John Richard Gott III (born February 8, 1947) is a professor of

astrophysical sciences Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the hea ...

Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...

. He is known for his work on

time travel Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Time travel is a w ...

and the

Doomsday argument The Doomsday Argument (DA), or Carter catastrophe, is a probabilistic argument that claims to predict the future population of the human species, based on an estimation of the number of humans born to date. The Doomsday argument was originally p ...

Exotic matter time travel theories

Paul Davies's bestseller ''How to Build a Time Machine'' credits Gott with the proposal of using

cosmic strings Cosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry-breaking phase transition in the early universe when the topology of the vacuum manifold associated to this symmetry breaking was not simpl ...

to create a

time machine Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Time travel is a w ...

. 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 Hawking proves that according to

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

closed timelike curve In mathematical physics, a closed timelike curve (CTC) is a world line in a Lorentzian manifold, of a material particle in spacetime, that is "closed", returning to its starting point. This possibility was first discovered by Willem Jacob van Sto ...

s cannot be created in a finite region of space unless there is exotic matter present which violates certain

energy condition In relativistic classical field theories of gravitation, particularly general relativity, an energy condition is a generalization of the statement "the energy density of a region of space cannot be negative" in a relativistically-phrased mathe ...

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 worlds The many-worlds interpretation (MWI) is an interpretation of quantum mechanics that asserts that the universal wavefunction is objectively real, and that there is no wave function collapse. This implies that all possible outcomes of quantum me ...

interpretation of quantum mechanics must be invoked to overcome the Grandfather paradox, 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 principle The Novikov self-consistency principle, also known as the Novikov self-consistency conjecture and Larry Niven's law of conservation of history, is a principle developed by Russian physicist Igor Dmitriyevich Novikov in the mid-1980s. Novikov inten ...

). 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 relativity In physics, the special theory of relativity, or special relativity for short, is a scientific theory regarding the relationship between space and time. In Albert Einstein's original treatment, the theory is based on two postulates: # The laws o ...

, he is not completely committed 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 Wall The Berlin Wall (german: Berliner Mauer, ) was a guarded concrete barrier that encircled West Berlin from 1961 to 1989, separating it from East Berlin and East Germany (GDR). Construction of the Berlin Wall was commenced by the government ...

and wondering how long it would stand. Gott postulated that the

Copernican principle In physical cosmology, the Copernican principle states that humans, on the Earth or in the Solar System, are not privileged observers of the universe, that observations from the Earth are representative of observations from the average position ...

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 50% confidence that it wouldn't be there in 1993 (1969 + 8·(1.5/0.5)). 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 ''

Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

'' was the first to apply the

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 Carter's alternative form of the

was delivered earlier that year, but Gott's derivation was independent.) He made a major effort subsequently to defend his form of the

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 Yorker ''The New Yorker'' is an American weekly magazine featuring journalism, commentary, criticism, essays, fiction, satire, cartoons, and poetry. Founded as a weekly in 1925, the magazine is published 47 times annually, with five of these issues ...

'' magazine a 95% confidence interval for the closing time of forty-four Broadway and Off Broadway productions based only on their opening dates.

Education work

He received the President's Award for Distinguished Teaching in acknowledgment of his work on the National Westinghouse/Intel Science Talent Search 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 was born in

Louisville, Kentucky Louisville ( , , ) is the largest city in the Commonwealth of Kentucky and the 28th most-populous city in the United States. Louisville is the historical seat and, since 2003, the nominal seat of Jefferson County, on the Indiana border ...

. He is a

Presbyterian Presbyterianism is a part of the Reformed tradition within Protestantism that broke from the Roman Catholic Church in Scotland by John Knox, who was a priest at St. Giles Cathedral (Church of Scotland). Presbyterian churches derive their nam ...

who distinguishes physical from meta-physical questions by their

teleology Teleology (from and )Partridge, Eric. 1977''Origins: A Short Etymological Dictionary of Modern English'' London: Routledge, p. 4187. or finalityDubray, Charles. 2020 912Teleology" In ''The Catholic Encyclopedia'' 14. New York: Robert Appleton ...

; he believes that his writings are entirely scientific (not trespassing into

theology Theology is the systematic study of the nature of the divine and, more broadly, of religious belief. It is taught as an academic discipline, typically in universities and seminaries. It occupies itself with the unique content of analyzing the ...

) because the motivation for the way things are (or might be) is never examined.

Notes

References

* Gott, Richard, J III. ''Implications of the Copernican principle for our future prospects'' (1993, Nature vol 363, p315) This was Gott's original description of the Doomsday argument. He later published a popularized version in... * Gott, Richard, J III. ''A Grim Reckoning'', 15 November 1997

New Scientist ''New Scientist'' is a magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publishe ...

(page 36). * Paul Davies, ''How to build a time machine'', 2002, Penguin popular science, gives a very brief non-mathematical description of Gott's alternative; the specific setup is not intended by Gott as the best-engineered approach to moving backwards in time, rather, it is a theoretical

argument An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialectic ...

for a non-

wormhole A wormhole (Einstein-Rosen bridge) is a hypothetical structure connecting disparate points in spacetime, and is based on a special Solutions of the Einstein field equations, solution of the Einstein field equations. A wormhole can be visualize ...

means of time travel. * J Richard Gott, ''Time Travel in Einstein's Universe: The Physical Possibilities of Travel Through Time'', 2002, Houghton Mifflin Books, * J. R. Gott, ''Pseudopolyhedrons'', American Mathematical Monthly, Vol 74, p. 497-504, 1967. * J. Richard Gott, ''The cosmic web - mysterious architecture of the universe.'' Princeton University Press, Princeton 2016, . * Neil deGrasse Tyson, Michael A. Strauss, J. Richard Gott, '' Welcome to the Universe: An Astrophysical Tour''. Princeton University Press, Princeton 2016, .

External links

* 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

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 the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

.
Abstract to Gott's "A grim reckoning" New Scientist article
- online content of the full article requires a paid registration.

* Rüdiger Vaas argues that Gott's self-creating universe is not rendered meaningless by Kant's first

antinomy Antinomy (Greek ἀντί, ''antí'', "against, in opposition to", and νόμος, ''nómos'', "law") refers to a real or apparent mutual incompatibility of two laws. It is a term used in logic and epistemology, particularly in the philosophy of I ...