Still no violation of Lorentz symmetry and Relativity:

Discussion in 'General Science & Technology' started by paddoboy, Dec 23, 2016.

  1. paddoboy Valued Senior Member

    Still no violation of Lorentz symmetry, despite strongest test yet
    December 23, 2016 by Lisa Zyga feature

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    This retroreflector was left on the Moon by astronauts on the Apollo 11 mission in 1969. Astronomers all over the world have reflected laser light off the reflector to precisely measure the Earth-Moon distance. Credit: NASA - NASA Apollo Archive, Public Domain
    (—Physicists have found the strongest evidence yet for no violation of Lorentz symmetry, one of the fundamental symmetries of relativity. Lorentz symmetry states that the outcome of an experiment does not depend on certain aspects of its surroundings, namely the velocity and the direction of its moving reference frame—properties that become relevant when studying astronomical objects and launching satellites, for instance, as well as for unifying quantum mechanics and general relativity.

    "We know that general relativity and the Standard Model of particle physics are not the ultimate theories," coauthor Marie-Christine Angonin at the Paris Observatory told "Furthermore, so far, it has been impossible to conciliate in one common theory these two aspects of physics. To succeed in this quest, almost all unification theories predict a breaking of Lorentz symmetry."

    To perform the improved test of Lorentz symmetry, the team of physicists from the Paris Observatory and the University of California, Los Angeles, analyzed 44 years of data from lunar laser ranging (LLR) observations.

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  3. paddoboy Valued Senior Member


    Testing Lorentz Symmetry with Lunar Laser Ranging:

    Lorentz symmetry violations can be parametrized by an effective field theory framework that contains both general relativity and the standard model of particle physics called the standard-model extension (SME). We present new constraints on pure gravity SME coefficients obtained by analyzing lunar laser ranging (LLR) observations. We use a new numerical lunar ephemeris computed in the SME framework and we perform a LLR data analysis using a set of 20 721 normal points covering the period of August, 1969 to December, 2013. We emphasize that linear combination of SME coefficients to which LLR data are sensitive and not the same as those fitted in previous postfit residuals analysis using LLR observations and based on theoretical grounds. We found no evidence for Lorentz violation at the level of 10−8 for s¯TX, 10−12 for s¯XY and s¯XZ, 10−11 for s¯XX−s¯YY and s¯XX+s¯YY−2s¯ZZ−4.5s¯YZ, and 10−9 for s¯TY+0.43s¯TZ. We improve previous constraints on SME coefficient by a factor up to 5 and 800 compared to postfit residuals analysis of respectively binary pulsars and LLR observations.

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  5. danshawen Valued Senior Member

    I would have thought that LIGO instrumentation, particularly with the sensitivity upgrades, was a more sensitive test. The actual detection of gravity waves are one other way to break the Lorentz symmetry described.

    The means for detecting asymmetries in LLDR equipment cannot detect or evaluate the very brief acoustic period asymmetries LIGO does. Assuredly they exist.

    There isn't any good reason I can think of that this experiment could not be upgraded to do more sensitive one arm interferometry together with an Eartbound optical delay line for the other leg. It would no doubt detect tides for a start. No one has done that with the moon itself as part of an instrument yet, or at least, not intentionally.
    Last edited: Dec 27, 2016
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