Are all dimensions created equal?

[pgrmdave]

Within the first three dimensions, there is no difference. They are all quite interchangable. While up and left are not the same thing, they are obviously quite similar. If the first three dimensions are the same, should that not hold for higher dimensions? Assuming that the fourth is time, we are moving through time, just like moving forward, or left, or up. If this is true, what information would be lost in thought experiments that reduce all dimensions by one, as in imagining people as two dimensional beings moving through a third dimension they call time?

[Tim_Lou]

dimensions are just a concepts......

there are only 2 dimensions (not the m theory) normally in my opinion, space and time.

 

they are totally different concepts... defining them as dimensions is just a way for us to understand... (so we can apply math calculation to it)

[Tormod]

Assuming that the fourth is time, we are moving through time, just like moving forward, or left, or up.

While it is commonplace to assume that the 4th dimension is time, there is really no need to specify it as "the fourth" dimension. We say space-time is 4 dimensional because it works with our models for 3 spatial and one time dimension, but the time dimension is completely different from the spatial dimensions (as Tim implied). The concept of space-time (as defined by Einstein) really tied these different concepts together.

 

We have discussed dimensions on and off in these forums before, you might want to try to search for dimension or similar keywords.

[BlameTheEx]

While it is commonplace to assume that the 4th dimension is time, there is really no need to specify it as "the fourth" dimension. We say space-time is 4 dimensional because it works with our models for 3 spatial and one time dimension, but the time dimension is completely different from the spatial dimensions (as Tim implied). The concept of space-time (as defined by Einstein) really tied these different concepts together.

 

I am not sure you are right there. Time is different to the other 3 dimensions, but perhaps only to the observer. In an absolute sense there might be no difference between the 4 dimensions (although I am taking a real interest in the idea that there IS a direction within the 4 dimensions that is locally valid as the direction of time, without regard to the velocity of observers).

 

Observer A travelling at near light speed, as viewed by observer B is time dilated in observer B's opinion, but not as far as A is concerned. Quite the reverse - A considers B to be time dilated. One way of looking at this is to say that both A and B are travelling through what they consider to be time at the same speed, but they each have a direction of time that points in a different direction in the 4 dimensions. A considers much of B's travel through time to be travel through space, and visa versa.

 

Sigh. This is difficult without diagrams.

[Tormod]

I think the main problem lies in our lack of understanding about what time really is. So there will be many ways to explain how dimensions are related.

[pgrmdave]

I had considered the effect we consider to be time simply a byproduct of the fourth dimension. bring it all down one dimension for simplicity. Imagine there are two-dimensional beings living in a two-dimensional universe. Assume that all of time, past present and future co-exist, but only the past can affect the present and present can affect the future. If every "frame" of time were stacked upon one another, it would become a third dimension. The beings within this dimension would think that there are three dimensions, two spacial and one time. I know this is a bad explanation, but it is difficult without graphs.

[Jonahtan]

I have read and heard that theorists believe that there may be as many as 10 or eleven dimentions. Can anyone provide a link to a website or thread about this topic? Im wondering if any likely dimentions have been conceptualized or considered or anything?

[pgrmdave]

http://superstringtheory.com/experm/exper3.html

In string theory, the set of physical quantum states usually contains a graviton that gives rise to gravitational interactions. Therefore, it has been widely assumed that the natural distance scale of string theory should be the Planck scale. However string theories contain many duality symmetries that connect a string theory at one distance scale to a different string theory at a different scale. So the idea of a distance scale itself is not as firm and reliable in string theory as it it normally is in quantum field theory.

 

I won't pretend to know anything about string theory, but this site seems to explain it well.

[Aki]

I have read and heard that theorists believe that there may be as many as 10 or eleven dimentions. Can anyone provide a link to a website or thread about this topic? Im wondering if any likely dimentions have been conceptualized or considered or anything?

 

In the M-theory, aka string theory, Edward Witten suggests that there must be 11 dimensions, in order for a string to stretch into a membrane or "brane". Here is a link to a set of videos,

http://www.pbs.org/wgbh/nova/elegant/program.html, it explains the 11th dimension in the the third hour.

[Jonahtan]

Thanks AKI, not only was the video on the 11 dimentions interesting and inciteful but many of the other videos were interesting as well!

[lindagarrette]

The 11 dimensions you refer to are the dimensions needed to methematically explain our universe in terms of string theory. There are lots more dimensions,

 

There is no such thing as a 11 dimension object, or a 4 dimension object. Time is often considered to be the fourth dimension to isolate the address of a point (a point in time).

[infamous]

This question of dimensions has been on my mind for some time now. I'm no authority but, the main source of confusion for myself is; if mindless particles can distinguish the difference between right and left, why do we insist that in empty there is no way of knowing the difference. Does't a point of origin determine that there might in fact be six spacial dimensions. I realize that this may be a stupid question, but I felt it necessary to ask anyway.

[Freethinker]

if mindless particles can distinguish the difference between right and left,

I'm not sure that suggesting an ability to "distinguish" is apporpriate. It would indicate selfawareness as one has to establish their position in order to "distinguish" a different one. The left/ right (up/ down, ...) designation can be perhaps better understood as our attempt to use existing termonology to help our human communications. Rather than actual dimensional directions for the particle. It is just another anthropomorphic left over.

Does't a point of origin determine that there might in fact be six spacial dimensions. I realize that this may be a stupid question, but I felt it necessary to ask anyway.

It's a good question. Not stupid. Glad you asked. But I am not sure of the context. While there is discussion of more than 4 dimensions in explanations of Superstrings, only the 3 spacial ones we deal with normally, are more than perhaps manifolds folded back on themselves. A point of origin only requires 6 dimensions in order to reference relative positions of the point of origin and another point (destination?) But each's location is determined by 3 dimensions.

[infamous]

I quess it would be true that for an observer looking in "as it were" on any activity in our universe, that only three spacial dimensions would be necessary to explain our existence. But what about the ones being observed, a mindless particle certainly is not aware of it's position in space but something about space must determine a difference between right and left. If there were no difference particles could only sprial in one direction while traveling through space. Maybe this is a function of a direction in time, and not a difference between right and left. I'm realy not sure myself, just like to understand this conflict of ideas a little better. Maybe you have some other ideas on this, thanks for any information about this that you might be willing to share.

[maddog]

A bit of wandering in this thread. To stay close to topic, I am interested in the theme about

time being either different or the same as the spatial dimensions. From SR they are

considered so. However, it may not look so when you consider the Minkowski metric used.

 

For a good read on time as a subject itself, I recommend a book titled, "About Time". I

forget the author. Do a google lookup. Fascinating stuff is considered. Only about 2 yrs

old material too. :Alien:

 

Maddog

[hefner]

.. what information would be lost in thought experiments that reduce all dimensions by one, as in imagining people as two dimensional beings moving through a third dimension they call time?

I think nothing would be lost. The time dimension is made analogous to the others by multiplying t times c, making it the distance light would cover in time t.

[paultrr]

When it comes to multidimensional theories and what exactly is physically possible I might suggest seeing gr-qc/0501026 which gives some hint that sets of 4 dimensions seem to be the most consistant. Thus, in a way not all dimensions are created equal, so to speak. As the author of this paper mentions a bit in brief this has implications when it comes to modern multidimensional theories like Brane Theory.