4 ms·
This is one of those ideas that is so wrong that it is right: > He reasoned that such particles, emerging from the surface of a star, would have their speed re
by RcouF1uZ4gsC 3y ago
This is one of those ideas that is so wrong that it is right:
> He reasoned that such particles, emerging from the surface of a star, would have their speed reduced by the star’s gravitational pull, just like projectiles fired upward from the Earth. By measuring the reduction in the speed of the light from a given star, he thought it might be possible to calculate the star’s mass.
>Michell asked himself how large this effect could be. He knew that any projectile must move faster than a certain critical speed to escape from a star’s gravitational embrace. This “escape velocity“ depends only on the size and mass of the star. What would happen if a star’s gravity were so strong that its escape velocity exceeded the speed of light? Michell realized that the light would have to fall back to the surface.
- synapsomorphy 3y agoI wouldn't say that. Yes, it's not exactly our modern understanding, but the core idea is the exact same: stars can get big enough that even light, which is super fast, can't escape them, and that was an entirely novel idea in his time.
- bmitc 3y agoI think it's more that the effective idea is the same, while the core idea is what is so vastly different. He was arguing as if light was affected by gravity. This is totally missing the rather revolutionary idea of general relativity, best explained by John Wheeler: "Spacetime tells matter how to move; matter tells spacetime how to curve".
- spindle 3y agoCan you say more about what's wrong about it? It seems plain right to me, in Newtonian physics, assuming only that light has a speed (which was not at all a crazy thing to think at that point), and historians of cosmology usually agree (source personal communication, so I could be wrong).