Infinitely divisible vs finitely divisible time

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In summary, the conversation discusses the concept of time and whether it is infinitely or finitely divisible. The uncertainty principle in quantum mechanics is brought up as a factor in this discussion. It is argued that if time is finitely divisible, particles must have definite positions and speeds, while if time is infinitely divisible, it is impossible to determine these qualities with certainty. The concept of Planck time is also mentioned, as well as the idea that the universe looks different at different scales and therefore time and space must be discrete. The conversation ends with a mention of the possibility of interactions between these discrete units forming particles and explaining the laws of physics.
  • #1
mercmisfire
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I have a bad habit of hearing a very basic discussion of something and then acting on that discussion without further investigation -- and that is a habit that I will continue with here :smile: . My question is about time, and whether the uncertainty principle requires it it to be infinitely or finitely divisible. The problem :

As I understand it, it is not only true that we cannot know with precision both the velocity and position of a particle, but that they do not possesses either of those qualities for us to know. If you cannot say that electrons EVER have a definite position or speed, then you have to admit that time is infinitely divisible.


The reasoning :

If time were finitely divisible, then definite smallest moments exist and you could pin down one moment and completely freeze a particle in that moment, since within that one moment of time, no action can occur -- action is change over time, change over time requires at least two moments of time. This would allow you to definitely know the particle's position, since everything that exists spatially, must exist in space, and to exist in space must exist in a position at any given time; if you know the time/freeze a particular moment, then you know the position. In pinning the same particle down in the next moment, you can definitely know its velocity, by comparing its two positions, which you know definitely, and how they differ across a definite amount of time, which you also know (since you have finitely divisible moments and have only allowed one to pass from one position to the next). So, if you have finitely divisible time, then particles must have definite positions and definite speeds. However, if time is infinitely divisible, then you cannot pin down one moment and it is impossible to definitely determine either position or speed -- you can only get closer and closer by making the chosen moment smaller and smaller --> however, there is no one smallest moment so you will never get small enough to allow the freezing of a particle in time (there is no such thing as one moment, so within any amount of time, there is always room for change since there is always more than one "moment" in any amount of time you chose) and so you can never know position or velocity definitevely (only approximately according to the smallness of the chosen moment). So, how about it --> is time finitely or infinitely divisible ? Am I way off base in my understanding ?
thanks,
-->merc
 
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  • #2
time, unlike quantum mechanics is infinitelly divisible, there is no set unit of time, like a quantum. You have answered your own question.
 
  • #3
There is a unit of time (very small - around 10-43 sec.) called Planck time. According to current ideas (subject to change), time intervals smaller than this are meaningless.
 
  • #4
mathman said:
There is a unit of time (very small - around 10-43 sec.) called Planck time. According to current ideas (subject to change), time intervals smaller than this are meaningless.

who are scientists to say what is meaningless. Nevertheless, it is meaningless to us, but in the quantum world, it is not.
 
  • #5
Nenad said:
who are scientists to say what is meaningless. Nevertheless, it is meaningless to us, but in the quantum world, it is not.


Meaningless as in there is no distinction between "now" and "then."
 
  • #6
It is precisely the quantum world which is making time less than the Planck time meaningless. It is not something dictated by scientists.
 
  • #7
Probably I miss understood you all

How can you say that the Planck time constant is insignificant... It's precisely in the now and then of it that resides the knowledge of the universe beggining. His constant is the time between the big bang and everything we know from the universe at this point. If one could tell what happened during that time interval many thing's would be explained. Some say that during that time interval the laws of physics as we postulat weren't applied... Who's to say?

So, one thing, not even space is finitely divisible... we would reach the notions of sources and sinks... punctual positions is space... that's fairly unlikely. I think if you could get a punctual mass (an electron isn't the case - It's vey big to be one...) you would probably know it's position precisely in the fourth dimension (time) ...
... so i really didn't get this post...
 
  • #8
The universe looks different at different scales therefore time and space must be discrete. If space was continuous, two items of different volumes would contain the same number of points, so measurement would not make sense. Calculus uses 'tending to' notation to avoid having to deal with the contradictory infinitesimals.
At one time it was commonly assumed that matter was continuous, but now we know that it is made of particles. If space and time are quantised, then it is possible interactions between these quanta could form particles and explain the laws of physics.
 
  • #9
This thread is 7 years old.
 

1. What is the difference between infinitely divisible and finitely divisible time?

Infinitely divisible time is a concept that suggests time can be divided into infinitely small segments, while finitely divisible time means time can only be divided into a finite number of segments.

2. Can time be divided into infinitely small segments?

According to the theory of infinitely divisible time, yes, time can be divided into infinitely small segments. However, this is a theoretical concept and has not been proven in reality.

3. How does the concept of infinitely divisible time relate to the theory of relativity?

The theory of relativity suggests that time is relative and can be affected by factors such as gravity and velocity. This means that time can appear to be infinitely divisible in some situations, but not in others.

4. Is there any evidence to support the idea of infinitely divisible time?

Currently, there is no concrete evidence to support the theory of infinitely divisible time. However, some mathematical models and theories, such as the Planck time, suggest that time may be infinitely divisible.

5. How does the concept of finitely divisible time impact our understanding of the universe?

The concept of finitely divisible time suggests that time is not continuous and can only be divided into a finite number of segments. This has implications for our understanding of the nature of time and how it relates to the fundamental laws of the universe.

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