Planck time at the speed of light

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Discussion Overview

The discussion revolves around the concept of Planck time in relation to objects moving at the speed of light, particularly focusing on whether a photon experiences time and how this relates to the notion of the smallest unit of time.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant asserts that from the perspective of an object moving at the speed of light, time stops, raising the question of whether a photon experiences a single "frame" or a duration of 5.39121e-44 seconds.
  • Another participant suggests that Planck time and Planck length arise from dimensional analysis and may lack specific physical significance, questioning the assumption that these represent the smallest units of time and distance.
  • A different participant challenges the initial claim about time stopping for light-speed objects, arguing that only massless objects can travel at light speed and that they lack a reference frame, thus negating the idea of experiencing time in the conventional sense.
  • Another response indicates that both the initial statements regarding time and Planck time are incorrect and references existing articles that address these misunderstandings.

Areas of Agreement / Disagreement

Participants express disagreement regarding the initial claims about the experience of time by photons and the significance of Planck time. Multiple competing views remain, with no consensus reached on the validity of the assumptions presented.

Contextual Notes

Some claims rely on interpretations of relativistic physics and the nature of massless particles, which may not be universally accepted. The discussion also touches on the implications of dimensional analysis without resolving the significance of Planck units.

Adgorn
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I know that if an object moves at the speed of light, from its persepctive time will stop to a halt. However the smallest unit of time should be the plank time. So my question is, will the object (say a photon) experience throughout its life a single still "frame", or will it experience 5.39121e-44 seconds?
 
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I had the same thought some time back and I was reminded here that Plank time / Plank length are numbers that arise from dimensional analysis, and they do not necessarily have specific physical significance.

Unless I misunderstood what I read at the time - there is no theory that says the smallest unit of time is the Plank time or that the smallest distance is the Plank length.
 
Adgorn said:
I know that if an object moves at the speed of light, from its persepctive time will stop to a halt.

No, it's not true at all, because:
1. objects with mass cannot move at the speed of light
2. only massless objects can move at the speed of light and for that objects there is no "perspective", there is no reference frame connected with them (that would violate the fact that light moves at c in all FORs) - and with that, you can't say that time will stop for them. Probably you've read that in some pop-sci book, you shoud totally forget about it :)
So, your question is based on totally wrong assumptions, so there is no answer to it.
 
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Adgorn said:
if an object moves at the speed of light, from its persepctive time will stop to a halt.
However the smallest unit of time should be the plank time.
Both of those statements are wrong, although these misunderstandings are so pervasive that we have FAQ and Insights articles explaining why they're wrong.
https://www.physicsforums.com/threads/rest-frame-of-a-photon.511170/
https://www.physicsforums.com/insights/hand-wavy-discussion-planck-length/ (although this discusses the Planck length, similar considerations apply to the Planck time)
This thread is closed because it is completely based on false premises.
 
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