The Bang In The Big Bang

Mar 18, 2014

When a team of astronomers announced yesterday that they had been able to peer back 13.8 billion years to the first few moments of the Big Bang, they were confirming the work of Alan Guth in the 1970s.

The researchers say they say they saw some of what gave the bang to the Big Bang — what made the universe expand as quickly as it did. It’s being called one of the greatest discoveries in science.

“It feels great,” Guth tells Here & Now’s Robin Young. “We certainly did not know that this kind of confirmation would be available, but turns out that it is and these folks found it and it’s fantastic.”

Now a professor of physics at MIT, Guth explains his work and the evidence of what’s called inflation.


  • Alan Guth, professor of physics at the Massachusetts Institute of Technology in Cambridge, Mass.
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When a team of astronomers announced yesterday that radio telescopes at the South Pole peered back 13.8 billion years to the first few tiny, split-second moments just before the big bang and got, as one researcher said, a signal - a telegram from the very earliest universe - they were confirming the work of Alan Guth. In layman's terms, they saw some of what gave the bang to the big bang.

The findings will be further tested, but it's being called one of the greatest discoveries in science. And astronomers say what they saw confirms that what Alan Guth theorized in 1979 looks right. Alan Guth is now professor of physics at MIT. He joins us in our studios. Congratulations. How are you doing?

ALAN GUTH: Thank you, Robin. Feels great. We certainly did not know that this kind of confirmation would be available, but it turns out that it is. And these folks found it and it's fantastic.

YOUNG: Well, take us back. First of all, how does it feel to be described as an itinerant, young physicist in the 1970s? That's how the New York Times describes you. I mean, you were newly married. You had a child. And from what it appears, scribbling and thinking what happened to particles caused by the big bang? If there was a big bang - this huge explosion that started our universe - then where did all the particles go? And you came across what?

GUTH: Well, yeah. I was working in particular on a certain kind of particle that we don't see. And the question was, why don't we see it? And I had been working on this for about a year, and we were trying to figure out what could suppress the production of this particular kind of particle. And it led very directly to this idea that's now called inflation.

YOUNG: Mm-hmm. And what does that mean? Because we know - we have an image in our mind of the huge bang. But inflation seems more of an ironing out of a bang.

GUTH: Well, that's right. The big bang theory, even though it was called that, never really was a theory of the bang. It said nothing about what bang, why it banged, or what happened before it banged.


GUTH: It really started just after the bang. So inflation is the bang of the big bang in the sense that inflation gives an explanation for the propulsion, which drove the universe into this period of gigantic expansion. And it takes the form of a repulsive kind of gravity, which could never exist if we only had Newtonian theory of gravity. But starting with general relativity, gravity is complex enough so it actually can either attract or repel.

YOUNG: And so there's this moment in time where there is this repulsion almost that creates this bang.

GUTH: Exactly.

YOUNG: But the particles couldn't be found because what they were. Tell us about the gravitational waves that these researchers actually saw. How does that fit into this?

GUTH: Right. Well, one of the things that inflation can do is produce gravitational radiation. Inflation is about the only thing we know of that could do it. So it's sometimes called the smoking gun for inflation. And these guys have seen it.

YOUNG: And what does it look like?


GUTH: It looks like patterns in the polarization of the cosmic microwave background. So they're measuring the polarization of the radiation as it varies across the sky and seeking out particular patterns, which are indicative of this gravitational radiation.

YOUNG: Because - I mean, let me try very simply here. Forgive me. But it seems as if it were just a bang, well, then everything would be all over the place. But when we look into the skies, in our universe, there are patterns. It feels almost as if things waved out in more of a quiet ocean effect. And you're nodding. And that tells you that there was this inflation that sort of gave it some symmetry.

GUTH: That's right, and you're right on. If it really was just a bang in the sense of an ordinary explosion, you would expect the universe to look vastly more lumpy than it does. That's the way explosions work. Inflation is more of a kind of a stretching. So as inflation is going on, the universe is caused to be more and more smooth and more and more uniformed due to this stretching effect of the repulsive gravity.

YOUNG: And, well, the response to this discovery is coming in. Marc Kamionkowski of Johns Hopkins - he's also an early time expert - is the one who said it is like a telegram sent from the first moments of time, a telegram wrapped in gravitational waves. What else does this mean that your theory has been confirmed and seen? What does that mean?

GUTH: Well, I guess, my take on it emotionally is that it's not entirely my theory, by any means. I'm the one who sort of put together the final steps, but this really is the - an example of the crowning glory of science as a whole, going back to antiquity. It relies on the foundation of Newton and the foundation of Einstein and all of cosmology and all of particle physics. So it really is, I think, a triumph of science that we can make a prediction which curiously depends on making hypotheses about the universe at times of a trillionth of a trillionth of a trillionth of a second after the big bang and send up satellites and put telescopes at the South Pole to measure very delicately this radiation - that's fantastic that this very minute effects could be measured - and by the time it's all done, lo and behold, there actually is a very good agreement between what has been observed and what our theories predict.

YOUNG: Quite something. How does your life change?

GUTH: As far as my life, I'll continue to do research. It actually may affect what I'm working on right now. I've been working with a group of people at MIT in trying to understand whether inflation could produce primordial black holes which could be responsible, perhaps, for the super massive black holes that are found in the centers of galaxies, which are something of a mystery.

And we're not sure at the moment whether or not the models we were considering are consistent with this new result or not, so it may very well show that what we're doing has been off-track or it may work out that everything working together.

YOUNG: One last question - and fascination with this - what does it say about the rest of the universe, this discovery?

GUTH: Good question. It - certainly, this new discovery goes a long way towards confirming inflation. And inflation does have things to say about the rest of the universe. We don't know for sure. The implications are still very much under study. But at least a large fraction of versions of inflation lead to the conclusion that our universe is not unique but rather our universe is just one pocket universe within a vastly larger and perhaps even infinite multiverse.

YOUNG: If there's a bang that led to the big bang that led to our universe, there's a bang that could lead to a big bang for other universes.

GUTH: Yeah, exactly. Once you describe something in terms of physical laws rather than some philosophical proclamation, physical laws do have an actual tendency of repeating the results over and over again.

YOUNG: Alan Guth, professor of physics at MIT, author of the theory of inflation or rapid expansion of the early universe. And some astronomers now say they confirm his early theories. Alan, thank you so much for coming to speak with us. And again, congratulations.

GUTH: Oh, thanks a lot, Robin. It was a pleasure to be here.

YOUNG: And something tells me that he and that team of astronomers led by John M. Kovak of the Harvard-Smithsonian Center for Astrophysics should be dusting off of a place on their shelves. You're listening to HERE AND NOW. Transcript provided by NPR, Copyright NPR.