## Tuesday, October 03, 2006 ... //

### Physics Nobel prize: Mather, Smoot, and CMB

The folks in Scandinavia have just announced that the

goes to John Mather (NASA), George Smoot (University of California at Berkeley) , their COBE project, and the experimental discovery of the cosmic microwave background anisotropy. Congratulations.

John Mather was the leader of the COBE project. This ancestor of BOOMERANG, MAXIMA, and WMAP has determined between 1989 and 1994 not only that the cosmic microwave background had a blackbody form with temperature 2.725 Kelvins plus minus 0.002 Kelvins, matching the Big Bang predictions: it had also found the anisotropies i.e. variations in temperature as small as 0.001% - something that Stephen Hawking had incidentally called "the most important discovery of the 20th century, if not all time".

As the figure above shows, there has been some progress from COBE to WMAP, too. ;-)

Among the three experiments aboard the COBE satellite, George Smoot was the boss of the differential microwave radiometer (DMR) experiment. The CMB temperature variations were measured by three DMRs. Even though the accuracy wasn't thrilling, the experiment also found the variations to be compatible with a scale-invariant spectrum (n=1), a hallmark of inflationary cosmology.

Smoot and string theory

You might think that the winners are a kind of managers. But they're also thinkers. For example, George Smoot has figured out that "[t]he basic idea is that God's on a budget." :-)

More seriously, later in the article, Smoot tells you how to understand that string theory predicts 9+1 dimensions. The anti-string-theory nutcases will surely not tell you that the last two classes of Smoot's course on relativity are about string theory - much more than what people like me can afford in their QFT courses.

In a recent mini-review of CMB, Smoot and Scott say on page 6 that "there is a great deal of activity on implications of string theory for the early Universe, and hence a very real chance that there might be observational implications for specific scenarios," something that the anti-string-theory nutcases would surely find "outrageous". ;-)

A book that Smoot co-authored,

is at amazon.com rank 3,500,000, even though it is essentially about the discovery that earned the Nobel prize today. Its cover also includes the quote by Stephen Hawking mentioned above.

I apologize in advance if my impression is distorted but John Mather is primarily an astrophysicist and an extraordinarily successful organizer. ;-)