# Thread: speed of light and time

1. so I heard that the more faster an object moves, that time goes slower (for the object).

so at the speed of light, would time stop? (I know only light can reach the speed of light, just saying).

So the real question is:
Since light moves at the speed of light, does light experience 0 time? And if it isn't so, does time affect light in any way?

2.

3. Time is merely a man-made measure of change. Some Dr Who fans in science talk of it as though it were a real dimension, getting the real world mixed up with TV.

The faster something moves, the slower it changes, so in a way, time does slow down for it. It is similar under heavy gravity where motion slows down on an atomic scale, so change is slower, so "time slows down".

Dr Who fans say light experiences no time. However, light can change speeds by changing mediums, at which point you have to ask if it "experiences time" as it slows down to c/2 in glass? Light of course does change in that it can red or blue shift, so "experiences time".

Photons are effectively immortal till they collide with something, as in we can detect photons which have been travelling for billions of years.

4. The light itself is not really effected. Its the observation environment of the observer that cause the effect.

5. Originally Posted by Hal
The light itself is not really effected. Its the observation environment of the observer that cause the effect.
I agree with it.
May be I don't know much abt. time - speed graph.

6. Originally Posted by onerock
so I heard that the more faster an object moves, that time goes slower (for the object).

so at the speed of light, would time stop? (I know only light can reach the speed of light, just saying).
Yeah, that would be an accurate statement.

So the real question is:
Since light moves at the speed of light, does light experience 0 time? And if it isn't so, does time affect light in any way?
It's sort of an N/A actually. Basically, time dilation affects things with mass. Light has no mass, so it isn't affected by time dilation. That said, light beams don't change as they age (discounting redshifting, which is assumed to be a property of the universe instead of the light), so in a way you could say that time for a light beam is frozen. But it's a pretty thinly stretched metaphor.

7. As far as I understand the Theory of Relativity, the limitation of objects to the speed of light only applies where the object has real, 4-dimensional weight - ie the object is a "normal" piece of matter possessing weight in our 3-dimensional and forward-moving time World.
Once you step out of that "World", the Law goverened by the Theory of Relativity breaks down, and objects can freely break the "light barrier". For example, "weightless" cosmic particles have been detected arriving down here on Earth before their cosmic reaction high above us took place, followed at the correct time later by their slower, conventional particles, that possess weight. Photons, with wave-particle characteristics can similarly travel at the speed of light since they, too, don't have any "weight" when they are a wave.
Astronomers consider the Universe family (ie all the infinite Universes comprising the Universe in toto) to be a membrane, like the surface of the sea; the latter cannot possibley have any "weight" since it is only an interface between the sea and the sky. But it exists in 3 dimensions, and, as an object, has length, breadth and height! It makes much use of its "time", and exists in ours, but is, at the same time, timeless ...
When you say "brane" for short in talking about the conceptual Universe, it can be heard and interpreted as "brain", since the heart and soul of the object that we call the "Universe" has to have an intelligence at its heart, controlling its development, and everythig that is within it. So even the Universe seems to have duality to give it the power and versatility to do great things ...

I'll leave it there for the moment since I'm going out with my wife for my birthday lunch, and she needs time for me to settle down before we go. And you need time to digest the implications of what I am implying ...

Andrew Slack (JAGZ in Paphos)

It's sunny and warm, and my motor cruiser beckons - but I have to go to lunch instead!

8. Originally Posted by Cyberia
Time is merely a man-made measure of change.
If that's so, then next time you set up a meeting with someone, just leave out the time ! Since time is not really real, you should have no problems meeting up anyway, should you ?

However, light can change speeds by changing mediums, at which point you have to ask if it "experiences time" as it slows down to c/2 in glass?
Nothing changes from the point of view of the light, it is the outside observer who performs a speed measurement who sees a change. Besides, the change is only due to different permittivity and permeability of glass - the light still moves at precisely the speed of light.

Light of course does change in that it can red or blue shift, so "experiences time".
Red/blue-shift has nothing to do with time - it is a change in energy.

9. Originally Posted by Andrew Slack
Once you step out of that "World", the Law goverened by the Theory of Relativity breaks down, and objects can freely break the "light barrier".
Not correct. An object either has rest mass, in which case it can never reach the speed of light, or it has no rest mass, in which case it will always move precisely at the speed of light.

For example, "weightless" cosmic particles have been detected arriving down here on Earth before their cosmic reaction high above us took place, followed at the correct time later by their slower, conventional particles, that possess weight.
No such thing has ever been detected.
You have any references ?

Astronomers consider the Universe family (ie all the infinite Universes comprising the Universe in toto) to be a membrane, like the surface of the sea; the latter cannot possibley have any "weight" since it is only an interface between the sea and the sky. But it exists in 3 dimensions, and, as an object, has length, breadth and height! It makes much use of its "time", and exists in ours, but is, at the same time, timeless ...
Brane Cosmology is only a hypothesis thus far, and certainly has nothing to do with "weight". You may wish to have read here :

Brane cosmology - Wikipedia, the free encyclopedia

When you say "brane" for short in talking about the conceptual Universe, it can be heard and interpreted as "brain", since the heart and soul of the object that we call the "Universe" has to have an intelligence at its heart, controlling its development, and everythig that is within it. So even the Universe seems to have duality to give it the power and versatility to do great things ...
Meaningless gibberish.

10. To you, yes, meaningless gibberish. I assume you're not a philosopher since, judging by your comments, you go by the science of Physics.

50 years ago I studied in St Andrews University's "School of Natural Philosophy" - the name of which serves as a warning that natural physics is a philosophy, not a science. The second year I was there the Government said that St A Uni was to modernise itself if it wanted grants from the UKGov, and part of this "moderniasation" was to rename it the School of Physics".

The Cosmic Particle experiment was about 40 years ago, and I currently don;'t have time to look up the references you demand ... Bye, I'm off to lunch.

Andrew

11. Originally Posted by Andrew Slack
To you, yes, meaningless gibberish. I assume you're not a philosopher since, judging by your comments, you go by the science of Physics.
Yes, that's pretty much it.

The Cosmic Particle experiment was about 40 years ago, and I currently don;'t have time to look up the references you demand
Petty.
Thing is, no particle arrives here before the process takes place which emits the particle. It just doesn't happen, so the reference is really a moot point.

12. Originally Posted by Andrew Slack

The Cosmic Particle experiment was about 40 years ago, and I currently don;'t have time to look up the references you demand ... Bye, I'm off to lunch.

Andrew
As a layman, it would be of great interest, if you could dig up the above mentioned experiment. Have a nice lunch.

13. Originally Posted by Andrew Slack
As far as I understand the Theory of Relativity, the limitation of objects to the speed of light only applies where the object has real, 4-dimensional weight - ie the object is a "normal" piece of matter possessing weight in our 3-dimensional and forward-moving time World.
Only massless particles can travel at the speed of light. Anything with mass has to travel slower than light. In our universe, that is.

Originally Posted by Andrew Slack
Once you step out of that "World", the Law goverened by the Theory of Relativity breaks down, and objects can freely break the "light barrier".
For "World", substitute "Universe".

Originally Posted by Andrew Slack
For example, "weightless" cosmic particles have been detected arriving down here on Earth before their cosmic reaction high above us took place, followed at the correct time later by their slower, conventional particles, that possess weight.
I think your memory might be playing tricks on you. It sounds to me like you might be referring to the supernova SN1987A, where the neutrino emissions caused by the core collapse reached us three hours before the light from supernova (because it takes time for the shock wave from the core to reach the surface and the star to actually go nova).

Originally Posted by Andrew Slack
Photons, with wave-particle characteristics can similarly travel at the speed of light since they, too, don't have any "weight" when they are a wave.
The particles travel at the speed of light, too. All massless particles have to travel at c.

Originally Posted by Andrew Slack
Astronomers consider the Universe family (ie all the infinite Universes comprising the Universe in toto) to be a membrane, like the surface of the sea; the latter cannot possibley have any "weight" since it is only an interface between the sea and the sky. But it exists in 3 dimensions, and, as an object, has length, breadth and height! It makes much use of its "time", and exists in ours, but is, at the same time, timeless ...
Brane cosmology has to have more than 3 dimensions and it is pure speculation at present so we do not consider the universe to work that way, it is just a suggestion of a possibility we do not even know to be possible.

Weight is a product of gravity, mass is not - do not confuse the two.

The surface of the sea (interface between sea and sky) you speak of has only 2 dimensions, but with intrinsic curvature. You are talking about topology.

Originally Posted by Andrew Slack
When you say "brane" for short in talking about the conceptual Universe, it can be heard and interpreted as "brain",
Only if you were in the medical profession and stumbled into a lecture on theoretical physics and didn't realise it. Or if you were lost in the jungles of south america and a tribe of natives gave you a very strong hallucinogen!

Originally Posted by Andrew Slack
since the heart and soul of the object that we call the "Universe" has to have an intelligence at its heart, controlling its development, and everythig that is within it.
Ah. So that's the agenda here. Intelligent design on a universal scale.

Your post is misplaced. It needs to be in the philosophy forum, at best.

14. Originally Posted by SpeedFreek
Ah. So that's the agenda here. Intelligent design on a universal scale.
If that is the agenda...well, very disappointing.

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