Falling into a Black Hole

You could fall into a black hole, but I'd never see you get there.

Odd, eh?

Reason being, Einstein's Equivalence Principle - which forms part of his General Theory of Relativity.  This states that an accelerating frame of reference is indistinguishable from a frame under the influence of gravity.

What does that mean?  It means that the force holding you in your seat right now would feel exactly the same as you'd feel if you were sitting in a rocket in space, but accelerating at 1g.

Pretty obvious, pretty boring so far.  However, we also know that Moving Clocks Run Slowly.  If you're moving through space, you move through less time than someone outside of your frame of reference.

And that gets interesting.  One of the consequences is that a photon (a "ray" of light) does not pass through time at all.  It moves so fast that it never ages.

If you wave your arm, then your hand is fractionally younger than your elbow.  And yet they're still attached.

Equally astonishing is that a clock on a high tower will run faster than a clock at the bottom of a tower.  I would have thought this is because it is simply moving faster (since it's on a further radius from the earth).  But actually, it's because the bottom of the clock is under the influence of gravity, and due to the Equivalence Principle, that clock is accelerating.

Ok, so this is exciting.  Because that means us earth-dwellers are moving through time faster than those in space. (Spacemen actually age less quickly, but this is because they orbit at 17,000mph). (If our clocks are running slowly, then we're passing through time faster - think about it over a beer).

So if gravity is cumulative enough to hold the galaxy together, then what on earth is the time curve like for the disc?  The galaxy must spin in a very funny way, if the centre of the galaxy is passing through time at a faster rate than the outside.  Actually, galactic discs really do have very odd spin ratios, attributed to dark matter.  How fast is time passing out in Extra-Galactic Space?  Does it pass at all?

Or, let's face it, at the time of the Big Bang?  Everything was much closer together back then, gravity must've been a massive force, and though other short-range forces would dominate, they wouldn't have gravity's influence over time.  Perhaps that question isn't relevant, because everything was uniformly dense.  But you can imagine this might drive "inflation", where the early universe did some things in strange amounts of time.

Now, back to the Black Holes.

A Black Hole is sufficiently dense that nothing (except imaginary particles like gravitons) can escape.  Not even light.  Something that dense does really weird things to time.

According to my physics books here, if you fell into a black hole, you wouldn't notice anything particular peculiar.  Except for the whole crushing-to-death thing.

To me watching, it would take an infinite amount of time for you to fall in.

So actually, you would watch the Universe end around you, probably in a very Douglas Adams style.

Now that's a funny concept.

And here's the question:  assuming this is so, how did Black Holes ever grow?  Presumably all the holes we can see are primordial, because it would have taken longer than our mere 13.7 billion years to see anything fall in?

Physics: gotta love it.

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