Happy Birthday, Special Relativity

In summary: Maxwell's equations are compatible with an ether frame2) classical mechanics is compatible with an ether frame3) Special Relativity is compatible with an ether frame4) the null result of the Michelson-Morley experiment is due to the undetected motion of the earth through the etherIn summary, the conversation discusses the 100th birthday of Special Relativity and the potential for General Relativity to be revised by 2016. Participants suggest giving SR a "birthday present" by improving our understanding and terminology, and encouraging critical thinking rather than attempts to falsify it. They also discuss the possibility of deriving SR from classical physics and the role of an ether frame in this. However, the idea of an ether
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  • #2
100 years young, still compellingly beautiful, and a long life ahead of her!
 
  • #3
Special Relativity is amazing and although it is its' 100th Birthday today, I predict that General Relativity will not live to its centennial, and will be revised sometime before 2016.
 
  • #4
Lets all give SR a present, whos with me
 
  • #5
Pengwuino said:
Lets all give SR a present, whos with me

How about a moratorium on amateur attempts to falsify it? No more trains, twins, spaceships,...
 
  • #6
Pengwuino said:
Lets all give SR a present, whos with me

How about a moratorium on amateur attempts to falsify it? No more trains, twins, spaceships,...

STO LAT!
 
  • #7
Trains, spaceships, etc... help us understand the consequences.

Here are some ideas for a "birthday present for SR":

1) draw more spacetime diagrams and appeal to geometry,
2) adopt consistent and unambiguous terminology [definitions!], and
3) eliminate poor phrases and poor analogies.

I think (1) helps make the algebraic calculations more concrete.
I think (2) gives us a common language.
I think (3) removes "myths" and other "folklore".
Otherwise, folks are arguing over semantics, often misusing or misinterpreting mathematical symbols.

(When we analyze forces on an object, we draw [or should be drawing] Free Body Diagrams before plopping down equations. We should do the same for analyzing situations in relativity.)

4) drop the word "Theory" when discussing Special Relativity.
[tex]\mbox{Theory of\hspace{-9ex}{\color{red}-------------} Special Relativity}[/tex]
[tex]\mbox{Special Theory of\hspace{-9ex}{\color{red}-------------} Relativity}[/tex]
[tex]\mbox{Special Relativity Theory\hspace{-7ex}{\color{red}-----------}}[/tex]
 
  • #8
All of you seem to have some background in relativity, hopefully one or more of you will be able to clarify something for me. My question is posted here - post #26. Although it would be helpful if you read the details of the problem as posted in the thread starter.
 
  • #9
selfAdjoint said:
How about a moratorium on amateur attempts to falsify it? No more trains, twins, spaceships,...

Never! Ether ether ether!

On a more serious note, people should be allowed to try to falsify things. If they figure something out that we all missed, more power to them! Didn't Einstein say one of the reasons he was able to come up with SR was that he thought like a child and went against conventional wisdom?

And by the way, when i ask this question to myself, i feel like I am asking a stupid question but i wanted to ask other people anyways incase its not actually stupid. Can you derive SR from classical physics?
 
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  • #10
geeze, we're such geeks.
 
  • #11
Pengwuino said:
And by the way, when i ask this question to myself, i feel like I am asking a stupid question but i wanted to ask other people anyways incase its not actually stupid. Can you derive SR from classical physics?

Yeah, why not? It's essentially a consequence of Maxwell's equations, which are purely classical. (Assuming of course that Maxwell's equations are written the same in all reference frames.) So yes.
 
  • #12
Pengwuino said:
Can you derive SR from classical physics?


All you NEED to derive SR is Einstein's 2 postulates. Of course all he had to base it on was Classical Physics. So I would guess if you wanted a derivation based on Classical Physics you need only read Einstein.
 
  • #13
robphy said:
4) drop the word "Theory" when discussing Special Relativity.
[tex]\mbox{Theory of\hspace{-9ex}{\color{red}-------------} Special Relativity}[/tex]
[tex]\mbox{Special Theory of\hspace{-9ex}{\color{red}-------------} Relativity}[/tex]
[tex]\mbox{Special Relativity Theory\hspace{-7ex}{\color{red}-----------}}[/tex]
So what exactly is your reason for dropping the word "theory"

Theory: a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"

Are you implying Special Relativity is not any of the above? :confused:
 
  • #14
robphy said:
Here are some ideas for a "birthday present for SR":

I'm not wearing socks tomorrow! :biggrin:
 
  • #15
Aer said:
So what exactly is your reason for dropping the word "theory"

Theory: a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"

Are you implying Special Relativity is not any of the above? :confused:

Maybe we should make it the Special Law of Relativity! Of course, that can cause problems when it needs revision, but Einstein deserves it. When did Newton's theories start getting called laws?
 
  • #16
Pengwuino said:
Never! Ether ether ether!

And by the way, when i ask this question to myself, i feel like I am asking a stupid question but i wanted to ask other people anyways incase its not actually stupid. Can you derive SR from classical physics?

The answer to your question is yes. Using basic classical physics and an ether frame you can derive equations that match the predictions of special relativity to almost 100%.
 
  • #17
Pengwuino said:
Never! Ether ether ether!

On a more serious note, people should be allowed to try to falsify things. If they figure something out that we all missed, more power to them! Didn't Einstein say one of the reasons he was able to come up with SR was that he thought like a child and went against conventional wisdom?

And by the way, when i ask this question to myself, i feel like I am asking a stupid question but i wanted to ask other people anyways incase its not actually stupid. Can you derive SR from classical physics?
Sir Joseph Larmorr (Lormar?) developed an ether theory superficially consistent with classical physics, and thus, in the first decade of the 20th century, Cambridge theoretical physicists dismissed Einsein's approach as both unnecessary and overly philosophical.

However, when GR came along, Larmor's theory was shown to fail miserably when trying to accommodate effects of gravitation. That is why his project was abandoned.
 
  • #18
wisp said:
The answer to your question is yes. Using basic classical physics and an ether frame you can derive equations that match the predictions of special relativity to almost 100%.

Using basic classical physics and an ether frame, one can predict that the Michelson-Morley expeirment should not have a null result. Unfortunately, experimentally, it does have a null result. This should be enough to show that the "ether" idea is not compatible with basic classical physics. Only a wild "ether enthusiast" could make the claims that wisp is making above.

At this point in time, one has to add in additional forces and/or "scalar fields" to have any sort of preferred frame or "ether". There is currently no direct experimental evidence that such forces or scalar fields exist. The assumption that such forces or scalar fields may exist is not "basic" classical physics, but a highly speculative extension to classical physics.
 
  • #19
arildno said:
Sir Joseph Larmorr (Lormar?) developed an ether theory superficially consistent with classical physics, and thus, in the first decade of the 20th century, Cambridge theoretical physicists dismissed Einsein's approach as both unnecessary and overly philosophical.

However, when GR came along, Larmor's theory was shown to fail miserably when trying to accommodate effects of gravitation. That is why his project was abandoned.

That was Larmor. And don't forget Voigt, who had an ether theory where the speed of light was independent of source speed, and actually derived some genuine relativistic results.
 
  • #20
pervect said:
Using basic classical physics and an ether frame, one can predict that the Michelson-Morley expeirment should not have a null result. Unfortunately, experimentally, it does have a null result. This should be enough to show that the "ether" idea is not compatible with basic classical physics. Only a wild "ether enthusiast" could make the claims that wisp is making above.

Scientists agree that the "null result" of the MMx does not rule out the existence of ether. And Dayton Miller's work did detect an ether flow effect when he repeated the MMX at altitude.
I believe there is a simple explanation for the null result on the Earth's surface on what effectively is a two-way light speed measurement.
I'm not a wild ether enthusiast, just someone open-minded enough to challenge views that do not comply with commonsense principles.
 
  • #21
I'm not a wild ether enthusiast, just someone open-minded enough to challenge views that do not comply with commonsense principles.

Fair enough but we have had many theads on ether alternatives to GR. The devil is in the details and I refer you to them. Look up ether, and also aether, in this subforum.
 
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  • #22
wisp said:
Scientists agree that the "null result" of the MMx does not rule out the existence of ether. And Dayton Miller's work did detect an ether flow effect when he repeated the MMX at altitude.
I believe there is a simple explanation for the null result on the Earth's surface on what effectively is a two-way light speed measurement.
I'm not a wild ether enthusiast, just someone open-minded enough to challenge views that do not comply with commonsense principles.

There are a lot of tests of special relativity nowadays, other than the MMX experiment. The MMX is just one experiment of a long line of experiments. Relativity has passed them all. Including a large number of tests of the "one-way" isotropy of the speed of light.

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#one-way tests

MMX is important because it is the first (and as far as I know the only) prediction that "ether theories" nave ever made. Ether theories failed this experimental test (their very first test). Any "ether theory" that we have now that is compatible with MMX is the result of a "fix-up" of a failed theory.

There are a very few varieties ether theories out there that actually are indistinguishable from special relativity. In these cases, the "ether" is not so much disproven as shown to be irrelevant. In these cases, you can use the ether if you want, but since the special relativistic expalantion is much more elegant, and more importantly much more widely understood, there is no compelling reason to use ether theories that are equivalent to SR.

Many more ether theorists than the few varieties that are compatible with SR _claim_ to have theories that are compatible with SR (read: indistinguishable from SR). These claims are often incorrect. This is unfortunate, because a few people seem to have mental blocks due to their personal philosophies which seem to prevent them from understanding or accepting special relativity. "Ether theories" could serve a potentially useful purpose in providing a philosophical interpretation of relativity that they might be able to accept philosphically.

My expeirence has been that it is only people who are attracted to ether theories are one who have a strict and rigid personal philosphy of how the universe "should be", one that they have made up in advance, and one that conflicts with relativity. In general, such people ignore the experimental results and go with their preconceived notions. Occasionally they can find a way to justify their pursuit of their preconceived ideas in as being "open minded", which is really rather ironic.

My experience has also been that people who urge others to be "open minded" really want other people to believe the exact same thing that they do :-).

In any event, being "open minded" isn't particularly compelling to me. Being correctly able to predict the results of experiments (i.e., being not "open minded", but being *right*) is the real goal, IMO.
 
  • #23
pervect said:
Including a large number of tests of the "one-way" isotropy of the speed of light.

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#one-way tests

I've spent a lot of time looking at the one-way tests and have not been convinced by the link suggested, which I believe was compiled by Tom Roberts and others. (PS: The link has gone off line)
I found his write up on ether classes missed out completely an important third class, which is the real answer. I posted a longer explanation on this or a similar forum a year back, explaining the errors in his work.

I'm not convinced that GPS tests are valid one-way tests, because all calculations are based on the assumption that the speed of light is constant. And the amazing accuracy that results has a lot of help from correction tables/factors added in.

With the recent progress made by researchers at the U.S. National Institute of Standards and Technology, soon we will have atomic clocks that are 1,000 times more accurate than current ones.
I hope soon that someone will have the sense to carry out a basic one-way speed of light test using two of these clocks and a laser. That will be the real test for SR.

The advantage of a good ether theory is that it will explain the physical cause of relativistic effects, something that relativity cannot do. The equations may not look as simple as the SR ones, but the important thing is to understand the truth so that real progress can be made.
 
  • #24
There is a class of ether theories that one-way tests cannot falsify - thoes are the ether theories that actually are equivalent to SR.

Relativity, however, makes a beautiflly simple prediction that is in accordance with all experiments to date:

This prediction is that the clock synchorinzation method that makes momentum an isotropic function of the measured velocity is the same clock synchroization method in which the speed of light is isotropic.

Thus when coordinates are used that make matter behave isotropically, light also is isotropic, and vice-versa - when coordiantes are used that make light behave isotropically, matter is also isotropic.
 
  • #25
Pervect

This was the basis for Tom Roberts' work on ether class types - if they are equivalent to SR then no experiment can divide the two. So why bother with the ether?

However, the important third class that he missed out can be shown to be only approximate to SR, and not 100% equivalent. New advances in clock technology should show up this difference, if people are prepared to look for it.
 
  • #26
When (if) we ever see reproducible results that falisfy SR, it'll be big news. People are working on improving timing and timekeeping all the time. When one of the big timekeeping organizations, like perhaps the US naval observatory, that does work all the time to improve our timekeeping, and does not have any particular axe to grind against relativity, finds that they have some experimental inconsistencies that won't go away, I'll sit up and take notice. Until that time, I'm going to be fat, dumb, and happy with a theory that seems to be working just fine.

People who are working to "disprove relativity" rather than working to "improve our timekeeping standards" are, I'm afraid, starting out with one strike against them in my personal opinion.
 
  • #27
wisp said:
The answer to your question is yes. Using basic classical physics and an ether frame you can derive equations that match the predictions of special relativity to almost 100%.

This is true as proven by Lorentz Ether Theory. It is also totally useless exrcise. SR (and later GR) suprseeded LET. The so called aether theorists are wasting their time.
 
  • #28
second postulate

Integral said:
All you NEED to derive SR is Einstein's 2 postulates. Of course all he had to base it on was Classical Physics. So I would guess if you wanted a derivation based on Classical Physics you need only read Einstein.
There are people who think that the second postulate is redndant!
 
  • #29
bernhard.rothenstein said:
There are people who think that the second postulate is redndant!

This is very interesting. Can you provide some proof of this? (references, links)
 
  • #30
pervect said:
Using basic classical physics and an ether frame, one can predict that the Michelson-Morley expeirment should not have a null result.

unless the ether has chosen to move around the sun with us so we never move through it at sufficient velocity to cause any noticable fringe shift.

Unfortunately, experimentally, it does have a null result.

i would say fortunately it has a null result. Einstein said something about pitying God, if it turned out that SR was wrong.
 
  • #31
second postulate redundant

clj4 said:
This is very interesting. Can you provide some proof of this? (references, links)
See
[1] N. David Mermin, "Relativity without light," Am.J.Phys. 52, 119-124 (1984)
[2] Achin Sen, "How Galileo could have derived the special theory of relativity," Am.J.Phys. 62 157-162 (1994) See also the references cited in this paper.
I think that the derivations are relatively complicated, involving so many intermediary steps, that I think nobody has introduced them in his teaching practice.
 
  • #32
bernhard.rothenstein said:
See
[1] N. David Mermin, "Relativity without light," Am.J.Phys. 52, 119-124 (1984)
[2] Achin Sen, "How Galileo could have derived the special theory of relativity," Am.J.Phys. 62 157-162 (1994) See also the references cited in this paper.
I think that the derivations are relatively complicated, involving so many intermediary steps, that I think nobody has introduced them in his teaching practice.

Thank you. Here is what I got for [1]:

"The relativistic addition law for parallel velocities is derived directly from the principle of relativity and a few simple assumptions of smoothness and symmetry, without making use of the principle of the constancy of the velocity of light."

This is not very interesting, there are a lot of papers like this. The application is very restrictive and it is not a fully developed theory.

Looks like [2] is the same thing as [1], not very interesting.
 
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  • #33
Never mind

Here is a better link:

http://scholar.google.com/scholar?num=100&hl=en&lr=&q=link:oxrtK336wDUJ:scholar.google.com/

From the list only :

http://arxiv.org/PS_cache/physics/pdf/0503/0503227.pdf [Broken]

is a complete derivation of special relativity and I am not sure it is correct (it has not been peered reviewed). Anybody cared to review it? Should be an interesting exercise. A brief look over it and it appears that this paper has the c'=c assumption accidentally hidden which would make it irrelevant.
 
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  • #34
clj4 said:
Thank you. Here is what I got for [1]:

"The relativistic addition law for parallel velocities is derived directly from the principle of relativity and a few simple assumptions of smoothness and symmetry, without making use of the principle of the constancy of the velocity of light."

This is not very interesting, there are a lot of papers like this. The application is very restrictive and it is not a fully developed theory.

Looks like [2] is the same thing as [1], not very interesting.
please have a look at
http:arxiv.org/abs/phyics/0602054
i feel that the derivation could avoid the second postulate if the first one is better exploited. Have you some ideea in that direction? In order to ease communication ou could use
dr_relativ@yahoo.com
 
  • #35
bernhard.rothenstein said:
please have a look at
http:arxiv.org/abs/phyics/0602054
i feel that the derivation could avoid the second postulate if the first one is better exploited. Have you some ideea in that direction? In order to ease communication ou could use
dr_relativ@yahoo.com

Never mind, I found it at http://arxiv.org/ftp/physics/papers/0602/0602054.pdf, there was a typo in your link.
I think that (see my comments on the other papers of this type) it is extremely difficult, if not impossible to drop the second postulate. I have seen a lot of papers attempting to do this (there is even a book published on this subject , see :https://www.amazon.com/gp/product/9810238886/?tag=pfamazon01-20) All the attempts are either:
-plain wrong (can you detect the error in this one? http://arxiv.org/PS_cache/physics/pdf/0304/0304087.pdf)
-allow the second postulate back in thru some "back door" (see my comments in the next post)
 
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<h2>What is "Happy Birthday, Special Relativity"?</h2><p>"Happy Birthday, Special Relativity" is a thought experiment that illustrates the concepts of time dilation and length contraction in Einstein's theory of special relativity. It imagines two twins, one who stays on Earth and one who travels on a high-speed rocket, and explores how their experiences of time and space differ.</p><h2>What is special relativity?</h2><p>Special relativity is a theory developed by Albert Einstein in 1905 that explains how the laws of physics work in the absence of gravity. It is based on two main principles: the laws of physics are the same for all observers in uniform motion, and the speed of light is constant for all observers regardless of their relative motion.</p><h2>How does "Happy Birthday, Special Relativity" demonstrate time dilation?</h2><p>In "Happy Birthday, Special Relativity", the twin who travels on the high-speed rocket experiences time passing more slowly compared to the twin who stays on Earth. This is due to the fact that the speed of light is constant for all observers, so the moving twin experiences time passing slower in order to maintain the constant speed of light.</p><h2>What is length contraction in special relativity?</h2><p>Length contraction is the phenomenon where an object appears shorter in the direction of its motion when viewed by an observer in a different frame of reference. This is a consequence of the fact that the speed of light is constant for all observers, so objects in motion appear to be shorter in order to maintain the constant speed of light.</p><h2>Why is "Happy Birthday, Special Relativity" important?</h2><p>"Happy Birthday, Special Relativity" is important because it helps us understand the counterintuitive concepts of time dilation and length contraction in special relativity. It also demonstrates the fundamental principles of the theory, which have been confirmed by numerous experiments and have greatly influenced our understanding of the universe.</p>

What is "Happy Birthday, Special Relativity"?

"Happy Birthday, Special Relativity" is a thought experiment that illustrates the concepts of time dilation and length contraction in Einstein's theory of special relativity. It imagines two twins, one who stays on Earth and one who travels on a high-speed rocket, and explores how their experiences of time and space differ.

What is special relativity?

Special relativity is a theory developed by Albert Einstein in 1905 that explains how the laws of physics work in the absence of gravity. It is based on two main principles: the laws of physics are the same for all observers in uniform motion, and the speed of light is constant for all observers regardless of their relative motion.

How does "Happy Birthday, Special Relativity" demonstrate time dilation?

In "Happy Birthday, Special Relativity", the twin who travels on the high-speed rocket experiences time passing more slowly compared to the twin who stays on Earth. This is due to the fact that the speed of light is constant for all observers, so the moving twin experiences time passing slower in order to maintain the constant speed of light.

What is length contraction in special relativity?

Length contraction is the phenomenon where an object appears shorter in the direction of its motion when viewed by an observer in a different frame of reference. This is a consequence of the fact that the speed of light is constant for all observers, so objects in motion appear to be shorter in order to maintain the constant speed of light.

Why is "Happy Birthday, Special Relativity" important?

"Happy Birthday, Special Relativity" is important because it helps us understand the counterintuitive concepts of time dilation and length contraction in special relativity. It also demonstrates the fundamental principles of the theory, which have been confirmed by numerous experiments and have greatly influenced our understanding of the universe.

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