This question seems to be a close parallel of this one, but it's about a different design by a different author.

I read a news article about a "helical engine" design by NASA engineer David Burns. The design allegedly exploits relativistic effects to seemingly violate conservation of momentum (as in the earlier question). It involves an oscillating mass which travels faster in one direction than the other, thus having higher relativistic mass on one side and imparting unbalanced momentum to its container.

But, Burns asks, what if the ring’s mass is much greater when it slides in one direction than the other? Then it would give the box a greater kick at one end than the other. Action would exceed reaction and the box would accelerate forwards (see video below).

Read more: https://www.newscientist.com/article/2218685-nasa-engineers-helical-engine-may-violate-the-laws-of-physics/#ixzz62dnGnjzh

Now, I'm not a physicist, but I'm just smart enough to have gotten the sense that this is almost certainly nonsense. As soon as I read "may violate the laws of physics" in the headline, in fact. Is it nonsense, and if so, what is unaccounted for in this model that would balance the momentum transfer at each side of each oscillation? How does the math play out?


closed as off-topic by Qmechanic Oct 17 at 19:58

This question appears to be off-topic. The users who voted to close gave this specific reason:

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    $\begingroup$ This notion amounts to a claim that relativistic dynamics as it is usually understood is wrong. The mainstream understanding of special relativity is one that conserves momentum without question. $\endgroup$ – dmckee Oct 17 at 19:26
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    $\begingroup$ Yup, it's all wrong. $\endgroup$ – knzhou Oct 17 at 19:32
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    $\begingroup$ Relativistic dynamics is different from Newtonian dynamics in a lot of ways. Force isn't parallel to acceleration anymore. Acceleration gets harder the faster an object moves. You can mimic some of these changes by just pretending that you still have Newtonian dynamics but the mass can change with velocity, but we don't use this language in physics because it's misleading -- there are many effects this idea can't capture. (For example, the fact that force is not parallel to acceleration.) It is a very fragile analogy that causes a lot of conceptual mistakes. $\endgroup$ – knzhou Oct 17 at 19:32
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    $\begingroup$ Hi TypeIA: The question appears to be about non-mainstream physics, which is off-topic. $\endgroup$ – Qmechanic Oct 17 at 19:38
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    $\begingroup$ Published in which journal? Peer-reviewed? $\endgroup$ – Qmechanic Oct 17 at 19:42