Alan Guth

Alan Guth

Overview
Alan Harvey Guth is an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 theoretical physicist and cosmologist. Guth has researched elementary particle
Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles. If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which...

 theory (and how particle theory is applicable to the early universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

). Currently serving as Victor Weisskopf Professor of Physics at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

, he is the originator of the inflationary universe theory
Cosmic inflation
In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density. The inflationary epoch comprises the first part...

.

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 first developed the idea of cosmic inflation
Cosmic inflation
In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density. The inflationary epoch comprises the first part...

 in 1979 at Cornell
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 and gave his first seminar on the subject in January 1980.
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Encyclopedia
Alan Harvey Guth is an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 theoretical physicist and cosmologist. Guth has researched elementary particle
Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles. If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which...

 theory (and how particle theory is applicable to the early universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

). Currently serving as Victor Weisskopf Professor of Physics at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

, he is the originator of the inflationary universe theory
Cosmic inflation
In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density. The inflationary epoch comprises the first part...

.

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 first developed the idea of cosmic inflation
Cosmic inflation
In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density. The inflationary epoch comprises the first part...

 in 1979 at Cornell
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 and gave his first seminar on the subject in January 1980. Moving on to Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

 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 positive vacuum energy
Vacuum energy
Vacuum energy is an underlying background energy that exists in space even when the space is devoid of matter . The concept of vacuum energy has been deduced from the concept of virtual particles, which is itself derived from the energy-time uncertainty principle...

 density (negative vacuum pressure). The results of the WMAP mission in 2006 made the case for cosmic inflation very compelling.

Early life


Alan Guth was born on February 27, 1947 in New Brunswick, New Jersey
New Brunswick, New Jersey
New Brunswick is a city in Middlesex County, New Jersey, USA. It is the county seat and the home of Rutgers University. The city is located on the Northeast Corridor rail line, southwest of Manhattan, on the southern bank of the Raritan River. At the 2010 United States Census, the population of...

. After his junior year at Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

, he enrolled in a five-year program where he could get his bachelor’s and master’s after two more years. 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. They have two children: Lawrence (born 1977) and Jennifer (born 1983).

Guth was at Princeton
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....

 1971 to 1974, Columbia
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...

 1974 to 1977, Cornell
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 1977 to 1979, and the Stanford Linear Accelerator Center
Stanford Linear Accelerator Center
The SLAC National Accelerator Laboratory, originally named Stanford Linear Accelerator Center, is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S...

 (SLAC) 1979 to 1980. Like many other young physicists of the baby boom
Baby boom
A baby boom is any period marked by a greatly increased birth rate. This demographic phenomenon is usually ascribed within certain geographical bounds and when the number of annual births exceeds 2 per 100 women...

 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.”

At the start of his career, Guth studied on particle physics
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...

, not cosmology
Cosmology
Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

. Guth's earliest work at Princeton was in the study of quark
Quark
A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...

s, the elementary particles that make up protons and neutrons. At Columbia, Guth studied grand unification (GUTs), focusing on the phase transition
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.A phase of a thermodynamic system and the states of matter have uniform physical properties....

s generated by spontaneous symmetry breaking
Spontaneous symmetry breaking
Spontaneous symmetry breaking is the process by which a system described in a theoretically symmetrical way ends up in an apparently asymmetric state....

. Most GUTs predict the generation of magnetic monopoles during spontaneous symmetry breaking, but none had ever been detected - the monopole problem.

Inflationary theory


Guth's first step to developing his theory of inflation occurred at Cornell in 1978, when he attended a lecture by Robert Dicke about the flatness problem of the universe. Dicke explained how the flatness problem showed that something significant was missing from the Big 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 a singularity
Gravitational singularity
A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system...

, 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 by Steven Weinberg
Steven Weinberg
Steven Weinberg is an American theoretical physicist and Nobel laureate in Physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and electromagnetic interaction between elementary particles....

 in early 1979. Weinberg talked in two lectures about the Grand 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 through phase 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 a supercooling
Supercooling
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid....

 during a delayed phase transition. This seemed very promising for solving the magnetic monopole
Magnetic monopole
A magnetic monopole is a hypothetical particle in particle physics that is a magnet with only one magnetic pole . In more technical terms, a magnetic monopole would have a net "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring...

 problem. By the time they came up with that, Guth had gone to the Stanford Linear Accelerator Center for a year, but Guth had been talking to Henry Tye
Henry Tye
Sze-Hoi Henry Tye is a Chinese-American cosmologist and theoretical physicist most notable for proposing that a brane and an antibrane attraction and annihilation with one another, causes cosmic inflation and his work on superstring theory, brane cosmology and elementary particle physics. He...

 back and forth. Tye suggested that they check that the expansion of the universe not be affected by the supercooling. In the supercooled state, a false vacuum
False vacuum
In quantum field theory, a false vacuum is a metastable sector of space that appears to be a perturbative vacuum, but is unstable due to instanton effects that may tunnel to a lower energy state. This tunneling can be caused by quantum fluctuations or the creation of high-energy particles...

 is produced. The false vacuum is a vacuum in the sense that it is state of the lowest possible density of energy; it is false in the sense that it is not a permanent state of being. False vacuums decay, and Guth was to find that the decay of the false vacuum at the beginning of the universe would produce amazing results, namely the exponential expansion of space. This solved the monopole problem, since the expansion dilutes the monopole density.

Guth realized from his theory that the reason the universe appears to be flat was that it was fantastically big, just the same way the spherical Earth appears flat to those on its surface. The observable universe was actually only a very small part of the actual universe. Traditional Big Bang theory found values of omega near one to be puzzling, because any deviations from one would quickly become much, much larger. In inflation theory, no matter where omega starts, it would be driven towards equal to one, because the universe becomes so huge. In fact, a major prediction of inflationary theory is that omega will be found to be one.

Two weeks later, Guth heard colleagues discussing something called the horizon problem
Horizon problem
The horizon problem is a problem with the standard cosmological model of the Big Bang which was identified in the 1970s. It points out that different regions of the universe have not "contacted" each other because of the great distances between them, but nevertheless they have the same temperature...

. The microwave background radiation discovered by Arno Penzias and Robert Woodrow Wilson
Robert Woodrow Wilson
For the American President, see Woodrow Wilson.Robert Woodrow Wilson is an American astronomer, 1978 Nobel laureate in physics, who with Arno Allan Penzias discovered in 1964 the cosmic microwave background radiation...

 appeared extremely uniform
Uniformity
Uniformity may refer to:* Distribution uniformity, a measure of how uniformly water is applied to the area being watered* Religious uniformity, the promotion of one state religion, denomination, or philosophy to the exclusion of all other religious beliefs...

, 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 million light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s. There was no time for one end of the cosmos to communicate with the other end, because energy can not 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 in touch with each other. Inflation then blew up the universe so quickly that there was no time for the essential homogeneity to be broken. The universe after inflation would have been very uniform even though the parts were not still in touch with each other.

Guth first made public his ideas on inflation in a seminar at SLAC on January 23, 1980. In August, he submitted his paper, entitled “The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems” to the Physical Review. He ignored magnetic monopoles because they were based on assumptions of GUT, which was outside the scope of the speech.

In December 1981, Guth read a paper from Moscow physicist Andrei Linde
Andrei Linde
Andrei Dmitriyevich Linde is a Russian-American theoretical physicist and professor of Physics at Stanford University. Dr. Linde is best known for his work on the concept of the inflationary universe. He received his Bachelor of Science degree from Moscow State University. In 1975, Linde was...

 saying that the whole universe is within just one bubble, so nothing is destroyed by wall collisions. This conclusion was made using a Higgs field with an energy graph that was originally proposed by Sidney Coleman
Sidney Coleman
Sidney Richard Coleman was an American theoretical physicist who studied under Murray Gell-Mann.- Life and work :Sidney Coleman grew up on the Far North Side of Chicago...

 and Erick Weinberg
Erick Weinberg
Erick Weinberg is a theoretical physicist who has spent most of his career at the Department of Physics in Columbia University. He obtained a PhD from Harvard in 1973. His advisor was Sidney Coleman with whom he discovered the Coleman-Weinberg mechanism for radiative spontaneous symmetry breaking...

. 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.

Current life


In the past Guth has studied lattice gauge theory, magnetic monopoles and instantons, 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.

Guth is the Victor F. Weisskopf
Victor Frederick Weisskopf
Victor Frederick Weisskopf was an Austrian-born Jewish American theoretical physicist. He did postdoctoral work with Werner Heisenberg, Erwin Schrödinger, Wolfgang Pauli and Niels Bohr...

 Professor of Physics
at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

 (MIT). So far, he has written about 60 technical papers related to the effects of inflation and its interactions with particle physics. He has won many awards and medals, including the Medal of the International Center for Theoretical Physics, Trieste, Italy, with Andrei Linde and Paul Steinhardt
Paul Steinhardt
Paul J. Steinhardt is the Albert Einstein Professor of Science at Princeton University and a professor of theoretical physics. He received his B.S. at the California Institute of Technology and his Ph.D. in Physics at Harvard University...

 and the Eddington Medal
Eddington Medal
The Eddington Medal, named after Sir Arthur Eddington, is awarded by the Royal Astronomical Society nominally once every two years for investigations of outstanding merit in theoretical astrophysics.- Recipients :* 1953 Georges Lemaître...

 in 1996, and the 2009 Isaac Newton Medal
Isaac Newton Medal
The Isaac Newton Medal is a prize awarded annually by the Institute of Physics and is valued at £1000. The award is given to a physicist, regardless of subject area, background or nationality, for outstanding contributions to physics...

, awarded by the British Institute of Physics
Institute of Physics
The Institute of Physics is a scientific charity devoted to increasing the practice, understanding and application of physics. It has a worldwide membership of around 40,000....

.

In 2005 Guth won the award for the messiest office, organised by the Boston Globe. He was entered by colleagues who hoped it would shame him into tidying up, but Guth is quite proud of the award.

Quotations

  • "It is said that there's no such thing as a free lunch. But the universe is the ultimate free lunch". — A. H. Guth
  • "It's actually safe to create a universe in your basement. It would not displace the universe around it even though it would grow tremendously"

Publications

  • Guth, Alan, "The Inflationary Universe: The Quest for a New Theory of Cosmic Origins". 1997. ISBN 0-201-32840-2 or ISBN 0-224-04448-6

External links