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Post by abacus9900 on Jan 31, 2011 16:29:10 GMT 1
We are often told that the cosmic speed limit is defined by the speed of light and that its speed always remains the same regardless of how fast an observer is moving with respect to it. The Shapiro Effect, however, has shown that the speed of light slows slightly in the presence of a gravitational field, so how can these two contradictory situations be correct?
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Post by Progenitor A on Jan 31, 2011 17:11:12 GMT 1
We are often told that the cosmic speed limit is defined by the speed of light and that its speed always remains the same regardless of how fast an observer is moving with respect to it. The Shapiro Effect, however, has shown that the speed of light slows slightly in the presence of a gravitational field, so how can these two contradictory situations be correct? Thanks for that. I have looked up the Shapiro effect and it is very interesting. This same problem has been highlighted in the effect upon the speed of light within the intense gravitational field of a black hole, whereby if it cannot escape it must be slowed down to a velocty near 0 Both of these apparently contradict the axiom that the speed of light in a vacuum is constant Would be interesting to find out the answer to this puzzle (in an understandable way)
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Post by abacus9900 on Jan 31, 2011 17:26:14 GMT 1
Precious chance of that happening here, naymissus. Most probably STA will just regurgitate the same, tired old ideas that have been patched up together in order to save face even though she does not really understand them herself. (Mind you she hasn't stop sulking yet. Do you think you may have been a bit too rough on her?).
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Post by Progenitor A on Jan 31, 2011 17:37:44 GMT 1
Precious chance of that happening here, naymissus. Most probably STA will just regurgitate the same, tired old ideas that have been patched up together in order to save face even though she does not really understand them herself. (Mind you she hasn't stop sulking yet. Do you think you may have been a bit too rough on her?). No I do not think so. Had she ever taken a reasonable positions and asked what was meant rather than the usual 'ignorant idiot' stance then there would have been no 'rough' response. Her approach is anti-science it is designed to kill off discussion, never listems to what others say and I personally think that this board would be better off without her But don't worry - she will be back! Or do worry! Now did you hear the radio programme 'Schrodingers Kittens' on Saturday? It had a number of distinguished scientists discussing QM I was interseed in Penrose saying that a neutron (or other particles) is in 2 places at once (though naturally it has never actually ben seen in 2 positions). I find that position so strange that Iwish it had been expnded upon. He also said that QM theories are so full of contradictions that he feels sure that they will son be rejected and replaced by a new and better theory!
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Post by abacus9900 on Jan 31, 2011 17:44:01 GMT 1
It's hard to tell about QM, naymissus. On the one hand we are told that QM is just odd and non-intuitive and we should just accept it, on the other hand we are also told that QM may be based on some kind of mathematical errors and things might be cleared up in time. But I would not bet myself against there emerging a completely new theory about QM that renders all the current ideas obsolete. We will just have to give it time.
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Post by mak2 on Jan 31, 2011 20:05:25 GMT 1
"In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuum, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity ; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)." – Albert Einstein (The General Theory of Relativity: Chapter 22 – A Few Inferences from the General Principle of Relativity)
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Post by Progenitor A on Jan 31, 2011 20:57:52 GMT 1
"In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuum, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity ; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)." – Albert Einstein (The General Theory of Relativity: Chapter 22 – A Few Inferences from the General Principle of Relativity) Well thankyou mak2, a very revealing statement from the mouth of the horse indeed! So the constancy of the speed of light, (like most other physical laws), has its limits! Why did not you, mak2 join in the multitudinous discussions that we have had on this particular subject elsewhere? REMARKABLE
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Post by abacus9900 on Jan 31, 2011 21:36:45 GMT 1
This shows that scientists can produce measurements but no sensible explanations. And the more they attempt to measure the more they contradict themselves.
Take infinity. What possible use can the concept of infinity serve? They talk of different infinities in maths which is pretty daft because, to me anyway, infinity cannot be defined so what meaning can it have in trying to pretend that there are different versions of it? This is a good illustration of the fact that all of maths is, in fact, a contrivance, and is the product of imagination.
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Post by buckleymanor1 on Feb 1, 2011 1:11:25 GMT 1
We are often told that the cosmic speed limit is defined by the speed of light and that its speed always remains the same regardless of how fast an observer is moving with respect to it. The Shapiro Effect, however, has shown that the speed of light slows slightly in the presence of a gravitational field, so how can these two contradictory situations be correct? Thanks for that. I have looked up the Shapiro effect and it is very interesting. This same problem has been highlighted in the effect upon the speed of light within the intense gravitational field of a black hole, whereby if it cannot escape it must be slowed down to a velocty near 0 Both of these apparently contradict the axiom that the speed of light in a vacuum is constant Would be interesting to find out the answer to this puzzle (in an understandable way) Not so sure that there is so much of a contradiction with regards the Shapiro Effect.The speed of light in a vacuum is regarded as being constant locally, when much larger scales are taken into consideration this tends to break down and becomes a bit nonsensical. A photon falling into a gravity well which is non local then climbing out can be shown to take a longer path but could be also interpreted as slowing down. Which interpretation you accept depends on you, most prefer the former.
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Post by Progenitor A on Feb 1, 2011 8:42:10 GMT 1
Not so sure that there is so much of a contradiction with regards the Shapiro Effect.The speed of light in a vacuum is regarded as being constant locally, when much larger scales are taken into consideration this tends to break down and becomes a bit nonsensical. A photon falling into a gravity well which is non local then climbing out can be shown to take a longer path but could be also interpreted as slowing down. Which interpretation you accept depends on you, most prefer the former. Yrs Buckley, I did consider your point in my mind before where the apparent slowing down may simply be due to the longer path that the light takes. But if it does take a longer path, that means that it is accelerated by gravity - the velocity changes. That has been considered before too - it is a prediction of relativity that has been observed. But the clincher is really what Einstein himself said in the quote kindly provided by mak2, don't you think so? I have never seen that before
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Post by Progenitor A on Feb 1, 2011 8:52:08 GMT 1
This shows that scientists can produce measurements but no sensible explanations. And the more they attempt to measure the more they contradict themselves. Take infinity. What possible use can the concept of infinity serve? They talk of different infinities in maths which is pretty daft because, to me anyway, infinity cannot be defined so what meaning can it have in trying to pretend that there are different versions of it? This is a good illustration of the fact that all of maths is, in fact, a contrivance, and is the product of imagination. I tend to agree with you. Mathematics, it seems to me, is like the Kimberley Mining operation; thousands of tons of rubbish have to be dug out to get a few (or many) diamonds, then some years later people scavange around the discard heaps and find a stone that is now useful. Not quite the same but some parallells. I wonder if the concept of infinity has any use? Someone said that is essential to some mahematical axioms but did not expand upon that. Anyway, I mean practical physical use (cop-outs apart)? Incidentally, after mak2's startling quote from Einstein yesterday, I looked at his posting history and though he does not say much, he could be the physicist that we need! How about it mak2? Are you the physicist we so desperately need?
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Post by abacus9900 on Feb 1, 2011 11:55:26 GMT 1
Is mak2 a physicist?
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Post by speakertoanimals on Feb 1, 2011 17:22:00 GMT 1
Wrong. The light is NOT accelerated by gravity, and in fact in General Relativity, THERE IS NO FORCE OF GRAVITY. Instead, what we see as gravity and the 'force of gravity' is instead more correctly interpreted as the curvature of space AND time. SO, IF we pretend that space and time are flat, then the actual paths of objects near the sun, to accord with Newtonian laws of motion (F=ma etc), requires a FORCE (gravity) to be acting. According to Einstein, this 'force' is actually an illusion (like centrifugal force), caused by the incorrect assumption (that space and time are flat). Hence why IF we again pretend that space and time are flat, the seeming lateness of our signal means the ONLY way we can explain it is by letting the light be 'slowed'. Whereas the proper explanation (contrary to the pop-sci answer being given by Einstein), is that the light went the same speed as it ever did, just that the space got bigger! Starling quote? No -- just that posters on here don't understand enough relativity to see that Einsteins quote doesn't actually contradict the axiom that the speed of light in vacuum is constant for all inertial frames of reference. Note inertial frame. So, gravity DOESN'T cause light to slow down, it just SEEMS to go slower, and the proper constant-speed-of-light explanation is that the space got bigger because gravity curved it and time. Because when you DO general relativity, the SAMe assumption about the speed of light goes right in there, whatever popular accounts might say. To further illuminate Einsteins quote before even more people go off and MISunderstand it: www.phys.ncku.edu.tw/mirrors/physicsfaq/Relativity/SpeedOfLight/speed_of_light.htmlMoral -- what is meant by 'the speed' of anything isn't as simple as some on here like to claim, and Einstein having one now outdated way of explaining his theory doesn't invalidate the proper statement, which is that light travels at c in all freefalling frames of reference -- and we have the complication that such frames are only defined locally in GR, but this is really getting into complications!. It should not be taken as surprising, just an indication that you haven't got your head round what speed actually means, and what constancy might mean in the general case. As I said before, 'speed' isn't as simple as you might think. And y9ou can't forget the words 'in vacuum', and 'in all inertial frames' or 'in all free-falling frames' in the constancy of light speed statement.
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Post by abacus9900 on Feb 1, 2011 19:00:39 GMT 1
All you are doing here STA (in common with all of your fellow physicists and fable-tellers) is moving the goalposts all over the place as it suits you! You are trying to convince people that there is no such thing as speed or time because it depends which definitions you fancy the best to cover your backsides. All a face-saving exercise I'm afraid.
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Post by helen on Feb 1, 2011 19:27:51 GMT 1
Speakertoanimals, I think this thread should be left to the acolyte Abacus and the bully Naysayer to discuss the nature of things amongst their selves. They clearly have ideas about the nature of things which as far as they are concerned they can support, between them. They claim to be searching for knowledge but dismiss anything that they can't get their heads round. This is called arguing from a state of incredulity. Come on Naymissus and Abacuss, open your minds a bit. Let's have some objective thought. Your bullying of speakertoanimals is becoming tiresome as it reveals your misunderstanding of the scientific process and does nothing for your reputations as practitioners of rational thought.
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