Colliding Galaxies Reveal Colossal Black Holes

Matt_dk writes "New observations made with the Submillimeter Array of telescopes in Hawaii suggest that black holes — thought to exist in many, if not all, galaxies — were common even in the early Universe, when galaxies were just beginning to form. Astronomers have found two very different galaxies in the distant Universe, both with colossal black holes at their hearts, involved in a spectacular collision."

Comments

It doesn't seem that surprising.

[IndustrialComplex]

I don't think that discovering early black holes is all that surprising given that concentrations of matter were much greater early on.

What I want to know, is how did the universe expand beyond its own swartzchild radius?

Re:It doesn't seem that surprising.

[pokerdad]

What I want to know, is how did the universe expand beyond its own swartzchild radius?

Depending on what you take the mass of the universe to be (and age too), we may not have hit it yet.

Re:It doesn't seem that surprising.

[JustinOpinion]

What I want to know, is how did the universe expand beyond its own swartzchild radius?

It didn't.

To compute the Schwarzschild radius of the universe, we need to know its mass. Recent measurements suggest that the universe is flat, and so may have infinite mass. However at a minimum we can count up the mass within the observable universe. The observable stars in the universe have a mass of ~2*10^52, but they are overwhelmed by dark matter, which brings the total mass within our observation volume to ~4*10^53 kg. So the Schwarzschild radius for the universe is:

r = (2*G*m)/(c^2) = 2*(6.7E-11 m^3kg^-1s^-2)*(4E53 kg)/(3E8 m/s)^2 = 6E26 m = 60 billion light-years.

Since the observable universe is ~46 billion light-years in radius, this means that the Schwarzschild radius of the universe is bigger than what we consider to be "the universe." In other words, we are well within the Schwarzschild radius, leading some people to describe the universe itself as a massive black hole that we are actually inside of.

The universe probably has a mass larger than what we can observe, making the radius even larger than the above estimate. If the universe truly has infinite mass, then the radius is infinite. In other words, the universe may not have a Schwarzschild radius at all.

This is also a decent description.

Re:It doesn't seem that surprising.

[gnick]

Schwarzschild radius:

The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is a characteristic radius associated with every mass. It is the radius for a given mass where, if that mass could be compressed to fit within that radius, no known force or degeneracy pressure could stop it from continuing to collapse into a gravitational singularity.

Thanks a lot... Before I was peacefully ignorant, but now you've tossed out a perfectly good question and revealed to me yet another topic for my List of Things I Know That I Don't Know...

Re:It doesn't seem that surprising.

[Xcruciate]

I have always thought that this might be the case. I think that space/time is infinite. In our little corner of this infinite void, we have our "universe" of matter and energy (galaxies, dark matter, etc.). A black hole forms and creates a singularity which sucks in matter and energy. One has to ask where that stuff goes. I surmise that the singularity just punches a hole in the fabric of space/time and dumps the matter/energy into another corner of the infinite space/time, thus creating a "big bang" and another universe somewhere else (another dimension, perhaps) and that this is a never ending cycle. I just think that "our" Big Bang is the result of this cycle.

What I want to know.

[AgentPhunk]

Is how to answer my 5-year old's question of: "Ok, but whats outside the universe?"

She gets solar systems, and has a pretty good handle on galaxies and that there are lots and lots of them. I'm still trying to explain the Big Bang, and keep getting hung up on what the universe is expanding INTO.

I know, even us Big People don't have a good answer, but what the heck do you tell a kid?

Layman's question

[BCGlorfindel]

I know I aught be able to work this out myself, but I'm not sure if general newtonian calculations would be accurate. Is it possible to orbit a black hole from inside the event horizon if it is big enough? It seems intuitively obvious that if you can't achieve escape velocity you shouldn't be able to reach an orbital velocity either but I thought I'd see if someone was willing to give a more solid answer.