Nobel Causes

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In search of this lumpiness, many groups, including Smoot's, sent radiation detectors on balloons and even in spy planes to altitudes where the CMB is almost completely unfiltered by Earth's atmosphere. Meanwhile, others calculated what level of fluctuation in the energy of the early universe would have allowed lumps, or seeds, to form. Smoot joined a group, led by Mather at NASA, that was working to get a sensitive, radiation-detecting satellite called COBE ("Cosmic Background Explorer") into orbit. By the time COBE was launched on November 18, 1989, astrophysicists had established that very tiny variations in the CMB--as small as a hundred­-thousandth of a degree--would indicate an early universe diverse enough to have produced the current one.

Smoot was in charge of a group of six instruments on COBE, called differential microwave radiometers, that looked for temperature variations called anisotropy in the CMB. Up above Earth, the orbiting COBE had unobstructed reception of the CMB in all directions. Smoot and his Berkeley team analyzed a year's worth of these temperature measurements--millions--looking for anisotropy; when they seemed to find it, they worked to convince themselves that it wasn't due to noise from the instruments on COBE.

In 1992, Smoot announced that COBE had found hundred-thousandth- of-a-degree variations in the energy of the CMB. His map of these variations, showing roughly which patches in the early universe were slightly warmer and which were slightly colder, has been called the universe's baby picture. "The amazing thing is, the universe is almost completely uniform," he says. "It's more uniform than a billiard ball." Smoot received his half of the Nobel Prize for his work on the map; Mather was honored for leading the COBE project and measuring the CMB's spectrum.

Astrophysicists say Smoot and Mather's announcement of COBE's results was a turning point for cosmology, when philosophical speculation about the universe's origins gave way to a science built on quantitative evidence. Smoot's map was subsequently verified by further balloon experiments and has since been enhanced by more sensitive measurements from WMAP, a NASA satellite still in orbit. Bertschinger likens Smoot and the other COBE scientists to explorers finding new continents. "You first find the continents and then explore the coastlines and make your maps more and more refined," he says.

The CMB map met with so much enthusiasm that Smoot wrote a book, Wrinkles in Time, "to show young people that being in science could be an adventure," he says. Now that he's won the Nobel Prize, Smoot says only half-jokingly that he feels even more pressure to be an ambassador for science. "I used to be an outlaw, always going to the fringes of physics, trying strange things, being rebellious," he reminisces.

In a universe thought to be 96 percent mysterious dark matter and dark energy, there are plenty of new and strange territories to explore. "I have a list of eight questions I think are really important," he says (see "Smoot's List," below). One day, Smoot plans to start a cosmological-physics center to address them. But for now, they're bullet points in his lectures--and the cosmic mapmaker keeps the list tacked to his wall.

Smoot's List
The eight cosmology questions that keep George Smoot up at night

1. Did inflation¹ happen? How?

2. What is dark matter?

3. What is dark energy?

4. Why is there more matter than antimatter in the universe?

5. Are there other relics² to be found (e.g., cosmic strings)?

6. Are there extra³ dimensions?

7. Do fundamental constants vary?

8. What other exotic forces might there be?

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¹ the exponential expansion of the young universe

² of the young universe

³ i.e., more than four (three spatial dimensions and time)