Oct. 26 – 2B03 26/10/2011 9:29:00 AM
Low mass stars – fusion stops when a carbon core is formed.
End product is a white dwarf
High-mass stars – can fuse elements up to iron.
End product: neutron star or black hole
Pressure (coming from nuclear reactions) outwards, stabilizing with equal
amount of gravity coming in.
If pressure outweighs gravity, star gets bigger. If gravity
outweighs, it contracts.
Massive star -> supernova -> supernova remnant.
All heavy elements came from supernovae (gold, lead).
If you squeezed earth into a tiny volume (1cm) -> the escape velocity would
be greater than the speed of light and would result in a black hole.
All the different escape velocities -> none close to the speed of light.
Every object has a critical value under which it becomes a black
hole -> The Schwarzschild Radius
We call it a surface – but its more like a barrier.
o Nothing within the S radius can ever come out.
Singularity – a point of infinite density.
Anything that falls in doesn’t come back in.
Gravitational force changes as you go inside a spherical object.
Black holes have alot of mass in a ridiculously small volume.
Higher density, larger the surface gravitational force.
If you are magically inside the event horizon (can’t really -> be ripped
apart), and you had a laser, light would not escape. Black hole – singularity, point at which density is infinite.
Event horizon -> space around which light cannot escape.
Black holes don't suck.
If you turn sun into a black hole, we wont be sucked or anything.
Gravity would remain the same.
Neutron star – pretty dense, 1/3 of the speed of c.
High density -> higher escape velocity .