10 Dimensions?

Question

I have heard about string theory etc. but not being a physicist by trade, I am trying and failing to come to terms with the concept of ten dimensions.

Everyone knows the first four, but what are the other six? Can anyone put it language an environmental scientist can understand?

I think it is ten, it may be more or less. I stand to be corrected.

Ok answer man, I get that, but how does time fit into that model? does it affect all of them?

Answer 1

The other six dimensions are very well explained (theoretically, of course) by Brian Greene in his book "The Elegant Universe." One version of Superstring Theory claims that that there are 10 or 11 dimensions. The first four, as you say, we know - our three spatial dimensions an the time dimension. Those first four dimensions are lumped together as "spacetime."

Apparently, when our universe began, it unfurled in three dimensions and time began, but, according to string theory, there were 6 or 7 other dimensions that curled up really small at the same time the other 4 dimensions expanded. How small? So small that we would need a linear accelerator light years long or maybe even as big as the known universe to have a chance of even detecting these extra dimensions. Ridiculously small. Smaller than the Planck Length (10^-35 cm). Which is convenient. Might as well say little green men live at those levels, can't disprove that either. But not quite, because there is some rhyme and reason for string theory.

The reason string theory has generated scientific interest in the past and every now and then gets a shot in the arm is because "it's the only game in town." Strings do away with the "zero point" problem that arises when trying to combine relativity theory with quantum theory, because even though strings are incredibly small, they are not "zero" in length.

What are strings? The theory is that electrons are strings, and quarks are strings. They are the most basic "uncuttable" unit in the universe, a universe that is made up entirely of strings. Two "up quarks" and one "down quark" make a proton. Two "down quarks" and one "up quark" make a neutron. Combine neutrons, protons, and electrons, you can have any atom in the known universe. I will skip a discussion of neutrinos and muons and other "stringy" exotic subatomic particles because this is already getting to be a bit lengthy, but the point is that everything is made up of strings, according to string theory.

The difference in how strings manifest in the real world is by their vibrational energies imparted to them by vibrating through these 6 other dimensions. The difference between an electron and a quark, for example, would be the difference in their vibration energies through these 6 other dimensions.

Mathematicians Kalabi and Yau came up with extradimensional theoretical shapes, aptly named "Kalabi-Yau" shapes. While these are difficult to illustrate on a 2 dimensional piece of paper, and part of what string theory is trying to do is limit the huge number of possible Kalabi-Yau shapes, they look like big knots of thick yarn intertwined (if you could magnify them a gazillion times, which we can't). The extradimensional geometry of these Kalabi-Yau shapes is what determines how a string will vibrate through it, and in turn this is what gives us the properties for the weight, spin, and other characteristics of the fundemental building blocks of matter.

This is a very rough description. String Theory starts there and then has strings vibrating not only linearly but sheet-wise, where a string can wrap itself around a 3 dimensional object like a membrane. Or take on collosal properties, like cosmic strings that are theorized to be millions of light years long, yet thinner than an atomic nucleus, and can be pictured as an imperfection in the fabric of empty space itself, like a crack in a mirror or in an icecube when you drop it into warm water.

The point of all this is that scientists have known for a long time that the Theory of Relativity (which involves things on a huge scale) and Quantum Theory (which involves things on the subatomic scale) are not compatible with each other. They both work, but it is a case where good fences make good neighbors. Since astrophysicists that study the properties of massive things and huge distances need not usually concern themselves with quantum physics, and vice versa, the two theorectical sciences got along, sort of. But when astrophysicists applying relativity theory studied massive things like black holes, they also had to deal with the initial conditions of the big bang, where everything was subatomic "quark soup" and the four forces -- the electromagnetic force (light), the strong nuclear force, the weak nuclear force, and gravity -- were the same, or "supersymmetric." The problem was, scientists could mathematically unify the first three forces, showing that at a certain temperature and pressure they are the same force, they could not quite make gravity fit into this Grand Unification Theory.

Enter Superstring Theory (the "super stands for supersymmetric). Superstring Theory has a good shot at unifying the four forces. It actually requires the theoretical "graviton." Theoretical because gravity is such a weak force compared to the other three, no one has yet discovered the "graviton." However, the math in string theory has not only revealed such a gravitational force particle, it actually requires it in order to work. That, and it requires the extra dimensions for the math to work out. That math is a long ways from being solved. The best they can do now is work with approximations.

String Theory is due for another shot in the arm and may get it after all the data supplied over the past few years from the "frame dragging" experiment launched by NASA is analyzed. That experiement involved two satellites in very high orbit around the Earth with the most perfect gyroscopes ever built, to try to measure if the Earth drags spacetime with it as it sweeps through its orbit around the sun. In other words, is the "nothing" of empty space actually "something?" According to string theory, and quantum theory, it is.

Answer 2

I have watched this video too many times to count...and why do people assume the 4th dimension is time? "Time" is merely the dimension above your own. The 4th dimension is more change than time. The 10th is a lie! A dot is not a dimension!

Answer 3

Wow, this is really difficult if this is not your field. These sort of concepts are difficult to understand, and even accept, because as adults we are so locked into a 3 D (what alone a 4D )understanding of the world around us. When we come to 10D then .......! It is difficult to say 'just accept the concept' because that will leave you searching for some mental picture of the concept. The mathematics is beyond most people's reach.

Answer 4

I'm pretty sure String Theory, M-theory and Brainworlds all require either 11- or 26-dimensional space. Don't remember hearing 10 mentioned.

Answer 5

I recently read 'The Elegant Universe' by Brian Greene.
It does a very good job of putting string theory into layman's terms.
I'm a failed physics student (from many years ago) & even I got on with most of it

Answer 6

A Rubik's cube is 3 dimensions. The 4th would be if the each square of the cube was a Rubik's cube. The 5th dimension would same but for the square of the smaller cube. on down to 10 or whatever dimension you wanted.

Answer 7

This website tries to answer your question in terms a layman would understand, there's a lot of reading involved though!! There are different short chapters which take you through it step by step and it's quite in depth for a popular science site.

http://tena4.vub.ac.be/beyondstringtheory/index.html

Answer 8

3 are the familiar spatial dimentions
1 is time
1 may be extended
6 are curled up tight in the Calabi Yau manifold

Answer 9

I can explain briefly what four spatial dimensions are ....

If you take a point (0 dimensional) and move it sideways leaving a trail, you end up with a 1 dimensional line.

If you take that 1 dimensional line and "trace" it along the 2nd dimension, then you'll end up with a square.

If you take that 2D square and "trace" it upwards (3rd dimension) then you'll end up with a 3D cube.

If you take that 3D cube and "trace" it into hyperspace, you'll end up with a 4D hypercube.

Basically, in hyperspace, one can move up/down, left/right, forwards/backwards, ana/kata. Ana/kata refer to physical directional movements beyond what we can visualise in 3D space.

If you flip a 2D square 180 degrees in the 3rd dimension, it becomes a mirror image of itself (from a 2D perspective). If you rotate a 3D cube 180 degrees in the 4th dimension, it becomes a mirror image of itself (from a 3D perspective).

If you trace the 4D hypercube along a 5th spatial dimension, you'll end up with a 5D cube. Keep this process going and you'll eventually end up with a 10D shape.

Answer 10

Another dimension eg: You look at a plant and see yourself looking at it from above. In other words, you actually see yourself looking at it from above the plant.