Julian Barbour (/ˈbɑːrbər/; born 1937) is a British physicist with
research interests in quantum gravity and the history of science.
Since receiving his PhD degree on the foundations of Einstein's
general theory of relativity at the
University of Cologne
University of Cologne in 1968,
Barbour has supported himself and his family without an academic
position, working part-time as a translator. He resides near Banbury,
1 Timeless physics
2 Machian dynamics
3 Criticism of Barbour's ideas
4.1 Sole author
6 Further reading
7 External links
His 1999 book The End of Time advances timeless physics: the
controversial view that time, as we perceive it, does not exist as
anything other than an illusion, and that a number of problems in
physical theory arise from assuming that it does exist. He argues that
we have no evidence of the past other than our memory of it, and no
evidence of the future other than our belief in it. "Change merely
creates an illusion of time, with each individual moment existing in
its own right, complete and whole." He calls these moments "Nows". It
is all an illusion: there is no motion and no change. He argues that
the illusion of time is what we interpret through what he calls "time
capsules", which are "any fixed pattern that creates or encodes the
appearance of motion, change or history".
Barbour's theory goes further in scepticism than the block universe
theory, since it denies not only the passage of time, but the
existence of an external dimension of time.
Physics orders "Nows" by
their inherent similarity to each other. That ordering is what we
conventionally call a time ordering, but does not come about from
"Nows" occurring at specific times, since they do not occur, nor does
it come about from their existing unchangingly along the time axis of
a block universe, but it is rather derived from their actual content.
J. M. E. McTaggart
J. M. E. McTaggart reached a similar conclusion in his
1908 "The Unreality of Time."
Barbour also researches Machian physics, a related field. The Machian
approach requires physics to be constructed from directly observable
quantities. In standard analytical dynamics a
system's future evolution can be determined from a state consisting of
particle positions and momenta (or instantaneous velocities). Barbour
believes that the Machian approach eschews the momenta/instantaneous
velocities, which are not directly observable, and so needs more than
one "snapshot" consisting of positions only. This relates to the
idea of snapshots, or "Nows" in Barbour's thinking on time.
Along with physicist Bruno Bertotti, Barbour developed a technique
called "best matching" for deriving gravitational equations directly
from astronomical measurements of objects' spatial relations with each
other. Published in 1982, the method describes gravitational effects
as accurately as Einstein's general relativity, but without the need
for a "background" grid of spacetime. According to physicist David
Wiltshire at the University of Canterbury in New Zealand, such a truly
Machian or relational approach could explain the appearance of an
accelerated expansion of the universe without invoking a causative
agent such as dark energy.
Criticism of Barbour's ideas
Lee Smolin repeatedly refers to Barbour's ideas
in his books. However Smolin is usually highly critical of Barbour's
ideas, since Smolin is a proponent of a realist theory of time, where
time is real and not a mere illusion as Barbour suggests. Smolin
reasons that physicists have improperly rejected the reality of time
because they confuse their mathematical models—which are timeless
but deal in abstractions that do not exist—with reality. Smolin
hypothesizes instead that the very laws of physics are not fixed, but
that they actually evolve over time.
Theoretical physicist Sean Carroll has criticised Barbour and all
physicists who adhere to a "timeless-view" of the universe:
The problem is not that I disagree with the timelessness crowd, it’s
that I don’t see the point. I am not motivated to make the effort to
carefully read what they are writing, because I am very unclear about
what is to be gained by doing so. If anyone could spell out
straightforwardly what I might be able to understand by thinking of
the world in the language of timelessness, I’d be very happy to
re-orient my attitude and take these works seriously.
1999. The End of Time: The Next Revolution in our Understanding of the
Universe. Oxford Univ. Press. ISBN 0-297-81985-2;
ISBN 0-19-511729-8 (paperback: ISBN 0-7538-1020-4)
2001. The Discovery of Dynamics: A Study from a Machian Point of View
of the Discovery and the Structure of Dynamical Theories.
2006. Absolute or Relative Motion?. ISBN 0-19-513203-3. Paperback
reprinting of The Discovery of Dynamics.
1982 (with B. Bertotti). Mach's Principle and the Structure of
1994 (with Vladimir Pavlovich Vizgin) Unified Field Theories in the
First Third of the 20th Century . ISBN 0-8176-2679-4.
1996 (with Herbert Pfister) Mach's Principle: From Newton's Bucket to
Quantum Gravity. Birkhaueser. ISBN 0-8176-3823-7.
Julian Barbour – Contact". Retrieved 1 October 2011.
^ Nature of Time
^ It is utterly beyond our power to measure the changes of things by
time ... time is an abstraction at which we arrive by means of the
changes of things; made because we are not restricted to any one
definite measure, all being interconnected. Mach himself was a sceptic
about time: "It is utterly beyond our power to measure the changes of
things by time ... time is an abstraction at which we arrive by means
of the changes of things; made because we are not restricted to any
one definite measure, all being interconnected."
^ Merali, Zeeya. "Is Einstein's Greatest Work All Wrong—Because He
Didn't Go Far Enough?". Discover magazine. Retrieved 10 April
^ Smolin L., (1997) Three Roads to Quantum Gravity
(pp. 119–121, 131); (2006) The Trouble with Physics
(pp. 321–22); (2013)
Time Reborn (pp. 92–5)
^ Monk, Ray (6 June 2013). "
Time Reborn by
Lee Smolin – review". The
Guardian. Archived from the original on 28 July 2013.
^ "Time Reborn: a new theory of time – a new view of the world".
Royal Society of Arts. 21 May 2013. Archived from the original on 28
Scientific work by others bearing on Barbour's theories
Anderson, Edward (2004) "Geometrodynamics: Spacetime or space?" PhD
thesis, University of London.
Anderson, Edward (2007) "On the recovery of Geometrodynamics from two
different sets of first principles", Stud. Hist. Philos. Mod. Phys.
Baierlein, R. F., D. H. Sharp, and
John A. Wheeler
John A. Wheeler (1962)
"Three-dimensional geometry as the carrier of information about time",
Phys. Rev. 126: 1864–1865.
Max Tegmark (2008) "The Mathematical Universe", Found. Phys. 38:
Wolpert, D. H. (1992) "Memory Systems, Computation, and The Second Law
of Thermodynamics", International Journal of Theoretical
743–785. Barbour argues that this article supports his view of the
illusory nature of time.
The End Of Time: A
Talk With Julian Barbour
Discover December 2000 From Here to Eternity
Killing Time A 25-minute feature about the idea that time is an
illusion, filmed by Dutch TV in December 1999 and first shown early in
The End of Time, Chapter One (requires free registration)
Video (with mp3 available) of Barbour discussion on Bloggingheads.tv
Does Time Exist? 2012 lecture at the Perimeter Institute for
ISNI: 0000 0001 1071 9009