1. What might a person experience if he/she were travelling at the speed of light

2.

3. Relative to what?

4. Nothing (or you could call it death).

5. Here's a famous physicist who asked that exact same question; http://en.wikipedia.org/wiki/Albert_Einstein.

6. Originally Posted by Ophiolite
Relative to what?
The speed of light is not relative. It is the one speed that transforms into itself in special relativity. If the speed of anything is c in any inertial reference frame, it is c in all inertial reference frames.

7. The prime principle of SR(Special Relativity) is this; Regardless of the inertial(translatory{no rotation} and Uniform{no accelerations}) frame of the observer "c"(speed of light{(3)10^8 meters per second}) will measure. To understand this, let us go play some pingpong on a train.

The train will be moving at a constant velocity(10 meters per second), from the west to the east, on some smooth straight flat track. Let's put a pingpong table and two players with an east west orientation(player "PA" east, player "PB" west), and one observer(observer "OA") standing against the north wall, in a car on this train. Let's have the train car be constructed with a large picture window in it's south wall. We also have another observer(observer "OB") standing on the ground outside, south of our train tracks.

Let's have our player's play pingpong, but not competitively. They are attempting to achieve a record for consecutive play. Let's have "OA" measure the speed of the pingpong ball. "OA" measures the speed of the ball as 2mps("mps" is meters per second) in both the east and west direction. Now when we have "OB" measure the speed of the ball in the east direction the ball's speed will measure as the sum of the train's speed(call it "TS") and the ball's speed(call it "BS") or "TS"+"BS"=12mps. When the ball is traveling west it's speed will measure as "TS"-"BS"=8mps.

Now let's replace the pingpong ball with a photon(an imaginary big one) and give the players mirrors for paddles. We're also going to set "c" at 100 mps(Remember "mps" is meters per second) for illustrative purposes. Obviously "OA" will measure the photons speed at "c" or 100mps in both the east and west directions. But what about "OB"? Remember the prime principle of SR; Regardless of the inertial frame of the observer "c" will measure. Well that means that in fact "OB" will measure the speed of the big imaginary photon as 100mps in both the east and west directions. Just like "OA" in the train car.

In conclusion, for "c" to be a constant for all observers, measures of space and time must become variables. I believe that my qualitative analysis of the basis of SR is sound(Please correct me if not). I have yet to attempt any quantitive(mathematical) analysis of this basis or the consequences thereof.

8. Originally Posted by DrRocket
Originally Posted by Ophiolite
Relative to what?
The speed of light is not relative. It is the one speed that transforms into itself in special relativity. If the speed of anything is c in any inertial reference frame, it is c in all inertial reference frames.
If one was travelling.

9. I hope you would not take this as a joke….but we have now Cassini-Huygens mission on Saturn, and will be moving toward Neptune. My point is, how about measuring the speed of light by transmitting from earth a message to Cassini-Huygens in Saturn to be transmitted back to earth as soon as received by Cassini. Now we have advanced astronomical telescope that can accurately measure the DISTANCE where Cassini is in Saturn. Thus, by comparing the data from Cassini and comparing it from astronomical telescope, we can measure the speed of light from both. This is not a joke.

When light was measured by Ole Roemer in the 16th century, the speed of light was somewhere 160,000 to 170,000 miles per second. Now astronomical telescope at that time was reliable, though crude. But the discrepancy is quite material, compared to speed of light of 186,000 miles per second, as measured by Michelson-Morley interferometer ON EARTH GRAVITATIONAL FIELD AROUND THE SUN.

My point of is this, the Michelson-Morley experiment was based on gravitational field of EARTH around the sun, while the Roemer measurement was based on gravitational field of Jupiter around the sun. Perhaps, only, the reason why the speed of light as measured by Roemer was much delayed/slower was because Jupiter has stronger gravitational field that could have slowed down the speed of light. This reasoning appears plausible, IF WE CONSIDER THAT LIGHT CANNOT ESCAPE BLACK HOLE BECAUSE OF STRONGER GRAVITATIONAL PULL THAN THE SPEED OF LIGHT.

THUS, THIS SIMPLE SUGGESTION FOR NASA TO ATTEMPT TO MEASURE THE SPEED OF LIGHT FROM BOTH CASSINI TRANSMISSION AND ASTRONOMICAL TELESCOPE AND COMPARE, MAYBE THE OUTCOME CAN BE MEANINGFUL . HOW ABOUT THAT, NASA?

Jsaldea12
11.18.10

10. Do some reading about interplanetary navigation and communication with space probes like Cassini and you will learn that such an experiment would be simplistic and irrelevant.

11. Also, a gravitational field does not slow down a photon.

12. Originally Posted by TheDr.Spo
Also, a gravitational field does not slow down a photon.
It does, however, cause the photon to take a longer path at the same velocity.

13. Originally Posted by jsaldea12
I hope you would not take this as a joke….but we have now Cassini-Huygens mission on Saturn, and will be moving toward Neptune. My point is, how about measuring the speed of light by transmitting from earth a message to Cassini-Huygens in Saturn to be transmitted back to earth as soon as received by Cassini. Now we have advanced astronomical telescope that can accurately measure the DISTANCE where Cassini is in Saturn. Thus, by comparing the data from Cassini and comparing it from astronomical telescope, we can measure the speed of light from both. This is not a joke.

When light was measured by Ole Roemer in the 16th century, the speed of light was somewhere 160,000 to 170,000 miles per second. Now astronomical telescope at that time was reliable, though crude. But the discrepancy is quite material, compared to speed of light of 186,000 miles per second, as measured by Michelson-Morley interferometer ON EARTH GRAVITATIONAL FIELD AROUND THE SUN.

My point of is this, the Michelson-Morley experiment was based on gravitational field of EARTH around the sun, while the Roemer measurement was based on gravitational field of Jupiter around the sun. Perhaps, only, the reason why the speed of light as measured by Roemer was much delayed/slower was because Jupiter has stronger gravitational field that could have slowed down the speed of light. This reasoning appears plausible, IF WE CONSIDER THAT LIGHT CANNOT ESCAPE BLACK HOLE BECAUSE OF STRONGER GRAVITATIONAL PULL THAN THE SPEED OF LIGHT.

THUS, THIS SIMPLE SUGGESTION FOR NASA TO ATTEMPT TO MEASURE THE SPEED OF LIGHT FROM BOTH CASSINI TRANSMISSION AND ASTRONOMICAL TELESCOPE AND COMPARE, MAYBE THE OUTCOME CAN BE MEANINGFUL . HOW ABOUT THAT, NASA?

Jsaldea12
11.18.10
NASA has done speed of light measurements from Cassini, but to test something else. There is a small delay in a light signal passing near the surface of the Sun predicted by GR. Cassini has been used to test this prediction and verified it to high accuracy. The accuracy of this text is magnitudes greater than the ~1% difference in light speed measurement by Roemer, and thus any difference even close to that would have been already noted.

14. Quoted: "NASA has done speed of light measurements from Cassini, but to test something else. There is a small delay in a light signal passing near the surface of the Sun predicted by GR. Cassini has been used to test this prediction and verified it to high accuracy. The accuracy of this text is magnitudes greater than the ~1% difference in light speed measurement by Roemer, and thus any difference even close to that would have been already noted."

A light passing through toward the sun moves faster but the same light passing outward from the sun is slowed a little, as accurately measured to a high degree of accuracy, as predicted by GR. Whatever is that that made the ELECTRO-MAGNETIC light behaves like that, re- moves faster toward and delayed moving outward, is actually due to the electro-magnetic gravitation al field of the sun.

The suggested experiment, sending a beam from earth to be automatically transmitted to earth, and comparing it with astronomical DISTANCE measurement is meant to see deeper the effect of gravitational field to light. Actually, I suggested this experiment to Dr. Annie Kenney, Director of Space Science, NASA, several years way back.

jsaldea12

11.22.10

____________

15. Speed is relative ..period (but understand it relative as anything).

16. Originally Posted by jsaldea12
The suggested experiment, sending a beam from earth to be automatically transmitted to earth, and comparing it with astronomical DISTANCE measurement is meant to see deeper the effect of gravitational field to light. Actually, I suggested this experiment to Dr. Annie Kenney, Director of Space Science, NASA, several years way back.

jsaldea12

11.22.10
What was her reaction to your suggestion?

____________[/quote]

17. Twice I sent it thru e-mails. There was no response. That was when Cassini was in Jupiter.

jsaldea12

11.22.10

18. Originally Posted by jsaldea12
Twice I sent it thru e-mails. There was no response. That was when Cassini was in Jupiter.

jsaldea12

11.22.10
I am surprised to hear there was no response!
Have you any ideas on why NASA failed to respond?

19. Originally Posted by Halliday
Originally Posted by jsaldea12
Twice I sent it thru e-mails. There was no response. That was when Cassini was in Jupiter.

jsaldea12

11.22.10
I am surprised to hear there was no response!
Have you any ideas on why NASA failed to respond?
One really doesn’t need to send a special signal to the Cassini probe to make a measurement of the speed of light. The probe is sending signals all the time. Those signals are probably eclipsed when the probe passes behind Saturn. Since the distance to Saturn and the orbit of the probe is known to a high degree of accuracy, the time gap between loss and recovery of the Cassini signals could be used to calculate the one way speed of light between Earth and Saturn.

But this kind of experiment has already been done with Jupiter’s moon Io.

20. Quoted: "One really doesn’t need to send a special signal to the Cassini probe to make a measurement of the speed of light. The probe is sending signals all the time. Those signals are probably eclipsed when the probe passes behind Saturn. Since the distance to Saturn and the orbit of the probe is known to a high degree of accuracy, the time gap between loss and recovery of the Cassini signals could be used to calculate the one way speed of light between Earth and Saturn.

But this kind of experiment has already been done with Jupiter’s moon Io."

You have given an idea how to measure the speed of light as the probe passes behind saturn..;just like the measurement already done on Jupiter.s moon Lo 3oo hundred years ago. Has it been done now? Nothing is wrong in asking.

jsaldea12

11.23.10

21. Quoted: "One really doesn’t need to send a special signal to the Cassini probe to make a measurement of the speed of light. The probe is sending signals all the time. Those signals are probably eclipsed when the probe passes behind Saturn. Since the distance to Saturn and the orbit of the probe is known to a high degree of accuracy, the time gap between loss and recovery of the Cassini signals could be used to calculate the one way speed of light between Earth and Saturn.

But this kind of experiment has already been done with Jupiter’s moon Io."

You have given an idea how to measure the speed of light as the probe passes behind saturn..;just like the measurement already done on Jupiter.s moon Lo 3oo hundred years ago. Has this kind of measurement been done now? Nothing is wrong in asking.

jsaldea12

11.23.10

22. Completing: You have given an idea how to measure the speed of light as the probe passes behind saturn..;just like the measurement already done on Jupiter.s moon Lo 3oo hundred years ago with a difference. Has this kind of measurement been done now: compare the speed of light based on the probe eclipse transmission and speed of light based on astronomical telescope actual distance measurement? Nothing is wrong in asking.

jsaldea12
11.23.10

23. Originally Posted by jsaldea12
Completing: You have given an idea how to measure the speed of light as the probe passes behind saturn..;just like the measurement already done on Jupiter.s moon Lo 3oo hundred years ago with a difference. Has this kind of measurement been done now: compare the speed of light based on the probe eclipse transmission and speed of light based on astronomical telescope actual distance measurement? Nothing is wrong in asking.

jsaldea12
11.23.10
Yes it has been done. See link below

http://www.amnh.org/education/resour.../p_roemer.html

24. Those experiments by Roemer and Huygens happened some three hundred years ago. what I would like is the experiment with Cassini-huygens probe now and compared with actual astronomical measurement on planet saturn. Perhaps the gravitational fields has something to do with speed of light..because electro-magnetic light wave interacts with gravitational field of saturn which is itself, electro-magnetic, the medium of light itself.

jsaldea12
11.23.10

25. The scientists watching that probe are implicitly doing these experiments every time they set their schedules for when the probe will pass behind the planet and when the signal will return. (Also, use the edit button.)

26. Originally Posted by MagiMaster
The scientists watching that probe are implicitly doing these experiments every time they set their schedules for when the probe will pass behind the planet and when the signal will return. (Also, use the edit button.)
Does anybody seriously think these "experiments" could have anything like the resolution and accuracy of the modern experiments that have determined the speed of light to be 299,792,456.2±1.1 m/s ?

Fer crissake, you need to know the speed of light in order to get the extremely precise distances that would be required for anything like the proposed astronomical observations and subsequent calculations -- resulting in circular reasoning.

I think I'll put my money on the guys at the NBS in Boulder.

27. I doubt if the suggested experiment has been performed: based on the specific location of earth around the sun and simultaneous time of specific arrival on earth of reappearance of eclipsing cassini at Saturn, naturally to take into consideration change of position of earth around the sun after several minutes light travel from Cassini to earth.. Can NASA clarifies? Maybe such experiment was performed but I doubt it, the experiment could mean nothing, it could further support the present constant speed of lighjt or it may bring new frontier to explore. Nothing is wrong with asking.

Jsaldea12
11.23.10

28. It takes approximately 3 hours for transmission from earth to Cassini-Huygens in Saturn and to be automatically transmitted back to earth. At that time the returned transmission is received on earth, an assigned modern astronomical telescope/s on earth can measure, accurately, the distance of Saturn. With these comparative data, computation of the speed of light based on automatic transmission and actual astronomical telescope is simple.

It is found out that this suggestion is not one of the missions of Cassini-Huygens. But reiterating, this is just a suggestion that can further support the constant speed of light or if electro-magnetic light can be affected by electro-magnetic gravitational field of Saturn. Because, as the ultimate example, electro-magnetic light cannot escape the greater electro-magnetic gravitational field of black hole.

Jsaldea12
11.23.10

29. Originally Posted by jsaldea12
It takes approximately 3 hours for transmission from earth to Cassini-Huygens in Saturn and to be automatically transmitted back to earth. At that time the returned transmission is received on earth, an assigned modern astronomical telescope/s on earth can measure, accurately, the distance of Saturn. With these comparative data, computation of the speed of light based on automatic transmission and actual astronomical telescope is simple.

It is found out that this suggestion is not one of the missions of Cassini-Huygens. But reiterating, this is just a suggestion that can further support the constant speed of light or if electro-magnetic light can be affected by electro-magnetic gravitational field of Saturn. Because, as the ultimate example, electro-magnetic light cannot escape the greater electro-magnetic gravitational field of black hole.

Jsaldea12
11.23.10
rubbish

gravity is NOT electromagnetic.

It is well-known how light is affected by gravity -- it id callrd general relativity.

Telescopes do not measure distance. If they did there would be no need for the use nof "standard candles" in astronomy.

Take a look at the precision to which the speed of light is known (about 9 decimal places) and reconsider your statements regarding the feasibility if this experiment. Remember that Saturn itself is moving at 9.69 km/s.

This is ridiculous.

30. At any time, the exact location of moving Saturn in relation to moving earth is plotted, with references to standard candles , using astronomical telescopes. Now there is Cassini-Huygens emitting different precise signals from Saturn...both methods need to be used just to try to know how gravitational fields of different bodies affect light....it is just as simple as that.

jsaldea12

11.24.10

31. Originally Posted by Ophiolite
Originally Posted by DrRocket
Originally Posted by Ophiolite
Relative to what?
The speed of light is not relative. It is the one speed that transforms into itself in special relativity. If the speed of anything is c in any inertial reference frame, it is c in all inertial reference frames.
If one was travelling.
I am appalled by the reasoning here, on a science forum no less.
You going against Albert now? The speed of light is relative to the observer.
If you in a space ship going half lightspeed, light passing you would still be
186000 mps, the reason for that is, as your speed increases, time slows down.
so the measurement of lightspeed gives the same result.
Am accused of not understanding science, tell me what I am missing here.
nokton.

32. Originally Posted by nokton
Am accused of not understanding science, tell me what I am missing here.
nokton.
The fundamental postulates of special relativity.

33. I like to expound about expanded GR… but I am still on probation. Will you withdraw that probation, and let me have freewill.

Jsaldea12
11.24.10

34. Originally Posted by nokton
I am appalled by the reasoning here, on a science forum no less. You going against Albert now? The speed of light is relative to the observer. Cut out your gobbledegook about inertial reference frames. If you in a space ship going half lightspeed, light passing you would still be 186000 mps, the reason for that is, as your speed increases, time slows down. so the measurement of lightspeed gives the same result. Am accused of not understanding science, tell me what I am missing here. nokton.
You have it all backwards! The speed of light is constant in all inertial reference frames. This is the cause for the relativity of distances and time between these frames. That's the essence of SR. You explain it the other way around. All other velocities are measured relative to certain reference frames. When you say that a space ship travels with half the speed of light, you must define the reference frame from which you measure this velocity. I suggest you read the "Special Relativity Primer" at the beginning of this sub-forum.

35. gravity is NOT electromagnetic.
Please give an example (including data of measurement, how it was measured etc) of one single determination of "the G term" as in Newtons formula with a torsionbalance where the charge difference within the instrument has been measured as being zero,absent. All measurements of G as far as I know this is only "assumed to be" (as not necessary to verify or given no thought)

The whole constellation of the instrument makes such a chargedifference more likely then unlikely. Therefor the above statement lacks experimental foundation.

I don,t know if Newton ever claimed this G in his formula to be a universal constant for all situations. I suppose for Newton G was much more an unknown factor then a known as he never had a value for it.
Therefor the electromagnetic nature for Newton's gravity can very well be hidden inside this G as a chargedifference can be hidden inside a torsionbalance.

Simply because of the torsionwire/fibre with typical high isolation/low conduction as the only connection between the main parts of the instrument.
Similar to how a chargedifference can exist between a copper lamp hanging on a wire and other objekts in a room. Even though there is a connection in both cases, there still is more or less constant chargedifference (thus not static as it can stay more or less constant with a constant conductive connection it constantly has to build up).

The question for proof here is not at my side here. I don,t give a specific value for the chargedifference....the chargedifference assumed as zero, zero is a specific value and asks for measurements to confirm it.....they don,t exist.

36. Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.

37. Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
Very good of you to point that out!
Whatever you are on could well be causing major brain damage.

38. Originally Posted by Halliday
Whatever you are on could well be causing major brain damage.
In his case I just don't see how that is possible.

39. Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
Exactly, well said, even kids agree on that, the problem is adults don't get it. Einstein had the brilliant idea to use the solar eclipse to study light bending, apart from that he has been blown out of proportion.

40. Originally Posted by Myuncle
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
Exactly, well said, even kids agree on that, the problem is adults don't get it. Einstein had the brilliant idea to use the solar eclipse to study light bending, apart from that he has been blown out of proportion.
Eh?? Have you studied physics to any meaningful level? Einstein is probably the greatest physicist who ever lived.

41. Originally Posted by sox
Originally Posted by Myuncle
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
Exactly, well said, even kids agree on that, the problem is adults don't get it. Einstein had the brilliant idea to use the solar eclipse to study light bending, apart from that he has been blown out of proportion.
Eh?? Have you studied physics to any meaningful level? Einstein is probably the greatest physicist who ever lived.
Yet you can't explain why exactly, unless you quote some mainstream books.

42. Originally Posted by Myuncle
Originally Posted by sox
Originally Posted by Myuncle
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
Exactly, well said, even kids agree on that, the problem is adults don't get it. Einstein had the brilliant idea to use the solar eclipse to study light bending, apart from that he has been blown out of proportion.
Eh?? Have you studied physics to any meaningful level? Einstein is probably the greatest physicist who ever lived.
Yet you can't explain why exactly, unless you quote some mainstream books.
You're quite right, Einstein's theories of relativity are so brilliant, accurate and fundamental that they can be found in mainstream books. And yet, you still appear to misunderstand them...

43. Originally Posted by Myuncle
Yet you can't explain why exactly, unless you quote some mainstream books.
1. His paper on Brownian motion provided strong evidence for the existence of atoms. The atomic theory is essential to all of chemistry and much of physics.

2. His paper on the photoelectric effect set the stage for the further development of quantum mechanics and re-introduced Newton's idea of a corpuscular nature of light. (This paper was the primary citation in his nomination for the Nobel Prize).

3. His paper on the electrodynamics of moving bodies introduced the special theory of relativity, which paved the way for both general relativity and quantum field theories.

4. his paper "Does the Inertia of a Body Depend Upon Its Energy Content?", established the equivalence of mass and energy, a pillar of modern particle physics, and nuclear physics.

5, His paper "Die Feldgleichungen der Gravitation (The Field Equations of Gravitation)", introduced general relativity, still our best theory of gravitation and a tour de force of physical reasoning by an individual that remains unmatched.

No books quoted, just facts and original sources in the legitimate physics literature.

44. I would guess quite a few people on this forum can explain why, but you wouldn't believe them anyway.
Let's go back to basics. How do you prove that there is air all around us. You can't see it or touch it, so you prove it by indirect means. You make certain predictions based on the theory of air, and then you verify these predictions, like blowing up a baloon or holding your hand out a moving car window,etc.
Relativity also makes predictions which can be tested for, like time dilation at speed and in gravity wells, bending of light due to space/time curvature, alterations to Newton's Gravitational theory close to a deep gravity well, etc.
All these experiments have been performed and verified the theory of relativity. The experimental results are readily available online. All it takes is a little googleing and a little reading.

You can read, can't you ???

45. Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
An even more direct example: they've put clocks on rocket ships and measured the twin paradox directly. The results matched predictions.

46. Originally Posted by MagiMaster
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
An even more direct example: they've put clocks on rocket ships and measured the twin paradox directly. The results matched predictions.
airplanes

http://en.wikipedia.org/wiki/Hafele-Keating_experiment

47. Originally Posted by DrRocket
Originally Posted by MagiMaster
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
An even more direct example: they've put clocks on rocket ships and measured the twin paradox directly. The results matched predictions.
airplanes

http://en.wikipedia.org/wiki/Hafele-Keating_experiment

Here's a good video clip explaining it (I think I saw it on PBS Nova, originally):

48. Originally Posted by DrRocket
Originally Posted by MagiMaster
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
An even more direct example: they've put clocks on rocket ships and measured the twin paradox directly. The results matched predictions.
airplanes

http://en.wikipedia.org/wiki/Hafele-Keating_experiment
Haven't they done it with the space shuttle too? (Then again, there's the clocks on the GPS satelites.)

49. Originally Posted by MagiMaster
Originally Posted by DrRocket
Originally Posted by MagiMaster
Originally Posted by mauriecb
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
An even more direct example: they've put clocks on rocket ships and measured the twin paradox directly. The results matched predictions.
airplanes

http://en.wikipedia.org/wiki/Hafele-Keating_experiment
Haven't they done it with the space shuttle too? (Then again, there's the clocks on the GPS satelites.)
I don't know if any similar experiment has been done with the shuttle.

GPS would be different. A key element in the Hafele-Keating experiment is that the clocks started together, were separated and flown in opposite directions around the world (twice) and brought back together and compared with each other and with the National Bureau of Standards atomic clock. The results agreed with the predictions of general relativity.

Bringing them back together illustrates an important aspect of GR. Time is a local concept. There is no global concept of time, so no real meaning to a comparison of time here with time there. All that really has meaning is a comparison of two clocks that move along different world lines in spacetime at points of intersection of those world lines. What the clocks measure is "proper time" which is the arc length of the world lines using the Minkowski metric. Note the great philosophical difference between special relativity and general relativity. Special relativity is just a local approximation to general relativity, and the Hafele-Keating experiment was an experiment in general relativity, including both the effects of gravity and of relative motion.

50. Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
I dont get why we have in the past months, have few people keep saying that Einstein's laws of GR and SR are bogus, or meaningless etc....?????????????????

51. Originally Posted by Heinsbergrelatz
Well when you get on your rocket ship let us know, becasue no one knows and thats why all of Einsteins theories are bogus.
I dont get why we have in the past months, have few people keep saying that Einstein's laws of GR and SR are bogus, or meaningless etc....?????????????????
It is not just the last few months. Internet science forums are full of people who think they understand physics and are sure that Einstein is wrong. Two thirds of them have minimal intellect, little knowledge and no sense. One third of them are smart enough and have done enough reading to be dangerous to themselves an unsupervised children.

52. Am quite disapponted with you all. No 1, lets take sciences understanding
of cosmology. Edwin Hubble stood you all on your heads in 1929.
The static universe was no more.
No 2, the big bang, you still insist in giving it a time frame, in particular,
the expansion, which you not understand so invoke planck time.
Not that at the moment of the bang, time,as we know it, did not exist,
nor did light.
nokton.

53. Originally Posted by nokton
Am quite disapponted with you all. No 1, lets take sciences understanding
of cosmology. Edwin Hubble stood you all on your heads in 1929.
The static universe was no more.
No 2, the big bang, you still insist in giving it a time frame, in particular,
the expansion, which you not understand so invoke planck time.
Not that at the moment of the bang, time,as we know it, did not exist,
nor did light.
nokton.
???? Or to put it more precisely: ????????

1. What has this to do with the thread?
2. What does your point 1) mean? How do you interpret E. Hubble's discovery that the redshift of galaxies correlates with their distance? Do you agree with the common interpretation of an expanding universe?
3. Hard to understand what you are aiming at with your point 2). Not to mention your confusing usage of multiple negations. What do you mean with "giving the Big Bang a time frame"?

54. Originally Posted by nokton
Am quite disapponted with you all..
Curiously that will not lead me to lose any sleep.

Originally Posted by nokton
No 1, lets take sciences understanding
of cosmology. Edwin Hubble stood you all on your heads in 1929.
Let us dissect that comment.
Edwin Hubble, a scientist, using observations collected by other scientists using scientific techniques, was able to reveal a heretofore unknown characteristic of the universe which he presented in a scientific paper in a peer reviewed journal. The findings were then examined, assessed, duplicated and discussed by other scientists, using the scintific method and broadly confirming his findings.

So Edwin Hubble did not stand us on our heads in 1929. Edwin Hubble did not enter the fray as an outsider, showing science and scientists to be wrong - which is what your tone implies. Hubble, as a member of the scientific establishment identified a significant suite of observations that opened up a new way of looking at the universe.

And that was all part and parcel of what science is very good at. So what was your point?

Originally Posted by nokton
No 2, the big bang, you still insist in giving it a time frame, in particular,
the expansion, which you not understand so invoke planck time.
Not that at the moment of the bang, time,as we know it, did not exist,
nor did light.
nokton.
You seem to be trying to address the issue that physical laws as currently understood become inapplicable very close to the point of origin. My simplistic understanding of this is that the inconsistencies and ambiguities existing close ot the origin are a reflection of the incompletness of our understanding of the physical laws, not a reflection of 'reality'

So, again, what is your point? That we don't know everything? Maybe that's why we continue with our research.

My point was, and is, that at the 'time' of the big bang, the laws of physics
as we now understand them were not determined.
That a singularity smaller than an atom can explode to the size of a golf
ball, in a billionth of a second defies light speed as we know it.
It defies all known laws of physics.
So so many astrophysisists
So, in our arrogence, we must explain it, and create an order of time
that did not exist then.
My contention to you is that the laws of physics as we understand them
now, were the result of the 'big bang' after the event, and not before.
hope you understand.
nokton.

56. What you seems to not understand is that there is a difference between moving through space and moving with space. Relativity puts the speed of light as the maximum (or an ever closer approximation to it) speed an object with mass can attain while moving through space. There is no limit though on the speed of inflation, so any matter that was carried along were not breaking relativity. In fact, in our current universe the furthest galaxies we can see are receding at close to the speed of light. All indications are that galaxies still further from us would be receding at even faster than C. They can do this, because they are moving with the expanding spacetime, not through it.

As for the laws coming into existence after T=0: you are correct about that. The fundamental forces did not condense until some very small time after the bang. This is accepted.

57. That a singularity smaller than an atom can explode to the size of a golf
ball, in a billionth of a second defies light speed as we know it.
Not really. In a billionth(10^-9) of a second light can travel about 1/3 of a meter. So a spherical event expanding at the rate of c(3*10^8 m/s) would be about 2/3 meter in diameter after one nanosecond. Much larger than a golf ball.

58. Originally Posted by KALSTER
What you seems to not understand is that there is a difference between moving through space and moving with space. Relativity puts the speed of light as the maximum (or an ever closer approximation to it) speed an object with mass can attain while moving through space.
In fact in general relativity the concept of speed, and iondeed the concept of space are local. What is constrained by the speed of light is local speed through local space.

Originally Posted by KALSTER
There is no limit though on the speed of inflation, so any matter that was carried along were not breaking relativity. In fact, in our current universe the furthest galaxies we can see are receding at close to the speed of light. All indications are that galaxies still further from us would be receding at even faster than C. They can do this, because they are moving with the expanding spacetime, not through it.
Almost.

Spacetime is not expanding. Spacetime, in general relativity, is static. It contains all of space and all of time, past present and future -- the whole enchilada -- and all mixed together by curvature.

So what is expanding ?

If you make the cosmological assumption, thnat the universe is homogeneous and isotropic, which seems to the case on the largest scales (and is patently false on smaller scales) then spacetime can be decomposed as a one-parameter foliation of space-like 3-dimensional hypersurfaces. The parameter serves as a surrogate for time, and the hypersurfaces as a surrogate for space. From the Minkowski metric on spacetime, the hyperspaces inherit a true Riemannian metric. Expansion means that the distance between points, measuted with that Riemannian metricc,increases with an increasing value of the "time"parameter. This is what is commonly called "metric expansion of "space".

So, what is expanding is space, in the sense noted above.

Originally Posted by KALSTER
As for the laws coming into existence after T=0: you are correct about that. The fundamental forces did not condense until some very small time after the bang. This is accepted.
Basically.

We don't have any viable theory that covers the fundamental forces among elementary particles in a high-gravity environment, nor at the sort of energy (temperature) expected then.

At some time shortly after the big bang when things bexpanded and cooled a bit, the models of general relativity and the Standard Model of particle physics are good approximations. this is probably what you mean by "condense".

59. Almost.

Spacetime is not expanding. Spacetime, in general relativity, is static. It contains all of space and all of time, past present and future -- the whole enchilada -- and all mixed together by curvature.

So what is expanding ?

If you make the cosmological assumption, thnat the universe is homogeneous and isotropic, which seems to the case on the largest scales (and is patently false on smaller scales) then spacetime can be decomposed as a one-parameter foliation of space-like 3-dimensional hypersurfaces. The parameter serves as a surrogate for time, and the hypersurfaces as a surrogate for space. From the Minkowski metric on spacetime, the hyperspaces inherit a true Riemannian metric. Expansion means that the distance between points, measuted with that Riemannian metricc,increases with an increasing value of the "time"parameter. This is what is commonly called "metric expansion of "space".

So, what is expanding is space, in the sense noted above.
Gee Doc, you should write a book about GR. Don't write a Hawking book, write a Penrose book. You know, throw some math meat down on it. Just say it like it is and then offer some careful explanation. If I were shopping for a GR book and I opened one from the shelf and read what you posted I'd probably buy it. If you are financially comfortable and dedicated to the cause of scientific literacy then you could release your book as an open licence PDF for free download. Myself, I would publish and sell, but that's only cause' I need money.

60. Gee Doc, you should write a book about GR. Don't write a Hawking book, write a Penrose book. You know, throw some math meat down on it. Just say it like it is and then offer some careful explanation. If I were shopping for a GR book and I opened one from the shelf and read what you posted I'd probably buy it.
I agree. I am now inspired to read up a bit about what you said and to try and make sense of it. :wink:

So, what is expanding is space, in the sense noted above.
I will remember this for future reference.

Spacetime is not expanding. Spacetime, in general relativity, is static. It contains all of space and all of time, past present and future -- the whole enchilada -- and all mixed together by curvature.
Interesting!

this is probably what you mean by "condense".
I was referring to the Grand Unification Epoch. I don't pretend to know how it works though, I just know that at some point the fundamental forces were one, until they "condensed" into four separate forces.

61. Originally Posted by KALSTER
[Grand Unification Epoch. I don't pretend to know how it works though, I just know that at some point the fundamental forces were one, until they "condensed" into four separate forces.
If you suspect this you are in good company.

If you know it then you are unique.

62. Originally Posted by GiantEvil
Gee Doc, you should write a book about GR. Don't write a Hawking book, write a Penrose book. You know, throw some math meat down on it. .
Other people have already done that.

General Relativity -- Robert Wald

Gravitation -- Misner, Thorne, Wheeler

Gravitation and cosmology : principles and applications of the general theory of relativity -- S. Weinberg

Penrose also did a nice job on GR and a lot of other things in The Road to Reality

63. Other people have already done that.
And other people have eaten chocolate cake, is that a reason to forgo a slice for yourself?
General Relativity -- Robert Wald
Haven't read that one. I have "Introduction to GR" by John Dirk Walecka. I need to learn the calculus of vectors before it doe's me much good. I also have "Understanding Einstein's Theories of Relativity" by Stan Gibilisco. It appears to be a good layman's sort of text. I should read the whole thing, it's not very big. I have reached a point of diminishing returns in my bibliophilism, my tendency of collection is interfering with my reading. But I digress.
Gravitation -- Misner, Thorne, Wheeler
I have "Gravity" by George Gamow. And just now looking over Ch. 3 there's some explanation of the calculus that I'm finding very helpful. Shows what happens when a person actually read's the book's they have. Although since different people tend to use the same language differently, it is good to have multiple expositions on the same subject available. Some chocolate cake is better than other's.
Gravitation and cosmology : principles and applications of the general theory of relativity -- S. Weinberg
Since the Faustian deal is purely mythological and there is no royal road to knowledge I have been attempting to abstain from going very deep into cosmology, for the reason of specialization. I do have some book's on astronomy of course, which tend to have fairly rigorous treatment's of the EM spectrum.
Penrose also did a nice job on GR and a lot of other things in The Road to Reality
I have that one, it's one of my favorites. If I merely wished to read it, I could accomplish such in under a month. I however have been attempting to understand it, so I've been at it(The Road to Reality) for a couple years and suspect I'll continue to be at it for a few more(years). I would also like to start in on either "Shadows of the Mind" or "The Emperors New Mind", which do you recommend?

64. Originally Posted by GiantEvil
Other people have already done that.
And other people have eaten chocolate cake, is that a reason to forgo a slice for yourself?
General Relativity -- Robert Wald
Haven't read that one. I have "Introduction to GR" by John Dirk Walecka. I need to learn the calculus of vectors before it doe's me much good. I also have "Understanding Einstein's Theories of Relativity" by Stan Gibilisco. It appears to be a good layman's sort of text. I should read the whole thing, it's not very big. I have reached a point of diminishing returns in my bibliophilism, my tendency of collection is interfering with my reading. But I digress.
Gravitation -- Misner, Thorne, Wheeler
I have "Gravity" by George Gamow. And just now looking over Ch. 3 there's some explanation of the calculus that I'm finding very helpful. Shows what happens when a person actually read's the book's they have. Although since different people tend to use the same language differently, it is good to have multiple expositions on the same subject available. Some chocolate cake is better than other's.
Gravitation and cosmology : principles and applications of the general theory of relativity -- S. Weinberg
Since the Faustian deal is purely mythological and there is no royal road to knowledge I have been attempting to abstain from going very deep into cosmology, for the reason of specialization. I do have some book's on astronomy of course, which tend to have fairly rigorous treatment's of the EM spectrum.
Penrose also did a nice job on GR and a lot of other things in The Road to Reality
I have that one, it's one of my favorites. If I merely wished to read it, I could accomplish such in under a month. I however have been attempting to understand it, so I've been at it(The Road to Reality) for a couple years and suspect I'll continue to be at it for a few more(years). I would also like to start in on either "Shadows of the Mind" or "The Emperors New Mind", which do you recommend?
You will need vector calculus, and a lot more for any of the books that I listed. They are serious texts.

I have both "Shadows of the Mind"and "The Emperors New Mind:". Neither is a favorite, despite my high regard for Penrose.

65. From what I understand "Shadows" and "Emperors" are both speculations concerning a quantum aspect of consciousness. Why didn't you like them? Perhaps I might be able to avoid purchasing and reading more material than necessary.

66. Originally Posted by GiantEvil
From what I understand "Shadows" and "Emperors" are both speculations concerning a quantum aspect of consciousness. Why didn't you like them? Perhaps I might be able to avoid purchasing and reading more material than necessary.
It is just a matter of what one vfinds interesting, I don't buy all of the Turing machine arguments with respect to consciousness. I'm not sure Penrose does either given some reported comments. I don't think anybody has a handle on consciousness, but I do think Penrose has as deep an understanding as anyone.

67. I'm vaguely familiar with the Turing machine-Halting problem-consciousness theorem. I heard of it here; http://www.listeningtowords.com/person.php?id=460. I've also ran into somewhere, some stuff about microtubules in the cytoskeleton and quantum processes. I think it's safe to say that NOBODY understands consciousness. I suspect that a valid TOE will be necessary to any such understanding. I further suspect that consciousness does involve currently unknown mechanism's, aspects.

68. Originally Posted by KALSTER
What you seems to not understand is that there is a difference between moving through space and moving with space. Relativity puts the speed of light as the maximum (or an ever closer approximation to it) speed an object with mass can attain while moving through space. There is no limit though on the speed of inflation, so any matter that was carried along were not breaking relativity. In fact, in our current universe the furthest galaxies we can see are receding at close to the speed of light. All indications are that galaxies still further from us would be receding at even faster than C. They can do this, because they are moving with the expanding spacetime, not through it.

As for the laws coming into existence after T=0: you are correct about that. The fundamental forces did not condense until some very small time after the bang. This is accepted.
Thankyou Kalster, my response to you is this. Correct me if I am wrong, but
did not Alberts equations conclude that space, time, and matter, co-exist,
and that our reality and physics, accept that they do, and one without the other
two, cannot exist.
Just a point for your consideration, Kalster, before T=0, light not born,
so how would the constraints of its future speed affect the initial expansion?
We are dealing here with is what for want of a word, pre-physics, nothing I
see in relativity explains this.
nokton

69. Originally Posted by nokton
As for the laws coming into existence after T=0: you are correct about that. The Thankyou Kalster, my response to you is this. Correct me if I am wrong, but
did not Alberts equations conclude that space, time, and matter, co-exist,
and that our reality and physics, accept that they do, and one without the other
two, cannot exist.
nope

70. Interesting thread. Here's something else interesting.

Originally Posted by KALSTER
... In fact, in our current universe the furthest galaxies we can see are receding at close to the speed of light. All indications are that galaxies still further from us would be receding at even faster than C...
Have a read of Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe by Davis and Lineweaver. Note this from the abstract:

"we can observe galaxies that have, and always have had, recession velocities greater than the speed of light"

Yep, space is expanding, not spacetime. You can't actually move through spacetime either. You move through space over time then represent this using worldlines drawn in a spacetime "block universe".

 Bookmarks
##### Bookmarks
 Posting Permissions
 You may not post new threads You may not post replies You may not post attachments You may not edit your posts   BB code is On Smilies are On [IMG] code is On [VIDEO] code is On HTML code is Off Trackbacks are Off Pingbacks are Off Refbacks are On Terms of Use Agreement