# Talk:Equivalence principle

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## Statement on photons in "The weak equivalence principle"

I believe the statement made on photons in the section "The weak equivalence principle" is incorrect as it stands. There is a factor of 2 in the deflection of photons by a spherical mass between the infalling trajectory at infinity and the outgoing trajectory at infinity when comparing the predictions of general relativity and of the equivalence principle alone. This factor comes (see for example Will's book "Was Einstein Right?", Oxford University Press, 1997) from the curvature of space, accidentally producing the same amount in deflection as the equivalence principle. But it would not be visible in a local frame of reference, because locality of the frame means it is so small that space(-time) curvature effects are negligible. In any case, the weak equivalence principle should hold for photons just as for any other (non-gravitating) particle. The question is not whether photons suffer the same acceleration as massive particles but whether the acceleration they suffer is the same in a homogeneous gravitational field and in a uniformly accelerating frame. Weak refers to all experiments not involving gravity. Whether gravitons behave the same in homogeneous gravitational fields and uniformly accelerated frames is out of the scope of the weak equivalence principle. It is the subject matter, so to speak, of the strong equivalence principle. Krenska (talk) 09:30, 19 June 2012 (UTC)

I have removed that statement. As I understand it, from the viewpoint of an observer on the surface of a gravitating body (or in an accelerating rocket), photons fall exactly like anything else. I have tidied up the reference to subjects which don't contradict the EP.--Keith Edkins ( Talk ) 16:52, 8 February 2013 (UTC)

## Geometric EP test

Geometric EP test inclusion is important. Bench EP tests and Nordtvedt effect plus lunar laser ranging validate the EP. 1.74 solar-mass 465.1 Hz pulsar PSR J1903+0327 plus a 1.05 solar-mass star are a stellar binary system [arxiv:0805.2396]. 15.3% [AP4 model, arxiv:astro-ph/0002232] vs. 0.0001% gravitational binding energy, 1.8×1011 vs. 30 surface gees, 2×108 gauss vs. 5 gauss magnetic field; compressed superfluid neutrons and superconductive protons [arxiv:1011.6142] vs. proton-electron plasma, extraordinary isospin and lepton number divergence; plus pulsar 11% of lightspeed equatorial spin velocity are EP-inert for orbit, periastron precession, and gravitation radiation orbital decay. Relativistic and quantum mechanical extreme divergences validate the EP. What remains to falsify the EP?

The vacuum is observed parity-even toward massless boson photons but trace parity-odd towards fermionic matter. Fundamentally test vacuum geometry toward mass with geometric Eötvös experiments. The universe paints with a broad palette. Somebody should look. — Preceding unsigned comment added by 68.4.88.182 (talk) 17:55, 18 August 2012 (UTC)

Please do not reinsert your original research into the article. Wikipedia is not a forum for you to espouse your pet theories. Stigmatella aurantiaca (talk) 02:22, 9 February 2013 (UTC)

## Geometric EP Test again

I removed the following original research by User:Spironis

• No composition or field contrast measurably violates the Equivalence Principle (EP)[1]. EP tests ignore test mass geometry, physical chirality, for the vacuum is observed to be mirror-symmetric toward massless boson photons[2]. However, matter is massed fermions. Matter falls with half the acceleration photons fall in a given gravitational field[3]. Photon vacuum symmetries are not identical to fermionic matter vacuum symmetries. Paired socks appear identical to a left foot (that is not mirror-symmetric). Paired shoes fit a left foot with different energies. If local left and right shoes fit into the vacuum with trace different energies, they vacuum free fall along trace different minimum action trajectories, violating the EP. This geometric EP falsification arises from Einstein-Cartan-Kibble-Sciama chiral spacetime torsion.
• Crystallography's shoe boxes are eleven pairs of enantiomorphic space groups [4]. Periodic lattices test spacetime isotropy overall[5]. Spacetime geometry, the EP, must be tested with massed chiral geometry. Enantiomorphic crystallographic space groups include P3121 versus P3221 single crystal α-quartz and P31 versus P32 single crystal γ-glycine. 31 screw axes are geometrically right-handed, 32 are left-handed. Control experiments contrast each α-quartz shoe against an amorphous fused silica sock, or each γ-glycine shoe against an achiral P21/n α-glycine sock. Somebody should look.

Please do no re-insert your original research into this article. Wikipedia is not a forum for you to espouse your pet theories. Your proposal superficially sounds interesting, and you seem facile in your use of jargon, but in the end, it is obvious that your proposal has no theoretical justification. Einstein-Cartan theory does not support your proposal. Your proposal is, so far as I can see, a wild stab in the dark, and it has never been set forth in a peer-reviewed journal. Stigmatella aurantiaca (talk) 19:47, 11 February 2013 (UTC)

## Where is the fallacy?

"being at rest on the surface of the Earth is equivalent to being inside a spaceship (far from any sources of gravity) that is being accelerated by its engines."

I know Einstein said this (or the equivalent), but I can think of it least two ways in which they do not appear to be equivalent:

1) If I am on the Earth, the force on my head is (marginally) smaller than that on my feet, whereas on an accelarating spaceship it is not; and

2) On the spaceship, the forces on my right and left sides are parallel; whereas on Earth, they are not: they meet at the centre of the Earth.

Where am I going wrong? Are these objections so stupid that no one has brought them up before? Paul Magnussen (talk) 00:06, 13 September 2013 (UTC)

I understand that both effects would be negligible if you're tiny enough — Preceding unsigned comment added by 77.242.202.229 (talk) 13:36, 7 February 2014 (UTC)

Answer: The the geometry of the gravitational field differed, if it was from a infinite flane, you couldn't tell. Then again the force would not drop off with distance either, but is iss theoretically concevible.

## Where is the fallacy2?

If you drop a clock in an accelerating elevator in space, it is not accelerating and hence can't be effected by time dilation from the acceleration.

So it would immediately resume normal time and tick faster than you experience time. If they are equivalent, then time dilation should also stop in a gravity field if you let gravity act on a clock (dropped or thrown).

You are essentially accelerating when you are stationary on earth, falling is like not accelerating relative to bent space(space-time).

I guess it is only kinda equivalent, either that or a clock dropped into a black hole will (all things being equal) appear to move at a normal rate to an observer at a safe distance as long as it freefalls. — Preceding unsigned comment added by 121.99.177.211 (talk) 22:16, 26 February 2014 (UTC)
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