Davide Castelvecchi over at Degrees of Freedom visits with one of the founding fathers of modern cosmology, Alan Guth.

Now professor of physics at MIT, Guth originated the now widely accepted theory of the inflationary universe. Guth’s idea, with subsequent supporting mathematics, was that the nascent universe passed through a phase of exponential expansion. In 2009, he was awarded the 2009 Isaac Newton Medal by the British Institute of Physics.

[div class=attrib]From Scientific American:[end-div]

On the night of December 6, 1979–32 years ago today–Alan Guth had the “spectacular realization” that would soon turn cosmology on its head. He imagined a mind-bogglingly brief event, at the very beginning of the big bang, during which the entire universe expanded exponentially, going from microscopic to cosmic size. That night was the birth of the concept of cosmic inflation.

Such an explosive growth, supposedly fueled by a mysterious repulsive force, could solve in one stroke several of the problems that had plagued the young theory of the big bang. It would explain why space is so close to being spatially flat (the “flatness problem”) and why the energy distribution in the early universe was so uniform even though it would not have had the time to level out uniformly (the “horizon problem”), as well as solve a riddle in particle physics: why there seems to be no magnetic monopoles, or in other words why no one has ever isolated “N” and “S” poles the way we can isolate “+” and “-” electrostatic charges; theory suggested that magnetic monopoles should be pretty common.

In fact, as he himself narrates in his highly recommendable book, The Inflationary Universe, at the time Guth was a particle physicist (on a stint at the Stanford Linear Accelerator Center, and struggling to find a permanent job) and his idea came to him while he was trying to solve the monopole problem.

Twenty-five years later, in the summer of 2004, I asked Guth–by then a full professor at MIT and a leading figure of cosmology– for his thoughts on his legacy and how it fit with the discovery of dark energy and the most recent ideas coming out of string theory.

The interview was part of my reporting for a feature on inflation that appeared in the December 2004 issue of Symmetry magazine. (It was my first feature article, other than the ones I had written as a student, and it’s still one of my favorites.)

To celebrate “inflation day,” I am reposting, in a sligthly edited form, the transcript of that interview.

DC: When you first had the idea of inflation, did you anticipate that it would turn out to be so influential?

AG: I guess the answer is no. But by the time I realized that it was a plausible solution to the monopole problem and to the flatness problem, I became very excited about the fact that, if it was correct, it would be a very important change in cosmology. But at that point, it was still a big if in my mind. Then there was a gradual process of coming to actually believe that it was right.

DC: What’s the situation 25 years later?

AG: I would say that inflation is the conventional working model of cosmology. There’s still more data to be obtained, and it’s very hard to really confirm inflation in detail. For one thing, it’s not really a detailed theory, it’s a class of theories. Certainly the details of inflation we don’t know yet. I think that it’s very convincing that the basic mechanism of inflation is correct. But I don’t think people necessarily regard it as proven.

[div class=attrib]Read the entire article here.[end-div]

[div class=attrib]Image: Alan Guth. Courtesy of Scientific American.[end-div]