* The Ten Dimensions explained * String Theory

[link to blogs.oracle.com]


By bblfish on Sep 06, 2006
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In my previous post on possible worlds I pointed to the excellent flash animation (click) that covers the 10 dimensions of string theory.

The summarise the points made in that film (worth seeing again and again):

The 0th dimension is the dot. You don't need any numbers to identify its position.

The first dimension is the line. You need two dots to define a line. Any other dot on that line can be located on that line using one real number that will give the distance of the third dot to the first dot using the distance of your first two dots as the unit. So on a ruler your first two dots can be the 0 and the 1cm dot. Every other dot is at some cm length from the 0.

the second dimension is the plane. You need two numbers to identify a point on a plane. Usually called the x and the y axis. On a plane you can find the distance between two points by drawing a line that does not go through your reference dot.

space is the third dimension. You need three numbers to determine the distance of an object in space. These are usually called the x,y and z axes.

space time is the fourth dimension: it requires four numbers to place a dot in space-time. 3 for the spacial position, and one for the time. The four dimensional world we live in, seen from the beginning of the universe to the end of the universe, is the actual world we live in.

The 5th dimension is the first dimension in which the notion of possible worlds starts needing to be used. Imagine some possible world a little different from this one (maybe one where you did not read this blog). This possible world will give you a unit of similarity measurement with which to compare the distance of other possible worlds to the actual one.

The 6th dimension will give you a plane of possible worlds. You can find out the similarity distance of two possible worlds from each other without having to go through the actual one. So with 6 dimensions it is possible to compare the distance of the world in which last Sunday I entered another café, with the world in which I made a huge groundbreaking invention when I was a child, without having to compare that to the actual world. We can also measure the distance of any of those to the possible world in which the earth was never created, for example. The 6 dimensions allow us to compare and position all the possible worlds that start with the same initial conditions (the big bang) as this one.

The 7th dimension will give you access to the possible worlds that start with different initial conditions (big bang). A point in the 7th dimension consists of all the possible worlds that start with the same initial big bang and lead to all the possible endings that such an initial condition can lead to.

The 8th dimensions gives us again a plane of such complete possible universe histories, which in the video they call infinity. We can there compare two such infinities without necessarily having to take ours into account.

With the 9th dimension we can compare all the possible universes histories starting with all the different possible laws of physics and initial conditions.

The Tenth dimension is the point in which everything possible and imaginable is covered. Since we can't imagine any further, we have to stop here.


David Lewis does not specify an upper limit to possible worlds: he does not exclude impossible worlds. It's just that it would be impossible for us to describe them (if indeed there are any).

Here are a couple of quotes worth remembering from that presentation. In the description of the 5th dimension the narrator says:

Quantum physics tells us that the sub atomic particles that make up our world are collapsed from waves of probability simply be the act of observation.

In the description of the 10th dimension he says

"In string theory physics tell us that superstrings vibrating in the 10th dimension are what create the subatomic particles which make up our universe and all the other possible universes as well. In other words all possible universes are contained within the tenth dimension".

[link to www.tenthdimension.com]