Hacker News Reader

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?

View on HN

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.

Reply on news.ycombinator.com