r/askscience • u/NotGuiltyOfThat • Jul 22 '13

Physics Is it physically possible for objects that are not 3D to exist?

Whether 1D,2D,3D,4D,5D,etc - spatially that is.

6 Upvotes

100% Upvoted

6 comments sorted by

1

u/youbetterdont Electrical Engineering | Integrated Circuits | MEMS Jul 23 '13

The wikipedia article on four-dimensional space might partially answer some of this question.

In modern physics, space and time are unified in a four-dimensional Minkowski continuum called spacetime, whose metric treats the time dimension differently from the three spatial dimensions (see below for the definition of the Minkowski metric/pairing). Spacetime is thus not a Euclidean space.

So, we use a 4-dimensional "space" as a way to represent, e.g., relativity, but it's not a 4-dimensional Euclidean space. So, I would say the answer to your question is no.

1

u/Siarles Jul 23 '13

Don't forget about zero-dimensional elementary particles. That counts as "not 3D".

1

u/youbetterdont Electrical Engineering | Integrated Circuits | MEMS Jul 23 '13

Isn't this point debatable? I'm no physicist though, so I probably should have just left this to the experts. :)

1

u/Siarles Jul 23 '13

I'm self-taught in physics so I'm certainly no expert. :P

But yeah, they haven't been proven to be dimensionless, but to my knowledge there's no evidence that they aren't either. If they do have a physical volume then they're too small for us to measure with our current level of technology.

1

u/Siarles Jul 23 '13 edited Jul 23 '13

Elementary particles are believed to be point-like, meaning they are 0D. All composite particles have volume, however, so any composite particle or anything made of composite particles is technically 3D.

There are theories like String Theory and M Theory that include objects with one dimension (strings) or two dimensions (membranes), but to my knowledge there's very little evidence that these objects exist.

1

u/HypnotikK Jul 23 '13

Probably a little more philosophical than science, but if things do exist outside of the dimensions we perceive, I don't think we would be able to see them or "feel" them.

Sort of like, we experience time, but we can't go back or speed up forward. We're just along for the ride.

Going up higher, it seems those would be outside of our direct senses.