4 ms·
One aspect of gravity waves is that other than being extremely weak, they cannot perform work. So they don't cause mechanical forces.
by kanzenryu2 3y ago
One aspect of gravity waves is that other than being extremely weak, they cannot perform work. So they don't cause mechanical forces.
- hughesjj 3y agoWait, really? Why not? That's fascinating Edit: ah, you mean for any practical purposes. Duh.
- aftbit 3y agoOh really? I didn't know that. If they cannot perform work, how can we detect them?
- heisenzombie 3y agoThe OP might be making a more subtle point, but my understanding is they absolutely can do work. We can measure the deceleration of binary neutron stars with a rate predicted by the emission of gravitational waves. Deceleration == work. However, we can also measure things that don’t do work, for example, a static magnetic field does no work on a charged particle (it cannot change its kinetic energy) but look at the swirls in a cloud chamber and it’s clear as day if there’s a magnetic field there.
- kanzenryu2 3y agoI'm wrong on the work thing, but I don't think we can always regard deceleration as work, since that only works for Newtonian mechanics. Under GR there is an extra term in the equation allowing for acceleration without work.
- tobinfricke 3y agoThis is not true, and in fact there is a very famous thought experiment called the "sticky bead argument" that was pivotal in developing the consensus that gravitational waves are a real, physical effect and not just a "gauge" effect (an artifact of the coordinate system): https://en.wikipedia.org/wiki/Sticky_bead_argument https://en.wikipedia.org/wiki/Sticky_bead_argument On the other hand, I definitely agree that gravitational waves are almost certainly too weak to cause any tectonic effects.
- kanzenryu2 3y agoI had heard that somewhere before, but it looks like I'm wrong