It's a mind-boggling concept. Our cosmos expanded from almost nothing to its first huge growth spurt in just a trillionth of a trillionth of a trillionth of a second. And that was after the Big Bang.
Scientists said they confirmed that theory by using this telescope at the South Pole to look at the oldest light detectable. The light reveals patterns and skewed light waves, shown here in red and blue, that were created by gravitational ripples during the... this incredible expansion known as cosmic inflation.
Sean Carroll is a physicist, cosmologist, and author at the California Institute of Technology, and he joins us now to explain all of this, and we need your explanation. Start by explaining cosmic inflation. What a term.
Well, it is. The term cosmic inflation was coined around 1980, when ordinary economic inflation was also very much in the news. And it was Alan Guth, who was a young physicist at the time, who came up with the idea that we need to explain certain very basic features of the universe. For example, it looks similar, it looks smooth all over the place. And so if in the very earliest moments the universe went through some enormously fast, super-accelerated expansion, it's like pulling at the edges of a sheet, and that expansion would actually smooth things out.
How does this compare to the, was it 1998, the discovery of dark energy? How does this compare to that? Well, it's very similar.
In both cases, we knew that this was a possibility. In both cases, we were a little bit surprised that it came along the way it did. Dark energy was a game-changer in terms of our understanding of the current look of the universe, what it's made of and so forth.
And we've been trying to understand the very earliest moments. Before yesterday, the earliest moment in the history of the universe about which we had data was one second after the Big Bang. And now, like you said, it's a trillionth of a trillionth of a trillionth of a second after the Big Bang.
So when we think of the universe, we think of something expansive and endless and almost unmeasurable. And you're saying that what we know about the universe so far is just a speck of that, of what it really is. Well, certainly, you know, we only see a certain finite amount of universe.
It's still very big. We see a part of the universe that has hundreds of billions of galaxies in it. And the amazing thing about the Big Bang model is that in the far past, 14 billion years ago, all of this stuff was squeezed down to an incredibly tiny...
distance. And so what physicists have done is to take the laws of physics as they understand them, to extrapolate them well beyond anything we had ever seen before, made a prediction, and that prediction came out to be correct. So we really have a much better idea now than we did a couple days ago that we're on the right track when it comes to what was happening right after the Big Bang. JUDY WOODRUFF, The New York Times, Now, those predictions have always been theories. How do you then go about proving a theory?
not to be a theory? And is that what we've actually done here? Has it been proven?
Well, you know, science in some sense never proves anything. It's all about gathering evidence, reaching conclusions, because the overwhelming amount of evidence goes for one model rather than some other model. So in inflation, you have a very well-defined theory of what could have happened right after the Big Bang. There are competitors to inflation, but none of them were really quite as well put together as inflation ever was. And inflation made this very specific prediction that the competitors didn't really make.
So right now, inflation is way above everything else we know when it comes to understanding the early universe. That's not to say that tomorrow some brilliant young scientist is not going to come up with an even better model. Why was this experiment done at the South Pole?
What is it about the South Pole that lends itself to explorations of space? You know, the South Pole is a little bit different than you would think. It's obviously very cold, like you would think, but it doesn't snow.
at the South Pole. The air is actually very, very dry, and it's at a very, very high elevation. There's snow on the ground, and it drifts around a lot.
But when you look up into the sky from there, you see the universe very, very clearly. So even though it's a tremendous pain to get down there, and once you're down there, if you're down there for the winter, you're not coming back until the winter is over, but it's a great place to do observational astronomy. Now, Now, for those of us who think this stuff is really cool, it is very cool. But what is the practical impact for most people when we talk about when we trumpet such exciting discoveries?
There's absolutely zero practical impact in the conventional sense. Understanding the origin of the universe is not going to cure any disease. It's not going to build you a better smartphone or anything like that.
What it will do is help us as a species understand our place in the cosmos. So I personally think that that should. affect your everyday life.
It helps us really appreciate what the universe is, how it behaves, and that has to feed into how we think about ourselves. So it informs the way we see our world and our place in the world, in the larger universe. Yeah, what separates us from merely existing, surviving from day to day, is that we are curious.
We are creatures that want to understand. Like Carl Sagan, whose Cosmos is back on TV now with Neil deGrasse Tyson, Carl Sagan once said, we are the universe's way of thinking about itself. We're a collection of atoms and particles, just like the rest of the universe, but we have the power to theorize, to go out there and collect data, and to understand the context, this wonderful universe that we live in. It sounds almost theological.
Well, I think it's a very similar impulse that drives people to theology and to science. You want to understand the bigger picture. I think that science is different than theology in many ways, one of which is you've got to make predictions, and if the predictions don't come true, we throw away your theory. So the wonderful thing now is that this extrapolation from Alan Guth and collaborators over 30 years ago somehow miraculously seemed to get the right answer, and our ability to comprehend our cosmos has been demonstrated once again. But it still requires corroboration.
Oh, absolutely. You know, this is the result of a specific telescope called the BICEP2 collaboration. And they're very, very good.
I know a lot of the scientists who are on this experiment, and they're super careful, and they try their best. But we're not going to absolutely believe it until someone else sees exactly the same thing. The good news is that there's half a dozen experiments that will be checking this result. So in a year or two, we will know absolutely sure whether or not this is real.
Sean Carroll at Caltech and author of The Particle at the End of the Universe. Thank you so much. My pleasure.
Thanks.