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Comment by milchek | Hacker News Reader

The animation comparing the helical engine with same mass vs with relativistic masses was super helpful, I wish more articles that went into physics had these kinds of simple illustrations.

>“I know that it risks being right up there with the EM drive and cold fusion,” he says. “But you have to be prepared to be embarrassed. It is very difficult to invent something that is new under the sun and actually works.”

This was actually my favourite part of the article and a beautiful reminder that it's OK to fail.

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The difference between this idea and the EM drive is that there's an at least somewhat plausible theory behind it, that's not entirely incompatible with known science.

EM drive proponents could make the same statement and it would be less credible in that context.

That's not to say that experimenting first and figuring out the theory later is a bad thing - that's often how science works - but generally, one follows strong evidence to reach a theory to explain it. EM drive proponents extrapolate wildly from extremely weak evidence. It's not good science.

The animations sure help, but I find the second one misleading because the ring bounces instantly and it has only 2 discrete sizes.

Instead of a discrete bounce, picture a slow motion elastic bounce where the ring gets heavier as it's being accelerated. It seems to me that when the box pushes the ring (left side), the ring would be gaining mass as it accelerates, thus cancelling the harvested movement, right?

I think the mass increase is not supposed to come from the forward/backward motion. Rather, the mass increase comes from rotating the ring.

Imagine the ring at the front of the ship spinning up to relativistic speed, then you push hard on it to get your ship moving a bit. Then you slow the ring down again before it hits the back, so it's much easier to bring back to the front.

Interesting, maybe that's why they chose a ring, although the article is not clear in that aspect.

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