Alan Guth | |
|---|---|
 Guth atTrinity College, Cambridge, 2007 | |
| Born | Alan Harvey Guth (1947-02-27)February 27, 1947 (age 78) |
| Alma mater | Massachusetts Institute of Technology (BS,MS,PhD) |
| Known for | Cosmic inflation Borde–Guth–Vilenkin theorem Inflaton |
| Spouse | |
| Children | 2, includingLarry Guth |
| Awards | Oskar Klein Medal (1991) Benjamin Franklin Medal for Physics of theFranklin Institute |
| Scientific career | |
| Fields | Cosmology,theoretical physics,particle physics |
| Institutions | Princeton Columbia Cornell Stanford Linear Accelerator MIT |
| Doctoral advisor | Francis E. Low |
| Part of a series on |
| Physical cosmology |
|---|
 |
Early universe |
Components · Structure |
Alan Harvey Guth (/ɡuːθ/; born February 27, 1947) is an Americantheoretical physicist andcosmologist who is theVictor Weisskopf Professor of Physics at theMassachusetts Institute of Technology. Along withAlexei Starobinsky andAndrei Linde, he won the 2014Kavli Prize "for pioneering the theory of cosmic inflation."[1] Guth's research focuses onelementary particle theory and how particle theory is applicable to the earlyuniverse.
He graduated from MIT in 1968 in physics and stayed to receive a master's and a doctorate, also in physics.
As a junior particle physicist, Guth developed the idea ofcosmic inflation in 1979 atCornell and gave his first seminar on the subject in January 1980.[2][3] Moving on to theSLAC Theory Group atStanford University, Guth formally proposed the idea of cosmic inflation in 1981, the idea that the nascent universe passed through a phase of exponential expansion that was driven by a positivevacuum energy density (negative vacuum pressure). The results of theWMAP mission in 2006 made the case for cosmic inflation very compelling.
Guth was born to aJewish family[4] inNew Brunswick, New Jersey in 1947 and grew up across theRaritan River inHighland Park, where he attended the local public schools.[5] After his junior year atHighland Park High School,[6] he left school and enrolled in a five-year program at theMassachusetts Institute of Technology where he could get his bachelor's and master's after two more years.[7] Guth obtained a bachelor's and master's degree in 1969 and a doctorate in 1972. In 1971, he married Susan Tisch, his high school sweetheart.[6] They have two children:Lawrence (born 1977) and Jennifer (born 1983).[8]
Guth was atPrinceton 1971 to 1974,Columbia 1974 to 1977,Cornell 1977 to 1979, and theStanford Linear Accelerator Center (SLAC) 1979 to 1980. Like many other young physicists of thebaby boom era, he had a hard time finding a permanent job, because there were far fewer assistant professorships than there were young scientists seeking such jobs, a phenomenon that has been referred to as the "generation of lost scholars."[9]
At the start of his career, Guth studiedparticle physics, notphysical cosmology. Guth's earliest work at Princeton was in the study ofquarks, the elementary particles that make up protons and neutrons. At Columbia, Guth studiedgrand unification theories (GUTs), focusing on thecosmological phase transitions generated byspontaneous symmetry breaking. Most GUTs predict the generation ofmagnetic monopoles during spontaneous symmetry breaking, but none had ever been detected—themonopole problem.
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Guth's first step to developing his theory of inflation occurred at Cornell in 1978, when he attended a lecture byRobert Dicke about theflatness problem of the universe.[10] Dicke explained how the flatness problem showed that something significant was missing from theBig Bang theory at the time. The fate of the universe depended on its density. If the density of the universe was large enough, it would collapse into asingularity, and if the actual density of the matter in the cosmos was lower than the critical density, the universe would increasingly get much bigger.
The next part in Guth's path came when he heard a lecture bySteven Weinberg in early 1979.[11] Weinberg talked in two lectures about theGrand Unified Theory (GUT) that had been developed since 1974, and how it could explain the huge amount of matter in the universe compared to the amount of antimatter. The GUT explained all the fundamental forces known in science except for gravity. It established that in very hot conditions, such as those after the Big Bang, electromagnetism, the strong nuclear force, and the weak nuclear force were united to form one force. Weinberg also was the one who emphasized the idea that the universe goes throughphase transitions, similar to the phases of matter, when going from high energy to low energy. Weinberg's discussion of why matter is so dominant over anti-matter showed Guth how precise calculations about particles could be obtained by studying the first few seconds of the universe.
Guth decided to solve this problem by suggesting asupercooling during a delayed phase transition. This seemed very promising for solving themagnetic monopole problem. By the time Guth and his collaboratorHenry Tye came up with that, Guth had gone to theStanford Linear Accelerator Center (SLAC) for a year. Tye suggested that they check that the expansion of the universe would not be affected by the supercooling. The supercooled state is afalse vacuum: It is avacuum in the sense that it is the state of the lowest possible density of energy; it is "false" since its state is not permanent. False vacuums decay, and Guth found that the decay of the false vacuum at the beginning of the universe would produce an exponential expansion of space. This solved themonopole problem, since the expansion proportionately reduces the monopole density.
Guth realized from his theory that the reason the universe appears to be flat was that it had enlarged to such an overwhelming size in comparison to its original size. The perspective is analogous to the apparent flatness of the Earth, on a human scale, when seen from its surface. Theobservable universe was actually only a very small part of theactual universe. Traditional Big Bang theory found values ofomega near 1 to be puzzling, because any deviations from 1 would quickly become much, much larger. In inflation theory, no matter where omega starts, it would approach 1 because of the scale of the universe's expansion. In fact, a major prediction of inflationary theory is that omega will be found to be precisely 1.
Two weeks later, Guth heard colleagues discussing something called thehorizon problem. The microwave background radiation discovered byArno Penzias andRobert Woodrow Wilson appeared extremely uniform, with almost no variance. This seemed very paradoxical because when the radiation was released about 300,000 years after the Big Bang, the observable universe had a diameter of 90 millionlight-years. There was no time for one end of the cosmos to communicate with the other end, because energy cannot move faster than the speed of light. The paradox was resolved, as Guth soon realized, by the inflation theory. Since inflation started with a far smaller amount of matter than the Big Bang had presupposed, an amount so small that all parts would have been causally connected with each other. The universe then inflated, and the homogeneity remained unbroken. The universe after inflation would have been uniform, even if its parts couldn't affect each other.
Guth first made public his ideas on inflation in a seminar at SLAC in January 1980. He ignored magnetic monopoles because they were based on assumptions of GUT, which was outside the scope of the speech. In August 1980, he submitted his paper, entitled "Inflationary universe: A possible solution to the horizon and flatness problems" to the journalPhysical Review.[12] In this paper Guth postulated that the inflation of the universe could be explained if the universe were supercooled 28 orders of magnitude below the critical temperatures required for a phase change.
In December 1981, Guth read a paper from Moscow physicistAndrei Linde saying that the whole universe is within just one bubble, so nothing is destroyed by wall collisions. This conclusion was made using aHiggs field with an energy graph that was originally proposed bySidney Coleman andErick Weinberg. Guth discussed this with Linde, who had independently been working on bubble inflation but without considering the flatness problem. Linde and Guth eventually exchanged papers on the subject.
By 1983, Guth had published a paper describing how his supercooled universe scenario was not ideal, as the "triggering mechanism" to exit such a state would require "extreme fine tuning of parameters" and felt a more natural solution was required.[1][13][14] However, this did not deter him from the belief that the universe expanded exponentially in a vacuum in its early lifetime.[15]
In the past, Guth has studiedlattice gauge theory, magnetic monopoles andinstantons,Gott time machines, and a number of other topics in theoretical physics. Much of Guth's current work includes extrapolating density fluctuations arising from various versions of inflation to test against observations and investigating inflation in "brane world" models.
He is theVictor F. Weisskopf Professor of Physics at the Massachusetts Institute of Technology (MIT). He has written more than 60 technical papers related to the effects of inflation and its interactions with particle physics.
Guth has won many awards and medals, including the Medal of the International Center for Theoretical Physics,Trieste, Italy, withAndrei Linde andPaul Steinhardt and theEddington Medal in 1996, and the2009 Isaac Newton Medal, awarded by the BritishInstitute of Physics.
In July 2012, he was an inaugural awardee of theBreakthrough Prize in Fundamental Physics, the creation of physicist and internet entrepreneur,Yuri Milner.[16][17]
In 2014, he was a co-recipient of theKavli Prize awarded by theNorwegian Academy of Science and Letters, together withAndrei Linde ofStanford University, andAlexei Starobinsky of theLandau Institute for Theoretical Physics, "for pioneering the theory of cosmic inflation."[1][18][19] That same year, Guth received the Golden Plate Award of theAmerican Academy of Achievement.[20]
In 2005, Guth won the award for the messiest office in Boston, organised byThe Boston Globe. He was entered by colleagues who hoped it would shame him into tidying up,[21] but Guth is quite proud of the award.[22]
When people said that gravitational waves would be the smoking gun for inflation, my response was that I thought the room was pretty filled with smoke already.
The nine are recipients of the Fundamental Physics Prize, established by Yuri Milner, a Russian physics student who dropped out of graduate school in 1989 and later earned billions investing in Internet companies like Facebook and Groupon.
It isn't the first time Guth's work has been honored. Last year, he received a $3 million award from the Fundamental Physics Prize Foundation. At the time, he told The New York Times that his bank account balance ballooned from $200 to $3,000,200.
