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I figure I'm going to get ridiculed for this question, and maybe deservedly so. The sensor images and eyewitness accounts from the Naval Aviators released last year of unexplained aerial phenomena support a claim that the craft maneuvered in a way that 'defied physics.' After observing the imagery it appears that 'defied physics' means that the craft can make changes in trajectory that are impossible unless they found a way to 'zero' out their momentum, and make instant changes in direction and velocity. For the sake of argument, if they could do this, could they travel faster than light?

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    $\begingroup$ Which step in any of the usual arguments against FTL travel do you think might become invalid under these circumstances? $\endgroup$
    – WillO
    Jul 3 at 23:46
  • $\begingroup$ None that I can think of. $\endgroup$ Jul 3 at 23:48
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    $\begingroup$ This is completely non sequitur. The statement is about acceleration when changing direction and you’re somehow equating high acceleration over short times to faster than light speeds. $\endgroup$
    – Brick
    Jul 3 at 23:51
  • $\begingroup$ Yes, well technically I did predict the reaction to the question accurately. $\endgroup$ Jul 3 at 23:55
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The standard physics answers are that there is no way to cancel out your momentum and no reasonable way to travel faster than light.

I would expect either that the observers are mistaken in what they saw, or there is an mundane explanation. But without better information, it is hard to say. I wouldn't take explanations such as aliens, particularly aliens with physics that contradicts known laws, seriously without some evidence that they exist. Seeing something that we cannot explain is just evidence that we don't understand what is going on. It is a far stretch to say that something impossible must be going on.

I won't ridicule you for your question - you are obviously trying to find out a sensible explanation. Nor down vote. But sorry, I don't have answers along the lines of what you have been hearing. There are good reasons to be skeptical. People have looked for ways to travel faster than light.

For example, Alcubierre drives are a theoretical way to do it. But they are really just mathematical games. They are a solution to Einstein's field equations that exhibit faster than light travel. To build one would require matter with negative mass. There is no reason to suppose such matter exists and good reasons to suppose it doesn't. Loosely, if you give me antigravity, I will give you faster than light travel.

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  • $\begingroup$ In context of the nontechnical nature of the original statements, “cancel out momentum” may just as well mean having an engine with extremely high impulse. Not to give too much credence to nonsense, but even on the fringe this seems more like a claim that our understanding of the limits of engineering doesn’t allow for the observed behavior rather than limits of science. $\endgroup$
    – Brick
    Jul 4 at 0:37
  • $\begingroup$ @Brick - I see your point. But I think that people who take this seriously may have heard a statement like "such a turn should be impossible because of momentum". They then say "well then something must cancel momentum." I expect they think that an advanced alien civilization must be able to make momentum go away, something like what you might see in movies. We do get a surprising number of questions that ask for explanations of special effects seen in movies. Seeing is believing. People are honestly trying to understand it. $\endgroup$
    – mmesser314
    Jul 4 at 0:51
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    $\begingroup$ And if you grant that momentum can be cancelled, it is a reasonable logical leap to FTL. No momentum means acceleration with no force. It would imply no energy change with speed change. Given this, it is a reasonable leap that you can make acceleration as big as you like and arrive at any speed you like. Yes, this violates various laws, but if you are not familiar with such laws, you might ask what is wrong with such reasoning. $\endgroup$
    – mmesser314
    Jul 4 at 0:56

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