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I have a question about my Physics Stack Exchange post: Possible reactionless drive

My question is [on hold] as "unclear what you're asking".

From my analysis the system should work and start to move after photons injection on trajectory and my question is if someone find an error in my reasoning and the (closed) system actually won't move.

It should work with current physics so I don't understand why my question was put on hold.

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    $\begingroup$ I agree with the OP. The question's superficial formatting is poor, but the setup is extremely clear. It also asks a perfectly mainstream question. We answer questions about why proposed perpetual motion machines don't work all the time, this is no different. $\endgroup$ – knzhou Oct 23 '16 at 4:20
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I didn't vote to close your question, and I wouldn't have picked the reason "unclear what you're asking." (And not all of the reviewers picked that reason, either, though that information is not obvious.) However, I agree that your question as it currently stands (v7) is a poor fit for Physics.SE. You've started with a system at rest that can be described using electrodynamics and relativity, both of which exactly conserve linear momentum, and you're asking whether that system can spontaneously develop nonzero linear momentum. From symmetry, the answer is: no, you've missed something.

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  • $\begingroup$ Thanks for feedback. $\endgroup$ – Misuser Oct 22 '16 at 5:26
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    $\begingroup$ I can't see what i'm missing so that's why i was asking for other people help :) $\endgroup$ – Misuser Oct 22 '16 at 5:27
  • $\begingroup$ Your last two sentences seem more like an answer to the question than a reason to close it. $\endgroup$ – Nathaniel Oct 30 '16 at 3:43
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    $\begingroup$ @Nathaniel "It doesn't work because it breaks a symmetry" is the answer to all reactionless-drive and perpetual-motion questions. They're off-topic in part because the people who ask them usually aren't satisfied with a general answer but want help finding the symmetry breaking in their specific scenario, which typically leads to answerers playing whack-a-mole with details of a scenario that exists only in the asker's imagination and often to frustration and bad feelings all around. $\endgroup$ – rob Oct 30 '16 at 15:10
  • $\begingroup$ "people who ask them usually aren't satisfied with a general answer but want help finding the symmetry breaking in their specific scenario" <-- I guess I just can't see the problem with that, or even imagine what the problem might be. Surely that's a large part of how we all learn - by understanding how the general applies to specific cases, and by asking questions when we can't see it. $\endgroup$ – Nathaniel Oct 30 '16 at 23:08
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    $\begingroup$ Also: since when are all reactionless-drive and perpetual-motion questions off topic? As far as I know they aren't. We have a policy against non-mainstream physics, but the criterion is that a question or answer "uses a non-mainstream theory as its premise and attempts to go forward in that direction". It very much doesn't ban questions that ask how to see why something doesn't work, and I don't think it should. $\endgroup$ – Nathaniel Oct 30 '16 at 23:13
  • $\begingroup$ @Nathaniel You make a good point. $\endgroup$ – rob Oct 30 '16 at 23:21
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As it looks like for me at least, the question is difficult to read and to understand because it is asked at the end of your calculations. However I don't think that's is a reason to close it, and I actually think it is a good question which deserves a proper answer, even if it it has a negative answer based on simple arguments.

I think you should consider rewriting it in a more easy to follow way, AND moderators to consider reopening the issue... For example you can postpone your calculations after the question is asked.

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    $\begingroup$ Thanks for your feedback. I'll consider the reformulation of the question. I'll ask around for help about reformulation. $\endgroup$ – Misuser Oct 26 '16 at 4:33

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