# Latest research in multidimensional space.

1. Jan 9, 2014

### MightyKaykoher

Their are three proven dimensions ( + time ) and we can only see two right? Google insists their could be more or even less. What was the latest research/expirements on multiple dimensions in the quantum world. What were the results?

-(a question coming from someone understanding a 1/4 of conceptual physics)

Thanks

2. Jan 9, 2014

### DennisN

I'm not up-to-date with the absolutely latest research/experiments, and the only thing I know about are particle experiments at e.g. the LHC, see:

This is advanced physics, though, and I know very little about it (almost nothing ).

3. Jan 10, 2014

### DennisN

Eh, by the way, I do not understand what you mean by "we can only see two right?". What we've currently got in our macroscopic world is 3+1 dimensions, 3 spatial and 1 temporal, which we all "can see". This is what we usually mean when we talk about dimensions in this way.

You can measure the height of a box, right? That's one dimension. You can measure the width of a box, right? That's another dimension. And you can measure the depth of a box, right? That's another dimension. And you can look at a watch, right? - that's the temporal dimension. So, there are 3 spatial dimensions and 1 temporal dimension.

4. Jan 10, 2014

### pupplesan

2-D Vision

I gather he means that the retina is an essential two dimensional receptor. Direct "perception" of the third dimension is derived. Nevertheless, obviously, we do live in three spatial dimensions.

5. Jan 10, 2014

### MightyKaykoher

Our eyes see a flat image which is perceived as 3d from the brain.

I don't think time is similar to the other three dimensions. I can't really see time, it just happens.

If we could see 3d, then I wonder if we could perceive the fourth? Or is the fourth not real, who knows! Still what expirements have been conducted?

6. Jan 10, 2014

### ZapperZ

Staff Emeritus
Before we go any further, you need to understand something very important here, or else you will continue to run into this roadblock.

When scientists/physicists say something to the effect that we can "see" or "observe" such-and-such a thing, very seldom do they mean seeing these things with the human eye! This is because, as I've stated elsewhere, the human eye is really a very, VERY poor detector! Therefore, such observations are always done via a variety of instruments that can detect certain things with better sensitivity and beyond the range of what we can see.

Secondly, the term "dimensions" need to be clarify here. When you take a physics or chemistry lesson, you'll learn to analyze your result using dimensional analysis. This means in terms of length, time, charge, etc., which are the "dimensions" of the units. What you are specifically asking about here is the three spatial dimensions and one temporal dimensions. When you start talking about both spatial and temporal dimensions, one must make it clear that, while they are connected, they are not identical to each other!

Thirdly, the reason why we know, at least in our classical world, that these 3+1 dimensions are there and are needed is because when we solve, say the equation of motion of a system, we need ALL of them to accurately determine the dynamics! If I solve, say, a particle doing down a spiral, trying to accurately describe its trajectory in only 2D space will give a horribly wrong description! This has nothing to do with seeing it in 2D with my eyes and my brain processing it into 3D. It has everything to do with matching experimental observation!

Zz.

7. Jan 10, 2014

### MightyKaykoher

I thought Einstein connected the three "spacial" deminsions with reletivity? Space time he called it. This is veering off topic( seeing we are in the quantum physics forums ), I was looking for a quantum explanation.

8. Jan 10, 2014

### ZapperZ

Staff Emeritus
I have no idea what mean by connecting the 3 spatial dimensions. Einstein's Special Relativity formulated the 3 spatial + 1 temporal, thus giving us 4 "dimensions".

We are not in "quantum physics" forum. We are in General Physics because this appears to be a question based on rather elementary (mis)understanding of what "dimensions" mean in physics. There is no "quantum explanation". Besides, even if there is, you need to learn how to understand the simple, basic idea of "dimensions" first before attempting to wrap your head around the "quantum explanation".

Zz.

9. Jan 10, 2014

### MightyKaykoher

If its basic then why can't someone provide a straight up answer? Maybe it is basic, but sometimes physics makes the simplest thing hard.

I put the "spacial" term in to satisfy an other posts reply.

I feel I know what a dimension is, or at least a basic understanding

What I mean by Einstein connected the three demininsions with time should be obvious.

I'm starting to question what something has to be to qualify as a deminsion.

But still, I'm asking, has their ever been any expirements or research on 5 deminsions (this number INCLUDES time). ANY?

Thanks

10. Jan 12, 2014

### DennisN

It doesn't matter at all . What matters is what kind of dimensions and how many we need to properly and accurately describe the physical processes we are interested in.

That's good, because it is actually important to be specific about what kind of dimensions you are talking about. First, I'd like to repeat what Zapper said above. There is another use of the word "dimension" in physics - the dimensions of physical quantities: see Dimensional Analysis (Hyperphysics).

Maybe. But since you seem to be asking about a fourth spatial dimension, I'm not so sure about it, see below (*).

I assume you mean what something has to be to qualify as a spatial dimension (like in classical physics), right? See below.

(*)

Yes . All thousands upon thousands of experiments which involve classical mechanics (movement, motion, trajectories) show that we need exactly three spatial dimensions to properly and accurately describe a physical process in our macroscopic world.

How to test it yourself? Throw a ball in front of you. How many coordinates (see Cartesian coordinates and/or Coordinate systems) do you need to completely describe the motion of the (center) of the ball with respect to your position? (since the ball is moving, its position is changing with time, so you need to measure time too).

Do you need another, fourth spatial coordinate, to describe the position of the ball with respect to your position?

Last edited: Jan 12, 2014
11. Jan 12, 2014

### Staff: Mentor

Yes. It is obvious that a 4th spatial dimension, if it exists, has to be different from the three dimensions we observe in our everyday life (see DennisN's post).
A 4th dimension could be hidden in some way - very small, for example, or in such a way that our matter cannot move in this "hidden" direction. There is a clever trick to look for that: the gravitational force between two objects is proportional to the inverse squared distance ($\frac{1}{r^2}$) because we have three spatial dimensions. If there are more, small, dimensions, this inverse square law would be violated for very small distances. This is tested both at particle accelerators (extra dimensions could lead to new particles, or even microscopic black holes) and with very precise experiments to measure gravitational forces on the micrometer-scale. So far, no deviation from the inverse square law was found.

12. Jan 12, 2014

### Jilang

What about the strong force? That only acts over small distances and doesn't follow an inverse square law.

13. Jan 12, 2014

### Staff: Mentor

That has a different reason, and a different distance law.
If the strong, weak or electromagnetic force would see extra dimensions, this would lead to notable deviations from our observations.

14. Jan 13, 2014

### Jilang

Thanks mfb, but the strong force that holds the protons and neutrons together has a different distance dependence to the force that holds quarks together doesn't?

15. Jan 13, 2014

### Staff: Mentor

It is the same force. There is an effective description for the force between protons and neutrons (modeled as pion exchange), and this has another different distance dependence, right.

16. Jan 13, 2014

### Jilang

It's an effective model that is true, but is it the only model possible that would give the same distance dependence? Would it be possible to do away with the virtual particle transfers and reformulate with a Coulomb type potential using higher dimensions instead?

17. Jan 13, 2014

### Staff: Mentor

No..

18. Jan 13, 2014

### Jilang

19. Jan 13, 2014

### PhanthomJay

There are no proven results on the extra spatial dimensions. We know that there are 3 spatial dimensions and one time dimension in so called spacetime. It is postulated by M-Theory (an offshoot of String Theory) that there may be and additional 7 spatial dimensions curled up small at Planck Length scales. That's pretty darm small and unobservable by any instrument and experimentally out of sight, such that the hidden dimensions, if they exist, may forever remain hidden. A Theory of Quantum Gravity may shed some light on this, perhaps. Just maybe.

20. Jan 14, 2014

### Staff: Mentor

A relation is does not mean they are the same thing.