Does the universe update time in some finite interval?

Question

I was listening to a lecture by leonard susskind and one of the analogies he used was a coin having two states and he "broke" time into intervals. He continued to say that at each interval of time, if the coin has a state of heads or tails, it remains heads or tails. Is this truly how the universe works? Or could it be that time is just an idea we use to describe the changing of configuration of a system ie our universe? This probably doesn't have an answer but is there any way to test this? I know in computer programs we use a refresh rate not sure if that is measurable if you were within the program.

Answer 1

If the Universe has such a time interval, we have not observed it yet.

Moreover: if the Universe's "refresh time" is less than a Planck time, roughly 10^-43 seconds, we have no direct way of detecting it, as any wave which we created which had that frequency would have a Schwarzschild black-hole radius bigger than its own wavelength, making it very hard to probe any universe properties at that frequency.

It has been variously proposed that there may be indirect ways to detect such things: for example hoping that some sort of interesting physics happening at a greater frequency has been redshifted, by Hubble's law, to an observable frequency. So there may be some hope to detect this sort of thing eventually. But as far as we can tell, no, the universe does not break time into "instants."

There is one further reason, a very special reason, not to expect the universe to break time into instants: this is because there would be a lot of models which worked that way which would not obey special relativity. Special relativity says that there are many different spacetime planes going through this particular moment which are each regarded as "the present" by different observers going through this point at different velocities. If the universe breaks time into instants, then it would be really surprising that the way it's breaking time up does not create any aggregate effects which ultimately appear as some sort of breach of special relativity permeating the cosmos. The basic problem is, "One of these spacetime planes is the True Present, but unfortunately all the laws of the update mechanism conspire to make it impossible to figure out which one it is." That seems weird, or like we're missing some deeper, more beautiful theory of how the world works.

With that said, one of the alternatives to Susskind's child (Susskind is the father of string theory) are the spin networks and spin foams characteristic of Loop Quantum Gravity. Without going into too much detail (as my only work has been in condensed-matter physics, I'm not very qualified), LQG does actually break spacetime into this sort of granularity at the Planck scale, and could therefore possibly give a sort of universal-update mechanism for the underlying stuff that space is made of, without violating quantum mechanics or relativity.