## Sunday, 20 February 2011

### Why we think there are multiple dimensions

As promised in my introductory blog post, I now want to explain where this idea of multiple dimensions originated. I need to talk about mathematics and physics. At this stage, I don't want to go into detail about the implications and ramifications of multiple dimensions but merely to describe the scientific basis for the claim that there are several more dimensions than the ones we are immediately aware of.

Prepare yourself for an introduction to the leading edge of advanced mathematics! I promise I'll make it as easy to understand as I can, but don't worry if you don't follow everything. There are a couple of videos at the bottom of this post that may be of some help. The important thing is that you get to the end of this post with a realisation that all of this is for real. It's not a flight of fancy. Here goes....

Einstein's general theory of relativity beautifully describes the physics of the universe on a large scale. It is also referred-to as the theory of gravity. It describes the motions of an apple falling from a tree, the rotation of a planet around a star, a star round a galaxy and even the motion of a galaxy itself. The mathematics of geometry are used in its formulation. However, it breaks down on the small scale. For example, it can't describe the motion of an electron within an atom.

For that, we need to turn to a different theory: that of quantum mechanics. A "quantum" is the name given to the smallest unit of any physical entity that is involved in an interaction. Quantum mechanics uses (amongst other things) the mathematics of probability to describe the behaviour of sub-atomic particles and is widely regarded as the most validated branch of science. In particle accelerators such as the European Large Hadron Collider and the US Tocomac at MIT, it predicts the outcome of atom-smashing experiments to an incredible degree of accuracy.

Just as general relativity can't explain quantum interactions, quantum mechanics can't explain interactions at the cosmic scale. The two branches of scientific theory are at odds with one another and yet we know from experiments and observations that the different worlds they describe are actually part of the same universe: the one we live in.. There must therefore be a bigger, overriding theory that unifies them at all scales.

This was one of the major scientific quests of the 20th century and Einstein went to his grave without a satisfactory answer. This all changed in 1985 when theoretical physicist John Hagelin developed a revolutionary idea that finally appeared to solve the conundrum. The "Grand Unified Field Theory" as it was called (GUFT), used the vibration and rotation of one-dimensional superstrings to model the behaviour of sub-atomic particles and the four fundamental forces of physics: the nuclear strong force, the nuclear weak force, electromagnetism amd gravity. "String Theory" was thus born.

Within a few years another four, apparently different, competing 10-dimensional GUFT's were developed. Clearly the universe couldn't exist in all 5 states - or could it? In the early 1990's one of modern physics' most revered theoreticians, Professor Edward Witten put to rest the growing doubts about string theory by unifying the five unified theories into a single theory which he called "Membrane Theory".

He did this by adding yet another dimension to the model making it 11-dimensional. Each 10 dimensional GUFT could now be thought of as a different aspect of the higher dimensional model. Think of it like a 3D cube that that can cast a number of different 2D shadows on a flat surface. Each shadow is a different representation of the cube in the lower (2D) dimension. Witten subsequently became sceptical about membranes and the theory is now referred-to as just "M-Theory".

An argument soon broke out amongst those closest to string theory about how to - or even whether to - interpret M-Theory in practical terms. I will discuss the concepts and meaning of dimensions in detail in my next post but, for now, suffice it to say that another SEVEN dimensions beyond the familiar three spatial dimensions plus the dimension of time has deeply profound philosophical and religious implications when taken literally.

Internationally famous physicist, Richard Feynman is reputed to have retorted "Just shut up and calculate" when asked to speculate about the implications of a multi-dimensional universe. The 11D GUFT model was very good at mathematically verifying the results of particle collision experiments and as far as he was concerned that's as far as it goes!

Needless to say, this whole blog is predicated on the assertion that it is right and valid to interpret M-Theory in words. The implications are massive in terms of where we humans fit into the true picture of reality. When I was employed as a professional mathematician by the Coal Board in the UK, we created models of economic and logistical systems that fitted all the data that we knew. We then purposely interpreted the models to tell us things about those systems for which we had no hard facts. Sometimes the revelations were unexpected but they invariably proved correct in the longer term as more data became available.
I therefore have an answer for those who doubt the validity of interpreting M-Thory: "Shut up and stop being afraid of the child you have given birth to."

Before I end this post it would only be fair to point out that we don't know for sure that there are multiple physical dimensions outside of space-time. M-Theory is just a theory and there are other interpretaions that have been put forward that don't include multiple dimensions. Having said that, the Large Hadron Collider at CERN is, as I write conducting experiments to try to test the theory, and according to a recent on-line news story the first tangible evidence may be discovered very soon.

My next post will be called "10 spacial dimensions: what does that mean?"
From the perspective of THIS universe, I am "The REAL" Jeff Hall :)

Further Information:

### The Elegant Universe - Einstein's Relativity

Here is a 7 minute clip about Einstien's theory of relativity

### Discovery of The Unified Field

And the great man himeself, John Hagelin talks about the unified field. Today he has moved on a long way and in fact is one of the major influences for the subject of this blog.