# That particles cannot escape.

1. Mar 1, 2005

### Sariaht

Most neutrinos move straight through the earth without colliding, right?

Imagine a very small particle that moves against a black hole. it cannot move straight through it without colliding or collapsing. If it does not collide then it can never have a starting speed against the black hole cause then it would go straight through and out on the other side. the only solution to the problem is that it collapses as soon as it begins to exist. but if it begins to exist right next to the black hole 2GM/r + v will always be c and it will never collapse (but a particle that collapses as soon as it begins to exist cannot possibly have a mass and thereby does not exist, or that is what i think). My question to you is wont 2GM/r + v be c for all particles in the black whole and thereby there length will be 0, they will never collide nore and therefore the black hole will never collapse, yes? perhaps not, if 2GM/r + v is c then all of the particles mass will be neverending (why the particles I talked about before cannot exist), that is if they are not stuck in the middle, which they must be, aint i right? cause then 2GM/r + v is not c... I think I have done something wrong here...

Last edited: Mar 2, 2005
2. Mar 1, 2005

### rachmaninoff

The trick is that it a black hole doesn't have a finite 'width' or diameter; the spacetime within the event horizon is so curved that the 'distance' from one side of black hole to the other is infinite. The geodesics of motion approach a singularity.

3. Mar 1, 2005

### Sariaht

I am actually thinking of something else right now. I thought that if a particle gains infinite mass in falling against a black hole, were did the extra mass come from? clearly the black hole only win the particles rest mass or something like that, so the other particles in the black hole must lose mass, right? And it must allways be like that no matter if it's a star or a black hole. Every particle gives speed and mass to every other particle. I wounder how much speed it gives relative to the mass it gives... That is variating i understand now.

And that trick you are talking about, are you sure that solves the problem?

Last edited: Mar 2, 2005
4. Mar 2, 2005

### Sariaht

I guess no particle can move through a black hole without colliding, no matter if it is a photon or neutral particle or a charged particle. Doesn't this mean something?