Those of you more learned than me in this topic, please bear with me here. Hopefully it presents an interesting and enlightening discussion for those of us who are just readers of science and may share some of this confusion.

We always talk of 3 dimensions of space and 1 dimension of time, as if the notions of space and time are fundamentally different. Space is a physical medium we can move in and time is causality. Even if we know now that spacetime is a thing and you can rotate from time to space and back again, physicists still always talk about "spatial dimensions" and "the time dimension" as if they are completely separate beasts.

However, to me, time looks just like another "spatial dimension".

Here is my reasoning:

A 0 dimensional object constitutes a single point.

A 1 dimensional surface or a line, is a COLLECTION or container of those 0 dimensional points in a sequence. Repetitions, if you will, of the point, out to infinity. This creates a "space" of a sort for additional points to exist in.

A 2 dimensional surface, or a plane, is a collection or container of those 1 dimensional lines in a sequence. Mathematically we see this as a "right angle" or new spacial dimension, but idea wise it's just taking the line and replicating it, and the "space" that the line replicates into is the new dimension.

3 dimensional surfaces are like the spatial world we live in, with X, Y, and Z. The 3rd dimension is a collection or container of 2d planes which can be said to be "stacked" on top of each other to infinity, creating the up and down axis. The sequence number at which the 2d plane is stacked on top of the previous one is the new 3rd dimensional Z coordinate. Note that if I'm a 2 dimensional being at coordinate Z1 I cannot at all see somebody at the previous 2d plane at Z0 nor the next 2d plane at Z2.

It seems to me if you continue this reasoning you get a 4th "spatial" dimension which is a sequential collection of 3D "spaces" stacked on each other. The coordinate number for this one is the order/sequence in which the current 3d space is stacked on top of the previous one. If I call that coordinate T, then it sounds like the order/sequence of 3d planes is just causality, with a 3d person having to move from T0 to T1 to T2 just like I'd have to move from X0 to X1 to X2 to move on the X axis. But I'm just seeing a different 3d space on the stack. Also, this notion jives with how we perceive past, present and future. Just as the 2D person at Z1 cannot see someone at Z0 or Z2, a 3d person at T1 or Now cannot see someone at T0 (the past) or T2 (the future.) This gives us the illusion that there is only one current time.

Going one step further into the nut hole, this (faulty, no doubt) logic suggests that a 5th dimension, as a collection of 4D timelines in a sequence, would contain every possible history that could happen. Which sounds like the many-worlds interpretation. Or maybe it could be seen as the "probability" of a timeline happening. But we haven't seen direct evidence of that so I'm mostly talking about the first 4 dimensions (3 space and 1 time).

Long story short, given the above, why don't we see time as another "space" in which 3D "snapshots of the universe at a given time" are collected? Or is that actually one correct way to talk about Time?

Is it correct to see additional dimensions as "containers" of instances of the previous one? To me it would seem to solve the "no right angles added past 3d" problem" by collapsing the 3d "snapshot of the present spatial universe" into a single point on the (1 dimensional?) line of Time. Rather than requiring another right angle that seems impossible to most people. But clearly I'm not a mathematician or physicist, just a hobbyist.

It is also odd to think that an object requires force to be moved through the spatial dimension (pushing a guy off a cliff), while moving through the time dimension happens seemingly constantly without any clear impetus to start it.

Thanks for reading this and any clarification you can provide. I'm sure the general public will learn something :)


There's a few pieces to this

  • You can think of dimensions as "containers," but that implies a meaningful ordering of the dimensions. In many cases, this is not possible (such as with the spatial dimensions). A lot of things we do with dimensions assume there's no meaningful ordering.
  • The idea of there being a collection of slices, each slice being a 3d universe, is an accepted philosophical model called a endurable model. We don't always use such models. There is also something called a "perdurable" model which captures the concept of an entity moving through time, rather than a collection of snapshots.
  • The reason time is treated separately from space is that the rules governing how things move in the temporal dimension appear to us to be different from those for spatial dimensions. We may indeed discover that there is a way to "rotate into the time dimensions," and on that day we would need to revisit our modeling.
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  • $\begingroup$ Thanks for taking the time and consideration to respond! I have another question based on your response. So, if I travel from X1 to X5 in a straight line, I must also necessarily travel through X2, X3 and X4. That seems to me to imply a meaningful ordering of the points on the X axis. Sure, my position on X is only relative to the other positions, but if I start at a certain point then I must have the nearby points in the sequence adjacent to me...right? Though I get the feeling that I am talking preschool and you are talking college algebra. Haha. $\endgroup$ – Michael_Lochlann Oct 22 '19 at 3:39
  • $\begingroup$ @Michael_Lochlann Yes, you'll have to travel throguh all intermediate points. That comes from the definition of a straight line. However, whether a straight line was the shape you wanted may be a more complicated question to answer. The general version of what you're talking about, by the way, is called a "flow." Arguably its job is to reduce higher dimensional or non-trivial topologies into nice easy lines so we can talk about going through X2 X3 and X4. $\endgroup$ – Cort Ammon Oct 22 '19 at 6:19
  • $\begingroup$ Ordering is less obvious in higher dimensions. For example, many systems are well described using complex numbers (which can be thought about as 2 dimensions). There is no total ordering of the complex numbers, so when you do calculations using them, you can't meaningfully use operators like greater-than. You have to do things like take their magnitude, and then order based on that. $\endgroup$ – Cort Ammon Oct 22 '19 at 6:20

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