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General Relativity And The Experiments...


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#1 Adam Nagy

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Posted 05 August 2009 - 02:28 PM

General relativity is a fascinating subject and to contemplate a bending, if you please, of spacetime is mind bending. Pun intended.

However, I have been wondering just how profound and measurable the results were from the solar eclipse that confirmed this distortion of spacetime for Einstein? How many times has this experiment been repeated since? How clear were the results and how were the positions of the stars near the suns parameter verified to be visually shifted based on the light bending around the gravitational field of the sun?

Does anyone have access to the actual data, images and methods used to achieve the pronouncement that spacetime exists and it does indeed bend?

#2 jason78

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Posted 05 August 2009 - 02:31 PM

General relativity is a fascinating subject and to contemplate a bending, if you please, of spacetime is mind bending. Pun intended.

However, I have been wondering just how profound and measurable the results were from the solar eclipse that confirmed this distortion of spacetime for Einstein? How many times has this experiment been repeated since? How clear were the results and how were the positions of the stars near the suns parameter verified to be visually shifted based on the light bending around the gravitational field of the sun?

Does anyone have access to the actual data, images and methods used to achieve the pronouncement that spacetime exists and it does indeed bend?

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Experiments that confirm Einsteins theories are carried out every day. GPS doesn't work without it.

#3 Adam Nagy

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Posted 05 August 2009 - 02:42 PM

Experiments that confirm Einsteins theories are carried out every day.  GPS doesn't work without it.

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Don't get me wrong, I think things like time dilation are really neat and I prescribe to it. What I want to see is the actual data. How much variance is there? I'm most interested in the images of the exact solar eclipse and the shifting of the visual position of stars that made Einstein's theory a sensation.

Do you know what these actual images were and how they went about showing the position of stars as seen without being behind the sun and the position of stars as seen in the proximity of the sun?

Wouldn't that be interesting to retrace the observational data as seen by Einstein and and subsequent improvements that followed?

#4 A.Sphere

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Posted 06 August 2009 - 12:03 PM

My favorite - Hulse-Taylor Pulsar! :lol:

http://www.astro.car...3thehulsetaylor

Wiki has a nice summary with reference links: http://en.wikipedia....eral_relativity

Edit: Except I just made it down to this sentence on the wiki:

Currently, the most sensitive of these is the Laser Interferometer Gravitational-wave Observatory (LIGO), which has been in operation since 2002. So far, there has not been a single detection event by any of the existing detectors.


Yuck. It sounds like the author is implying that LIGO scientists thought they would have a detection by now. The first few stages of the LIGO detector were constructed so that we could learn how to build the detectors. It was known that the sensitivity wouldn't be high enough to detect grav waves because the event rate within the range we can see (10-14 Mpc) is low. So the probability of detection prior to Advanced LIGO is really low. Like one every 70 years or something. Advance LIGO is the final product - it doesn't go on line until after 2011. The phases LIGO is in now are experimental. Galileo would have been better off building a 20 inch refracting telescope but he didn't know how - same is true for LIGO - they are learning!

Give LIGO a few more years and they will detect a gravitational wave - then we will have another critical test of General Relativity!

#5 Adam Nagy

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Posted 06 August 2009 - 01:12 PM

Thanks for the links, A.Sphere. I'll have to ponder the gravitational waves concept. Can you decipher this image for me?

Posted Image

What makes it a success? I understand that the stars can be seen shifted but how much and how was the experiment verified for accuracy?

#6 CTD

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Posted 07 August 2009 - 01:57 AM

Give LIGO a few more years and they will detect a gravitational wave - then we will have another critical test of General Relativity!

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I'm not holding my breath for any of them to acknowledge failure. GR is a vital component of all big bang models, and a great you-can't-knowist propaganda tool as well.

#7 A.Sphere

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Posted 07 August 2009 - 11:33 AM

I'm not holding my breath for any of them to acknowledge failure. GR is a vital component of all big bang models, and a great you-can't-knowist propaganda tool as well.

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Actually if we don't find a gravitational wave it would be impossible to fake the results. LIGO is a collaboration involving over 600 scientists world wide. If we don't find a gravitational wave it will be truly exciting because that means something is very wrong with the way we understand the universe - mysteries = job prospects for up and coming researchers like myself as well.

However, if we do find gravitational waves we won't just find one. We will find many of them. I won't hold my breath for you to accept cold hard science and I predict that you will deny the measurements LIGO makes even if presented with many gravitational wave signals.

#8 A.Sphere

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Posted 07 August 2009 - 11:37 AM

Thanks for the links, A.Sphere. I'll have to ponder the gravitational waves concept. Can you decipher this image for me?

Posted Image

What makes it a success? I understand that the stars can be seen shifted but how much and how was the experiment verified for accuracy?

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The apparent postiion of the stars change in precise aggreement with GRT. This is because the path the light takes to us is being perturbed by the sun. Are you asking how this image allowed him to measure it?

#9 Adam Nagy

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Posted 07 August 2009 - 11:45 AM

The apparent postiion of the stars change in precise aggreement with GRT.  This is because the path the light takes to us is being perturbed by the sun.  Are you asking how this image allowed him to measure it?

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Yup, that's exactly what I'm asking.

#10 Adam Nagy

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Posted 07 August 2009 - 11:55 AM

I only see two stars that are clear and I circled them but I guess other stars can be discernible especially if you have an image of the same bit of sky at the same scale without the sun there:

Posted Image

#11 CTD

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Posted 07 August 2009 - 05:03 PM

Actually if we don't find a gravitational wave it would be impossible to fake the results.  LIGO is a collaboration involving over 600 scientists world wide.  If we don't find a gravitational wave it will be truly exciting because that means something is very wrong with the way we understand the universe - mysteries = job prospects for up and coming researchers like myself as well.

However, if we do find gravitational waves we won't just find one.  We will find many of them.  I won't hold my breath for you to accept cold hard science and I predict that you will deny the measurements LIGO makes even if presented with many gravitational wave signals.

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Actually, you're just repeating propaganda. There is no test at all of GR involved. GR doesn't require gravity waves because it treats gravity as a field.

It is something like this: The body (e.g. the earth) produces a field in its immediate neighbourhood directly; the intensity and direction of the field at points farther removed from the body are thence determined by the law which governs the properties in space of the gravitational fields themselves.

That's from the same book by Einstein, in section 19, which is entitled "The Gravitational Field".

So if no "gravity waves" are found, they can say "see Einstein was right, and gravity is a field". Either way, it'll spin as a "great proof".

#12 A.Sphere

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Posted 07 August 2009 - 06:36 PM

Actually, you're just repeating propaganda. There is no test at all of GR involved. GR doesn't require gravity waves because it treats gravity as a field.
That's from the same book by Einstein, in section 19, which is entitled "The Gravitational Field".

So if no "gravity waves" are found, they can say "see Einstein was right, and gravity is a field". Either way, it'll spin as a "great proof".

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Einstein predicted gravitational waves CTD. A gravitational wave is a perturbation of spacetime - or rather a perturbation of the gravitational field. Fields do not have to by static - in fact they are often dynamic. These waves are specific phenomenon that Einstein predicted that must radiate away energy. The Hulse-Taylor pulsar measurements have already matched the general relativity prediction of radiated gravitational waves. That was a strong indirect measurement that they exist. They won the nobel prize for it.

I predict that if gravitational waves are not found they will blame the experiment for some time until some one comes up with a theoretical model that explains why - then that model will be investigated and GRT would have to be overturned (similar to when Michelson and Morley didn't measure the aether - the physics community blamed the experiment until Einstein solved the problem). Let me make this clear: if there are no gravitational waves then GRT must be fixed or discarded for something better. It is the ultimate test of GRT.

If we find them it will open up a new bandwidth for astronomical observations - much akin to the radio revolution.

#13 CTD

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Posted 07 August 2009 - 07:56 PM

Einstein predicted gravitational waves CTD.

Don't confuse man with theory. GR doesn't require the waves. Particles will do, or a field can simply be a field.

A gravitational wave is a perturbation of spacetime - or rather a perturbation of the gravitational field.

That'd be an alleged perturbation.

Fields do not have to by static - in fact they are often dynamic.

They don't have to be dynamic. That's the point.

(similar to when Michelson and Morley didn't measure the aether - the physics community blamed the experiment until Einstein solved the problem).

You people just live to repeat antihistory, don't you? Michelson and Morley did indeed detect an aether. Their measurements did not match the expected value, which was based upon an heliocentric universe.

I've presented historic evidence in another thread.
http://www.evolution...?showtopic=2083

or just see the pdf
http://www.aip.org/h...F/michelson.pdf

Let me make this clear:  if there are no gravitational waves then GRT must be fixed or discarded for something better.  It is the ultimate test of GRT.

No it ain't. These things are never submitted to ultimate tests by their proponents. You-can't-knowism is antithetical to such testing. A field need not be explained as anything more than a field, and this is all GR requires.

If we find them it will open up a new bandwidth for astronomical observations - much akin to the radio revolution.

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If they're found they'll exceed the assumed value of "c" by so much it'll make all their heads spin. Gravity works now, and I mean right now! It may not be instantaneous, but it's gotta be mighty fast. If they're looking for slow, lumbering waves, they may well be out of luck. Looks to me like Einstein's gonna be wrong in any case.

#14 A.Sphere

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Posted 08 August 2009 - 10:44 AM

Don't confuse man with theory. GR doesn't require the waves. Particles will do, or a field can simply be a field.


GR does require the waves. Its a direct consequence of the theory. There must be a field mechanism to radiate energy away from a system undergoing non-uniform motion (similar to electromagnetic waves coming from accelerated charges - except EM is easier because is linear). Einstein made the prediction about grav waves immediately after formulating GRT. Its an integrable part.

That'd be an alleged perturbation

.

It has been indirectly measured. Read up on Hulse-Taylor pulsar and tell me what did they find?

They don't have to be dynamic. That's the point.


But of course in a non-linear theory like GR they do have to be. Matter tells spacetime how to bend - if you have an oscillating body whose mass distribution is varying with time then the bending of spacetime will also be varying with time - thats called a gravitational wave.

You people just live to repeat antihistory, don't you? Michelson and Morley did indeed detect an aether. Their measurements did not match the expected value, which was based upon an heliocentric universe.


:o Huh? They found that no matter how their apparatus was rotated there was zero change in the speed of light. They measured zero. Do you understand this?

I've presented historic evidence in another thread.
http://www.evolution...?showtopic=2083

or just see the pdf
http://www.aip.org/h...F/michelson.pdf


Oh boy I can't wait!

No it ain't. These things are never submitted to ultimate tests by their proponents. You-can't-knowism is antithetical to such testing. A field need not be explained as anything more than a field, and this is all GR requires.


Wrong. GR requires a dynamic field because mass in the universe is not static. If you studied GR you would learn that mass bends spacetime. If the mass is dynamic so is space time - it is central to GR theory.

If they're found they'll exceed the assumed value of "c" by so much it'll make all their heads spin. Gravity works now, and I mean right now! It may not be instantaneous, but it's gotta be mighty fast. If they're looking for slow, lumbering waves, they may well be out of luck. Looks to me like Einstein's gonna be wrong in any case.


lol. No. According to GRT gravitational waves (like light) move on the null geodesic. They move at the speed of light. Gravity is fast - its the same as the speed of light. If God made the sun disappear Earth wouldn't feel the gravitational effects for 8 minutes - same time it take light to reach us. Newton thought of gravity as instantaneous but Einstein changed that. Of course they are not looking for slow waves - you need to study GRT alot better before you make proclamations about it. They are usually covered in introductory textbooks in like the 4th chapter. Its not like you have to dig that deep.


EDIT: By the way - we have much better technology available to repeat the michelson morley experiment - in fact I have done it with much better equipment and repeated their results - it was a requirement in one of my courses. I didn't find an aether either - much to my dismay. I would have loved to so I could collect my Nobel prize money and retire.

#15 CTD

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Posted 08 August 2009 - 06:24 PM

GR does require the waves.  Its a direct consequence of the theory.  There must be a field mechanism to radiate energy away from a system undergoing non-uniform motion (similar to electromagnetic waves coming from accelerated charges - except EM is easier because is linear).  Einstein made the prediction about grav waves immediately after formulating GRT.  Its an integrable part.

Yaddah yaddah yaddah. They won't find what they're expecting, and nobody at all who believes in GR now will question it then. Fields don't require waves - never have, never will.

.

It has been indirectly measured.  Read up on Hulse-Taylor pulsar and tell me what did they find?

What do you care?

:lol: Huh?  They found that no matter how their apparatus was rotated there was zero change in the speed of light.  They measured zero.  Do you understand this?

I do understand outright lies. Your mention of apparatus indicates you're not just repeating the textbook lie either; you want to sound like you know some of the history. I do know the history, as will anyone who follows my link and investigates. You just made my ignore list. Be not seeing you.

Newton thought of gravity as instantaneous but Einstein changed that.  Of course they are not looking for slow waves - you need to study GRT alot better before you make proclamations about it.

In other words, I have to agree, and believe it's all true. Get real. Attempts have been made to measure the speed of gravity, and it leaves light standing still. Newton may yet be vindicated, although I know quite well who'll never admit it.

EDIT:  By the way - we have much better technology available to repeat the michelson morley experiment - in fact I have done it with much better equipment and repeated their results - it was a requirement in one of my courses.  I didn't find an aether either - much to my dismay.  I would have loved to so I could collect my Nobel prize money and retire.

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If you had repeated it the way they did it, you would've obtained the same results. Others have.

#16 A.Sphere

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Posted 08 August 2009 - 07:12 PM

Yaddah yaddah yaddah. They won't find what they're expecting, and nobody at all who believes in GR now will question it then. Fields don't require waves - never have, never will.


I hope we don't find what we are expecting. That would be exciting.

CTD - saying something like "fields don't require waves - never have, never will" doesn't even make sense. You have no idea what you are talking about. Einstein's field equations of general relativity are wave equations! They allow us to describe perturbations of the gravitational field.

The meaning of the approach called "FIELD THEORY" is an attempt at understanding the dynamics of fields. Hence the word DYNAMIC. Every introductory GR book covers this. Don't believe me - pick up GR books by Hartle, or Weingberg, or the infamous Wald. Its fundamental to the theory.

.What do you care?


:lol:

I do understand outright lies. Your mention of apparatus indicates you're not just repeating the textbook lie either; you want to sound like you know some of the history. I do know the history, as will anyone who follows my link and investigates. You just made my ignore list. Be not seeing you.


Run rabbit run :D

In other words, I have to agree, and believe it's all true. Get real. Attempts have been made to measure the speed of gravity, and it leaves light standing still. Newton may yet be vindicated, although I know quite well who'll never admit it.
If you had repeated it the way they did it, you would've obtained the same results. Others have.


This is by far the most insane statement you have ever made. Gravitational waves propegate at the speed of light. Show me in the literature where it says otherwise. I guarantee that you will not be able to. If you can't point to any so called experiments that show that two objects communicate via gravity faster than light then I suggest you humbly admit it.




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