A Matter of Time

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'Time is just one damn thing after another.. " - Paul Davies ...LOVE it! #BestQuoteOfTheDay : )

I cannot express in words how much I enjoy these lectures in physics, either classical or quantum mechanical. I believe anyone interested in either subject should make it a habit to download these videos and give them a listen. It is not all about entertainment, rather, it is about learning that makes these forums so educational or intellectually stimulating. Thanks for uploading these videos.

"I think that you just logically self-destructed" -Max Tegmark Awesome put down. Almost as good, but certainly less subtle, than the phrase attributed to Pauli: "Not is only is it not correct. It's not even wrong.'

Maudlin's alternative topology axioms are just a special case of one-dimensional open set point topology that he rejected at the start. So he really did not add anything new to "geometry", and in fact he made open set topology just harder to do for general spaces. All he really claims is that the geometrical basis for physics can be a restricted field of open set topology. What's more, he is wrong about putting directions on open sets. Most open sets admit a vector field which is often orientable. But further, many of the more interesting and perhaps physically relevant geometrical spaces are non-orientable. Such are spacetime that contain closed timelike curves. So while Maudlin's Line Axioms are a useful simplification, it is hard to credit that they can be used as a complete basis for mathematical physics as we currently know it, especially if close timelike curves can be found, since then time would not be orientable as Maudlin seems to think it is, and that's a response Davies should have mentioned, to whit, one can possibly do experiments to show spacetime is non-orientable which would empirically justify Davies interpretation that we what perceive is time asymmetry of states, not time flow or time direction. Of course, when time asymmetry is observable then a natural direction to time can be defined, it is phenomenal though, not fundamental in the laws of physical (physical states are not physical laws), I think that's what Davies was trying to say, but they kept interrupting him. Another thing is that Maudlin's language is nothing but Penrose-Rindler Twistor theory. And Tegmark is right that this does not help explain the psychological "flow" of time. And Davies is correct, in the sense that the best science can determine is that the "flow of time" is psychological, and is based on the rock solid reality of time asymmetry. A simple thought experiment can show this, imagine a putative Strong AI entity run in a computer that is set up with future boundary conditions at our "present" and then run entirely backwards in computer simulation time from our perspective. Would the AI have a consciousness? We might grant yes (some philosophers would say yes, at least plausibly, by any reasonable Turing test and assuming functionalist theories of consciousness) but then this AI creature would experience a flow of time exactly opposite to ours. Meaning that flow of time is real enough, but is relative to states of consciousness, in other words, flow of time is real psychology but illusory as fundamental physics. The root of Maudlin's confusion I think is precisely that, as he points out, time is one-dimensional, and therefore there are only two orientations that time permits, and so it is too easy to be fooled into thinking one of those orientations is the real objective flow direction of time. Once one realises this source of easy enticement I think Davies' view becomes far more sensible.  BTW: I read a few comments dissing Maudlin, but as Tegmark pointed out, the discussion got most interesting when Maudlin made his provocative claims about an intrinsic direction to the time dimension. Even if someone ultimately is spouting nonsense, it can reveal useful truths or questions that have not been fully answered.

It would be nice if these WSF films put the name of the panelists in the description above, and even better if it included a very short one or two line bio for each.  Often a panelist will say something that makes me wonder about their occupation - math, physics, philosophy etc. and many times I'd love to see the correct spelling of their names.  As it is now I have to go back to the beginning to listen to the introductions again.  Besides that - I LOVE WSF - Keep up the wonderful uploads!

I love to watch the World Science Festival. Keeps my brain working and therefore young. Brain exercises for real.

This is more than my brain can handle. Had to watch it in small fragments. Very fascinating!

Another gem! My favourite topic and Paul Davies as a guest, he's one of my favourite physicists. This channel is absolutely wonderful!

Why do I feel like I just watched chess game between a man and a pigeon? You know the one where the man knows the rules and makes moves based on experience and careful judgment, while the pigeon knocks over the pieces, shits on the board, and struts around like it won.

When I look back at my perception of the world as a Kidd, everything from a grain of sand to the stars felt like pure information.every single shred of light my eyes looked at was as interesting as life itself. I miss that feeling of magic so much...

Always good to see a discussion on something that doesnt even exist! Time is what we use to measure change, flow or process. There is always only this moment now, but everything flows into this moment and creates what we call action or flow (process or change) and we then experience 'time' as a result of this happening. There is always only now and as Immanuel Kant puts it : Time and space are the framework within which the mind is constrained in order to construct its experience of reality.

It's somehow getting creepy how good the youtube algorithm know's what I'm thinking about, e.g. the topic of time as literally every day I get exactly the videos recommended that are fitting to the topic, not only trivial ones like time. Synchronizities can be quite irritating ^^

Absolutely love these debates & lectures WSF. Yet this was one of the most awkward, vague and deflecting panel I have yet to watch. Don't get me wrong, complete respect for every view, and every person willing to share their view on a subject. Yet the breakdown in the last 40mins was hard to watch. Wow.

This is an amazing group of people to have a discussion on time with.

One problem here is that Physicists tends to assume that the algebraic relationships we daily use, are the truly unique one. The math relationships that commonly we use is one of the infinite algebras that can be defined. And you can reformulate the complete physics theory using a different form of (well defined) math. Differents foundations can predict same results that the commonly used math and eventually provided new properties.

Really interesting lecture!!! On a side note, they should have the YouTube posters on the panel as they have all the answers and know everything lol.

Amazing discussion, really makes you stop and wonder how beautifully complicated the world around actually is.

Space is information. Time is the clock rate (think CPU clockrate) that that information is processed at, ie. evolves. Spacetime is a localized cluster of computation. The more space you have in a cluster, the slower information is processed, so everything else evolves faster (think being at the edge of an event horizon and seeing the universe fast forward to its end, a lot of information is queued - compressed like space - in front of you and you process it but at a much slower speed due to the large amount). And gravity is just the force that creates local computing clusters and at the same time prevents too much information from clustering together by way of Hawking radiation. In those clusters, there are specialised decisional cores created by intermolecular forces (biological systems). More analogies can be made. In the end you can argue that the universe is just a very complicated super computer very different from and a whole lot more complex than human-made super computers. A fixed length simulation. An experiment to see if artificially created consciousness can ascend the boundaries of their enclosing universe.

Tim you are my hero! (1) your fellow panelists don't get the difference between the language and the story (2) any aspect or reality could be deemed an illusion (composed of or reducible to other phenomenon) or thought of as emergent from all the other aspects of reality (3) physics hasn't answered the big questions about time and space so I think it is a bit premature to be calling Time an illusion with certainty (4) quantum mechanics seems to describe a limit to our knowledge of physical reality - when we impose macroscopic conceptual models and parameters onto and constrain the very small - and so maybe this means we need a meta-language to overcome the limits of current mathematical approaches which is based on the wave function and linear algebra. In the realm of Time, there is still an important role for metaphysics to play in this whole debate. (5) How can there be an asymmetry in something that does not exist (6) the ancient Greeks intuitively knew that we lived in a dynamic universe where change (time) was fundamental. Who can argue with an ancient Greek? (7) How can anything move (Zeno) without change (flow) in space? Motion is not just an ordering of configurations - how did those configurations arise and unfold? (8) Einstein was wrong about Quantum Mechanics too! (9) These other guys are creating a problem due to the misuse of language. (10) There may need to be a distinction made between time as we perceive it and time as the entropy of the universe and time on the quantum scale. Anyhow thanks for bringing some intellectual integrity to this debate. (11) Physicists also don't understand gravity, dark matter or black holes (12) How can time be malleable if it doesn't exit (13) how can the twin that travels near the speed of light be younger, if time does not exist? Yes his cells are in a different configuration because time has flowed at a different rate due to his acceleration. Time defines the rate of change in a system under different influences and conditions relative to others. Thus it is an aspect of physical reality and one that defines our lives and our very existence. No time, no change, no physics. Also thanks to the moderator for pointing out that a theory (time is an illusion) must be falsifiable.