Timeline for Can the equivalence principle be tested to high precision in a human-sized lab falling through the horizon of a black hole, in principle?
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| May 6, 2011 at 0:01 | comment | added | finbot | In my question I say "in principle". Yes there is "inherent fuzziness" to use your words. But that doesn't mean the EP can't be tested to high precision in a human-sized lab in principle; those tests can be easily found with a simple web search. I've read your post and comments a few times; what I see is that you're just saying the black hole can't be too small or else it'll invalidate the result at some precision. Yes that's true. But it doesn't prevent a high-precision test of the EP in principle, like for a larger black hole. If you think I've misinterpreted you please tell me how. | |
| May 5, 2011 at 18:30 | comment | added | Willie Wong | To say it another way, at regions with large curvature, EP is only expected to hold (to a certain fixed precision) for experiments at a sufficiently small scale. To try to probe the theory with larger scale apparati is meaningless in the sense that your designed experiment already falls outside the regime for which the theory is applicable. | |
| May 5, 2011 at 18:22 | comment | added | Willie Wong | My post tried to explain why it is pointless to try to stick a "human sized lab" everywhere you can and measure the deviation of dynamics from flat space dynamics by reducing measurement error. For any fixed scale of experiment and any precision your experimental devices can discern, there is a mass limit below which, at the apparent horizon, the fuzziness built-in to the statement of EP is already bigger than your experimental error, so your experiment can't confirm EP more than a less precise experiment. | |
| May 5, 2011 at 18:16 | comment | added | Willie Wong | Without seeing the fine prints of those test that you found, I cannot say whether they are valid or not. You seem to be missing the point of my post, so let me say it again. There are two spots which will cause a disagreement between your measurement and the dynamics as predicted in flat space. First is due to unavoidable experimental error (and I assume when you say "high precision" you mean to try to minimize this as much as you can). The second is due to the inherent fuzziness in the statement of the equivalence principle. This fuzziness comes from local curvature effects. | |
| May 5, 2011 at 14:05 | comment | added | finbot | If those tests are valid then, looking at the rest of your post, the answer should be "yes", not "no". You haven't given any reason it wouldn't be possible in principle to test the EP at the same high precision in a human-sized lab falling across a horizon. Have you? I realize the crossing of the horizon would take only a fraction of the test's duration. I'm not suggesting that the crossing of the horizon would be happening during the entire test. | |
| May 5, 2011 at 13:52 | comment | added | finbot | If the statement "testing the equivalence principle to high precision" is in itself meaningless, then why can I find tests of the EP to high precision? Do you think those tests are invalid? | |
| May 5, 2011 at 13:13 | history | edited | Willie Wong | CC BY-SA 3.0 |
fixed spelling and some computations.
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| May 5, 2011 at 13:02 | history | answered | Willie Wong | CC BY-SA 3.0 |