3 ms·
I think the balloon analogy is used because people have an easier time imagining that rather than an infinite surface. That, and stretching a surface intuitive
by rhn_mk1 4y ago
I think the balloon analogy is used because people have an easier time imagining that rather than an infinite surface.
That, and stretching a surface intuitively imparts momentum on things on top, whereas it's not the case here.
- floxy 4y agoDoesn't dark energy add momentum?
- rhn_mk1 4y agoWhy would it?
- floxy 4y agoI thought dark energy was the reason the non-gravitational-bound galaxies are accelerating away from each other? If they are accelerating, that would be a change in velocity, which seems like a change in momentum. ?
- rhn_mk1 4y agoThe name "acceleration" is just as misleading as "expanding" here, but maybe useful. Our galaxy is non-gravitationally-bound to a lot of other galaxies, and we "accelerate" away from them. Yet we don't really feel that. We also obviously can't accelerate away from all of them, when they are in random directions. That's because the "acceleration" describes the change of distance, without changing position. Without changing position, there's no change of momentum. That "acceleration" is a consequence of the expansion/stretching described in the article.
- floxy 4y agoWhy is it called dark energy if energy isn't changing?