| Julian Barbour | |
|---|---|
| Born | 1937 |
| Residence | Oxfordshire |
| Citizenship | British |
| Fields | physics |
| Alma mater | University of Cologne |
| Known for | Time as illusion |
Julian Barbour (born 1937) is a British physicist with research interests in quantum gravity and the history of science.
Since receiving his Ph.D. degree on the foundations of Einstein's general theory of relativity at the 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, England.[1]
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His 1999 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. (In fact, the emergent ordering is probably not the single line of conventional time, but a branching structure like that of many worlds theory).
The philosopher J. M. E. McTaggart reached a similar conclusion in his 1908 The Unreality of Time. And in one of his last letters, Einstein wrote "People like us, who believe in physics, know that the distinction between past, present and future is only a stubborn, persistent illusion."[2]
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). The Machian approach eschews the momenta/instantaneous velocities, which are not directly observable, and so needs more than one "snapshot" consisting of positions only.[3] This relates to the idea of snapshots, or "Nows" in Barbour's thinking on time.[4]
Barbour is cited in two books by Lee Smolin, his (1997) Three Roads to Quantum Gravity (pp. 119–121, 131) and his (2006) The Trouble with Physics (pp. 321–22).