Re: Do Blackholes rotate on an axis?

Yes, black holes do spin. The short answer to "how do they start to spin"
is that black holes come from spinning stars, so black holes must spin
faster. 

To give you a better idea of why this happens, let me explain how a black
hole forms:

When a massive star (8 to 10 times as massive as the sun) begins to run out
of fuel, its life is almost over. For tens of millions of years the gas
pressure caused by the hot interior of the star has held the star up
against the crushing force of gravity. But when the fuel runs out, the star
can no longer continue create the heat needed to maintain the high gas
pressure. Then gravity wins out and begins to squeeze the star very
quickly. In a matter of hours, the star shrinks by *billions* of
kilometers.

Now this shrinking could cause a number of things. You could be left with a
rapidly spinning neutron star or a black hole, depending on whether the
core of the old star is massive enough to make it collapse all the way.
But in any case, the resulting object is going to be much, much smaller
than the original star, which was spinning to begin with. All stars,
without exception, rotate. The sun rotates on its axis about once every 30
Earth days. 

Now if you squeeze any star, it will wind up spinning a lot faster. 
The reason behind this is "conservation of angular momentum". This is
basically like saying that a rotating object has a certain amount of
"spinnyness" and if there are no external torques (a torque is a force
applied about an axis) on that object, changing the way the mass is
distributed (eg: shrinking an object, or stretching it out into a propellor
blade) will cause it to either speed up or slow down, since only a torque
can change the "spinnyness" of an object. 

A practical illustration of this is a skater. Imagine one swooping into a
spin with his arms held out parallel to the ice. When he pulls his arms in,
he begins to spin faster and faster. Same physics as a collapsing star,
with the same result.