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People had been probing the cosmic background radiation for 30 years, but no one had detected any deviation from absolute smoothness, no hint of the beginnings of the structure that dominates the present universe. Then Smoot detected variations in temperature measured in millionths of a degree . . .

George Smoot on the Birth of the Universe

by Monte Davis



"We have reached back in time to the origin of the universe. We have launched a little space probe to receive the faint whispers of the cosmic explosion of fifteen billion years ago, and we have measured the structure of the Big Bang itself, less than a fraction of a second after the universe started to expand."

To make up stories that explain the mysteries of the universe is the work of all humanity, through all the ages. But to concoct a scientific version of Genesis, and build instruments to hunt for the very hallmarks of Creation, and then to succeed in finding them — that is the special privilege of cosmologists like George F. Smoot. Leading the team that made what Stephen Hawking calls "the discovery of the century, if not all time," cosmologist George F. Smoot announced the stunning breakthrough at an American Physical Society meeting in April 1992. After 20 years of maniacal attention to detail in validating experimental results, Smoot, 47, suddenly found himself catapulted to stardom.

Sitting now beneath overloaded bookshelves (guardrailed for earthquake safety) in his office at the University of California's Lawrence Berkeley Laboratory, Smoot's face is flanked by two computers on cluttered tables behind him. A little laptop that accompanied him on a recent trip to NASA's Goddard Spaceflight Center perches between the larger machines, downloading into one parent's hard drive. Smoot talks in rapid-fire bursts that leap from one idea to another like electrical impulses. His great booming laugh is amplified by his large frame and the abandon with which he surrenders himself to the humor in the moment. His thoughts turn repeatedly to the time when all matter and energy were crunched into an almost infinitely hot, infinitely dense point before rushing headlong into the inflationary expansion that has created this universe.

American astronomer Edwin Hubble gathered the first evidence in the Twenties that the universe was expanding. When he observed the distant galaxies moving away from us at prodigious speeds, they looked to him like they'd been expelled in some primordial explosion — if their flight path could be run backward, they would all coalesce into the original fireball. Belgian cosmologist Georges Lemaitre first voiced the idea of a "primeval atom" in 1927. But the theory got its enduring name — the Big Bang — when English astronomer Fred Hoyle, who believed the universe always had and always would exist in a "steady state," derided the sudden-birth notion.

Smoot was a boy in Florida when scientists began amassing support for the Big Bang. The theory made good predictions about the abundance of hydrogen and helium and explained why the sky is dark at night: Fiery starlight must dim and cool in an ever-enlarging cosmos where stars are born from gravitational collapse and later die. The Big Bang also implied the existence of a faint afterglow of radiation, a relic of the original explosion.

Scientists in 1948 suggested that 15 billion years ago, this cosmic background radiation must have been unimaginably hot. But spreading itself thin in the intervening millennia would have hushed it to a faint whisper of low-energy microwaves far colder than ice. In 1965, Arno Penzias and Robert Wilson at Bell Labs accidentally detected, identified, and measured the temperature of the low-energy microwaves at 2.73 degrees above absolute zero.

The smoothness of the cosmic background radiation recalls the time when the universe was as uniform as homogenized milk. Today, in contrast, it is awfully lumpy, broken up into people, planets, stars, galaxies, clusters of galaxies, and giant walls of superclusters surrounding giant voids. The cosmic background radiation, then, carries our best key to the distant past.

People had been probing the cosmic background radiation for 30 years, but no one had detected any deviation from absolute smoothness, no hint of the beginnings of the structure that dominates the present universe — no one until a team headed by Smoot detected variations in temperature measured in millionths of a degree. These minuscule differences show the ripples in spacetime, where matter first began to clump gravitationally about 10,000 years after the Big Bang. Radiation from regions of higher density expended more energy trying to escape a deeper gravitational well and therefore appeared slightly cooler than average. Radiation from regions of lower density retained more heat. Smoot's team charted these differences in radiation from detectors aboard the Cosmic Background Explorer satellite, or COBE (rhymes with Dobie). The detectors were just barely capable of distinguishing the temperature variation signals from the noise generated by the equipment itself.

Oval-shaped maps in shades of pink and blue decorate Smoot's office, depicting the pattern of temperature fluctuations across the heavens. As bright and gay as enormous Easter eggs, the maps summarize hundreds of millions of observations COBE collected during its first year in orbit. They represent a herculean task of data analysis to discern the pattern in the welter of noise and to single out that pattern from overlying extraneous signals, including radiation emitted by our Milky Way galaxy and the motion of Earth, solar system, and our galaxy through space.

In his efforts to validate his results before announcing them, Smoot tried to imagine every scenario that might have distorted the data. Unable to see anything wrong, he offered a pair of plane tickets to anywhere in the world to the team member who could uncover a mistake in method or interpretation. When his offer failed to turn up an error, the COBE team went public. "If you're religious," said Smoot at the press conference after the formal announcement, "it's like seeing God."

OMNI

What possessed you to use the G-word when you announced the COBE findings?

Smoot

I invoked God because it's a cultural icon people understand — but there's something deeper. Talking about cosmology, you can't help making the connection to religion. In all religions, all cultures, there's always, "In the beginning." Either you started from something or you didn't, right? I got letters from religious people. About half said, "That's great. It's wonderful what you've done." The others said, "You don't need those experiments. You should read the Bible and learn more. It's right here in the Bible."

Even so, few letters were antagonistic. Most criticism came from scientists who find the idea threatening because it's an unresolved issue personally. To get into science, a lot of scientists may have rejected religion initially but then later never went back and got comfortable with that rejection.

OMNI

Were your parents religious?

Smoot

They were Protestant — not strongly religious, but we went to church when I was young. Anyway, I'm comfortable with it.

OMNI

Did the public's response to your version of creation surprise you?

Smoot

Yes. I thought the finding would appear in texts and popular books on cosmology and only then leak down to the media. But it drew tremendous attention — and it was good news. In science, the news is often that something awful has happened — Chernobyl has blown up or some electrical appliance has become dangerous. Since the COBE announcement, my nephew has decided he wants to be a scientist, because, "You get famous and get to discover the universe!"

We have to change the public's very stereotyped view of scientists: an extreme parody of Einstein, a brilliant but whacky guy with no practical sense, who somehow gets great stuff done. Or the mad scientist, Frankenstein. Or guys in white lab coats who're robots disguised as humans, and generally considered to be nerds.

OMNI

What role models did you have when you were growing up?

Smoot

I read about people like Galileo. My father was a hydrologist at the U.S. Geological Survey, and my mother a science teacher. But there's a small percentage of people who just have to know exactly how things work, and I'm probably one of those who would have become a scientist even without scientific role models around. I'm just wired to do it.

OMNI

Like Galileo you were the first to turn a new instrument to the heavens and see something no one else had seen.

Smoot

Almost any time a new instrument is turned on, somebody finds something new. What I love about Galileo is that he did science by observation and experiments. He kicked over the apple cart in astronomy. Copernicus may have started it, but Galileo turned the telescope to the sky, and wrote what he saw.

OMNI

Who directly influenced you?

Smoot

Enrico Fermi has been a hero since MIT. The teachers who influenced me directly were themselves taught by Fermi. As postdocs at Berkeley, a bunch of us would lunch with Luis Alvarez, Emilio Segre, and Owen Chamberlain, who had all known Fermi and all won Nobel Prizes. They used to love to give us war-story quizzes on problems in nuclear physics they'd faced. Sometimes we managed to figure them out. Nowadays, you don't learn much nuclear physics; it's out of fashion. Particle physics, cosmology, astrophysics, mathematical topology — these are where people think the frontier is.

OMNI

Many of those hot topics meet at the Big Bang. How do you see it as a creation myth?

Smoot

It's a great one, perfect for the modern world, because it's glitzy and high-tech.

OMNI

Where do you place the beginning of modern cosmology?

Smoot

When I was a graduate student in particle physics at Brookhaven about 20 years ago, scientists were discovering that the proton is made of quarks. They'd been trying to measure the diameter of the proton really accurately but kept finding it to be soft and mushy with hard points in it. We now know that protons and neutrons are both made of quarks, and so their collision may involve two quarks in each particle, or three, or one. As particles get closer, the repulsive barriers between them collapse, so one can imagine protons and neutrons colliding and suddenly dissolving into a bunch of pointlike particles whose interactions get weaker and weaker as you push them together. That's when I began realizing that maybe we could think about extrapolating the Big Bang back to the beginning, back past the first millionth of a second.

Well, suppose everything in the universe consists of pointlike quarks with no finite extent, and the more you push them together, the less they resist? Then there's no limit to how many you can get into something the size of a head of a pin. The difference between protons and quarks could be infinite — which fits much better with the Big Bang model's implication that you're manufacturing spacetime. The suitcase expander unfolds and you've got more suitcase.

OMNI

How does inflation fit into the Big Bang theory?

Smoot

Inflation is the engine that drove the formation of spacetime. The inflationary model holds that a small region of the early universe — say less than a millionth of a millionth of a proton — expanded in a tiny fraction of a second, faster than the speed of light, to something about 100 meters in size.

OMNI

Faster than the speed of light?

Smoot

Things moving apart faster than the speed of light don't actually move; the distance between them just has to grow. The only thing that travels faster than light is spacetime. Essentially all the spacetime we're in now was created during that tiny fraction of a second. Tiny fluctuations, quantum mechanical effects, got stretched to sizes of cosmological consequences. These small fluctuations from the origin of the universe are what have grown to be galaxies, clusters of galaxies, and the larger-scale structure we observe today. Inflation is a transcendent concept linking the very small and very large.

OMNI

It's said that the COBE findings unified astrophysics on the largest scale with quantum physics on the smallest scale.

Smoot

That was the trend of cosmology anyway. COBE just found the pieces and put them on a firm observational foundation. With the COBE data so strongly supporting the Big Bang, everybody feels quite confident. But the Big Bang itself is what ultimately makes the connection between astrophysics and particle physics, because if you go back far enough, space gets denser and hotter until eventually you're having particle interactions.

OMNI

What do you mean by particle interactions?

Smoot

You don't have particles at the beginning, just this stuffed-in, energy-dense space that's going to turn into particles, energy, and present-day space. It doesn't seem unreasonable or outrageous to me now that I've gotten used to thinking of space as flexible, stretchable, and having real substance. It's a real thing on its own. Energy-dense space can turn into the space we're used to, and particles. I think of it as a metamorphosis, like the difference between the caterpillar and the butterfly. You wouldn't think butterflies and caterpillars were related until you noticed that one went into the cocoon and the other came out. Well, particles and space are not so distinct anymore.

Space has certain properties that differ from what we learned in school. Aristotle was reasonably close to the truth when he suggested that matter and space we somehow connected, and that empty space by itself didn't make sense. Nevertheless, the idea that space was just emptiness with a rigid coordinate system became entrenched. People got frozen into this concept.

OMNI

We imagine at the moment of the Big Bang that matter began shooting into this vast, empty space from some dense, central starting point.

Smoot

That's the general misconception, but a lot goes on in what we think of as empty space. The Big Bang doesn't expand into space. It is space. Space itself expands, and as it does, it increases the distance between matter that was once densely packed. One can picture the expanding universe by thinking of galaxies as dots drawn on a balloon. As you blow it up, the galaxies fly apart in all directions, but it's really the increasing space itself that widens the distance between galaxies. I can't emphasize enough that space is what's expanding, not the galaxies moving out into space.

Inflation represents the extreme case, where space is not only very flexible, but also has the ability to warp and expand. It can be deformed both in its curvature and scale. During inflation, space has a lot of substance in terms of energy density. Now imagine that the energy density puts ripples in space. Where the curvature of the ripples is positive, particles will eventually converge, the way lines of longitude on a globe converge at the poles. If you take ripples of all different sizes and scales, you'll end up having particles converging on all different sizes and scales — the stars, galaxies, and clusters of galaxies. Where the curvature is negative, particles will flow away, leaving voids.

You're creating all the space. There was essentially nothing there. I haven't resolved this, but I think of space and time as complementary, but time is really different from space. I always hated when people taught me in special relativity that time and space are the same thing, because they're obviously not. You can rotate an object in space, but if you try to rotate it in time, you have to trade off space and time in a funny way. When we try to calculate what a rotation looks like, instead of keeping the distance constant, the spatial distance grows or subtracts.

Imagine this little cube: You open it up; it unfolds and unfolds and unfolds, and pretty soon it's a big as everything. Somehow I've crunched everything down to virtually nothing. Then I start unfolding space and time and trade them off. When I get a little space, I get time; more space, more time. This is a tricky picture because of this concept of space having these intrinsic properties of curvature — that it can change its curvature and stretch its scale and trade it off for time. The ratio of tradeoff for spacetime depends on the curvature, which depends on energy density. If you make the density just right, then the curvature of space is just right, so the unfolding costs you zero. So it's sort of funny; you're creating space and all the energy in it and doing it for no cost. That somehow violates your common sense. But the fact is, you couldn't collapse it all back down — right?

OMNI

Have you other mental pictures of the Big Bang?

Smoot

My favorite analogy is an infinite petri dish full of rapidly dividing cells. If a cell mutates, it makes many similar cells around it, so the infinite petri dish has regions that look totally different from each other because of local mutations. In one area, a red-mutating cell creates a growing blob of red cells. Around it are white or clear cells, and over there's a bunch of blue cells. The regions made early grow big during the inflationary period because the expansion is accelerating. The distance between any two points grows at an exponential rate. Regions made later can never get to be as large.

OMNI

Do you have a visual image of cold dark matter?

Smoot

Well, it's not there. It's a more abstract question like, "How do you visualize strength or loudness?" I have prejudices about cold dark matter. I don't think of it as being visual, but substantive. I imagine ripples in spacetime going through metamorphoses, from energy density to radiation and particles. During a period of expansion lasting about 10,000 years, the radiation cools continuously until the particles by their gravitational attraction begin to move toward forming structure. These were particles of nonbaryonic dark matter, I should say.

OMNI

Ordinary dark matter might include invisible things like burnt-out stars and black holes, right? But nonbaryonic dark matter is fundamentally different from matter as we know it?

Smoot

Yes. The early universe is so hot and rapidly expanding that nothing can clump together. But about 10,000 years after the Big Bang, the dark matter can start saying, "Let's pay attention to ourselves instead of the radiation." It can start clumping. The only kind of matter then is nonbaryonic dark matter, a non-light-interacting, non-electromagnetically interacting material. The matter we're used to interacts with and generates light, so we can see it as stars. But nonbaryonic dark matter is free to follow the curvature of space earlier than regular matter and is very effective at forming structure.

It's a structure you can't see at first — as though an invisible man were leaving his footprints all over the place. Then, when the universe cools enough for matter that interacts with light to finally get released, at about 300,000 years after the Big Bang, the ordinary atoms collect in the footprints like dust. The ordinary matter quickly streams into the ready-made structures of those invisible forms. We're still trying to fill in some skipped steps in the cold-dark-matter model.

OMNI

Tell me a story about your experiments, something calamitous or funny.

Smoot

That would have to be a balloon story. I've had incredible mishaps losing balloon payloads in the jungle, ocean, badlands. Once we were flying from the airport in Watertown, South Dakota, where it's always windy because there are no hills. The locals joke, "There's nothing between us and the North Pole but a barbed-wire fence — and it's down." We had to wait days for the winds to be low enough at sunset until finally getting a launch.

So that evening, four guys are out filling the balloon while I'm doing the final equipment and crew check-out. A long cable runs from the balloon to our payload, which is hanging on a big crane about six stories high. The idea is to steer the truck with the crane underneath the balloon as it rises. When the time is right, and it has the weight, you push the release mechanism at the end of the crane to let go of the cable, and the whole thing just wafts off into the night.

Some of the telemetry and command equipment was hanging down so low from the payload gondola I was afraid it might get caught on a tire during the ascent. So I told our electrical engineer, John Gibson, to stand on the front of the crane where he could hold these antennas, and then lift and throw them out of the way as the balloon went up. Anyway, once the balloon was inflated, one member of the launch crew stayed with it while the other three started walking back toward the crane and rest of us. Since the launch crew didn't have walkie-talkies, and it was close to dusk, they decided to flash the headlights of a parked car as a signal for the guy at the balloon to let it rise.

One guy gets into the car to be the signal man, and goes to turn the car around so the headlights will face the balloon. When he shifts to drive, the car's back-up lights flash. Naturally the first guy releases the balloon. The other two guys are still 15 feet away from the crane cab when they see the balloon start rising. They run and jump onto the crane and try to get it started to steer underneath the balloon. Meanwhile, it's drifting off to the side, and I'm afraid it's going to pull the crane over on top of everybody. I yell to John, the engineer, to jump off the crane. Others start yelling too, and a few run toward the crane. There was so much confusion nobody could tell what the hell was going on. Then the cable release mechanism let go, freeing the payload, which goes up and smashed into the side of the boom, puncturizing the pressurized capsule. And the balloon goes up carrying a load of useless, damaged equipment.

Also it's drifting towards the outskirts of the city, meaning we have to let it go higher. By the time we could have let it down, of course there's a fog. It's dark, foggy and we can't find the balloon and payload. It had landed about a mile from the site of the original "little house on the prairie," in the middle of some farmer's soybean field.

When the farmer gets up the next morning, as the fog ia thinning, he sees this huge egg-shaped gondola — 13 feet long, covered with aluminized mylar — like a giant baked potato or flying saucer in his back yard. Just about the time he gets out there, the search plane flies over and spots the thing, then comes diving down on it. The pilot calls us and we drive right over. The farmer thought it was a great experience. He got $100 dollars for his damaged soybeans and the American flag attached to the gondola.

OMNI

What had you been trying to do?

Smoot

Test the Big Bang. That led to the next project: looking at he background radiation to see if we could detect any irregularities — anisotopies — in it. I got involved after reading Jim Peebles's PHYSICAL COSMOLOGY and an article by Dennis Sciama, both of which suggested you could measure whether the universe is rotating. At the same time, you could improve the measurements of the microwave background by a factor of 5000 over what anybody else has done.

"This is the experiment for me!" I said. I'd started out doing antimatter searches, and never found any. In fact, on the last two microwave background experiments I hadn't found any either, but had just set upper limits for the smoothness of the radiation. That's important, but not as exciting as finding something. And with this experiment we'd see whether the universe was rotating and expanding.

OMNI

What about finding ripples in space-time?

Smoot

When I started out by trying to detect irregularities — anisotropies — in the background radiation. I expected to measure something about the dynamics of the universe, and thought the origin of galaxies was a trivial problem. I mean, galaxies were there, obviously, and must have formed from lumps, but it was no big deal to me then. Only after we started making measurements did I see it as a problem. We got down to measuring a part in 2000, pushing down the limits of what we could detect, and still weren't seeing anything. The universe looked perfectly smooth.

OMNI

If the universe proved to have no irregularities, then you can't use gravity to explain its structure?

Smoot

Right. And there was no other good explanation for galaxy formation, so cosmologists were in a tight spot. But in 1973, we didn't even know how much trouble we were in. I was just thinking about how to measure the radiation to detect the universe's rotation. One person was already trying to do this from a mountain top, and another group was attempting it from balloons. I wanted to try it with airplanes. At NASA Ames in Mountain View, I saw the U-2. NASA had flown U-2s for Earth resources, photographing crops and the coast of California to make sure it was protected. I talked about it, and Luis Alvarez and the others in my group got excited, so we went ahead with the U-2. But all the hatches on the U-2 were bottom hatches; this was, after all, a spy plane, designed to look down. After many dealings, Lockheed finally configured an upper hatch that let us look out into space.

OMNI

Instead of finding rotation of the universe, you discovered the motion of the galaxy.

Smoot

We found a pattern in the background radiation — a dipole — that showed the Milky Way was moving through the radiation. We calculated the speed of the galaxy at 600 kilometers per second. We took the plane to Peru to repeat the work in the Southern Hemisphere, to show the effect was not just some local anomaly. It was pretty clear the universe was lumpy.

There had to be an enormous mass capable of pulling our galaxy around at such high speeds. Our galaxy is a huge, tenuous thing, and if you try to accelerate it by just grabbing hold at one end, it will come apart. You have to pull all of it together and with almost the same force or else it will stretch apart. For a whole cluster of galaxies, like our local group of 14, you need a much bigger mass, still farther away, to pull them together. Only after the U-2 results, around 1979, did I realize that these huge masses must exist out there and that we had to look for them. I figured we'd find the variations in the background radiation, and find them soon.

OMNI

Yet it was ten years before the COBE satellite was ready for liftoff. After the space shuttle Challenger disaster, it had to be redesigned to ride on a rocket instead of the shuttle. How did you feel on that morning in 1989?

Smoot

Some nervousness, because it was the moment of truth! Alpher and Herman, two of the guys who predicted the cosmic background radiation, were there at Vandenberg Air Force Base. The sun was barely starting to come up as we faced the Pacific Ocean. I could see our shadows falling forward, toward the launch pad. When the motors turned on and the rocket started to lift, our shadows were suddenly thrown behind us. I remember how quickly the rocket seemed to turn and go away behind me. And all of a sudden, the Dela rocket's 1-in-30 failure rate seemed awfully high.

I crossed my fingers that it was in orbit and working. I wanted the DMR [Differential Microwave Radiometer] turned on immediately. I knew that couldn't happen because there was checkout stuff to do, but as the spacecraft flew over the South Pole one hour after takeoff, the reflected sunlight produced extra power to burn. So the DMR [Differential Microwave Radiometer] turned on. Then we knew it had survived the launch. In January 1990, two months after the launch, the satellite measured the full spectrum of the background radiation, showing that it matched the Big Bang theory's prediction precisely.

OMNI

Your own work on COBE involved measurements of minuscule differences in the radiation's temperature.

Smoot

That's why the experiment took so long and was so hard. We're talking about differences of one part in 100,000 — or smaller. It's like measuring the distance between New York and San Francisco to within one foot. That may seem like a simple matter of calibrating your car's odometer really precisesly and driving across the country. But you've got to take into account the fact that the roads aren't straight. And what happens when you pull off for gas? If it's a warm day and your tires expand? That changes the measurements — perhaps 50 feet in a mile. It's not easy to measure with great accuracy.

We showed that space is ten times as homogeneous as we thought, that it is uniform to one part in 100,000. That's extremely uniform. No manmade thing, not even a billiard ball, is anywhere near that smooth. The universe turned out to be smoother than ever. But the big news is — it's got tiny wrinkles. All people can talk about, in fact, are the imperfections. It's like looking at a beauty queen and focusing on the tiny mole over her left eye or on her one gray hair.

OMNI

How did you feel when you realized what you had found?

Smoot

We didn't see it right away. The first thing that became clear was the quadrupole pattern, which didn't arise from our motion in space — like the dipole we'd seen with the U-2 — but from the cosmos itself. Instead of announcing that finding right away, I said, "We've got to check it over." In that year of checking, we saw that not only was there the quadrupole, which is like the second harmonic of the dipole, but there were other irregularities — octupole and hexadecupole — representing the third and fourth harmonic. We found a whole spectrum of irregularities of all different sizes. We'd uncovered a whole bunch of puzzle pieces at once. It was comparable to finding that the DNA strand was a double helix. I remember sitting here, looking at the curve [on the graph of data points], and saying, "Aha! Aha!" I was pretty sure but wanted it checked. Your credibility is very important. I'd anticipated that once we made the announcement, we'd be in for three or four years of controversy.

OMNI

Instead, you've found agreement and confirmation.

Smoot

Well, so far. And the second year looks much like the first. So the only thing we have to worry about is, are the data in agreement from one year to the next because something is wrong with our software? I have a lot invested in it now. If I'm wrong, I'll have a difficult time living it down.

OMNI

Haven't you already received confirmation from an MIT experiment with balloon equipment?

Smoot

Some. That experiment covered about a quarter of the sky. While not quite as sensitive as the COBE DMR maps that cover the whole sky, that experiment's results covering a quarter of the sky correlate well with ours. A primarily Spanish-British experiment in the Canary Islands is also scanning strips across the sky with three telescopes specially designed to look at three frequencies so they can fine-measure. And we're hoping for more follow-ups. The analogy is: Columbus discovers America, or at least shows the world there's a continent there. Then Magellan comes over and finds that there are really several continents. Now you want to map in more detail — trace out what Florida looks like. With COBE, we've seen the broad outline of the structures. Now we want to map in detail, particularly on the structure of galaxies and superclusters of galaxies. Our original COBE map is on a mammoth scale. The smallest spots are objects the size of the Great Wall and the giant void in Bootes. We'd like to get down to the supercluster or cluster size.

OMNI

What might smaller-scale measurements reveal?

Smoot

More about how structure formed in the early universe. We now have the outline, and I hope we'll go on to some kind of astronomy — seeing how the individual fluctuations grow, first on different scales because that would give us different snapshots of the early universe. Once particular structures are targeted, maybe we can trace some examples through time — see them in more than one phase so we can follow their evolution.

OMNI

How often do you put the accumulating data into the model?

Smoot

We're now close to making a two-year map, with software we think is adequate to deal with two years' worth of data. That's taken almost another year. We make the map in pieces, and we're merging the six-months maps for the first two years. About four years from the beginning of its mission, COBE will have lived its expected life. The rest would be insurance, essentially. I don't know, but after eight years of data, I would tend to be bored.

OMNI

You're ready for the next thing?

Smoot

Yes. We want to go back to the South Pole, where we measured the low-frequency spectrum in 1989 and 1991, and make a series of observations of the spectrum toward the longer wavelengths. We made better maps of galactic emissions at long wavelengths then, but we need new data to calibrate those maps. To make maps with more sensitivity, or at different angular scales, you want to measure galactic emissions more accurately — not only so you can understand it better, but also to subtract it away, to see the extragalactic stuff. We built this huge portable radio telescope dish and want to take it to the South Pole or some cold dry place where we can scan the southern sky. It's the least well mapped. Then we want to go up into South America, or Australia, the southern U.S., then the northern U.S. to calibrate all the maps. And get a good absolute measurement. We're trying to set up an international collaboration so we can make measurements with the same dish at different sites.

OMNI

What other pursuits will you follow beyond COBE?

Smoot

I like to push the envelope; I'm thinking about gravity waves. I think inflation is the right model of the early universe. And inflation could certainly make gravity waves, so there's a well-defined relationship between density perturbations and gravity waves. Measuring both of them, you can test if inflation is the right concept. If inflation's right, then I can rest easy, because now I have a paradigm I can visualize, calculate, and am personally and philosophically comfortable with.

OMNI

How widely accepted is the inflationary model?

Smoot

Probably 10 or 20 percent of people in cosmology don't believe in it. They propose topological defects, phase transitions, or other things as the seeds of the structure. Conceivably, some of their theories could still be right. Things fit too well, and sometimes I worry about getting to love inflation too much so that it stands in my way of detecting something else. I think — I hope — I'm mature enough to be able to step back and look at the data without too much preconception.

But when I saw that curve back in February 1992, I said, "Boy, inflation is right." I didn't have so much vested interest in inflation until that moment. I tried to keep all the theory out of the paper announcing the discovery. All these theories, including cold dark matter, might be dead in ten years while the data should still be right. But I couldn't resist putting in a paragraph about how the fluctuations fitted with inflation. So I didn't succeed entirely.

OMNI

Where do you draw the line between accepted theory and speculation?

Smoot

The Big Bang is standing on firm footing, inflation on much less firm footing. But it's reasonable to tell people about it, because it's a beautiful idea and stretches your mind. It's also likely to be right. Now dark matter is on more tenuous ground. It's like you sometimes see cartoons where people are standing out in the middle of nothing? Well, they could be standing on dark matter.

OMNI

Where the characters run off cliffs and don't fall down until they look below?

Smoot

They could be running off cliffs onto dark matter! What are cartoon characters made of, anyway? Seriously, detecting dark matter will revolutionize particle physics and tell us how to change the standard model which now has many loose ends. Standard models exist in both particle physics and cosmology. In fact, the inflationary Big Bang is the standard model in cosmology. I suspect dark matter will be a key, interlocking puzzle piece, but we won't know what that is until we find it.

OMNI

We often hear the word elegance in describing a powerful idea or theory. What does it mean to you?

Smoot

A theory can be elegant in one of two ways: It can tie diverse ideas together in a neat way, or it can appear just plain beautiful in its formulation. People like general relativity because its equations are equivalent to poetry in math. The written equations have beautiful lines to them, like haiku. The elegance comes in the simplicity and internal rhyme.

OMNI

Does the universe have something like free will? Or did it have to advance to this stage in this way?

Smoot

It could have gone many different ways. Like a human life — do you have to end up a certain way? No, you have many accidental branches and choices along the way. However, after you're born and get bigger, you learn a lot, end up coping with the world, and presumably gain perspective and maturity as you go along, and then finally die. Do people have any choice in that? The answer is, they have a lot of choices, but the envelope is prescribed. I'd guess the universe also has a lot of choices, accidental things along the way, but the overall envelope is prescribed.

The logical extension of this is, "If the universe develops from a simple state, then forms all these stars, galaxies, what have you, and keeps getting more complex, how likely is it that intelligent beings exist on other planets?"

Well, it's extremely likely — because of inflation. Even if the probability is extraordinarily small, the universe probably contains many more than the few billion galaxies we can see. You could say we live in a special place, and the universe ends just past our horizon. There's no way to prove or disprove that idea. But if we don't live in a special place, then the scale of the universe is probably a hundred to a million times bigger than what we can see. That's my viewpoint.

[end]


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This article copyright © 1994 by Monte Davis. Used by permission. All rights reserved.



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