It doesn’t matter how much you say about them, there’s still more to say.  It doesn’t matter how much you know about them, you barely know anything at all.  We’ve talked at length about what black holes are, what they do, how they do it, and what may happen after they’ve done it.  We all know about Hawking Radiation, microscopic black holes, and event horizons.

Doesn’t the term “event horizon” sound like it fell right out of The Twilight Zone?

Since most people know I’m very interested in black holes, I get a lot of questions and comments on the subject.  Here are a few of the topics most discussed in my email:

Image created by ESA/NASA/JPL – a Black Hole Concept drawing

A good “rule of thumb” in the empirical sciences goes like this:  For every action there is an equal, and opposite, reaction.  How does that work with black holes?

The “flip-side” to the black hole coin could very well be the hypothetical “white hole”.  Matter is drawn inexorably into the black hole, compressed by enormous energy into a singularity, and released (explosively) by the white hole.  The puzzler in this theory is if it happens at all (and it seems as if it must), why don’t we see it happen around us all the time?  After all, there doesn’t seem to be a shortage of black holes.  Some scientists are saying that the ejection of matter at the white hole is happening all around us, all the time.  It simply creates another “universe” when it happens.  The next step along this line of thought is the speculation that we have indeed experienced a white hole in this universe.  We called it “The Big Bang”.

Remember, the existence of a white hole it purely hypothetical.  By its very definition, we couldn’t produce one in this universe since its existence could only be manifest by the formation of another universe.  Tricky little problem in logic, that.

NASA/ESA STScl   X-Rays from heated material falling into a black hole

Let me give you a quick aside here;  if you fall into a black hole, you are not going to encounter a “worm hole” and travel through time, space, or dimension.  If you fall into a black hole, the only thing you’re going to encounter is a singularity, and that’s not a pleasant prospect.  Worm holes are an even iffier proposition than white holes.  Even if they did exist, and there was a way to travel through them (and control where you were going), you would not want to go through one.  Trust me, you do not want to go there.

Illustration of space-time “fabric” being warped by a black hole

Black holes are now thought to be at the center of most, if not all galaxies.  The gravitational pull of the black hole may very well be instrumental in holding the galaxy together.  When galaxies collide, or “merge”, it appears that their respective black holes orbit each other, creating a binary system, until they also collide.  The largest black hole located so far, OJ287 (a BL Lac object), is believed to be one center of such a collision of galaxies. OJ287 is thought to contain 18 billion (that’s “b” as in “boy”) solar masses, and is one member of a binary system.  Its smaller companion (“only” 100 million solar masses), will eventually be absorbed.   OJ287 is in the constellation of Cancer.

There is indeed a black hole at the center of The Milky Way.  It’s about 27,000 ly away, and is believed to be 4 million solar masses.  Here is an image of the center of our galaxy, combining images from Chandra, Hubble, and Spitzer.

Brought to you by NASA/ESA, SSC, CXC, and STScI

And finally, to look at our galactic center, churning around our own black hole:

Journey to the Galactic Center