Linked Questions

127
votes
14answers
35k views

Is time continuous or discrete?

I was coding a physics simulation, and noticed that I was using discrete time. That is, there was an update mechanism advancing the simulation for a fixed amount of time repeatedly, emulating a ...
78
votes
4answers
23k views

Is the Planck length the smallest length that exists in the universe or is it the smallest length that can be observed?

I have heard both that Planck length is the smallest length that there is in the universe (whatever this means) and that it is the smallest thing that can be observed because if we wanted to observe ...
61
votes
7answers
23k views

Is spacetime discrete or continuous?

Is the spacetime continuous or discrete? Or better, is the 4-dimensional spacetime of general-relativity discrete or continuous? What if we consider additional dimensions like string theory ...
20
votes
3answers
2k views

Space-time in String Theory

I would like to understand how Physicists think of space-time in the context of String Theory. I understand that there are $3$ large space dimensions, a time dimension, and $6$ or $7$ (or $22$) extra ...
18
votes
7answers
4k views

Does Quantum Mechanics assume space and time are continuous?

I was confused when I was listening to a Quantum Mechanics lecture online. Are space and time assumed to be continuous or discrete in Quantum Mechanics? I can see the question is vague, but this is ...
17
votes
1answer
373 views

If time isn't continuous, what is the best-known upper bound on the length of time intervals?

There have been several questions about whether time is continuous or not and it seems like the answer isn't currently known. I know quantum mechanics treats time as continuous and any mathematics ...
16
votes
4answers
860 views

Can physics get rid of the continuum?

Almost every physical equation I can think of (even though I don't actually feel comfortable beyond the scope of classical mechanics and macroscopic thermodynamics, as that's enough for dealing with ...
10
votes
3answers
4k views

Is space infinitely divisible?

As a child I remember hearing the popular paradox presented by Zeno proposing that Achilles could never catch a tortoise in a race since he would have to traverse the infinite space between himself ...
8
votes
3answers
178 views

How do we know that spacetime is uncountable/continuous/etc.?

Every major theory in physics - from classical dynamics, to quantum mechanics, to general relativity - makes assumptions about the structure of spacetime. Among the most common assumptions are that ...
6
votes
2answers
2k views

Discreteness of Spacetime and Violation of Lorentz symmetry

It is usually said that existence of discrete spacetime violates Lorentz symmetry. What quantity is used to quantify such violation? I mean could someone points a reference for a derivation that shows ...
6
votes
3answers
2k views

What are some approaches to discrete space-time used in modern physics?

This thought gave rise to some new questions in my mind. What are the consequences for: How would it affect duality i.e. particle, wave property of photons? How does this statement affect the ...
6
votes
2answers
2k views

How could spacetime become discretised at the Planck scale?

I didn't have much luck getting a response to this question before so I have tried to reword and expand it a little: In early 2010 I attended this inaugural lecture by string theorist- Prof. ...
6
votes
2answers
658 views

Can universal continuity be experimentally falsified?

It is an unresolved question whether the universe is discrete or continuous in its intricate quantum level structure. See for example: Is the universe finite and discrete? How could spacetime become ...
5
votes
2answers
116 views

Is the space of possible positions of a particle in QM discrete?

I recently updated my understanding about quantum mechanics from popular science level to basic undergraduate level. What surprised me is that for the quantum state of a particle, the wave function ...
5
votes
1answer
101 views

Will an eventual discreteness of spacetime have consequences in the light of Noether's theorem?

No doubt Noether's theorem holds for the symmetry of translations in space and time. But what if we zoom in on very small lengths and times, and spacetime maybe becomes discrete? Will this have ...

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