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Comment by brainfish | Hacker News Reader

I would be surprised if it is not, given the success of spacetime treating it as just another dimension.

I don't know about any experimental proofs that either time or space is definitely discrete, or definitely continuous.

Both Planck length and Planck time are way too short for current experimental techniques.

Slightly unrelated but your comment led me to actually learning what the Planck length is, and the Wikipedia article for it has a great section on how to visualize it [1].

Figured others might enjoy this!

1. https://en.wikipedia.org/wiki/Planck_length#Visualisation

What does that have to do with it being discrete?

I am unconvinced that time is a real dimension, sure we can model movement/interactions of particles as a 4th dimension, but nothing in our understanding of physics requires it being a physical reality. IMO it's less space-time and more just space, it's just the rate of change slows with more mass.

There's at least one prominent physicist [1] who is working on showing that time is an emergent property of quantum physics rather than a fundamental one.

[1] https://www.preposterousuniverse.com/blog/2013/10/18/is-time...

If time isn't real, then when you say "rate of change", I ask "rate of change with respect to what?"

He's not claiming time isn't real, which the definition of "real" is difficult and troubling to define in itself.

I think he doesn't consider time to be 4th (or part of 3+1 or \R^3 \times \R ) dimension... or in heat equation language: that the domain is a not parabolic cylinder.

Check out "The Order of Time" by Carlo Rovelli! You might find it interesting. He explains (WAY more eloquently than I could) that time is most likely an interpretation of underlying physical law, rather than a fundamental part of it!

An illusion, if just a fancy one.

I have a hard time buying that, given the Lorentz Transform. Time is just as much a real dimension as space is. (Or are the dimensions of space also "an interpretation of underlying physical law"?)

I believe the Lorentz Transformation more than I believe eloquent arguments.

"A Planck time unit is the time required for light to travel a distance of 1 Planck length in a vacuum"

https://en.wikipedia.org/wiki/Planck_units#Planck_time_and_l...

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