Three Dimensions Of Spacetime, Why do we need a fourth, again?

When you think about a 1d of time, its not really 1d, its common to all the 3d of space so should actually be 3d of time. Moderator: That is a meaningless quibble, and so the early prediction that your post is rubbish can be made at this point. It appears that you don't have a meaningful and consistent definition of dimension. Even if we had 3d of time xt,yt,zt they would all hold the same value in the same scenario xt = yt = zt. I think in reality that is the case, as time would affect all things in all dimensions of space. In mathematics its logical to say a 1d of time and take all the like values of xt,yt,zt and call them t and use 3d of space x,y,z. In reality there’s only 3d of spacetime. If we had to separate spacetime and make space and time two different entities, we’d have 3d of space and 3d of time.
So, by my understanding, a single forth dimension of time is a mathematical concept for grouping the like 3d of time.

Even for higher or lower dimensions theres still only 3d, they share the same spacetime as our local dimensions, only the scales of the embedded fractal dimensions change.

Or?

This post has been edited by rpenner on Apr 3 2009, 07:45 AM

Haven't collected thoughts about it yet, but briefly, when you say that you have a dimension, say depth, you automatically assume that is is completely described with an integer, and completely described in time with a direction (because if it has an end it's a "measurement", of course!).

Though there is plenty of mathematical reason to do it, there is no philosophical reason to stick to seeing the world around you just like that.

For instance, you could also say "Depth is Cantor dust" and be perfectly justified. If you are into theory writing it wouldn't take 5 minutes to write a whole theory based on Cantor dust dimensionality, and next time you go for a hot dog you could use the napkin to write it.

You would have to be willing to lick your fingers

The point is that if you start considering your dimensions as fractional, the four known dimensions wouldn't add up to 4. It would be significantly below that, but not below 3.

So you'd have to have points that belong not only to two or three dimensions, but also could belong to 4 or more than that, because 3andabit-d would always have points that belong to multiple objects in multiple dimensions -if it weren't so, your universe might end up with a shadow of a tesseract that could never represent a tesseract, or with a square that could never be used to represent a cube, and that would be illogical.

The final dimensionality of your world description would have to be transcendental enough that if it can be described, then it exists, and if it exists, it is included in your final tally of Cantor dusts.

(Sorry, as I said, I haven't collected thought about it.)

IAMoraes

"So you'd have to have points that belong not only to two or three dimensions, but also could belong to 4 or more than that, because 3andabit-d would always have points that belong to multiple objects in multiple dimensions -if it weren't so, your universe might end up with a shadow of a tesseract that could never represent a tesseract, or with a square that could never be used to represent a cube, and that would be illogical."

To me we are facing the problem that a dimension - an ordinate - cannot be be described accurately by any number - because a number is an approximation - a number exerts a certain accuracy and said accuracy is no better defined that the amount of calculus put behind - the number of integers defining it - If we want to describe physical world according to a 3D concept - we need a kind of "body" a kind of dimensionality - and we cannot describe such a dimensionality or "object of sameness" within our number system - with any mathematical tricks - because the description of smallest object of sameness requires even smaller objects of sameness in order to describe and so on --

I personally like to think of the universe like a cat. In that it has nine lives, hence, the universe actually has 36 dimensions. Space is comprised of three dimensions with time being attributed to being the fourth. and our cat, is actually living its nine lives all at once via branes. It then concludes that 1 cat is 4 dimensions and 9 cats are 36 dimensions.