How Einstein may have got the theory of relativity wrong

[dArKeR]

A century after Albert Einstein published his most famous ideas, physicists commemorated the occasion by trying to demolish one of them.

Yesterday astronomers were to tell experts gathering at Warwick University in England to celebrate the anniversary of the great man's "miracle year" that the speed of light -- Einstein's unchanging yardstick that underpins his special theory of relativity -- might be slowing down.

Michael Murphy, of the Institute of Astronomy at Cambridge University, said: "We are claiming something extraordinary here.

http://www.taipeitimes.com/News/world/archives/2005/04/12/2003250160

[Maple]

1. There are no constants

anywhere.

[demwing]

10. Ever?

If not, then thats a constant. :)

[Birthmark]

2. That's a whole lot of nuttin'!

Check out the many vital qualifications that are in the story. They show that the headline is wholly misleading.

From the article:
"Murphy's team did not measure a change in the speed of light directly."

"The observations, from the Keck telescope in Hawaii, suggest that the way certain wavelengths of light are absorbed has changed."

"If one varies with time then the other probably does too, meaning Einstein got it wrong."

"Other astronomers disputed the findings, and a smaller study using a different telescope last year suggested no change."

****

A better title might be "Guy claims Einstein got it wrong." That wouldn't be as exciting, I guess. ;)

[Maple]

3. We have slowed it

and speeded it up ourselves.

The speed of light isn't sacred you know.

Neither is Einstein.

[Birthmark]

4. Of course relativity isn't sacred.

But if one wishes to overturn a fundamental idea in physics...well, they have to do much, much better than that.

[Maple]

6. They already did

http://www.csmonitor.com/2003/0711/p02s02-usgn.html

and

http://www.space.com/scienceastronomy/generalscience/faster_than_c_000719.html

[Birthmark]

11. Um, no.

Neither one of those overturns Einstein. The second one claims to, but it is suspect and will have to be confirmed.

[aeolian]

16. Nope.

Neither experiment refers to the vacuum speed of light, which is the constant c. (And I am mighty suspicious that the second experiment does anything more than illustrate the delta-E/delta-T Heisenberg uncertainty)

[dArKeR]

8. I thought we should have made Einstein and Reagan saints before the Pope

[aeolian]

12. No, we have never "speeded up" light.

We have never observed either matter or energy traveling faster than c (the speed of light in a vacuum). And the "slowing" of light refers to the reduced speed of propogation in a dense medium such as air or diamond, not some fundamental change in space.

Yeah, the speed of light is pretty sacred to physics. Which is why its so important to know weather or not it is changing.

[aeolian]

15. ahhh, but

"Murphy's team did not measure a change in the speed of light directly."

You don't have to measure c directly. The speed of light shows up in so many equations. It's actually possible to accurately measure the speed of light studying the strength of electric and magnetic fields inside some known material.



"The observations, from the Keck telescope in Hawaii, suggest that the way certain wavelengths of light are absorbed has changed."

"suggest." Well, that's just what you say when you think you've observed something but aren't sure. There may be other explanations. They're just floating an idea here.



"If one varies with time then the other probably does too, meaning Einstein got it wrong."

If two quantities share a well defined mathematical relationship, then the way one quantity changes against another can be easily determined.



"Other astronomers disputed the findings, and a smaller study using a different telescope last year suggested no change."

THAT's the one you should have made bold-face. That's the real seed of doubt.

[Squeegee]

21. Other possible explanations

According to Loop Quantum Gravity theory, the discreteness of space and time will cause subtle changes in the perceived speed of certain wavelengths of light over great distances. So, it is possible that what the scientists observed isn't a change in the speed of light over time, rather the change in the speed of light over distance. If this turns out to be true, it would not invalidate Einstein's theory of General Relativity, but it would really give strong support for LQG theory.

[wtmusic]

5. Special relativity doesn't depend at all on an absolute speed of light

it just says that measurements of space and time are relative to whatever the speed happens to be.

The fact that light travels slower through water or a prism is not at all inconsistent with special or general relativity.

[aeolian]

14. The two fundamental precepts of special relativity are

1) the speed of light is constant to all observers
2) the laws of physics are the same for all inertial reference frames

[Salviati]

17. Actually...

the first should read:

1) the speed of light _in vacuum_ is constant to all observers

The speed of light passing through materials is not constant, and will depend on the material as well as the reletive motion between the material and the observer...

[aeolian]

18. Yes, I know, but thank you for catching that.

When a physicist says "speed of light", the "in vacuum" is generally assumed. (just like when expressing mass in MeV, when the real unit is MeV/c2, it's just easier) So, sorry if I dropped into jargon there.

[Salviati]

19. Of course...

Half the time when I offer up clarifications to someones post, I'm pretty sure they know what's really up, but the clarification is mostly for the non-physicists out there who are reading the thread...

[aeolian]

22. Well, in that case: greetings, fellow physicist! Have a drink on me.

...unless, of course, you're a recovering alcoholic, in wich case I'd be happy to treat you to a tall glass of orange juice.

[dave29]

7. until we understand what "time" is

we will not understand light, or gravity or speed.

The speed of anything is relative... just sitting at your desk you may not realize you are hurtling at over 100,000 mph around the center of the galaxy.

[wtmusic]

9. ah, but that's the point

the speed of light is the same whether measured flying 100,000 mph toward the source or 100,000 mph away from it.

The theory of relativity ironically describes the speed of light as being wholly unrelative to anything.

[aeolian]

13. ^^^^ what wtmusic said. :)

[aneerkoinos]

20. DSR

Speed of light (in vacuum) possibly not constant but varying a little is not a new claim; the data from measurements is ambivalent.

There's an excellent book on constants by John D. Barrow, The Constants of Nature.

The strongest challenge to dethrone Einstein is the theory called Doubly Special Relativity, which could be confirmed experimentally (or not) allready next year:
http://www.physicspost.com/articles.php?articleId=129

[Maple]

23. This isn't a science forum

It's a tabloid forum.

Next up...astrology and how that supports Einstein.

Sheesh.

[aeolian]

24. What? *scratches head*

I don't understand what your critique is...