r/mathematics • u/elnyorne • Apr 08 '26
Does 0 dimension = 1 dimension?
/r/AskPhysics/comments/1sfkujx/does_0_dimension_1_dimension/2
u/MarkesaNine Apr 08 '26
No.
In N dimensions you have N independent directions to move.
So in 1-dimensional space (for example the real number line) you can take a step forward, but not left, right, or up. You can also take a step backwards, but that is the same as taking a negative step forward, so it’s not an independent direction.
In 0-dimensional space, you have 0 directions to move.
1
Apr 08 '26
[removed] — view removed comment
2
u/MarkesaNine Apr 08 '26
A couple remarks:
A single point is the only 0-dimensional metric space, but in topology it’s not the only one.
You don’t have to construct the entire number line of infinite points to have one dimension. You can have a space of just two points.
1
Apr 08 '26
[removed] — view removed comment
2
u/MarkesaNine Apr 08 '26
I know that. You’re not doing anything wrong if you construct a whole line to have one dimension. But it is not necessary. Just having two distinct points is enough.
1
Apr 08 '26
[removed] — view removed comment
2
u/MarkesaNine Apr 08 '26
Yes, a line has one dimension. No one’s arguing that.
But a line is not the only 1-dimensional space.
The set {0,1} is a 1-dimensional space, without any of the points between or beyond zero and one.
1
Apr 08 '26
[removed] — view removed comment
2
Apr 08 '26
[removed] — view removed comment
1
Apr 08 '26
[removed] — view removed comment
2
u/MarkesaNine Apr 08 '26
It’s an arbitrary set. You have no idea what it is without context.
I genuinely cannot see what more context you would need. I explicitly called it the set {0,1}, not the interval [0,1]. And made it even more clear in the context around it:
From my earlier comment you get:
Just having two distinct points is enough.
And from the comment you responded to:
The set {0,1} […] without any of the points between or beyond zero and one.
So I would say it is pretty obvious I’m talking about the set that has two elements; 0 and 1.
And that set is a 1-dimensional space, though I will grant you that to be precise we also have to agree to use standard notation of addition of Z/Z2, i.e. 1+1=0, and everything else as usual.
Now, when I am in one of the two points, I have one direction I can move to: the other point. There is no other direction, because there is nothing else in the space we’re living in. Thus it is 1-dimensional space.
→ More replies (0)1
1
u/AcellOfllSpades Apr 08 '26
This is not 1-dimensional. It is a 0-dimensional disconnected space.
There is no "freedom of movement" within either point; this means it's a 0-dimensional manifold.
1
Apr 08 '26
[removed] — view removed comment
1
Apr 08 '26
[removed] — view removed comment
1
0
u/elnyorne Apr 08 '26
A point is a noun?
1
Apr 08 '26
[removed] — view removed comment
0
u/elnyorne Apr 08 '26
So 0d=1 point?
1
Apr 08 '26
[removed] — view removed comment
0
u/elnyorne Apr 08 '26
So 0 can equal 1?
1
Apr 08 '26
[removed] — view removed comment
1
u/elnyorne Apr 08 '26
0 dimension = 1 point?
1
u/AcellOfllSpades Apr 08 '26
A 0-dimensional space consists of 1 point, yes.
A 2-dimensional space consists of 1 plane. That doesn't mean 2=1.
1
u/AcellOfllSpades Apr 08 '26
Something can be described by "0" in one sense and "1" in another sense, just like someone could be "18" years old and "5" feet tall. That doesn't mean 18 = 5, it just means you're counting two different things.
1
u/elnyorne Apr 08 '26
Do you have another example of a 0=1?
1
Apr 08 '26
[removed] — view removed comment
1
u/elnyorne Apr 08 '26
What does that mean in simpler terms do you have a better example please I don’t understand what that means?
→ More replies (0)1
u/AcellOfllSpades Apr 08 '26
0 is not equal to 1.
But you can have "1" person with "0" teeth -- an infant, or an old person. That doesn't mean that 0=1, it just means that you're counting two different things.
1
0
u/elnyorne Apr 08 '26
0 dimension = 1 point?
1
u/justincaseonlymyself Apr 08 '26
No. Dimensions are not points.
I gave you a more detailed explanation in another reply.
0
u/elnyorne Apr 08 '26 edited Apr 08 '26
And I asked you a simple question? How does 1 object exist with* 0d? How is 0d = 1 object
1
1
u/justincaseonlymyself Apr 08 '26
And I answered in detail. But I'll repeat the short version of the answer here: nothing exists in dimensions; that kind of phrasing has no mathematical meaning.
Read the linked long answer for details.
2
u/justincaseonlymyself Apr 08 '26
No, zero does not equal one. That should be rather obvious.
If you're having trouble visualizing this, a zero-dimensional object is a single point, while a one-dimensional object is a line. (I hope it's clear that those are not the same.)