Is Time Quantized?

John's post about scientists measuring the shortest interval of time ever inspired me to actually Google a question that I've pondered for quite some time: is time quantized?

For those of you who are not familiar with the idea of quantization, one of the fundamental things ever discovered in physics occurred in 1900 when Max Planck worked out that energy is not infinitely divisible - there's a minimum unit of energy that is indivisible. That unit of energy (a "quantum") is so small that for us humans, it seems like energy (say, how hot something is) is a smooth gradient.

So, back to my original question: is there a fundamental unit of time, which is not further divisible into smaller units? In other words, is there a quantum of time?

Some physicists pegged the smallest unit of time that have any physical meaning as Planck time, the amount of time for a photon to travel the distance of 1 Planck length (a unit of length, equal to 1.6 x 10-35 m, where gravity, space time and "regular" physics cease to be valid and the effects of quantum mechanics dominate). 1 Planck time is about 10-43 seconds).

The closest answers that I found was provided by Scientific America circa 1999:

"The brief answer to this question is, 'Nobody knows.' Certainly there is no experimental evidence in favor of such a minimal unit. On the other hand, there is no evidence against it, except that we have not yet found it. There are no well-worked-out physics theories incorporating a fundamental unit of time, and there are substantial obstacles to doing so in a way that is compatible with the principles of General Relativity. Recent work on a theory of quantum gravity in which gravity is represented using loops in space suggests that there might be a way to do something roughly along these lines--not involving a minimum unit of time but rather a minimum amount of area for any two-dimensional surface, a minimum volume for any three-dimensional region in space and perhaps also a minimum 'hypervolume' for any four-dimensional region of space-time."

The article describes 3 more answers (tldr: "dunno") to the question: Link

Do we have any physicists in the audience that can provide a better answer? Say that there is a quantum of time - what does that mean to our understanding of reality?


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It seems to me that there is a quantum of time because there must be. If a particle's position is quantized then when did the particle travel from one quantized position to the next? That "when" cannot be determined therefore whatever time passes between that particle's current location and the next must be a "quantum of time". That being said, there is no such thing as time. Time is "the passing of iterations". The universe apparently computes its entire state in the period which, for lack of a better description, we call "Planck Time". So you can not travel through time because that would involve running the iterations backward in order to arrive at the previous state. Nor can you travel forwards in time because those iterations have not occurred yet and thus the state has not been determined. I suppose that traveling backwards in time might be conceivable if someone was kind enough to save off the state at whatever iteration we would like to travel back to, but that would not actually be "time travel" as we think of it but rather just re-experiencing a previous state. Anyways here is a more interesting question. What calculation describes the relationship between planck time and the speed of light? What I mean is that Einstein asserted that your experience of time slows to 0 as you approach the speed of light. So is planck time different at the speed of light? How can that be?
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