# Experimental support for SR & GR

1. May 25, 2004

### Chi Meson

I would like to create (with everyone's help) a list of experiments etc that support SR and GR.

These should be reproducable experiments, or profound predictions that have been upheld, as well as objects/systems that use SR/GR calculations on an everyday basis.

I would predict that such a list could get lengthy, so hopefully just a description of the "experiment" and maybe a web page that shows data would be most appreciated.

If this thread takes off, I'll be maintaining the list starting with the second post.

2. May 25, 2004

### Simon666

No doubt the perihelion shift of Mercurius will get named, but a German schoolteacher named Paul Gerber reached the same result years before Einstein using Newtonian physics and the assumption the propagation speed of gravity is not infinite. Just a note.

3. May 25, 2004

### quartodeciman

some older resources online:

Relativity FAQ - What is the experimental basis of the Special Relativity Theory? --->
http://www.weburbia.demon.co.uk/physics/experiments.html [Broken]

Living Review: The Confrontation between General Relativity and Experiment --->
http://relativity.livingreviews.org/Articles/lrr-2001-4/ [Broken]

Last edited by a moderator: May 1, 2017
4. May 25, 2004

### Staff: Mentor

Can't forget my personal favorite: http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Unit5/gps.html [Broken].
Besides being a device that depends on Relativity, experiments can be conducted using it as a tool.

Last edited by a moderator: May 1, 2017
5. May 25, 2004

### turin

Particle accelerators come to mind.

6. May 25, 2004

### robphy

By Googling, I found this on Gerber
"Gerber's Gravity" (Kevin Brown)
http://www.mathpages.com/home/kmath527/kmath527.htm
and
(if you have access)
"A simple approach to the experimental consequences of general relativity"
(Peter Rowlands) Phys. Educ. 32 (January 1997) 49-55
http://www.iop.org/EJ/abstract/0031-9120/32/1/020
[which cites
Roseveare N T 1982 Mercury’s Perihelion from
Le Verrier to Einstein (Oxford: Clarendon) pp 137–44]

I haven't read any of these carefully yet.

7. May 25, 2004

### robphy

8. May 25, 2004

### chroot

Staff Emeritus
9. May 26, 2004

### Simon666

10. May 26, 2004

### Janitor

11. May 26, 2004

### Chronos

question: what propogation speed of gravity explains the perhelion shift of mercury? and how does it compare to the speed of light? this could be important.

12. May 26, 2004

### Chi Meson

Thanks everyone so far. So far it's been mostly a list of many lists, but I am going through the sites one by one. I'm compiling a nice reference list which I will post here when it's in a coherent form.

So far, the effect I like the most is the "transverse Doppler effect." This is mentioned in the site offered by Chroot.

Do keep them coming folks. Thanks again.

13. May 27, 2004

### Chi Meson

OK. I'm looking for a website reference that has data/discussion about the increase of the B-field required to hold a relativistic proton in a circular path (e.g. as required at CERN). I've tried a few googles, but I'm getting overwhelmed by articles that are a little too arcane/advanced. Anyone got something on this?

14. May 27, 2004

### ZapperZ

Staff Emeritus
Actually, do you only want references with complete web access, or are you also collecting journal citations?

Zz.

15. May 27, 2004

### Chi Meson

Journals are fine, but the level of difficulty should be so that a BS physicist could follow, so some PhD level papers are "too much." I don't need each and every support of SR/GR. This list was originally intended as a starting point for my AP student's final projects (and the project is to be "paperless").

Ideally, what I'm putting together will be a list in which:

...a brief paragraph description of prediction/result/experiment that supports SR and/or GR, followed by one or two websites that contains some or most of the specific results from that experiment. It does not have to contain all of the data, but should contain a deeper description of the set-up, and significant, conclusive data.

FOr example, I've got two good sites for the Sagnac effect:
http://citebase.eprints.org/cgi-bin/citations?id=oai:arXiv.org:gr-qc/0305084 [Broken]
http://www.mathpages.com/rr/s2-07/2-07.htm

I'm right now looking for a site that deals with the Haefele-Keating (atomic Clocks) experiment. There are lots of sites that mention it, and some that provide the final "delta t's", but I can't get one that goes into specifics of the equations used and preditictions made.

BTW, I'm not expecting you folks to write the paragraphs; I'm just hoping to get tuned in to experiments I hadn't heard of. So far It's going well. I'll attach a draft here probably next week.

Last edited by a moderator: May 1, 2017
16. May 30, 2004

### meteor

I'd like to add the COW experiment, performed in 1975; it demonstrates the equivalence of inertial mass and gravitational mass at the quantum level.

17. Jun 1, 2004

### Chi Meson

Could I have more information on this experiment? I googled "COW experiment" and the closest thing I got was a Cesium/barium radioactivity college lab outline.

18. Jun 1, 2004

### Chi Meson

Here's how it looks so far. I've attached the document as an MS Word file. Our system has up-to-the-minute virus protection, so you shouldn't have to worry about any bugs, but play it safe anyway.

Last edited: Oct 25, 2005
19. Jun 1, 2004

### turin

I don't follow what you mean by "COW," (is that an acronym?). If you mean the word "cow," then the column of Cs resin in the radioactivity experiment is called a "cow" and the extraction of the metastable Ba (into which the Cs decays) is called "milking the cow." The extraction is performed by titrating an ionic solution that reacts with Ba but not with Cs. My experience with this experiment is that the solution does not do its job (i.e. you get excessive amounts of Cs in your sample).

20. Jun 1, 2004

### Creator

Chi Meson and Turin. The "COW" experiment is short for Collela, Overhauser and Werner, who were the authors of a notable experiment (in the 1970's I believe). However, it wasn't about proving equivalence principle.

It was a neutron diffraction experiment that showed conclusively that the relative phase of the neutron wavefunction is altered by the presence of a gravitational field.
It was the first indication of how gravity affects a particle on a quantum level.

Creator

Last edited: Jun 1, 2004
21. Jun 3, 2004

### Chi Meson

Thank you Creator.

BTW, good job with trees and stuff (or was that you?)

22. Jun 3, 2004

### Creator

Yep, ... trees, animals, people,...the whole ball of wax.

23. Jun 18, 2004

### Nereid

Staff Emeritus
I think 'the speed of gravity' is 'c' in GR (hard-coded, not an input parameter), so any experimental result consistent with GR is also support for 'speed of gravity = c'. Putting aside GR, how would you go about testing the difference between the speed of gravity and c, even in principle?

24. Jun 18, 2004

### loseyourname

Staff Emeritus
One example that routinely comes up in particle accelerators is the increased half-life of particles moving near c. Take the $\mu$-meson, which has a resting half-life of 1.87 x $10^-6$s. At a speed of 0.95c, the half-life is measured at 6.00 x $10^-6$s. This is in accordance with the Lorentz transformation for time dilation,
$$\Delta t' = \frac{\Delta t_{0}}{\sqrt{1 - (v^2/c^2)}}$$,
confirming that aspect of SR. A little like the GPS, I don't think this was ever done as an experiment with the intent to confirm SR, but the measured quantities do behave in accordance with the theory.

Last edited: Jun 18, 2004
25. Jul 2, 2004

### zefram_c

Don't forget all the high precision measurements in Quantum Electrodynamics, which incorporates SR as a building block.