How Many Dimensions Are There? 11-Dimensional World and String Theory

Published by
Bob Pershing, M.Sc.

What if there are more than three dimensions in our universe? String theory suggests there are 11 of them. Let’s explore this intriguing theory and its possible applications.

Since ancient days, humans have been familiar with the sense of 3-dimensionality of space. This idea was better understood after the theory of classical mechanics by Isaac Newton was presented about 380 years ago.

This concept is now clear to everyone that space has three dimensions, meaning that for every position, there correspond three numbers with regards to a reference point that can direct one to the right location. In other words, one can define sequences of positions in three independent ways.

This fact has its trace not only in physics but in other aspects of our life such as the biology of every living creature. For example, the inner ear of almost all vertebrates is composed of exactly three semicircular canals that sense the position of the body in the three dimensions of space. The eye of every human too has three pairs of muscles by which the eye is moved to every direction.

Einstein’s special theory of relativity further developed this concept through its revolutionary idea that time should also be regarded as a 4th dimension. This notion was a must for the theory to resolves inconsistencies of Newtonian mechanics with classical electromagnetism.

Once a strange concept, after more than a century of its presentation, it is now a widely accepted concept in physics and astronomy. But still, one of the greatest mysteries and challenges of our era is the origin of the three dimensions of space, the origin of time as well as details of big bang why does space have three dimensions and not more?

This might be perhaps the most difficult question of physics.

Higher-dimensional space

The possibility of the existence of even higher dimensional space came about on the pure theoretical work of physicists who were trying to find a consistent and unified theory capable of explaining gravity within the framework of quantum mechanics.

Einstein’s general theory of relativity is a classical theory since it is valid only at large distances. It is capable of making its successful predictions such as retrogression movement of the planet mercury, bending of light beams passing by massive objects, black holes, and many similar phenomena at large distances.

However, it cannot be used at the quantum level since there is no quantum theory capable of explaining gravitational force.

Unification of fundamental interactions

It is known that there are four types of interactions in nature: strong and weak nuclear forces, electromagnetism, and gravity. The relative strength of these forces differs with the gravitational field being the weakest force in nature.

During the past 100 years, physicists have long dreamed of unifying all fundamental fields and units of matter into a single self-consistent model. In the late 1960s, Steven Weinberg and Abdus Salam managed to unify two of these fields, i.e., weak interactions and electromagnetic field in a genuine theory named electroweak.

The theory was later confirmed by its predictions. However, despite enormous efforts by physicists all over the world, there has been a little success for the unification of all four interactions into a single theory, with gravity being the most difficult one.

String theory and multidimensional space

In conventional quantum physics, elementary particles, such as electrons, quarks, etc., are regarded as mathematical points. This notion has been a long source of heated debate by physicist especially because of its deficiencies in dealing with gravity.

The general theory of relativity is incompatible with quantum field theory and numerous attempts to use a point-like particle model of quantum theory have failed to offer a consistent explanation of the gravitational field.

This was the time that string theory attracted a lot of attention aimed at finding a sound quantum theory for gravity. The way that string theory resolves the problem is by giving up the assumption that elementary particles are mathematical points and developing a quantum model of one-dimensional extended bodies named string.

This theory reconciles quantum theory and gravity. The theory once regarded as a purely theoretical conjecture is new regarded as one of the most consistent theories of quantum physics, promising a unified quantum theory of fundamental forces including gravity.

The theory was first suggested in the late 1960s to describe the behavior of particles called Hadrons and was later developed in the 1970s.

Since then, string theory has undergone many developments and changes. By the mid-1990s, the theory was developed in 5 different independent string theories, but in 1995, it was realized that all versions where different aspects of the same theory named M-theory (M for “membrane” or the “mother of all string theories”).

It has now become the focus of theoretical work for its success in explaining both gravity and the inside of an atom at the same time. One of the most important aspects of the theory is that it requires the 11-dimensional space with one time coordinate and 10 other spatial coordinates.

Testing and Experimental Results

The important question about M-theory is how it can be tested. In science fiction, extra dimensions are sometimes interpreted as alternate worlds, but these extra dimensions could simply be too small for us to feel and examine (on the order of 10-32 cm).

Since the M-theory is concerned about the most primitive entities of our universe, it is really a theory of Creation, and the only way to test it is to re-create the Big Bang itself at an experimental level. Other predictions of the theory that are to be tested include Super-symmetric particles, Extra dimensions, Microscopic black holes, and Cosmic strings.

Such an experiment needs a huge amount of input energy and speed that is beyond the present level of technology. However, it is expected that in the coming years, the new LHC (Large Hadron Collider) at CERN could test some of these predictions for the first time, providing more clues to the multi-dimensionality of our universe. If the attempt is successful, then the M-theory may give answers to the following fundamental questions:

  • How did the universe begin?
  • What are its fundamental constituents?
  • What are the laws of Nature that govern these constituents?

Conclusion

As of now, there are no definite empirical results confirming M-theory and its 11-dimensional space, and the verification of the theory is a great challenge for physicists.

There is even a new theory called F-theory (F for “father”) that introduces another dimension, suggesting a 12-dimensional space with two-time coordinates instead of one!

The renowned physicist John Schwartz has even gone further by saying that there may be no fixed dimension for the final version of M-theory, making it independent of any dimensionality of space-time. Finding the real theory needs much more time and effort and till then the multi-dimensionality of the universe is an open case.

As the physicist Gregory Landsberg said if the tests are successful, “This would be the most exciting thing since humanity discovered the Earth is not flat. It would give us a whole new reality to look at, a whole new universe.”

References:

  1. http://einstein.stanford.edu
  2. Introduction to M-theory
  3. Eleven Dimensions of the Unifying Theory by Michael Duff (Jan.14, 2009)

View Comments

  • Four planes: Microspatial, macrospatial, and hyperspatial.
    1. MICROSPATIAL: r, s, t axes. These take the shape of circles with two points on each: 1 and 0, signifying for different states( real/imaginary, top/down, etc. Quanta in any point on this three-dimensional plane cannot be at the ")" or "1" point on any of those axes, because it is not physically possible. A quantum particle might shift it's position into an imaginary or complex number to perform quantum tunnelling or superposition, and then bring it back to a real number. Explains a lot of things. Remember, these axes are circular. This also means a quantum particle can choose to "exist" or not. Maybe the reason we don't notice ourselves blinking in and out is either that we do it fast or half of our particles are in another state, making our net change 0.
    2.MACROSPATIAL: x, y and z axes. These appear as straight lines, ranging from 0 to infinity. We are accustomed to this.
    3. HYPERSPATIAL: u, v and w axes. These are so big we can barely understand. The axes for these might actually be spirals, as those are the third perfectly- shaped 1d manifold (straight line, circle, spiral. think about it.) and it is the only one that expands exponentially as it wraps around. However, spirals look confusing in 1d, so imagining it in 3d would be mind-bending. The thing to note is that this plane is all about exponential increase, instead of linear(macro) or in form of a sine/cosine wave(micro if look very well). Now, what could change an object's quality exponentially(volume) and manipulate the macrospace? Scaling! So we can say that if you increase an object's w axes from 1 to 2, the x, y and z would go from n to 2n at the same time! You can see how by adding v and u, things can excalate very quickly.
    4. ALPHA-OMEGA: This consists of the alpha dimension(0D) and the omega dimension(10D) Don't have any idea what they are, but the fact they exist before and after would indicate that the four planes like each's three dimensions can be interchanged(rotation), meaning there is no order.

    I believe the word "time" is just a summary of hyperspace, same way that distance/space is a summary of macrospace. So altering Einstein's space-time, I would propose (random name)-space-time, showing 3 axes representing micro, macro and hyperspace(then would alpha-omega signify as another 4th-dimensional time?)
    This theory also makes sense because for the dimensional limits, we have
    0-1(oscillating change)
    0- infinity(linear change)
    0- infinity^2(exponential change)
    which could be rewritten as
    0 - infinity^0
    0- infinity^1
    0- infinity^2
    as you can see, 0 1 2.
    There you have it! 11 dimensions!
    I didn't do any reasearch, don't shout at me.

  • This 4th plane could also wrap around the other three related planes like the 4th dimension wraps around the other three related dimensions.
    I named them planes because I had nothing else in mind. Universe was already used, reality was also used(real/complex/imaginary).
    PS: If you think of the way the four planes arrange themselves as similar to how the 1 s and 3 p subshells of an atom, when merged into 3 sp2 and 1 p, which split themselves to 1/2 p, sp2, sp2, sp2, 1/2 p, then maybe you might find something interesting!

  • If 3 dimensions make one plane, 4 planes makes one...universe I guess, then maybe there 5 nests(one in another) of universes, each universe containing infinity^11(for each dimension) other smaller ones. If each mini- universe is expanding, meaning it generates space, then maybe that space leaks through the infinite(but very small) border that block our universe from theirs. If infinity of those mini-universes are all leaking out tiny amounts of space, then that would also cause the expansion of our universe. This is a wild shot, but what if dark matter is are just clumps of these "white-hole" universes, and black holes and normal matter are made of "black-hole" universes, which, instead of expanding, shrinks from infinity to a single point, a reverse big-bang. Maybe gravity doesn't PULL things together, maybe it DELETES space!
    Also, in microspace, an object cannot be 1 or 0 on ALL the axes at any point in time. THAT is not possible.

Published by
Bob Pershing, M.Sc.