Can Travel Exist Beyond the Planck Length?

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Discussion Overview

The discussion revolves around the concept of travel at scales approaching the Planck length, exploring whether movement is possible beyond this scale and the implications of discreteness in time and space. Participants engage with theoretical implications, comparisons to existing theories, and the nature of physical quantities at such small scales.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question whether a traveler can move beyond the Planck length, suggesting that movement may cease as there is no concept of half a Planck length.
  • Others argue that the Planck length is not a definitive smallest length but rather a convenient scale for certain theoretical contexts, comparing it to the concept of half a nanometer.
  • A participant notes the significant difference in magnitude between the Planck length and a nanometer, emphasizing the challenges of experimental verification at such small scales.
  • There is a suggestion that if reality is discrete at the Planck scale, it raises profound implications for our understanding of time, length, and matter as discrete rather than continuous quantities.
  • Some participants draw parallels between the implications of discreteness in fundamental physics and established theories like statistical mechanics and quantum theory.
  • Concerns are raised about the aesthetic nature of some reasoning regarding the Planck length and its implications, indicating a divide between scientific rigor and theoretical speculation.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of the Planck length and its implications, with no clear consensus on whether travel is possible beyond this scale or the nature of discreteness in physical quantities. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants highlight limitations in current understanding and the challenges of measuring phenomena at the Planck scale, noting that existing theories may not fully account for the implications of discreteness.

Who May Find This Useful

This discussion may be of interest to those exploring theoretical physics, particularly in the realms of quantum mechanics, string theory, and the foundational nature of space and time.

wolram
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Take a circle that can be (traveled) by some thing, then keep reducing it in
size until distinct Planck lengths are reached, does this mean that the traveler can not move any more, as there is no such thing as half a Planck
length ?
 
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The Planck length is not a precise smallest length.
It is just a convenient dimensional length appropriate for some cases.
It would be like saying there is no half a nanometer.
 
Meir Achuz said:
The Planck length is not a precise smallest length.
It is just a convenient dimensional length appropriate for some cases.
It would be like saying there is no half a nanometer.

a hellava difference in order of magnitude between a Planck Length and a nanometer!

In fact, the Planck Length and Planck Time (or there abouts, some of us might view units with [itex]4 \pi G[/itex] normalized to 1 as more of a natural choice for "natural units" than just normalizing [itex]G[/itex] as in Planck Units) are not necessarily the discrete units of length or time of some discrete physics or cellular automa system that have been hypothesized by some. but there are some elegant reasons for some to think that it would be so, however such reasoning might be considered to be aesthetic, rather than science. since the Planck Length or Planck Time are so damn small, i don't foresee human beings ever being able to construct an experiment that would allow measurement in anywhere close to this scale. so if reality truly is discrete with something around the Planck Length and Planck Time as the size of cells in some kind of grid, i don't think that human beings will ever know.
 
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isnt the inplication still quite huge here, even if these incredibly small things are undetectable? the idea that time and length (and matter) are discrete rather than continuous quanities.
 
wolram said:
Take a circle that can be (traveled) by some thing, then keep reducing it in size until distinct Planck lengths are reached, does this mean that the traveler can not move any more, as there is no such thing as half a Planck length ?
Sounds vaguely like how M theory in 11 dimensions can reduce itself in Type IIA string theory in 10 dimensions by letting the radius of it's compactified dimension go to zero in the non-perturbative limit.

The coupling strength is related to the string length, but having spent the last fortnight reading textbooks and papers on this stuff, the Planck length isn't mentioned often (though I might have just missed it, I skim a lot of things).
 
"however such reasoning might be considered to be aesthetic, rather than science"
 
jasc15 said:
isnt the inplication still quite huge here, even if these incredibly small things are undetectable? the idea that time and length (and matter) are discrete rather than continuous quanities.

This is part of my question, ie discrete rather than smooth, it surly makes a
BIG difference to how things work.
 
We already know that fields like fluid mechanics and thermodynamics are incomplete in that they assume matter as being continuous rather than as discrete particles. the step from thermodynamics to the more complete statistical mechanics (or kinetic theory, I am not too sure of the difference as i haven't studied either of them) as i understand it is what led to quantum theory and the idea of the discrete atom. If matter is discrete, then why not time and distance? With the symmetry of the universe, this doesn't seem too far an assumption.
 

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