B Do We Cross Infinity When Moving from A to B?

  • Thread starter Thread starter Deepak K Kapur
  • Start date Start date
  • Tags Tags
    Movement
Click For Summary
The discussion centers on the concept of moving from point A to point B in a space that contains an infinite number of points. Participants clarify that while there are indeed infinite points between A and B, one can still traverse the finite distance in finite time. The conversation references Zeno's paradox, emphasizing that mathematical concepts of infinity do not hinder physical movement. It is noted that the perception of moving point by point does not reflect the reality of motion, which occurs continuously rather than in discrete jumps. Ultimately, the discussion concludes that the mathematical treatment of infinity does not contradict the ability to reach point B from point A.
  • #31
russ_watters said:
How does this relate to your original question? Aren't we talking about reality here? If you take 1 step, you take one step. Not 100, not 1000, not a million, not infinity, one. That's reality. It is almost like you are trying to disprove reality by making up a scenario that isn't reality and disproving that!

[edit] From your second post (which it doesn't appear anyone really answered directly):

No. But so what? You don't do that. You can't do that -- the way you actually move is different. So what use does this question have?

My original question also meant point by point 'traversing'. May be I was not able to make it clear..

I am not trying to disprove anything,I just want to clear my doubts...So, please tell me...

When I take a step how many points do I traverse?

If it's infinite points, how can infinity be ever traversed?
 
Physics news on Phys.org
  • #32
Deepak K Kapur said:
My original question also meant point by point 'traversing'. May be I was not able to make it clear..

When I take a step how many points do I traverse?

If it's infinite points, how can infinity be ever traversed?
These questions are not identical to each other. When you take a step you take one step. You don't do "point by point traversing" (stopping at every point), but you do cross an infinite number of points.

So again: "point by point traversing" is not a thing. It doesn't exist. It isn't how reality works.
 
  • #33
russ_watters said:
You don't do "point by point traversing" (stopping at every point), but you do cross an infinite number of points.

I think the two ideas in the above statement are contradictory.

If there is no stopping, the concept of a point ceases to exist,IMO.

Then, a 'point' is just a fictitious tool. Points don't correspond to reality.

Perhaps, a 'continuum' has no proper definition.
 
  • #34
The way I resolve this issue both mathematically and intuitively is to recall that a sum of an infinite series of fractions can be finite. For a convergent series, this it true. For a divergent series, this is not true. Take the convergent series 1/2 + 1/4 + 1/8 + ... The sum of this series is 1. One statement of Zeno's paradox is, in order to cover a given distance, you first have to go 1/2 the distance, then a little later, 1/4 the distance, later still, 1/8 the distance, and since there are an infinite number of such steps, with each step taking a finite time, how can you cross the entire distance in finite time? For constant velocity of transit, time and difference are transferable, and the sum of the infinite series of time steps is thus finite.
 
  • #35
Deepak K Kapur said:
I think the two ideas in the above statement are contradictory.
Sorry, they are not.
If there is no stopping, the concept of a point ceases to exist,IMO.
Why? That makes no sense. The universe is filled with points that people don't travel to and stop. Whether you stop at a point has nothing to do with whether they exist (as real entities or non-physical, mathematical tools).
Then, a 'point' is just a fictitious tool. Points don't correspond to reality.
Fictitious tool or not is not a critical issue, but they most certainly do correspond to reality; The math works.
Perhaps, a 'continuum' has no proper definition.
That's just not true. We have a definition that works: you invented your own definition, that doesn't work, and are trying to use it to say reality is wrong. It makes no sense. Why do that? Why not just use what works?

You kind of jumped the shark with that post!

We've reached a point where I think we both realize that what you are saying does not match reality, but instead of accepting that it means what you are saying is wrong, you are clinging to the idea that reality is wrong. Reality can't be right or wrong, it just is. So you have to choose for yourself whether you want to describe it accurately or not. But don't say there is no logic to it: I've given you a method whereby you can physically demonstrate to yourself that what you are saying doesn't match reality and a logic/definitions that do. What works, works! What does not work does not work! Choose to accept what works!
 
Last edited:
  • #36
russ_watters said:
Sorry, they are not.

Why? That makes no sense. The universe is filled with points that people don't travel to and stop. Whether you stop at a point has nothing to do with whether they exist (as real entities or non-physical, mathematical tools).

Fictitious tool or not is not a critical issue, but they most certainly do correspond to reality; The math works.

That's just not true. We have a definition that works: you invented your own definition, that doesn't work, and are trying to use it to say reality is wrong. It makes no sense. Why do that? Why not just use what works?

You kind of jumped the shark with that post!

We've reached a point where I think we both realize that what you are saying does not match reality, but instead of accepting that it means what you are saying is wrong, you are clinging to the idea that reality is wrong. Reality can't be right or wrong, it just is. So you have to choose for yourself whether you want to describe it accurately or not. But don't say there is no logic to it: I've given you a method whereby you can physically demonstrate to yourself that what you are saying doesn't match reality and a logic/definitions that do. What works, works! What does not work does not work! Choose to accept what works!

Ok I go by your post... Why to defy authority...

But still...I can't believe that an infinity of points can be traversed...
 
  • #37
Deepak K Kapur said:
If there is no stopping, the concept of a point ceases to exist,IMO.
You seem to confuse the mathematical concept of a point with dots indicating bus stops on a map.
 
  • #39
A.T. said:
You seem to confuse the mathematical concept of a point with dots indicating bus stops on a map.

I mean the concept of points ceases to exist/is an exercise in futility in this case i.e. when a body moves..

I may sound politically incorrect or may sound against establishment but when we put extremely small values in equations of say garvity, bizarre results usher in...

This implies that we can't make distances extremely small as we do in a continuum.
 
  • #40
Deepak K Kapur said:
I may sound politically incorrect ...
No, just incorrect.
 
  • Like
Likes Vanadium 50 and russ_watters
  • #41
There are statements in mathematics which canot be proved within mathematics.
Mathematics is language of Physics and hence all things in Physics cannot be proved using mathematics.
Even the scientifically we canot talk of faith at all and fix the ideas.
This just keeps an Evolutionary(not biology) pressure on further developments in nature.May be even to the extent of knocking the door of Philosophy.
 
  • #42
Extremely small! Quantum mechanics jumps in and even Einstein and Schrodinger never liked it.
Sorry for going away from the original question.
Anyway in some arguments above time is getting introduced which is not needed here as it is pure mathematics.
 
  • #43
Deepak K Kapur said:
Ok I go by your post... Why to defy authority...
There is no authority here; you are arguing against reality. Observations you can make yourself.
But still...I can't believe that an infinity of points can be traversed...
There is nothing to believe or not believe - you can demonstrate for yourself how reality works!
Edit: Er, well, I guess you can choose to disbelieve the results of your own logic and experiments, but why would you want to do that?
 
Last edited:
  • #44
Deepak K Kapur said:

Yes, and that article essentially states what I said earlier. There's no good, rigorous answer to your question. That doesn't mean that things are contradictory, or that math doesn't describe reality very well, only that we don't don't have a good answer at this time.

Deepak K Kapur said:
I may sound politically incorrect or may sound against establishment but when we put extremely small values in equations of say garvity, bizarre results usher in...

This implies that we can't make distances extremely small as we do in a continuum.

That is incorrect. The equation relating the strength of Newtonian gravity to the masses of two objects and the distances between them holds for any values you put in, no matter how large or how small. There's nothing wrong with the math. The problem is in how you use the math. If you don't use it correctly, you certainly get nonsensical results (as the article demonstrated since it used Newtonian gravity instead of Special/General Relativity).
 
  • #45
Deepak K Kapur said:
Just go through this..

https://www.physicsforums.com/insights/struggles-continuum-part-1/
[Separate post]

I mean the concept of points ceases to exist/is an exercise in futility in this case i.e. when a body moves..

I may sound politically incorrect or may sound against establishment but when we put extremely small values in equations of say garvity, bizarre results usher in...

This implies that we can't make distances extremely small as we do in a continuum
The problem with gravity does not relate to your issue with motion. I'm sorry, but it looks to me like you and I worked on a coherent line of logic together and when we got to the end, you didn't like the result and now are running from it/changing the subject. Again, yes, at some point personal choice to accept the truth for what it is or not. We can't help you like reality, we can only show you what it is.
 
Last edited:
  • #46
Let me reiterate this:
Drakkith said:
On the contrary. The math works just fine. There is nothing else that describes the universe more accurately that the correct application of math. I think the issue here is that you're searching for an 'intuitive' answer when there really isn't one.

To elaborate a bit on my previous post, this is actually a well known 'paradox' and there really isn't a single solution to it outside of math. Obviously we can move from point A to point B. Since we model the universe using math which uses 'points', it follows that even though there are an infinite number of points in between A and B, we also travel through all of these points as we move from A to B. The resolution is simply to accept this as a fact, much like how we accept certain things as axioms in math. Math deals with infinities and infinitesimals just fine and there's nothing paradoxical about moving between two points from the standpoint of math.

This 'resolution' may not be the one you wanted or even be a resolution at all, but I feel it's the only real answer you can get.
Right. It's a simple fact, plus simple logic leading to a simple answer. Digging deeper into questions like "Is the universe quantized?" doesn't have any bearing on that. More to the point, I don't thing digging deeper will provide any additional understanding for you if you can't understand/accept the concepts on the most basic level.
 
  • #47
russ_watters said:
Let me reiterate this:

Right. It's a simple fact, plus simple logic leading to a simple answer. Digging deeper into questions like "Is the universe quantized?" doesn't have any bearing on that. More to the point, I don't thing digging deeper will provide any additional understanding for you if you can't understand/accept the concepts on the most basic level.

Drakkith says there is no good rigorous answer to this question...

You say the answer is very simple...

(At least one of you is lying or confusing deliberately)

Therefore...
I say 'I quit'.

Thanks everybody. God Bless!
 
  • #48
Deepak K Kapur said:
(At least one of you is lying or confusing deliberately)

That's not very nice.
 
  • #49
Deepak K Kapur said:
Drakkith says there is no good rigorous answer to this question...

You say the answer is very simple...

(At least one of you is lying or confusing deliberately)
Don't do that. If you are unsatisfied and want to quit, fine, but in the future please try harder not to be combative and argumentative and instead try to learn. Embedded in the quote is a direct answer to your question that exactly matches what I said:
Drakkith said:
Since we model the universe using math which uses 'points', it follows that even though there are an infinite number of points in between A and B, we also travel through all of these points as we move from A to B.
Anyway, looks like we are done. Thread locked.
 
  • Like
Likes rumborak

Similar threads

  • · Replies 13 ·
Replies
13
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
7
Views
5K
  • · Replies 1 ·
Replies
1
Views
1K
Replies
5
Views
1K
Replies
14
Views
30K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 9 ·
Replies
9
Views
5K
  • · Replies 50 ·
2
Replies
50
Views
8K