Do time and space occur in quantum units?

Click For Summary

Discussion Overview

The discussion revolves around the nature of time and space in the context of quantum physics, specifically whether they can be considered as discrete units or if they exist in a continuous form. Participants explore theoretical implications, research directions, and the challenges of empirical verification related to these concepts.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that there is currently no evidence to support the idea that space or time are discrete units, citing General Relativity's view of continuous movement through space-time.
  • Others mention ongoing research aimed at quantizing space-time, particularly at the Planck scale, as a way to address issues where quantum mechanics and relativity intersect.
  • There is a reference to the difficulty of empirically verifying theories related to Planck time and Planck length, indicating a debate on these concepts.
  • One participant introduces the idea of Doubly-Special Relativity (DSR), which attempts to incorporate an invariant length scale while preserving Lorentz invariance, suggesting a theoretical framework that could accommodate discrete aspects of space-time.
  • A participant expresses uncertainty about whether minimal limits like Planck units imply that time and space must be discretely quantifiable, acknowledging the challenge of framing these questions without a solid understanding of contemporary theories.

Areas of Agreement / Disagreement

Participants do not reach a consensus; instead, multiple competing views remain regarding the nature of time and space, with ongoing debates about the implications of quantum mechanics and relativity.

Contextual Notes

The discussion highlights limitations in current understanding, including the unresolved nature of the relationship between quantum mechanics and general relativity, and the challenges of probing the smallest scales of space and time.

Who May Find This Useful

This discussion may be of interest to those exploring theoretical physics, particularly in the areas of quantum gravity, relativity, and the foundational aspects of time and space.

arcadesonfire
Messages
2
Reaction score
0
Hi folks, I've never taken a real quantum physics course, so this question miiight be really silly, but here it is:

I'm wondering if there's any research going on or any established theories about time and space themselves occurring in quantum units rather than occurring in a continuum that can be divided over and over ad infinitum.

In other words, can a quantum particle exist anywhere, or is there evidence suggesting that it must exist at a quantifiable point on a space/time grid?

Or is there strong evidence or proof that space/time are definitely continuums where there's always a position between any two points?

Anyone ever run across any discussions of this or have any suggestions for things i should read?

Thanks!
 
Physics news on Phys.org
There is no evidence showing that space or time are discreet units. According to General Relativity, a particle moves continuously through space-time (space and time). These are both relative units and have no meaning outside of a relativistic context. Depending on the relative energy of 2 particles, the distances between the two (when choosing the right frame of reference) range from ~0 (at velocities ~c) to the resting distance d (where v' [the relative velocity] = 0).

However, there is work being done to quantize space-time in order to simplify physical problems with space-time at and smaller than the Planck scale. Quantum field theory breaks down at the Planck scale and this is the driving force and one of the final problems in coming up with a TOE (theory of everything). This is one of the instances when QM and Relativity clash.

**It's difficult (understatement) to probe into smaller and smaller information (Planck constant) about time/distance, mass/energy, etc. Just as its very difficult to probe light without mucking up your results (e.g. slit test).

At the current state of things, its impossible to tell if space-time is continuous or not at very small scales. Just as the mechanisms which cause randomness in QM are not explained, whether its turtles all the way down, whether there is an infinite universe or pink dragons just out of our line-of-sight, it's generally physics taboo to project your own opinions about "whats going on behind the scenes" without evidence of any kind.

I think that often times personal taste influences the understanding of physics. I've been guilty of it many times myself.

String theory (bleh) is taking a stab at quantum gravity, there is loop theory, and a whole muddled up mess of other things to confuse the crap out of everyone on the topic of 'how small is the smallest'.

Check out Wikipedia for a start:
http://en.wikipedia.org/wiki/Quantum_spacetime
 
Last edited:
Simfish said:
Isn't there a debate about this? About Planck time (http://en.wikipedia.org/wiki/Planck_time) and Planck length? Anyways, such theories will be very difficult to empirically verify.

Agreed. Just throwing what information I had at him.
 
http://en.wikipedia.org/wiki/Doubly-special_relativity

In principle, it seems difficult to incorporate an invariant length magnitude in a theory which preserves Lorentz invariance due to Lorentz-FitzGerald contraction, but in the same way that Special Relativity incorporates an invariant velocity by modifying the high-velocity behavior of Galilean transformations, DSR modifies Lorentz transformations at small distances (large energies) in such a way to admit a length invariant scale (planck length)[/color] without destroying the principle of relativity. The postulates on which DSR theories are constructed are:

1. The principle of relativity holds, i.e. equivalence of all inertial observers.
2. There are two observer-independent scales: the speed of light, c, and a length (energy) scale λ (η = 1 / λ) in such a way that when λ → 0 (η → ∞), special relativity is recovered
 
Thanks for all the replies folks. I've got a lot to read up on to understand the things being researched. I had been wondering if any minimal limits (like Planck) were interpreted as signs that time/space had to be discreetly quantifiable, but then again, even if we couldn't see between one point and another, that doesn't mean there isn't something between...

But at the moment, i think i don't even have a good enough understanding of the contemporary quantum and relativity theories to frame my wonderings correctly. So i'll be researching all the things you've brought to my attention.

Thanks again!
 
this article was being discussed in all the forums recently
http://www.sciencemag.org/content/301/5637/1169.1.summary
 
a good place to start reading and to ask questions is here in the "beyond" forum https://www.physicsforums.com/forumdisplay.php?f=66

there are both string theory and loop quantum gravity discussions (as well as other topics related to quantum gravity research programs)
 

Similar threads

Graduate Quantum superposition: Is a problem of space-time worldview?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Wave-packet in configuration space
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Wave function of particle / quantum field in space, also in time?
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Are time and space continuous or discrete?
  • · Replies 8 ·
Replies
8
Views
3K
High School Can particles appear from "actual" nothing including no space?
  • · Replies 28 ·
Replies
28
Views
6K
Graduate How to derive Quantum Mechanics in curved physical space?
  • · Replies 6 ·
Replies
6
Views
2K
Graduate Do entanglement networks encode a unique, local historical record?
  • · Replies 2 ·
Replies
2
Views
2K
Graduate Quantum properties and Van Hove singularty
  • · Replies 5 ·
Replies
5
Views
542
High School Is gravitized quanta the solution rather than quantum gravity?
  • · Replies 3 ·
Replies
3
Views
2K
Graduate Do we need stochasticity in a discrete spacetime?
  • · Replies 2 ·
Replies
2
Views
1K