Comment by milchek | Hacker News Reader

Comment by milchek | Hacker News Reader

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Non-physicist here, so excuse the layman rambling, but to me this was always something I just assumed when asking myself how fast is time? I just figured it was a constant because it is, it doesn't slow down or speed up - well, except for when you're doing really tedious work of course!). So, I just always assumed that if it's a constant, then it must be equal to the fastest or slowest constants we know.

That always leads me to this (probably) crazy rabbit hole I can never quite articulate or resolve that no doubt countless others have wondered about - what if it's not moving at all? What if time is 'solid'?

I guess the best way to explain what I mean here is like a flip book. On each page there is a drawing, if you look at one page you just see a static drawing. If you look at the book, it's just a static book. But if you flip through the pages, it animates and appears to be moving.

What if our experience of time is just like this 'flip book' experience, where in actuality, our experience of time is that we are moving through it, but time is not moving at all?

I'd love to know if there have been any other studies or discussions about this? Because if time is a constant, it could also be 0, no?

Non-physicist answer:

If you switch to viewing the universe as purely a mathematical construct, all these questions will fall away. :) The notion of ontologically privileged time or even space is based on us elevating our model of the universe into objective fact for no reason. Anything that the brain would notice even in a timeless, purely mathematical universe is thus an unneeded addition purely on Occam grounds.

For instance, we may ask the question: "would my brain, if you computed its output given its inputs, output data like 'I exist, I am conscious, I notice the flow of time passing, the present moment is ontologically privileged to me'? It seems obvious that it would; that is, the mathematical answer to the question of "what does my brain output" is that sentence. But a mathematical question cannot be ontologically privileged. We see thus that these notions of ours are necessarily vacuous; any conception of 'time', 'now' and 'me' must be relative, depending purely on the surrounding mathematical/causal structure, or else not exist at all - since even if they did exist, our noticing them is not dependent on their existence, and thus Occam bids us to discard them.

This is in the same vein as the thought-experiment about the One-Electron Universe [https://en.wikipedia.org/wiki/One-electron_universe].

The idea is, maybe everything in the universe is just 1 electron looping through 4D space over and over, interacting with itself at various points of the loop. Comes about from the observation that antimatter can be described perfectly as just regular matter moving backwards in time.

Thanks for linking that, I had not heard of it before - very cool. The theory from Yoichiro Nambu about production and annihilation of particle-antiparticle pairs really struck me as interesting! That said, I'm a real novice with all of this so I need to do some further reading.

You might find this explanation interesting https://www.lesswrong.com/posts/rrW7yf42vQYDf8AcH/timeless-p...

Bravo. I get why this guy has a following now.

BTW, I think Vonnegut had this right in 1969:

"I am a Tralfamadorian, seeing all time as you might see a stretch of the Rocky Mountains. All time is all time. It does not change. It does not lend itself to warnings or explanations. It simply is. Take it moment by moment, and you will find that we are all, as I’ve said before, bugs in amber."

Thank you for sharing.

> What if time is 'solid'?

You can adopt a perspective where time is solid. But then the question is, why are particles arranged in this solid time exacly as if they were moving in a real time.

As a metaphor, imagine that you are a god, and you are trying to create a 4D universe with solid time, where the same laws of physics (rephrased in the solid-time language) apply. How would you do it? Ultimately, you would have to create the earlier parts of the solid time first, then the following parts of the solid time, etc, until the end of the universe. It wouldn't work any other way, essentially because of chaos theory; the state at T+1 depends on the details of state at T, so you would have to create the T slice of solid time first, and the T+1 slice later, depending on it.

If you remove the time from the universe naively, you are sweeping it under the rug... into the process that created the universe. But isn't this just adding an extra complexity? If the "process that created the universe" can have real time, why not the universe itself? Isn't this just an extra epicycle?

The only way out is if you used your godlike powers to create all possible states of universe simultaneously -- not just our universe, but literally every possible combination of particles -- and then connect them causally in a way that respects the laws of physics. You don't have to create time T first and time T+1 later, if you create all possible realities first, and then just draw an arrow from each T into the corresponding T+1.

So, instead of the frozen version of our universe (where time = linear movement from the beginning of the movie towards its end), you get a frozen version of everything possible (where time = tracing a path across the everything, following the local currents of causality).

The advantage of the latter model is that you get the parallel universe for free; it just means that local causality is not a single arrow pointing from the current place, but rather a collection of arrows.

But you still need to think (in both models) how to make them compatible with known quantum physics. How to model quantum interference, entanglement, etc.

I think you're adding an assumption that isn't justified, that this god would have had to start at what we call t=0, i.e. big bang.

Part of timless physics is that there is no privileged moment in time.

The laws of physics allow god to start at any point in the configuration space of the universe and evolve toward any direction.

This isn't prevented by chaos theory. Chaos theory happens regardless of where you start your t=0. The laws of physics are 100% symmetric (CPT symmetry).

This does not mean we will necessarily recurr either. The laws of physics are symmetric, but due to the Past Hypothesis (prior condition of the universe was very low entropy), we experience an emmergent direction in time, and if the universe is infinite and unbounded it seems like it wont recurr.

I don’t see the obstacle of making that compatible with QM. Just have the state space which you described (which would be the Hilbert space), and then the Schrödinger equation specifies which curves through the state space are “progression through time”.

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