4 ms·
When people say gravity is weak, they usually mean "relative to other forces of nature" Put a small magnet above a paperclip. When the magnet is close enough,
by cobbzilla 10y ago
When people say gravity is weak, they usually mean "relative to other forces of nature"
Put a small magnet above a paperclip. When the magnet is close enough, the paperclip will jump up and stick to it.
At that moment, the magnetic force of the magnet pulling the paperclip upwards is larger than the gravitational force of THE ENTIRE EARTH pulling it downwards.
- kqr 10y agoIs gravity as a force weak, or are we just used to materials where the electrical charge is disproportionate to its mass? Maybe the kilogram is just a tiny unit compared to the coulomb, and if that relationship was normalised the forces would appear abouh equal. All tongue in cheek, of course. They're just different ways of saying the same thing. In our collective experience with our regular materials, magnetic forces, when present, tend to be stronger at short distances than gravitational forces.
- gpderetta 10y agoThe coupling constants of the various fields are unitless and the gravity coupling constant is order of magnitude smaller than the others.
- kqr 10y agoThat is cool information. Where can I read more about that?
- rlpb 10y agoI suppose it's a scale thing. At a small scale, including human scale, gravity is weak and the other forces are strong. At a large scale, the other forces don't really exist at all, and so it is gravity that is strong.
- greglindahl 10y agoOh, I totally get the usual reason. But as an astronomer, when I look up at the night sky, I think about how all that glowing stuff was assembled by gravity, with magnetism playing a supporting role by driving the Balbus-Hawley instability in accretion disks[1]. 1: https://en.wikipedia.org/wiki/Magnetorotational_instability https://en.wikipedia.org/wiki/Magnetorotational_instability
- cobbzilla 10y agoI agree, gravity does create its most beautiful artwork at the cosmic scale.