Alan Guth

     . . . is Weisskopf Professor of Physics at the Massachusetts Institute of Technology. Elected a member of the National Academy of Sciences and recipient of many academic awards, Professor Guth was one of Newsweek's "Top 25 American Innovators" and among Science Digest's "100 Brightest Scientists Under 40." Science magazine recommends his eminently readable book general audience book The Inflationary Universe for "anyone interested in ideas or the history of ideas."

Universes for Free


Want to understand the origin of our observable universe -- perhaps 100 billion galaxies, each containing 100 billion stars? Look deep within the atom. Cosmologist, meet particle physicist. MIT Professor Alan Guth is both cosmologist and particle physicist. He also is credited with "inflation theory," a modification of standard cosmology's Big Bang theory. Inflation explains the very earliest fractions of a second after creation, when all the mass in our observable universe was compressed into a space smaller than a proton.

      Working closely with other physicists, Dr. Guth came up with an explanation of how the observable universe got to where we are right now. If Guth's inflation theory is right -- and he and a legion of other cosmologists and physicists believe it is -- all the matter that we see today (stars, galaxies, planets, us) would have resulted from the early inflationary phase he proposed. The time frame? 10 to the minus 37 seconds. That's a part of second so short it requires a decimal point and 37 zeros in front of the one to account for it. Short. Very Short.

      So what's the short course on "inflation"? Negative energy in the form of gravitational fields expanding exponentially. According to inflation theory, matter was actually created as space expanded at a colossal expansion rate. (It only takes about 100 doublings to get from that "smaller than a proton" to the size of today's observable universe.) The expansion was driven by a force most of us don't even know exists: gravitational repulsion. Guth's mathematics show how the expansion itself could create matter in just the right way, so that as the expansion proceeds, the observable universe gets closer and closer to where we know, in fact, we ended up. Right now.

      When his adventure began in the late 1970's, Alan Guth and his physicist friend Henry Tye were just trying to figure out if there was any way that they could make cosmology consistent with particle physics' new Grand Unified Theories. How did Guth and Tye come up with a revolutionary new idea? They questioned their own assumptions -- assumptions about the conservation of energy, about the nature of gravity, about how a brand new universe would cool.

      How old is the universe? All we can do is date the universe we recognize, the beginning of the rapid expansion which is now slowing down. But theorists aren't slowing down. In much the same way double entry bookkeeping ends up at zero, physicists are now theorizing that a universe could be created with zero energy. If they're right, an infinite number of universes is as mathematically plausible as just one. In fact, there may be a very, very long pre-history -- before the "Bang" -- with infinite universes entirely possible.

      Meanwhile, Guth is confident that both cosmologists' observations and theories will be revolutionized in the next 5 to 10 years. Answers to Big Questions are on the horizon. How will physicists and cosmologists find these answers? Working together. Especially in the sciences, finding answers takes a community, especially when the question is as big as the origin of the universe. Or universes.



[This Program was recorded November 2, 1998 in Cambridge, Massachusetts, U.S.]


Conversation 1


Alan Guth gives us a glimpse into the rapidly changing world of cosmology and an introduction to the ideas he brought together to create "inflation theory" -- now several theories. It's a twist on the Big Bang theory which suggests that many of the important events that shaped our universe, happened in a fraction of a second, about 10 to the minus 37 seconds -- that's a decimal point, 36 zeros and a one. He explains cosmology as the study of the universe as a whole and a study of the history of the universe and joins the speculations about the history of the universe which may go well beyond the one we can observe.



Conversation 2


Professor Guth elaborates on the link between particle physics and cosmology, explaining the consequence of the extreme heat of the universe at the time it formed. Particle physics describes how matter might behave at such extraordinarily high energies and densities. He explains what in particle physics -- the source of much of the impetus of the cosmology of the last 20 years -- is well understood and observable, with the increased acceptance of Grand Unified Theories in the late 1970s. He tells why it is important,contrary to human expectations, that gravity is actually extraordinarily weak on the scale of elementary particles and that it is unique among the forces for being a long-range force and always attractive. ÊHe describes the three other primary forces of nature: the strong interactions, electromagnetic interactions and the weak interactions. He describes the joy physicists experience as they uncover the universe's secrets.




Conversation 3


If inflation theory is right (and Professor Guth is confident it is) it explains the origin of essentially all the matter and energy and contents of the universe (though not of the universe itself). In simple terms, he offers inflation theory's basic hypothesis of how the universe started with an unexpected gravitational repulsion being the driving force behind the Big Bang. And while the early universe would have undergone this colossal expansion, matter would actually be created as the space expanded. All the matter we see today would have resulted from that early phase of colossal expansion, compressed to a size far smaller than the size of a proton. Today's cosmologists' basic questions are, in effect, the same ones humans have asked throughout history, though approached in a more detailed way than found in the Biblical book of Genesis. Professor Guth recreates the adventure that led him and his colleague, Henry Tye, to the formulation of Inflation Theory.



Conversation 4


Still speaking in laypeople's terms, Alan Guth continues with his youthful quest for a new theory of cosmic origins, when he and others were attempting to make cosmology consistent with particle physics' Grand Unified Theories. In the course of explaining how the universe got to where we are today, Dr. Guth makes sense out of phase transitions, supercooling, magnetic monopoles, gravitational repulsion and exponential expansion while solving the "flatness problem" and exposing "the big loophole" in the idea of the conservation of energy.




Conversation 5


There has been a big change in what physicists think about things, including the idea that at zero energy, there are essentially an infinite number of possible states. He goes on to tell what physicists are currently wrestling with. He shows how the idea that you could build a universe with zero energy means that you could just as well build an infinite number of universes as one universe, with most versions of "inflation" predicting there should be an endless, infinite creation of universes, not just one. The observable universe, he reminds us, is just plain BIG -- something on the order of 100 billion galaxies with galaxies containing about 100 billion stars. He continues to stand in awe of how gigantic it all is, explaining how he and most physicists are fascinated that the more they learn about nature, the simpler nature appears. He gives a glimpse of what "string theory" or "super string theory" is about. Cosmology, he assures us, is an observational science and shows how new observations are interacting with evolving theories, offering possibilities for how observations will probably revolutionize cosmology again in the coming 4 or 5 years.



Conversation 6


Physics, according to Professor Guth, is very much a community -- no idea is ever the product of one person, including "inflation." Physicists' universal language -- mathematics -- is affirmed to be magical, working along side English as the worldwide vernacular, both increasingly available to scientists everywhere on the Internet.




Related Links:

Alan Guth's astonishingly readable book The Inflationary Universe: The Quest for a New Theory of Cosmic Origins is published by Addison-Wesley, part of the Perseus Book group. It is a Helix Book.


And, here's a little background information on Paula Gordon and Bill Russell, the Program co-hosts.



Professor Guth extended the same generous spirit in welcoming us to his office at M.I.T. as he does to readers in his wonderfully accessible book. We thoroughly enjoyed our sojourn into the domain of a world-class physicist and a lovely human being. Our thanks to Alan Guth.

Peter Hale, senior publicist at Perseus Books, did a masterful job orchestrating our schedule so that this conversation could happen. We thank Peter for being a notable professional in his own right.




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