4 ms·
He's talking about acceleration, not really movement. But I don't think it's accelerating either, not really.
by smosher 13y ago
He's talking about acceleration, not really movement. But I don't think it's accelerating either, not really.
- XorNot 13y agoA satellite in orbit is always accelerating as well, and will remain in constant motion if the orbit is far enough out (i.e. well beyond atmospheric drag). I'm about half-way through this and it feels more and more like it was written by someone who would also ask why a permanent magnet can support a load against gravity without expending any energy - it's the same fundamental attribution error. EDIT: In fact finishing it, I'm really confused as to what's new here. Giant external magnetic field, and stuff just coasting in a circle? Nothing about this feels implausible in a classical sense with a ring of charged ions.
- format 13y agoIt's a popsci article. I wouldn't go criticizing the scientists based on this.
- tzs 13y ago> A satellite in orbit is always accelerating as well, and will remain in constant motion if the orbit is far enough out (i.e. well beyond atmospheric drag). If general relativity is correct, that system will generate gravity waves which will take away energy and the orbit will decay. This is a small effect, however, so we generally don't have to worry about it. E.g., Earth's orbit is decaying by about the width of a hydrogen atom every few hundred years.
- baddox 13y agoWouldn't tidal forces influence Earth's orbit much more than gravitational radiation? Although I suspect both are far too small to measure on a human time scale.
- sageikosa 13y agoThe ion lattice is in its ground state, it can't release any more energy to get into a lower state, but it moves. They couldn't get a lattice into the ground state until recently due to excess heat from contaminants in the "trap".
- coldtea 13y ago>EDIT: In fact finishing it, I'm really confused as to what's new here. Since 1) the Nobel-winning physicist, 2) the peer reviewed journal AND 3) the main critic of his theory agree that there is something new there, you probably ARE confused as to what they really meant. I think an appeal to authority is appropriate here. Time and again I've seen simplistic comments in tech forums, putting down new scientific theories based on some misunderstanding of what new they claim, with the argument that "it's just like" some other older theory. And all this criticism usually based on a 10000 miles high explanation of the idea in some popular science article. As if that is enough to capture all the nuances of the thing. I may not be quite proficient in Physics to be able to say what's the case here (then again I doubt many if any at HN are at the level of the article's professor), but I've seen the same kind of responses many times in comments about other fields of study.
- caf 13y agoThe difference here is that normally when you have something coasting in a circle like that, it's possible to remove energy from the system and have it stop doing that. For example, tidal forces are constantly removing energy from the Earth-Moon system. Here, the theory is that the system is already in its lowest-energy state, despite the fact that part of it is still in motion.
- simonh 13y agoYou hit the nail on the head, thank you.
- smosher 13y agoThe point is, iiuc, the only rest state is rotating and at a particular rate at that. That's quite a bit different than coasting, which could have various different speeds (or ~none) depending on the amount of inertia in the system—but I think even that is removed here.