# The Naked Scientists Forum

### Author Topic: the 4th dimension  (Read 5290 times)

#### UScaV

• Jr. Member
• Posts: 11
##### the 4th dimension
« on: 23/10/2003 04:28:10 »
I had an option of doing a project on the 4th dimension last year, I didn't actually do it but I looked at some books and website and things, and most of them were about the 3 dimensions we know, and that the 4th dimension is time.  I don't really understand this concept, but one way I saw it related was this:  Let's say you've got a little square isolated to the 2nd dimension.  He can move up and down on the X and Y axes (plural for axis), but he can't move vertically through the height dimenson.  Since he can't see it or ever actually move in this way, there's really no way for him to possibly understand this.  You can try to explain it to him, but there's no way he can really know unless he expieriences it himself.

So I suppose if there were a creature that could use the 4th dimension it could move in and out of our vision using the 4th dimension, which I suppose could be time, meaning he could time travel?  Anyway, I was just wondering what other theories were out there about this topic, and if there has ever been any speculation about something less than 1 dimension or more than 4.

#### tweener

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##### Re: the 4th dimension
« Reply #1 on: 23/10/2003 05:40:15 »
It's past my bedtime, but I can't resist a thread on dimensions.  There has been a HUGE amount of speculation about higher dimensions. You could fill a good size library with studies on dimensional spaces.

Thinking of the fourth dimension as time isn't too difficult.  Think about an intersection of two streets.  Cars can travel through the intersection using some time to do so. Each car that passes through takes up the same space (in X, Y, and Z directions).  What keeps the cars from crashing is the time dimension - they occupy the same X-Y-Z space, but not at the same time coordinate.

If there was an overpass, then multiple cars can occupy the same X-Y space, at the same time, but they are separated in the Z dimension. (Assuming that Z is up-down relative to the surface of earth).

The fourth dimension doesn't have to be time.  Maybe T is the first, and X, Y, and Z are 2, 3, and 4.

I have skimmed through several theories about dimensions in the universe.  Some postulate seven is the magic number.  Some say 11.  Some say 12.  Some say several hundred.  Adding one more dimension to X, Y, Z, and T gets over my head, so I'll have to save additional comments for later.  Lack of sleep and medium quantities of alcohol seem to help in understanding higher dimensional spaces.

------------------------
No words of wisdom here.

#### chris

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##### Re: the 4th dimension
« Reply #2 on: 23/10/2003 10:08:26 »
Tweener - that was brilliantly explained. Nicely done ! I've never come across such a nice analogy so well put.

UScaV - what did you do your project on in the end?

Chris

"I never forget a face, but in your case I'll make an exception"
- Groucho Marx

#### Pappy

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• Posts: 71
##### Re: the 4th dimension
« Reply #3 on: 23/10/2003 20:10:16 »
Interesting subject, as tweener indicated, a lot of material has been written on the suject (of which I understand little!). However, I understand the "superstring theory" requires 9 spatial dimensions and speculation is these other dimesions are very small thus we do not interact with them in daily life. The theoretical possibility of extra dimensions is exciting and their discovery might someday completely change our view of spacetime.

However, I'm certain my clothes drier moves between dimensions.......and leaves socks behind in the process!

#### Ylide

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##### Re: the 4th dimension
« Reply #4 on: 25/10/2003 06:53:14 »
Time exists so everything doesn't happen all at once.

Space exists so everything doesn't all happen to you.

[:p]

We operate in three physical dimensions, not counting time, so our brains have a hard time comprehending a 4th physical dimension.

Imagine a being that existed only in a 2 dimensional XY plane.  Try explaining to that being that being a hypothetical situation where there are an infinite number of XY planes, and all he has to do to get to them is go "up" or "down."  He wouldn't know what you meant.  Try explaining how something could be occupying the same XY coordinates at the same time, but on a higher dimension.

Now, to make the analogy fit us...imagine you're told that something can occupy the same X, Y, and Z coordinates at the same time.  But on a higher dimension.  Lets call it the ZZ axis.  Ming boggling, eh?

Mathematicians have it all figured out on paper.  We just don't know how to do it for real yet.  If you really want to warp your brain, check out n-dimensional geometry theory.

http://en.wikipedia.org/wiki/Polychora

(shameless plug for wikipedia...they rock)

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#### tweener

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##### Re: the 4th dimension
« Reply #5 on: 25/10/2003 16:11:57 »
wikipedia is a really cool site.  Thanks for the link Jay!

I'm going to show the polychora link to my son - he'll love it.

#### Quantumcat

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##### Re: the 4th dimension
« Reply #6 on: 28/10/2003 18:00:24 »
Some analogies I made up and like:

There's a man in two dimensions who wants to see inside a circle, but no matter which way he goes around it there are no holes and he can't see the contents. Finally he decides to cut a side open and he can see the things inside. A man in the third dimension (like us) can see the circle and everything inside with the tiniest of glances. We can see all. Then a man from the thrid dimension has a sphere in his hand. no matter which way he turns his head he cannot see inside. He finally decides to cut open a side to see what's inside. A man in the fourth dimension can see the whole sphere and everything inside all at the same time with a single glance. He can see all.

A man makes a circle on the ground and keeps increasing the radius, eventually the circle is a straight line and then it curves the wrong way when he increases it more then it traps him!! Can you guess? He's on a sphere ... then he goes to a three d space and blows up a balloon, the balloon becomes flat then it curves towards him the more he blows in it then he is surrounded by the balloon it traps him and he can't get out! He's in a 4D hypersphere!

I used to have more but forgotten them now.

Am I dead? Am I alive? I'm both!

#### vanvinhhoang

• Jr. Member
• Posts: 10
##### Re: the 4th dimension
« Reply #7 on: 03/10/2005 09:06:15 »
If we consider space-time as an unique object, do you think that time is a strange piece. In normal thought, we can not accept an ideal that we could inverse the dimentional of time, everything happen from past- present-future, while all the another componient of space can be inversed with no problem. Nowaday, physics has reached many progresses. But as you know, we get some big problems, i.e the Unification Theory, dark matter, no evidence about SUSY, ... So that a question here is that the reason maybe the absence of constraints in which time must be forced to pass only one direction. But if these constraint will be discoveried, so how about the CPT invariance.

#### another_someone

• Guest
##### Re: the 4th dimension
« Reply #8 on: 11/10/2005 23:44:14 »
quote:
Originally posted by vanvinhhoang

If we consider space-time as an unique object, do you think that time is a strange piece. In normal thought, we can not accept an ideal that we could inverse the dimentional of time, everything happen from past- present-future, while all the another componient of space can be inversed with no problem. Nowaday, physics has reached many progresses. But as you know, we get some big problems, i.e the Unification Theory, dark matter, no evidence about SUSY, ... So that a question here is that the reason maybe the absence of constraints in which time must be forced to pass only one direction. But if these constraint will be discoveried, so how about the CPT invariance.

Is the 'direction' of time anything more than merely human perception?

If we look at a road from London to Birmingham, we do not ask which direction it goes, we merely look at all the connected bits of tarmac that make up the road, and consider it one long connected road.

If we then look at a car that is in London at 10:00, and in Birmingham at 12:00, and look at all the separate instances of that car in the times between 10:00 and 12:00, we say that the car has moved from London and Birmingham, but is this really anything more than merely our perception of the linkage of a single car over time.  If we could simultaneously perceive the total connected instances of the car between 10:00 and 12:00, it would be no different to the connected bits of the road that exist between London and Birmingham, and the notion of direction would not be an issue.

Yes, time is strange, but not so much that it is of itself strange, but that our relationship with it is strange, that we can instantaneously perceive an image in two dimensions, and gain enough indirect information from our stereoscopic vision to instantly model the world in three dimensions; and yet we cannot look through time with the same ease that we can look through space.  Our memories allow us to look in one direction in time, and yet we have no way to view time with such ease in the other direction.  None of this can tell us anything about the direction in which time moves, or if it moves at all, but tells us about the limitations of our perceptions of time.

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##### Re: the 4th dimension
« Reply #8 on: 11/10/2005 23:44:14 »