Cosmologists Reveal Evidence of Inflationary Universe Scientists don't know just how our universe was formed at that first instant, but they have some theories about what happened in that tiny fraction of a second later. These ideas go beyond the big-bang theory. Inflation suggests that in its first few moments, the universe underwent a massive growth spurt, inflating space from a tiny speck to a universe in under a trillionth of a second.
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Cosmologists Reveal Evidence of Inflationary Universe

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Cosmologists Reveal Evidence of Inflationary Universe

Cosmologists Reveal Evidence of Inflationary Universe

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IRA FLATOW, host:

This is TALK OF THE NATION, Science Friday. I am Ira Flatow. A little bit later in the program, we'll be talking about the exhibition of human cadavers currently opening here in New York, and we'll look at an important patent case now before the Supreme Court.

But first, a look back to, oh, 13, 14 billion years ago when the universe was just an infant.

Scientists don't know just how our universe was formed at that first instant, but they have some pretty good theories about what happened in a tiny fraction of a second later. These ideas describe just the point, what took place right after the big bang, something called inflation.

Now inflation suggests that in its first few moments, actually under a trillionth of a second after the big bang, the universe underwent a massive growth spurt, inflating space from a tiny speck to, well, a universe and all, as I say, under a trillionth of a second.

To try to figure out what happened in that moment, scientists look at very faint light, sort of an afterglow, that can been seen now as microwaves. If inflation theory is right, the force driving inflation should fall over time and you should be able to see that change, a downshift, in the microwaves all around us today.

Well, astronomers reported last week that their recent measurements of those microwaves do fall in line with the predictions made by inflation theory, a great day for cosmology, as at least one scientist described it. Joining me now to talk more about it is Charles Bennett. He's professor of physics and astronomy at Johns Hopkins University. He's also the principal investigator for the Wilkinson Microwave Anisotropy Project or the WMAP, as it's known. That's the team that measured those microwaves. Welcome to Science Friday, Dr. Bennett.

Dr. CHARLES BENNETT (Wilkinson Microwave Anisotropy Project): Thank you. My pleasure to be here.

FLATOW: Did I get that description right? Do you want to modify it in some way?

Dr. BENNETT: Well, there is one modification I would make, although it's a bit of perspective, and some of my colleagues may not say it the same way that I do. But I view this inflation theory as being, actually, something that came before the big bang, not really as part of the theory but an add-on to it.

So one very common misconception is that the big bang theory actually describes a big bang, which it really doesn't. It's a very unfortunate name for the theory. The big bang theory actually describes the development of the universe from a very hot and concentrated initial phase and then through a cooling and an expansion to the universe that we see today.

FLATOW: Was it not a derogatory phrase when it was first used?

Dr. BENNETT: It was, it was intended to be a derogatory phrase making fun of the theory, and you can imagine sort of looking back in time, and it's getting hotter and denser as you look back in time, and then this idea of an explosion. But there's actually nothing in the physics of the theory that describes any explosion at all.

So the big question is what powered the big bang, what got it started, what happened before it? And that's really where this inflation theory comes in.

And I should draw a distinction that the big bang theory is really extremely well established. There's a lot of very detailed data. The theory has made predictions. Measurements have been made to show that those predictions are good. Inflation has been a little less certain, and it still is a little less certain than the big bang theory, which is why it's so important to look at the predictions that the theory makes and to take data and to try to figure out whether those predictions are good or not.

FLATOW: What does the inflation theory answer that was the problem in physics that required to have it?

Dr. BENNETT: Well, there were some things that the big bang theory didn't explain one way or the other that made the inflation theory interesting to start with. One of those was we see this light that you mentioned all across the sky, and it's very uniform across the sky, and the question is what, you know, where did it come from and how did it arrange itself to be so uniform across the sky?

Now, it also shows itself to have properties that it was once in equilibrium with material, with matter, yet there was nothing in the big bang theory that explained how that could happen. And there are some other problems, too, that simply were not addressed by the big bang theory. So when Alan Guth at MIT first suggested this idea that this huge inflation in the early days of the universe could simultaneously explain all of these things, it was a very intriguing idea.

Since that time, both the theory has been developed and observations have proceeded to try to put the theory to a test, and this is just another, this is another step in testing this theory, and it's a fairly significant step as well.

FLATOW: So the theory says that there was this huge inflation that was, not a linear explosion, but, like, it's been described, I remember, over the years as if you opened a bottle of soda pop and all the fizz starts coming out all at once.

Dr. BENNETT: Yeah, in fact, it's, I mean, it's really there's no way to imagine it. It was so very sudden that really, in far less than a trillionth of a second, you go from what are microscopic, submicroscopic quantum mechanical fluctuations, up to astronomical sizes, literally in the blink of an eye, and this is, you know, this, it's hard for me to imagine it. It's hard for anyone to imagine it.

But the point is that the theory actually makes some specific predictions. And we're seeing these predictions getting borne out in data. I have to say it amazes me that it's even possible to have data on things that relate to the first trillionth of a second, but we have this extremely valuable afterglow light that we've learned so much from over the years. It was predicted that this light would exist from the actual big bang predictions, that there would be a light left over. This was predicted by Ralph Alpher who works at the, who was at the Johns Hopkins Applied Physics Lab back in 1948 doing this as a Ph.D. thesis.

And it wasn't discovered until 1964 at the Bell Telephone Labs with Arno Penzias and Bob Wilson who later won a Nobel Prize for the discovery.

FLATOW: Right.

Dr. BENNETT: But since that time, we've been using this light much like a fossil to study the imprint of things that happened very, very long ago in the history of the universe because this light has been traveling across the universe for over 13 billion years, and it's invaluable for learning about what happened.

FLATOW: How far back can we get to that under thousandth, or how far into that inflation can we actually see?

Dr. BENNETT: Well, the light itself is a bit like looking on a cloudy day out your window up at the cloud. The light was scattered around early on in the universe, like light is scattered in a cloud, and we looked back and we only see the lower surface of the cloud. Well, we only see the light coming from a surface in the universe, and this surface was not as early as inflation, but inflation put its markers on the distribution of material and the physics of the early universe, and that's been imprinted onto this light.

So we can't actually see back beyond that time, but we can use the light to probe what happened earlier, and so we're matching up different versions of what might have happened earlier with what they would cause the light to look like, the patterns and the light and then we're looking to see whether we see those patterns.

Inflation is a, is in a sense an idea and within this idea is a paradigm. There are many specific inflation models, and what we're actually starting to do now is sort out which of those could have happened and which might not have happened because of the patterns that they would produce in this light.

FLATOW: Using this new data that you've come up with, do you have to reshape any ages or sizes of the universe now?

Dr. BENNETT: Well, our team estimated back in 2003 that the universe was 13.7 billion years old, and our new data, which is much more powerful than the older data, gets basically exactly the same answer. We also determined the contents of the universe, combining our data with other invaluable data about the universe, to find that about 74 percent of the universe is dominated by some kind of thing we call dark energy, and whenever we hear the word dark it means we don't understand it.

So we have dark energy dominating the universe. And then the next biggest contributor is about 22 percent of dark matter and you guessed the dark means we don't know what it is.

FLATOW: Right.

Dr. BENNETT: And then there's four percent of atoms, and this is what we spend all our time in school learning about in chemistry class. But it's only four percent of the universe. And those, this content of the universe that we reported on last time is still holding up.

The new things that we're learning about is pinning down a little better when the first stars formed, which now looks to be about 400 million years after this inflationary epic. And most importantly, how, starting to pin down whether inflation happened and what kind of inflation happened.

FLATOW: Well, so what would seal the deal for whether it happened?

Dr. BENNETT: Well the one, there's a number of predictions of inflation that actually have already been shown to be good, and we've got a new one here. There's one that many of us would really like to see, that I think would seal the deal. And that is that inflation theory generically predicts that there should be gravitational waves generated. And the gravitational waves would also affect the solstice flight.

And we have the best measurements yet on the light, but it's not a detection, it's an upper limit. And we would really like to dig down and see if we can actually find those gravitational waves. I think if saw those, that would really be the smoking gun.

FLATOW: You talked about this huge inflation and it happened so instantly. We know that the dark energy is a repulsive force, are they related somehow?

Dr. BENNETT: I think that's an excellent question. We believe that the universe started with some kind of dark energy force that drove this tremendous inflation. And currently, there appears to be another accelerated expansion of the universe, which was completely unexpected, and we don't have really any idea what's causing it. That's a very active topic right now to try to understand.

And your question is an excellent one, is, what are the similarities and differences between what happened very early on in inflation and the current inflation that's happening, thankfully at a much more moderate rate, or we'd all be in trouble.

FLATOW: Well, I mean could that be the release of the dark energy right there at that instant, you know?

Dr. BENNETT: Well it's --

FLATOW: Exerting itself and causing the universe to expand?

Dr. BENNETT: The inflation at the very earliest times in the universe is a more natural thing because the energies involved at the time were much, much higher energies than we see in the universe today. And for various reasons, that's a much more natural picture. It's very, very surprising that there would be this kind of expansion today in a fairly low energy physics domain and that's really got us all puzzled.

FLATOW: Well I'll let you off the hook, because it's a great topic and we talk about it a lot. And we'll keep following it. I want to thank you for taking time to be with us today, Dr. Bennett.

Dr. BENNETT: Thank you very much.

FLATOW: That's Charles Bennett, professor of physics and astronomy at Johns Hopkins University, and principal investigator for the W. Math Project.

We're going to take a short break, when we come back we're going to look inside Bodies: The Exhibition, a display of human cadavers opening now, running now at New York's South Street Seaport. So don't go away, we'll be right back.

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