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Not only is the universe stranger than we imagine, but it is stranger than we *can* imagine.
I like to follow cosmology and quantum physics where I can, two subjects that both confuse and excite. Over the years they have provoked a lot of curiosity about the universe in which we live, simply because it's just so much more complex than we'll ever have a snow flake's chance in hell of understanding. They turn the everyday stuff of life into what can only be described as science fiction, even though much of it is indeed fact. Fairy tales, with supporting evidence.
M theory though, just makes my mind melt. It's just such a difficult concept to visualise, and if we can't visualise things, then we have great difficulty understanding them. I persevere with the theory never-the-less, because it could be at the heart of everything that is, and has ever been.
It starts with a problem - the observation that sub-atomic particles, each do not occupy a single location in space as one would expect, but instead a multitude. It sounds nuts, but that is the truth and it is what we've observed. The apparent answer to the problem - that there are an infinite number of parallel universes and that sub-atomic particles dematerialise from one and rematerialise into another all the time. It's a stretch of imagination to say the least, but many scientists are beginning to believe that this indeed might be true.
We've all heard of the possibility of parallel universes before, hell, any watcher of Red Dwarf would be an expert in this field by now. But, I've always believed that this sort of thing was just a bit of a thought experiment, and that the likelihood of parallel universes existing outside of a vivid imagination was going to be almost none. To find out that there are many scientists out there, that are far, far more intelligent than I who believe that parallel universes could, and moreover probably do, exist, just bewilders me. If these people are right though, our vision of the universe (multiverse?) is set to expand exponentially in the not-so-distant future.
M theory stems from a long-existing hypothesis called string theory. String theory itself is simple - that what we always perceived to be point particles (such as electrons, leptons, neutrinos etc.), are instead, small 1-dimensional strings of approximately 1 Planck length. The way the strings vibrate, and the frequencies that they produce, are all that is needed to form all the laws of physics.
String theory though, isn't all that clear cut. The real problem with it, is that it is not singular, but instead plural. There have been at least 5 string (or superstring) theories developed up to recent times, and 5 is not a good number for the explanation of the way the universe works. There should be only one. What was needed, was some rationalisation and a large amount of refinement. Or, perhaps, just a relatively minor adjustment as we shall see.
The hardest thing to understand about string theory is its dimensionality. We see the world in 3 dimensions; up and down, left and right, forwards and backwards. This is intuitive. If we add the temporal dimension, that of time, we get to 4 dimensions without too much brain-ache. The world exists in time and space, matter occupies space and time changes the configuration of the occupancy. It's quite simple. String theory predicts that the universe has not 4 dimensions, but 10. That, is very difficult to imagine.
According to string theorists, 1 of those 10 dimensions is that of time which of course we understand very well. The rest however, are all said to be in space. How can there be 9 dimensions in space? Surely, 3 dimensions is all that is needed to describe space? In string theory, 6 of those spatial dimensions are at the truly microscopic level which helps in allowing us to understand why we don't see them, but doesn't explain how they exist separately to something that we are so used to perceiving in 3 dimensions.
Then, as if it wasn't difficult enough to understand already, string theory evolved, to become just that little more complicated, by adding another dimension to its stock. This single act, unified all the variations of string theory together into a single construct. It seems as though they had all been viewing the same thing from different angles, and that the added dimension allowed them to see the picture as a whole. This evolution, changed string theory into M theory. Strings changed into membranes.
It should be said though, that M theory and all its preceding variations on string theory, are in reality all just hypotheses. The plain fact is that all of these theories are incomplete and to all intents and purposes impossible to test. Furthermore, working on these theories is only really the domain of mathematical savants as the mathematical basis for these theories is extremely complex. Indeed, Edward Witten (the Father of M Theory), has suggested that a new mathematical language is probably required to fully describe the theory. Ergo, it's not for the likes of me to understand how these things actually work.
Despite this though, many physicists have started to examine how M theory might be precisely described, how it might be mathematically constructed and also how it might be able explain difficult observations. All this examination and thought experiment has already taken them to one place - a place where an infinite number of parallel universes exist. This of course, is why string theory was developed in the first place, so at least it is consistent in that respect.
How can this multi-dimensional multi-verse exist? How can 11 dimensions be visualised? Well, this is where we run into trouble. No-one really knows. These added dimensions are all mathematical in nature and their effects are all hypothetical. So, trying to get a handle on how a multi-dimensional universe can exist, let alone how multi-verses can all exist in the same space, is almost impossible. How on Earth can you visualise what you cannot see and who's description defies everything that you think you know? Well, you can't can you?
Ignoring that for a moment though, what else have we learnt from M theory?
Well, what M theory does well, and string theory didn't really do at all, is explain how the big bang might actually have happened. This is a huge step forward as no other theory until now has been able to do this with any real satisfaction. In theory, and only in theory, if two membranes that form part of the 11th dimension touch, then that would initiate what we call a big bang. Seems too simple to me, but that's the theory. Imagine if you could do this yourself? Make a machine that warped the eleventh dimension in such a way that it made two membranes touch - you could create your own pet universe in your spare time. I just don't know.
Apart from that though, M theory has done little else to prove itself so far. Initially proposed in 1995, it has had a fair amount of time to mature so this is a little disappointing. Given the complexity of its makeup though, it isn't all that surprising that people are having a hard time working with it and progressing it further. But we will get better, and time will tell whether we are just an infinitesimally small part of the universe, or whether we are an infinitesimally small part of a universe amongst an infinite number of universes.
Either way, you've got to feel humble.
[Posted 05/02/2009] |
