Quick thought on eternity

Face · 10-04-2012, 04:17 PM

Quote:

Originally Posted by tore

Why do you see gravity as weak?

Gravity is always there, constantly. A star is like a bike rider trying to go up a tall hill. As long as it has energy (fuel) to keep the engines burning, it exerts an outward pressure against gravity, pushing its stuff outwards from its core like the rider going uphill. As it burns out, that pressure drops off - it can no longer go "uphill" against gravity - and the star starts to compress or implode, like the bike rider losing his energy and rolling down the hill backwards.

Slightly naive example, but I don't see gravity as a weak force overcoming the strong force of a burning a star just like I don't see a tall hill as a weak force beating a bike rider.

Think of the force applied vs typical volume needed to apply it.

As a really simple and crude demonstration magnetism for example, two magnets need to be pulled apart, two stones of a similar size don't.

Or how the gravitational attraction between electrons and protons is completely negligible compared to electrical attraction.

Which is why gravity is labled a weak force, in comparison to the other fundamental forces (at short ranges).

Guybrush · 10-05-2012, 02:52 AM

Quote:

Originally Posted by Face

Think of the force applied vs typical volume needed to apply it.

As a really simple and crude demonstration magnetism for example, two magnets need to be pulled apart, two stones of a similar size don't.

Or how the gravitational attraction between electrons and protons is completely negligible compared to electrical attraction.

Which is why gravity is labled a weak force, in comparison to the other fundamental forces (at short ranges).

All true. Perhaps my question could be more delicately formulated, but the reason I asked Neapolitan was because I was curious as to why he thought of the weakness of gravity as interesting when it comes to black holes from dying stars because in those cases, the mass of the object is so immense that the gravitational pull it exerts is anything but weak.

And I guess I wanted to make the point that for the star - the energy needed to push its stuff outwards will eventually leave it, but gravitation won't. Well, okay, it shoots matter off into space, but essentially, gravity would still have to "win" sooner or later.