The problems of string theory.
Engaging with the mysteries of the cosmos is a thrilling and fascinating thing. I’d encourage anyone to try it. Try to get good sources for understanding, say, quantum mechanics. You can make progress. Of course, I do not understand everything about the universe, nor would I claim as much. I’ve developed my own theory of quantum gravity, though I would not say that I have a theory of everything. And a lot of people are intimidated by phrases such as ‘quantum gravity’ or ‘string theory’, but really there’s not that much to be intimidated by. I’ll try and explain here.
String theory, as the name suggests, posits that all matter and energy are composed of fundamental objects, loops of energy known as ‘strings’. String theory also posits that extra dimensions exist in the universe. This is one of the major conundrums of string theory, and the original string theory managed to parse the number of dimensions in the universe down to eleven. Some superstring models nowadays posit as many as twenty-seven different dimensions to the universe. This is how the problem breaks down: take our four-dimensional universe and then say that it’s possible to have a four-dimensional simulation within that universe. Then, say it’s possible, within the simulation to have another four-dimensional simulation. If you take this scenario to be accurate, you then end up with twelve dimensions, assuming that the ‘real’ universe you started out in wasn’t, in itself, a simulation.
The simulation hypothesis arises as a consequence of thinking about extra dimensions and higher dimensional states. Many people look to the example of Flatland, the mathematical book about people living in a two-dimensional world encountering three-dimensional reality; and, indeed, we can have these sort of discussions so long as we don’t neglect our own four-dimensional reality. We can add in out our created three-dimensional reality; the reality of fiction and simulation; and we’d then end up with seven dimensions of time and space. Or eleven. Or fifteen. Or nineteen. Or however many dimensions ad infinitum when we realise that an infinite regress exists in this possibility that we can keep adding in simulated universes within simulated universes. So, really, there are an infinite, or undefined, large number of extra dimensions. But that’s string theory, and is string theory reality? Who knows.
We have no real way (yet) of testing for extra dimensions. We have no way of knowing whether or not parallel universes to this one exist. Furthermore, the question of extra dimensions really relates to parallel universes. These universes would have to exist in an ethereum of sorts in a realm of quantum objects that we cannot yet detect. Perhaps we will see signs of, say, supersymmetry in the next generation of particle accelerators. Perhaps we will find evidence of cosmic superstrings. I don’t know. String theory could, perhaps, be a theory of everything; or M-theory, more likely, would be the theory of everything; though I suspect string theory is at least incomplete as a theory of quantum gravity. It acknowledges the role of the electrical field in gravitation, that is one positive of the theory. Though I didn’t find any reference to a simultaneous exchange of W+ and W- particles in any of the literature I’ve read on string theory, so I still think my model is unique.
My model does not have gravitons, unlike string theory and loop quantum gravity. I think they both fall down as theories of quantum gravity for including gravitons and not seeking to explain gravity using the assemblage of particles we have in the Standard Model at present. That’s what I was doing when I began my own work on quantum gravity. That said, the larger problem with string theory is this issue of extra dimensions and untestable consequences of the theoretical framework; we might find answers in the future in computer science even as we begin producing more sophisticated simulations of reality and, perhaps, plugging into them ourselves via some sort of neural linking technology. A lot of people take scientists to be traders in jargon and I really have the impression that people in the string theory camp and the loop quantum gravity camp are talking at cross purposes, that a synthesis between the two frameworks should be sought. In doing so, we might amend this outstanding philosophical problem of the implied infinity in the dimensionality of the universe.
Why an ‘infinite’ number of dimensions? Because we don’t know how many there are and we assume the true number of dimensions to be inclaculably huge. What are the dimensions of pure thought and imagining? Does the mental realm have its own dimensionality? We could even, via this, begin exploring cognitive neuroscience elements of the problem. Again, the problem seems to be somewhat transcending science and getting into very speculative, very philosophical, very artsy territory; we might seek to show how logic (i.e. mathematics) cancels out certain infinities as being possible in a logical sense. Do certain infinities exhibit contradictions in their logical framework? And, what sort of infinities does string theory portend if it purports to be a theory of everything? I once said that if people had a theory of everything they’d soon want a theory of anything. Maybe that’s the truth. Maybe there are realms of mathematical sophistication that we’re yet to plug and that, for the time being, certain things exist outside our understanding.
What seems certain to me is that we’re headed for a new epoch of STEM. We’re headed towards something really quite bold, breathtaking and transformative in terms of how we understand the world. We might be days away from finding a habitable exoplanet with the JWST. We’re watching huge machines get launched by SpaceX and Elon Musk. We might be in the generation that finally cracks quantum gravity and delivers everyone a model for nature that can be understood and appreciated by people at large. We might make maths and physics arts subjects instead of sciences; or treat them as combinations of art and science, much like engineering. In any case, there exists problems with string theory, but these might not be insoluble, and a fusion or synthesis might exist between string theory and other quantum gravity models.
