explanation for him always solving his selected problems could there be?) Staying truthfully on topic this far makes him shining (a dull boy) he cant resist adding:
If alzheimers wont kill him his drug habits and smoking will.

Originally Posted by sigurdW

The bastard sigurdW was born and raised in 1945 by Swedish mother and Russian prisoner of war.

If any of that is true (and you give me no confidence to believe anything you say) then I would congratulate you on your excellent command of English.

I would, however, point out that it is not perfect and as a result, when you see something written that appears not to make sense, perhaps your first thought should be, "is this a problem with my knowledge of the language [or, equally, science]?" This might be more constructive than assuming you are absolutely perfect and charging in with criticisms and attacks on everyone who expresses another opinion [and, equally, of science you do not understand].

I find it rather depressing when people who should be old enough to know better act like 12 years olds. It is bad enough that 12 year olds act like 12 year olds.

The older members seem to justify it on the basis that they don't have to care any more or something. Wrong. You are old enough to know better.

Originally Posted by sigurdW

IF the reason its impossible is because the sWclock violates the "you know what" principle
THEN Im satisfied.

But sigurdW, I have already told you the reason in post 55 - it would violate the equivalence principle. I have even provided you references...?
By your own statement above you should have been satisfied back then.

I dont mind if Im PROVEN wrong in my suspicion but it irritates me that Im opposed and deliberately misunderstood every step on the way!

See above. Since it violates the EP, it cannot be constructed, therefore your proposed experiment is not physically possible.

Hi Markus

Sorry to jump in at such a late stage but you have raised a personal bugbear of mine. Violating a current scientific theory does not make something physically impossible. The mere possibility of the creation of such a clock, for want of a better example in this thread, assures me that the equivalence principle is falsifiable and thus a reasonable scientific proposition. It does mean you would have quiet a battle convincing me that your miracle clock works the way you say it does though. However, that is a question about my beliefs regarding the universe and not about what is physically possible.

Anyway, that's my two cents on the matter.

Originally Posted by river_rat

Hi Markus

Sorry to jump in at such a late stage but you have raised a personal bugbear of mine. Violating a current scientific theory does not make something physically impossible. The mere possibility of the creation of such a clock, for want of a better example in this thread, assures me that the equivalence principle is falsifiable and thus a reasonable scientific proposition. It does mean you would have quiet a battle convincing me that your miracle clock works the way you say it does though. However, that is a question about my beliefs regarding the universe and not about what is physically possible.

Anyway, that's my two cents on the matter.

Hi river_rat,

I understand your point, and in general I would have to agree with you that mere violations of principles do not constitute a physical impossibility. However, in this particular case the existence of such a clock would be tantamount to the existence of an absolute reference frame in relation to which one can determine his/her state of motion - this would invalidate not just the equivalance principle, but the entire theory of relativity.
I am not currently aware of any empirical evidence which can support such an absolute frame, while on the other hand there is plenty of evidence to support the theory of relativity as it is, i.e. without any absolute rest frames so that two inertial observers can only measure their relative speeds.

For that reason I will maintain that, in the context of this thread, the theory of relativity should remain a valid point of reference, in accordance with currently accepted scientific knowledge.

Appreciate your input though !
I am being told by other members of this forum that you are very knowledgeable about these matters - what's your take on this discussion ?

Originally Posted by Markus Hanke

Originally Posted by sigurdW

IF the reason its impossible is because the sWclock violates the "you know what" principle
THEN Im satisfied.

But sigurdW, I have already told you the reason in post 55 - it would violate the equivalence principle. I have even provided you references...?
By your own statement above you should have been satisfied back then.

I dont mind if Im PROVEN wrong in my suspicion but it irritates me that Im opposed and deliberately misunderstood every step on the way!

See above. Since it violates the EP, it cannot be constructed, therefore your proposed experiment is not physically possible.

We agree so far. good!
Lets take the next step,
do something practical:

Theres two identical clocks on different floors and we have verified that the clocks that were synchronized in the beginning of the experiment now are no longer so: the clock that was moved some floors up has a lower speed, demonstrating that time passes with different speed in differents frames. We synchronize a new clock with the ground floor clock. The new clock is connected to a barometer and a computer, able to speed up or lower the speed of the clock depending on the air pressure. If the air pressure is as it is on the higher floor then the computer speeds the clock up enough so it remains syncronized with the groundfloor clock.
Then we move it to the higher floor to see what happens...
Will it be verified that it works with the same speed as the groundfloor clock?

This is no sWclock since it only works for a few selected frames, but:
The clock is doing what an sWclock is supposed to do and perhaps,
if the approximation is good enough
then maybe the Principle is violated by an existing object?

Suppose we continue the experiment
and construct better and better approximations...
Why will we not get to a point where we cant tell the difference
between the approximation and the real impossible thing: An sWclock?

The experiment was clumsily done, all clocks should be synchronized togethen
then we move the two clocks simultaneously to the higher floor.
We need then not go down to the lower floor...
If the two clocks on the same floor dont work with the same speed then we approximated an sWclock.
So tell this hotly tempered troll what went wrong with its first experiment?

Originally Posted by river_rat

Hi Markus

Sorry to jump in at such a late stage but you have raised a personal bugbear of mine. Violating a current scientific theory does not make something physically impossible. The mere possibility of the creation of such a clock, for want of a better example in this thread, assures me that the equivalence principle is falsifiable and thus a reasonable scientific proposition. It does mean you would have quiet a battle convincing me that your miracle clock works the way you say it does though. However, that is a question about my beliefs regarding the univer se and not about what is physically possible.

Anyway, that's my two cents on the matter.

Very sensible position you take! You are exactly right you know? The principle of equivalence is not LOGICALLY true. Yours a perceptive way of making precise what im accusing (on friendly terms!) Marcus of doing! When I try to examine what is needed to falsify the principle, he does not follow my chain of thought from its beginning to its conclusion. He interrupts all the time saying its impossible.
(Actually I like it... He shows me he is watching what Im doing, and I appreciate that!)

I almost forgot:"Markus miracle clock"? Its MY clock!

Originally Posted by sigurdW

The principle of equivalence is not LOGICALLY true.

The principle of equivalence is empirically true to the best of our knowledge, even though you might not find it logical. In fact logic is utterly irrelevant here, the scientific method is based on empirical evidence.
Or would you like to present some empirical evidence that the equivalence principle, and thus all of relativity, is wrong ? I am not aware of any violations of this principle ever having been detected in any experiment - or do you have some valid references to the contrary ?
I'm afraid your little thought experiment won't be quite enough to overturn a century of science without some hard, empirical, peer reviewed and verifiable evidence.

You may also wish to answer this :

It does mean you would have quiet a battle convincing me that your miracle clock works the way you say it does though.

Originally Posted by sigurdW

The clock is doing what an sWclock is supposed to do and perhaps,
if the approximation is good enough
then maybe the Principle is violated by an existing object?

No, because this relies on an outside frame of reference - the surrounding air and its pressure. Do the same in vacuum and it no longer works.

Originally Posted by Markus Hanke

Originally Posted by river_rat

Hi Markus

Sorry to jump in at such a late stage but you have raised a personal bugbear of mine. Violating a current scientific theory does not make something physically impossible. The mere possibility of the creation of such a clock, for want of a better example in this thread, assures me that the equivalence principle is falsifiable and thus a reasonable scientific proposition. It does mean you would have quiet a battle convincing me that your miracle clock works the way you say it does though. However, that is a question about my beliefs regarding the universe and not about what is physically possible.

Anyway, that's my two cents on the matter.

Hi river_rat,

I understand your point, and in general I would have to agree with you that mere violations of principles do not constitute a physical impossibility. However, in this particular case the existence of such a clock would be tantamount to the existence of an absolute reference frame in relation to which one can determine his/her state of motion - this would invalidate not just the equivalance principle, but the entire theory of relativity.
I am not currently aware of any empirical evidence which can support such an absolute frame, while on the other hand there is plenty of evidence to support the theory of relativity as it is, i.e. without any absolute rest frames so that two inertial observers can only measure their relative speeds.

For that reason I will maintain that, in the context of this thread, the theory of relativity should remain a valid point of reference, in accordance with currently accepted scientific knowledge.

Appreciate your input though !
I am being told by other members of this forum that you are very knowledgeable about these matters - what's your take on this discussion ?

Hi Marcus! Look at your blue sentence: Please acknowledge it was not me daring to claim this!

ALL they CAN hold against me, is that I ASKED if the measuring of the age of the universe COULD have any consequenses for the Theory of Relativity!

Im very sorry if I disprove the theory, I pray for forgiveness and promise never to do it again

​I think the first part of my thought experiment is near its finale, and I think Ill put the beginning closer to end so you dont have to scrollback to see how I started .

Originally Posted by sigurdW

When Special Relativity was invented the age of universe was not known, and the topic question was as far as I know not adressed in advance. So what is the answer? It seems obvious that the speed which the universe gets older by (Edit: as you perceive it), is a function of the speed of your frame relative to the universe. The faster your speed, the faster the universe seems to grow old. And it takes you a longer time to discover how old the universe was at a certain moment in your local time. But still the universe may perhaps have the same age everywhere independently of our speed.

Perhaps its a problem there because if it is so then it seems you can define simultanity without using light rays and middle points:
If the age of the universe is the same for two events then they are simultaneous.

Measuring the age of the universe directly seems an unpractical method but cant we use a clock
(Edit: and this is the sWclock.) that alters its speed depending on what changes of speed it happens to experience? Accelerate and the clock will speed up so its speed always is the same as the speed the universe ages with. Then comparisation of speeds with an ordinary clock showing local time will reveal your actual speed through space!

Is this possible or is something wrong?

I try to avoid claiming there might be something wrong with the Theory of the Relativity
because thats a one way ticket to "The Heaven of Trolls".

But now it seems clear to some observers that IF an sWclock is possible THEN the Principle of Equivalence is violated!

Perhaps its now legitimate to attempt to show how to make and test one?
Yours Trolly sigurdV
(End of part one.)

Originally Posted by sigurdW

Lets take the next step,
do something practical:

Theres two identical clocks on different floors and we have verified that the clocks that were synchronized in the beginning of the experiment now are no longer so: the clock that was moved some floors up has a lower speed, demonstrating that time passes with different speed in differents frames.

No, it has a higher speed (Pound-Rebka experiment). The clock on the lower floor ticks slower than the clock on the higher floor. The clock on the lower floor is gravitationally redshifted in relation to the clock on the higher floor. The clock on the higher floor is gravitationally blueshifted in relation to the clock on the lower floor.

Originally Posted by sigurdW

​IF an sWclock is possible

It is not possible.

Originally Posted by Markus Hanke

Originally Posted by sigurdW

The clock is doing what an sWclock is supposed to do and perhaps,
if the approximation is good enough
then maybe the Principle is violated by an existing object?

No, because this relies on an outside frame of reference - the surrounding air and its pressure. Do the same in vacuum and it no longer works.

IF there is a universal frame... THEN its outside or inside any of our frames of reference?

And: We were discussing the first APPROXIMATION of an sWclock.
It was defined only for use in frames close to ground here on Earth.
And it used only one sense...what other sensors are there?
Cant we pack them all into an improved second approximation?

Since this is a thought experiment all its properties must be defined.
Then we build a spaceship around it.(BRB)

Originally Posted by SpeedFreek

Originally Posted by sigurdW

​IF an sWclock is possible

It is not possible.

Isnt it "misquoting" to quote part of a sentence
and present it as a claim of mine?
And then deny the claim I never made??

Am I claiming an sWclock really is possible?
That it is a fact that sWclocks exist?

Let me see a complete and not forged quote showing that I do so.
Or else, Mr, I will insist that you are a forger!

Will you please, as you read this,
correct your erroneous quote to include the whole sentence.
So I can tell the readers what follows, if it is as you say!


A quote is evidence of claims.
Is it ok to falsify evidence?
What says the forum rules?
Will moderators care?

Originally Posted by sigurdW

​I think the first part of my thought experiment is near its finale, and I think Ill put the beginning closer to end so you dont have to scrollback to see how I started .

Originally Posted by sigurdW

When Special Relativity was invented the age of universe was not known, and the topic question was as far as I know not adressed in advance. So what is the answer? It seems obvious that the speed which the universe gets older by (Edit: as you perceive it), is a function of the speed of your frame relative to the universe. The faster your speed, the faster the universe seems to grow old. And it takes you a longer time to discover how old the universe was at a certain moment in your local time. But still the universe may perhaps have the same age everywhere independently of our speed.

Perhaps its a problem there because if it is so then it seems you can define simultanity without using light rays and middle points:
If the age of the universe is the same for two events then they are simultaneous.

Measuring the age of the universe directly seems an unpractical method but cant we use a clock
(Edit: and this is the sWclock.) that alters its speed depending on what changes of speed it happens to experience? Accelerate and the clock will speed up so its speed always is the same as the speed the universe ages with. Then comparisation of speeds with an ordinary clock showing local time will reveal your actual speed through space!

Is this possible or is something wrong?

I try to avoid claiming there might be something wrong with the Theory of the Relativity
because thats a one way ticket to "The Heaven of Trolls".

But now it seems clear to some observers that IF an sWclock is possible THEN the Principle of Equivalence is violated!

Perhaps its now legitimate to attempt to show how to make and test one?

An sWclock is not possible.

Originally Posted by SpeedFreek

Originally Posted by sigurdW

​I think the first part of my thought experiment is near its finale, and I think Ill put the beginning closer to end so you dont have to scrollback to see how I started .

Originally Posted by sigurdW

When Special Relativity was invented the age of universe was not known, and the topic question was as far as I know not adressed in advance. So what is the answer? It seems obvious that the speed which the universe gets older by (Edit: as you perceive it), is a function of the speed of your frame relative to the universe. The faster your speed, the faster the universe seems to grow old. And it takes you a longer time to discover how old the universe was at a certain moment in your local time. But still the universe may perhaps have the same age everywhere independently of our speed.

Perhaps its a problem there because if it is so then it seems you can define simultanity without using light rays and middle points:
If the age of the universe is the same for two events then they are simultaneous.

Measuring the age of the universe directly seems an unpractical method but cant we use a clock
(Edit: and this is the sWclock.) that alters its speed depending on what changes of speed it happens to experience? Accelerate and the clock will speed up so its speed always is the same as the speed the universe ages with. Then comparisation of speeds with an ordinary clock showing local time will reveal your actual speed through space!

Is this possible or is something wrong?

I try to avoid claiming there might be something wrong with the Theory of the Relativity
because thats a one way ticket to "The Heaven of Trolls".

But now it seems clear to some observers that IF an sWclock is possible THEN the Principle of Equivalence is violated!

Perhaps its now legitimate to attempt to show how to make and test one?

An sWclock is not possible.

Are you making a statement of Scientific Fact, or do you express an opinion of yours?

You express yourself so monosyllably so its difficult to tell.
But if you dont want to be understood then its ok with me
if you decide to return to wherever you came from.
I do not wish to insult you, I only think things should be done in a scientific way:

Its slightly unusual for Scientific Statements to be as simple as: "An sWclock is not possible."
That a such and such is not possible seems to be a statement
used either as a conclusion of an argument,
within an argument or perhaps as the title of a short essay.
Your statement just seem to come out of nowhere.
In what context is it meant to fit? Is it intended to prove or disprove something?

Do you try to prove the Principle of Equivalence to be true?
Perhaps you think the following is a valid proof?

1 An sWclock is not possible.
2 Therefore The principle of Equivalence is true.

Some people have what we call a repetitive compulsive behaviour:
They repeatedly utter sentences like: (K*** my a**!)
Without really meaning what they say,
they just cant help repeating the same thing ad nauseatum.
Are you perhaps suffering from something equivalent?

Originally Posted by SpeedFreek

Originally Posted by sigurdW

Lets take the next step,
do something practical:

Theres two identical clocks on different floors and we have verified that the clocks that were synchronized in the beginning of the experiment now are no longer so: the clock that was moved some floors up has a lower speed, demonstrating that time passes with different speed in differents frames.

No, it has a higher speed (Pound-Rebka experiment). The clock on the lower floor ticks slower than the clock on the higher floor. The clock on the lower floor is gravitationally redshifted in relation to the clock on the higher floor. The clock on the higher floor is gravitationally blueshifted in relation to the clock on the lower floor.

I think you are correct. Thank you.
We practical men sometimes makes mistakes ... say ...
Minus for plus and vice versa.
You remember perhaps how that happened
when the sign for the electron was selected?

Originally Posted by sigurdW

Perhaps its now legitimate to attempt to show how to make and test one?

That sounds a bit difficult. We know of no process or procedure by which you can measure your absolute velocity. You may have more luck (and economic benefit) spending that time making a perpetual motion machine or some other epistemically impossible device.

Originally Posted by river_rat

Originally Posted by sigurdW

Perhaps its now legitimate to attempt to show how to make and test one?

That sounds a bit difficult. We know of no process or procedure by which you can measure your absolute velocity. You may have more luck (and economic benefit) spending that time making a perpetual motion machine or some other epistemically impossible device.

No! Something warns me agains your advice, it says to me: You have no legitimate reason for believing this rat to give good advice, assuming he means well then remember that you proved long ago that 1+1= 1 only if you dont understand what you speak about!

PS To show Im a good sport I will let you explain what your words mean to you if you survive this and your next two tests: You are in the cannibal village and they give rats "free choice" if the rat will be served as dinner or as lunch...
They ask you to say whatever you like :if its not true then its dinner and if true then you are lunch...must they pinch you for you to speak out? Remember that screams are not true!

PPS Sorry! I mean "squeeks" in your case.

This is just trolling.

Originally Posted by AlexG

This is just trolling.

I think so too so lets prove youre correct:
1 The word "this" in "This is just trolling" refer to "This is just trolling".
2 Acording to the definition of truth then for all x: "x" is true if and only if x is true.
3 AlexG said: This is just trolling."
4 Therefore AlexG was trolling! (quod erat demonstrandom)