Ask a NASA astronomer! How did Stephen Hawking change the world?

Stephen Hawking was one of the greatest scientific and analytical minds of our time, says NASA's Michelle Thaller.

Michelle Thaller: Yes Jeremy, a lot of us were really sad with the passing of Stephen Hawking. He was definitely an inspiration.

He was one of the most brilliant theoretical physicists in the world, and of course, he overcame this incredible disability, his life was very difficult and very dramatic and I for one am really going to miss having him around. And I certainly miss him as a scientist too. He made some incredible contributions.

Now, Stephen Hawking was something that we call a theoretical physicist, and what that means is that people use the mathematics of physics to explore areas of the universe that we can’t get to very easily.

For example, conditions right after the Big Bang, the beginning of the universe, what were things like when the universe was a fraction of a second old? That’s not something we can create very easily in a laboratory or any place we can go to, but we can use our mathematics to predict what that would have been like and then test our assumptions based on how the universe changed over time.

And one of the places that is also very difficult to go to is, could we explore a black hole? And this is what Stephen Hawking was best known for.

Now, black holes are massive objects they’re made from collapsed dead stars, and the nearest black hole to us is about 3000 light years away. That one is not particularly large, it’s only a couple times the mass of the sun. The biggest black hole that’s in our galaxy is about four million times the mass of the sun and that actually sits right in the heart of the Milky Way Galaxy.

And right now you and I are actually orbiting that giant black hole at half a million miles an hour. These are incredibly exotic objects. The reason we call them black holes is that the gravity is so intense it can suck in everything, including light. Not even light, going through space freely at the speed of light, can escape a black hole, so talk about dramatic exotic objects that are difficult to do experiments on.

Stephen Hawking laid down some of our basic understanding of how a black hole works.

And one of the things he actually did was he even predicted that black holes can die. You would think that a collapsed star that forms a bottomless pit of gravity would exist forever, but Stephen Hawking used the laws of quantum mechanics and something called thermodynamics, how heat behaves in the universe, to prove that maybe black holes can evaporate over time. And of course, that’s a hugely significant thing.

One of the reasons I think it’s very unfortunate he died is we’re actually right on the cusp of being able to do actual experiments with black holes. And I know that sounds like a strange thing to say, but there are some particle accelerators, I mean specifically the Large Hadron Collider, which is in Europe, that are about to get to high enough energies they’re going to smash particles together so hard that so much energy is generated they might be able to make tiny little black holes. And by the way, this is entirely safe. Don’t worry about it at all. Stephen Hawking showed us that black holes evaporate, they actually die away and the smaller a black hole is the faster this happens.

So these little black holes—we’ll probably be lucky if we can detect them, they’re going to die in millionths of a second.

And the Large Hadron Collider gets nowhere up to the energy of natural events all around us. Right now there are high energy particles slamming into our atmosphere a couple miles above our heads, and they are many, many hundreds of times the energy that the Large Hadron Collider will ever be able to get up to. So I am saying actually that there are probably tiny little black holes forming all around us, they evaporate away so quickly they’re very hard to detect. Stephen Hawking predicted the exact energy that black holes give off when they evaporate, and it may be that in just a few years time we’re going to observe that in a particle accelerator and realize he was right.

Now, there’s another thing that’s kind of poignant, and that Stephen Hawking just before his death, just in the last couple of years was beginning to unravel some of his previous theories. He thought that maybe we had all been fooled and maybe black holes don’t work the way we thought they did.

Now we know black holes exist, we see these massive objects in the middle of galaxies or up in the sky when we look at the stars, we know that they’re there, but he thought that maybe we really don’t understand how an event horizon works. An event horizon is basically the point of no return. You can’t get any closer to a black hole and escape. Even light cannot escape this event horizon.

And Stephen Hawking began to wonder if quantum mechanics doesn’t really allow a true event horizon. You may have heard of something called quantum entanglement, that you can take two particles and you can actually combine them in such a way that they respond to each other, they have to actually adjust to what the other particle is doing. We don’t understand this very well yet.

We’ve known about it for a hundred years, even Albert Einstein knew about quantum entanglement, but what happens if you take two particles that are linked in this way and one goes down a black hole and you still have the other one? Is it possible that these two particles can still talk to each other even though one is beyond the event horizon and no information should be able to get out?

This question was starting to lead Stephen Hawking in a new direction.

He was starting to think that maybe quantum entanglement was a proof that our simple understanding of black holes was wrong, and he was starting to formulate new ideas about how black holes could work with quantum entanglement. And he’s not here right now to lead us on that anymore.

And yes there are brilliant physicists that will take over, and I think will discover things about quantum entanglement and how black holes might deal with that. I think it may lead to a breakthrough, which is the equivalent of another Einstein.

I think it may be that our current laws of physics are going to fall apart because right now we cannot understand how quantum entanglement and a black hole could possibly work together. When we do we’re going to have brand new physics, and in a way Stephen Hawking will be one of the parents of that.

Stephen Hawking was one of the greatest scientific and analytical minds of our time, says NASA's Michelle Thaller. She posits that Hawking might be one of the parents of an entirely new school of physics because he was working on some incredible stuff—concerning quantum entaglement— right before he died. He was even humble enough to go back to his old work about black holes and rethink his hypotheses based on new information. Not many great minds would do that, she says, relaying just one of the reasons Stephen Hawking will be so deeply missed. You can follow Michelle Thaller on Twitter at @mlthaller.

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