John Richard Gott III is a professor of
astrophysical sciencesAstrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
at
Princeton UniversityPrinceton 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....
. He is known for developing and advocating two cosmological theories with the flavor of
science fictionScience fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...
:
Time travelTime travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future of that point without the...
and the
Doomsday argumentThe Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far...
.
Exotic matter time travel theories
Paul DaviesPaul Charles William Davies, AM is an English physicist, writer and broadcaster, currently a professor at Arizona State University as well as the Director of BEYOND: Center for Fundamental Concepts in Science...
's bestseller
How to Build a Time Machine credits Gott with the proposal of using cosmic strings to create a
time machineTime travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future of that point without the...
. Gott's machine depends upon the antigravitational tension of the (hypothetical) strings to deform space without attracting nearby objects. The traveler would follow a precise path around rapidly separating strings, and find that he or she had moved backwards in time. Gott's solution does require that the strings are infinitely long, though: a theorem by
Stephen HawkingStephen William Hawking, CH, CBE, FRS, FRSA is an English theoretical physicist and cosmologist, whose scientific books and public appearances have made him an academic celebrity...
proves that according to
general relativityGeneral relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
,
closed timelike curveIn mathematical physics, a closed timelike curve is a worldline in a Lorentzian manifold, of a material particle in spacetime that is "closed," returning to its starting point...
s cannot be created in a finite region of space unless there is
exotic matterIn physics, exotic matter is a term which refers to matter which would somehow deviate from the norm and have "exotic" properties. There are several uses of the term....
present which violates certain
energy conditionIn relativistic classical field theories of gravitation, particularly general relativity, an energy condition is one of various alternative conditions which can be applied to the matter content of the theory, when it is either not possible or desirable to specify this content explicitly...
s, while cosmic strings would not be expected to violate these conditions, so strings of finite length wouldn't work.
Gott also proposed a "time mirror": a time travel device based on the principle of time delays. The device would be situated near a black hole some hundred or more light years from Earth. The device would act as a light collector and would power the light rays deformed and curved by the gravitational depression of the black hole. The collector would then reveal the past as detailed by the photons that had originated from Earth.
Since Gott believes that time travel is not cosmologically excluded, he has presented the possibility that the universe was created out of itself (at a later time). This controversial suggestion was published with Li-Xin Lin, and it was described by Gott as "it would be like having one branch of a tree circle around and grow up to be the trunk. In that way, the universe could be its own mother."
In his own book,
Time Travel in Einstein's Universe: The Physical Possibilities of Travel Through Time, Gott argues that travel to the past is quite possible, although probably only after the construction of a working device (
during its existence), and certainly not onto the time traveler's own past timeline (he argues that either the
many worldsThe many-worlds interpretation is an interpretation of quantum mechanics that asserts the objective reality of the universal wavefunction, but denies the actuality of wavefunction collapse. Many-worlds implies that all possible alternative histories and futures are real, each representing an...
QMQuantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
interpretation must be invoked to overcome the
Grandfather paradoxThe grandfather paradox is a proposed paradox of time travel first described by the science fiction writer René Barjavel in his 1943 book Le Voyageur Imprudent . The paradox is this: suppose a man traveled back in time and killed his biological grandfather before the latter met the traveler's...
, or that all time travel remain self-consistent, i.e., one can visit the past but not change it, as in the
Novikov self-consistency principleThe Novikov self-consistency principle, also known as the Novikov self-consistency conjecture, is a principle developed by Russian physicist Igor Dmitriyevich Novikov in the mid-1980s to solve the problem of paradoxes in time travel, which is theoretically permitted in certain solutions of general...
). Although he is keen to emphasize that time travel itself is a commonplace physical phenomenon, by this he means time travel into the future at varying rates through
special relativitySpecial relativity is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".It generalizes Galileo's...
, he is not completely committal on the subject of time travel to the past. The book does say that nothing known excludes such travel, but he doesn't completely rule out the possibility that future research may prove it impossible.
Copernicus method and Doomsday theory
Gott first thought of his "Copernicus method" of lifetime estimation in 1969 when stopping at the
Berlin WallThe Berlin Wall was a barrier constructed by the German Democratic Republic starting on 13 August 1961, that completely cut off West Berlin from surrounding East Germany and from East Berlin...
and wondering how long it would stand. Instead of extrapolating a set of developments in world geo-politics (
futurologyFutures studies is the study of postulating possible, probable, and preferable futures and the worldviews and myths that underlie them. There is a debate as to whether this discipline is an art or science. In general, it can be considered as a branch under the more general scope of the field of...
), Gott used his relative ignorance to his advantage by saying that the
Copernican principleIn physical cosmology, the Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position. More recently, the principle has been generalized to the relativistic concept that humans are not privileged observers of the universe...
is applicable in cases where nothing is known; unless there was something special about his visit (which he didn't think there was) this gave a 75% chance that he was seeing the wall
after the first quarter of its life. Based on its age in 1969 (8 years), Gott left the wall with 75% confidence that it wouldn't be there in 1993 ((8/.25) + 1961).
In fact, the wall was brought down in 1989, and 1993 was the year in which Gott applied his "Copernicus method" to the lifetime of the human race. His paper in
NatureNature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
was the first to apply the
Copernican principleIn physical cosmology, the Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position. More recently, the principle has been generalized to the relativistic concept that humans are not privileged observers of the universe...
to the survival of humanity; His original prediction gave 95% confidence that the human race would last for between 5100 and 7.8 million years. (
Brandon CarterBrandon Carter, FRS is an Australian theoretical physicist, best known for his work on the properties of black holes and for being the first to name and employ the anthropic principle in its contemporary form. He is a researcher at the Meudon campus of the Laboratoire Univers et Théories, part of...
's alternative form of the
Doomsday argumentThe Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far...
was delivered earlier that year, but Gott's derivation was independent.)
He made a major effort subsequently to defend his form of the
Doomsday argumentThe Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far...
from a variety of philosophical attacks, and this debate (like the feasibility of closed time loops) is still ongoing. To popularize the
Copernicus method, Gott gave
The New YorkerThe New Yorker is an American magazine of reportage, commentary, criticism, essays, fiction, satire, cartoons and poetry published by Condé Nast...
magazine a 95% confidence interval for the closing time of forty-four
BroadwayBroadway theatre, commonly called simply Broadway, refers to theatrical performances presented in one of the 40 professional theatres with 500 or more seats located in the Theatre District centered along Broadway, and in Lincoln Center, in Manhattan in New York City...
and Off Broadway productions based only on their opening dates. He was more or less 95% correct.
Education work
He received the President's Award for Distinguished Teaching in acknowledgment of his work on the
National Westinghouse/Intel Science Talent SearchThe Intel Science Talent Search , known for its first 57 years as the Westinghouse Science Talent Search is a research-based science competition in the United States for high school seniors. It has been referred to as "the nation's oldest and most prestigious" science competition. In his speech...
high school student science competition. He is an active promoter of the public awareness of science at the popular level, and Princeton students have voted him the school's outstanding professor several times.
Gott is a Presbyterian who distinguishes physical from meta-physical questions by their
teleologyA teleology is any philosophical account which holds that final causes exist in nature, meaning that design and purpose analogous to that found in human actions are inherent also in the rest of nature. The word comes from the Greek τέλος, telos; root: τελε-, "end, purpose...
; he believes that his writings are entirely scientific (not trespassing into the
theologyTheology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...
) because the motivation for the way things are (or might be) is never examined.
See also
- Kip Thorne
Kip Stephen Thorne is an American theoretical physicist, known for his prolific contributions in gravitation physics and astrophysics and for having trained a generation of scientists...
's writings on wormhole time travel marked the introduction of the subject's serious discussion in physics
- Regular pseudopolyhedrons, infinite periodic polyhedra in 3-space
External links
- Where did the Moon come from?- A recent magazine article by J. Richard Gott
- "J. Richard Gott on Life, the Universe, and Everything" an interview with science & spirit magazine which briefly covers Gott's personal views on the major controversies he has stirred up. He combines his two more controversial positions by saying that he would like to travel 200,000 years into the future to see whether his Doomsday argument
The Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far...
prediction would pay off.
- Q & A with Dejan Vinkovic illustrated with a few pictures and a GIF animation of a self-creating universe, in which Gott advocates the importance of the average person having an education in science and especially physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
.
- Abstract to Gott's "A grim reckoning" New Scientist article - online content of the full article requires a paid registration.
- A link to the entire New scientist article.
- Gott & Li's 1998 self-creating universe model compared with other cosmological models of time Rüdiger Vaas argues that Gott's self-creating universe is not rendered meaningless by Kant
KANT is a computer algebra system for mathematicians interested in algebraic number theory, performing sophisticated computations in algebraic number fields, in global function fields, and in local fields. KASH is the associated command line interface...
's first antinomyAntinomy literally means the mutual incompatibility, real or apparent, of two laws. It is a term used in logic and epistemology....
of pure reason.
- http://www.princeton.edu/astro/people/faculty/jrg/ J. Richard Gott, III - Astronomy Faculty page at Princeton on Gott and the Copernican Principle.