Black Holes: What the Movies Get Wrong

Any of you recognize this?

To those who don’t, it probably looks like a pretty unimpressive, blurry ring. In fact, this is the first ever image of a black hole, taken with an interferometer the size of the Earth.

If you’re a science geek, you’ve no doubt seen tons of artists’ conceptions of black holes on the internet. Most use a great deal of artistic license. Some of my favorite “images” of black holes used to be the ones that look like ripples in the fabric of space. Imagine my disappointment when I realized that’s not the case at all.

Black holes are singularities—infinitely dense places of zero radius with at least 3 M (solar masses) of star stuff—surrounded by an event horizon, inside of which gravity is so strong that even light cannot escape. That’s why it’s called a black hole.

But they are not “holes” in the usual sense. They are not giant space potholes that you can easily stumble into, and you certainly don’t fall into them the same way you would a pothole.

So…what are black holes really like?

Continue reading

What is Gravity, Anyway?

Welcome to my second “Science Answers” post! About a month ago, I sent out a post requesting science questions from all of you; you can find it here. This post addresses the second of the questions I was asked. If you have a question, you can ask it in the comments here or on that post, or ask it in an email. Or find me on Facebook!

Q: What is gravity? (asked by Simon)

Wow…great question. This is a question the greatest scientific minds have asked and tried to answer for centuries. It’s a question not even Stephen Hawking, the scientific genius of the century, has fully answered.

There are a few parts to the gravity question, and they have each been addressed one by one over time:

  • How does gravity work?
  • What is gravity?
  • Why does gravity work?

Isaac Newton stood on the shoulders of the giants before him—Aristotle, Ptolemy, Copernicus, and Kepler—and figured out how gravity works. But he was at a loss to explain what exactly this mysterious force was.

Einstein built on Newton’s work and came up with a theory for what gravity is—that is, distortions in space-time.

spacetime

We have yet to understand why gravity works. Why is space-time warped? Why do objects distort it as if it were the material of a trampoline? What exactly is the nature of space?

But, lucky for me, the question above specifically asks what gravity is. And that, I can explain.

The best way to do that is to turn one of gravity’s oldest tricks, one that has perplexed scientists and philosophers for thousands of years: What makes the planets move? Continue reading