# Julian Barbour

Julian Barbour (born in 1937) is a British physicist with research interests in quantum gravity and the history of science.

## Quotes

* Thus, even now, three and a half centuries after Galileo... it is still remarkably difficult to say categorically whether the earth moves...
** Absolute or Relative Motion, Cambridge University Press, 1989, p. 226
* In fact, I once had a discussion with a distinguished astrophysicist who said to me, well, this is what Mach said, and this is what Mach did and what he required. And I said to him, now excuse me, if you don't mind me saying, what you've just told me is your interpretation of Dennis Sciama's interpretation of Einstein's interpretation of Mach. And he said you're quite right. I’ve never read a word of Mach.
* (November 16, 2024)"The Physicist Who Says Time Doesn't Exist". Theories of Everything with Curt Jaimungal, YouTube. (quote at 14:08 of 1:54:14)

### Killing Time (2000)

    A documentary film by Ijsbrand van Veelen. A Source. The film was awarded Premio Arte, 2000 Teleciencia-Scientific Film Festival (Portugal) & Bronze Dragon, 2000 Beijng International Scientific Film Festival (China) Also see: "Killing Time: A Film by Ijsbrand van Veelen" Films & Videos on Philosophy and Philosophers (Apr 1, 2019) p. 12.
* [T]ime is really an illusion... and motion too... [T]hey are not really there in the external world. They are put into the world by us, in the way we interpret it, and by our brains...
* If you could freeze the camera now and... show me as I am, and all the atoms... and... the whole universe... like a snapshot, the would be... a NOW.
* If you could look microscopically... at... my hemoglobin molecules... you would not recognize me from one second to another. In my body, every second, one hundred million million million... hemoglobin molecules... is destroyed, and the same number is created. So... at each split second, I'm really a very different person.
* [T]he work that I did with... Bruno Bertotti has shown... time that is measured by clocks is... an average of all the changes in the universe.
* [I]f you imagine two NOWs... there will be some difference between them, and if you work out some weighted average of all of that difference... you can call that... the amount of time between them. ...[T]his has nothing to do with some substance... It's just difference between those two things. ...[T]his is the quantity that is... being measured by my watch...
* [T]his is very different from the Newtonian picture where Newton presupposes there's a river of time flowing, that is there before anything is put into it. ...[T]he things are there first, and the time is deduced from it afterwards.
* [A NOW] has no duration. ...[I]t's absolutely instantaneous. There is no thickness to it. Nothing changes. ...So these instants, in one sense, are truly eternal, because they never change, and on the other hand, because nothing changes, they are experienced as a flash. ...[It]'s a nice contradiction... [T]he eternal is experienced as a flash, because nothing changes.
* There is nothing in between... [NOWs]. Each are separate snapshots. ...These [real photographs] ...are not changed by ...reversing the order ...It may be convenient for ...for the way we think about the world and for ordering our experiences, to suppose that these come in a certain order; but ...the picture is not changed... the snapshot is... self-contained.
* [W]hat we call yesterday is self-contained and has its experience of being yesterday, and today has memories of yesterday; and therefor I say that it's later... but each is completely self-contained, and there's no reason why you should put one... here, and another one there...

### Julian Barbour on the nature of time (May 5, 2009)

    John Templeton Foundation. Discussion touches upon on Barbour's "The Nature of Time" (Mar 2009) arXiv:0903.3489. Video source for Clip 1. Barbour does not speak in Clip 2.
* How do you define duration? What does it mean to say that a second today is the same as a second tomorrow? Newton in his... Principia... 1687, gave a... definition of absolute time, which he says flows uniformly without relation to anything external... [H]e says... if nothing... were to happen in the universe... if everything froze... time would still pass uniformly. ...[S]o ...time exists before anything else...
* Richard Feynman... said, "Time is what happens when nothing else does." ...[T]hat's ...not the right way to think about time.
* [I]n 1898... Henri Poincaré wrote... "On the Measure of Time" and he said... there are two fundamental problems to do with time. One... with the definition of duration... What does it mean to say that a second today is the same... [H]e said there's another issue... [not] so widely recognized. ...[H]ow do you define simultaneity at spatially separated points?
* He... explain[ed] how the astronomers... had to grapple with the problem of defining definition, because for 2 1/2 millennia there had been just one standard of time... the rotation of the earth. ...[T]hat had provided an incredibly accurate clock. It's... lost only a few hours in 2 1/2 thousand years. ...Very easy to use. Astronomers only... had to glance at the night sky, at the... Big Dipper... to tell the time within a minute or two... But in the 1890s a crisis developed when they found that using the earth... and... Newton's laws of motion and gravity... the Moon was speeding up. ...[T]hey thought ...the earth was slowing down because of the tidal effects of the moon... and... this would mean that the earth was not a good timekeeper at the accuracy that they wanted.
* Poincaré clearly posed these two problems and... seven years later... independently... Einstein and Poincaré... solved... the problem of defining definition at spatially separated points...
* Einstein... revealed... extraordinary things... [H]is space and time seem to be knit together in a way you can't pull them apart... [S]omeone moving relative to me at any speed would... divide space and time in different ways... [T]he huge excitement about simultaneity meant that the... issue of duration has... been forgotten...

### Bit from It (2011)

    Essay submitted Third FQXi essay competition (2011) on the subject Is Nature Analog or Digital? Sources: 1, 2.
* Wheeler argued that anything physical... derives its... existence... from discrete detector-elicited information-theoretic answers to yes or no quantum binary choices: bits.
* [T]hings, not information, are primary. ... 'bit' derives from 'it'.
* I argue... this weakens but not necessarily destroys the argument that nature is fundamentally digital and continuity an illusion.
* Ontological primacy should not be given to information but to things, as has always been the standpoint of realists.
* I find no reason to reverse the standard assumption of physics... what we experience can be explained by the assumption of an external world governed by law.
* It is a mistake to believe that the digits 0 and 1, being abstract, represent the immaterial. Quite... the contrary... they stand for something quintessentially concrete.
* Greek astronomers observed intricate motions of the sun, moon, and planets on the two-dimensional sky. They explained them—saved the appearances—by positing simple regular motions... in three dimensions. The success... [was] brought to a triumphant conclusion by Kepler...
* Shannon information... [which] he also called entropy or uncertainty... involves things (...Shannon ...messages) and probabilities for those things.
* [S]ymbols have no meaning if divorced from the entities that they represent.
* The concepts of message and probability enable one, for a definite source of $N$ messages, to define Shannon’s information. If $p_{i},\quad i=1,2,...,N$, is the relative probability of message $i$ and $\log p_{i}$ is its base-2 logarithm, then the information $I$ of the given source is(1) $\quad I=-\sum _{k=1}^{N}p_{i}\log p_{i}$.The minus sign makes $I$ positive because all probabilities, which are necessarily greater than or equal zero, are less than unity (their sum being$\textstyle \sum _{i}^{N}p_{i}=1$, so that their logarithms are all negative.
* Structure and variety are central to my critique of 'it from bit'. For we can only talk meaningfully about a thing, including a 'bit', if it has distinguishing attributes. The way that they are knit together, as in the taste, shape and colour of an apple, defines the structure of the thing.
* There is one metalaw of science: it cannot exist without structured things. Structured variety is the ground of being. That is what gives content to both science and life.
* Consider the example of a time capsule... geologists... establish[ed] detailed correlations between the structure of fossils and rocks... They concluded... an immense age of the earth, vastly longer than the bible-deduced... 6000 years. They explained... a long process... in accordance with... laws of nature. They discovered deep time... and... present evidence for it extends today... to all branches of science, especially cosmology and genetics.
* [S]tability of solids, the fossils and rocks... exist... essentially unchanged. ...[T]he configuration carries intrinsic semantic information... different intelligent beings can in principle deduce the law or process.. Support for this is is the independent discovery of evolution by natural selection by Wallis and Darwin.
* [W]e must distinguish three kinds of information: [1] Shannon’s information, the uncertainty as to which message will be selected from a source; [2] factual information, the content of such a message; and [3] intrinsic semantic information, which distinguishes a random message, or configuration, from one that carries meaning and to some extent explains its... genesis. All... have... underpinning in things.
* Shannon-type message sources could not exist if the universe were not subject to laws of nature and far from thermal equilibrium.
* Information theory would never have got off the ground if structured things—configurations—did not exist.
* Probabilities without things are... nothings.
* If we are to speak about ontology, as opposed to efficient coding in communication channels, the most important symbol in (1) is not $p$ for probability but $i$ for the thing, or configuration, that has the probability $p_{i}$.

## Quotes about Barbour

* A more serene vision of the end comes from Julian Barbour, a philosopher who has collaborated with cosmologists in building a peculiar picture of reality that he calls Platonia. In Platonia, all possible configurations of matter exist. There is no passage of time, merely a set of unconnected instants, or "nows". We experience the illusion of time because many of these nows are arranged as if they had evolved through time. Barbour thinks that the possibilities in Platonia should be infinite, and so the comforting illusion of time should be infinite too.
** Stephen Battersby, "The End of Time" New Scientist: The Collection Issue One: The Big Questions (2014) Ed. Graham Lawton, Ch. 6 Time, p. 93.
* [A]t least naively time has completely disappeared from the formalism. This has led to what is called the "problem of time in quantum cosmology", which is how to either A) find an interpretation of the theory that restores a role for time or B) provide an interpretation according to which time is not part of a fundamental description of the world, but only reappears in an appropriate classical limit. ...The most well formulated attempt of type B), which is that of Barbour, may very well be logically consistent. But it forces one to swallow quite a radical point of view about the relationship between time and our experience.
** Stuart Kauffman, Lee Smolin, "A New Approach to the Problem of Time" Towards Quantum Gravity (2000), Proceedings, Polanica Poland, 1999 Ed., Jerzy Kowalski-Glikman, pp. 119-120.
* [T]ime is not an illusion, but the flow of time is. So is change. In spacetime, the future exists and the past doesn't disappear. When we combine Einstein's classical spacetime with quantum mechanics, we get quantum parallel universes... This means there are many pasts and futures that are all real—but this in no way diminishes the unchanging mathematical nature of the full physical reality. ...[A]lthough this idea of an unchanging reality is venerable and dates back to Einstein, it remains controversial... with scientists I greatly respect expressing a spectrum of views. ...Julian Barbour argues in his book The End of Time not only that change is illusory, but that one can even describe physical reality without introducing the time concept at all.
** Max Tegmark, Our Mathematical Universe: My Quest for the Ultimate Nature of Reality (2014) p. 276.

## External links

* Barbour, J @arXiv.org Research Papers
** The Nature of Time award winning paper
* Platonia.com Julian Barbour’s web site
** Books
** Research Papers
* YouTube Videos
** Julian Barbour search YouTube videos
** JulianBarbour6161 channel
** Killing Time (2000) documentary film