As I pointed out, in the previous post below, Lee Smolin explains, in his newest book The Trouble with Physics, that there are four distinct advantages of the string theory approach over the particle theory approach to physics, which make it extremely compelling to many physicists. These are its ability to “automatically” provide solutions that the particle approach cannot provide:
However, the key to all this “magic” is that the string concept of a one-dimensional entity has two ends (points) and a middle, which also happens to be the distinguishing feature of the LRC’s SUDR|TUDR combo. In the case of the LST community’s string theory version, it all started with Grebiele Veneziano’s discovery of the remarkable formula that explains a pattern in the data of strongly interacting particles, which, when interpreted physically, has properties analogous to rubber bands. When the entities of the formula gain energy, they stretch, and, when they release energy, they contract, just like rubber bands do. Smolin explains:
Veneziano’s formula thus was a doorway to a world in which the strongly interacting particles were all rubber bands, vibrating as they traveled, colliding with one another and exchanging energy. The various states of vibration would correspond to the various kinds of particles produced in the proton smashing experiments.
Of course, the interest in them at the time is to be understood in the context of the leading edge attempts to explain the strong force of the atomic nucleus, and several theoretical physicists, including Leonard Susskind, came up with the same idea about the same time. However, while the standard model’s QCD theory eventually met the challenges of explaining the strong nuclear force more successfully, it soon became apparent that the idea of using this one-dimensional entity, as a fundamental element, replacing the concept of a point particle altogether, was an even bigger and more exciting prospect than explaining the strong interactions. Hence, string theory, as the fundamental theory of physics, increasingly gained momentum, after a somewhat shaky beginning, as a failed theory of strong interactions.
The most important development in the early history of string theory, the one that really prepared it as a candidate for a fundamental theory, was Pierre Ramond’s modification that made it a discovery of supersymmetry. In this form, bosons and fermions were mixed together, and the twenty-six dimensions, which the theory required originally, were reduced to ten dimensions. This was huge, and when it was discovered that these “strings,” as they came to be called, could interact in ways consistent with quantum mechanics and special relativity, and that the bosons of the theory not only contained photons, but also the theoretical quantum of gravity as well, the so-called gravitons, things really started to heat up. Smolin writes:
The fact that string theory contained gauge bosons and gravitons changed everything. Scherk and Schwarz proposed immediately that string theory, rather than being a theory of the strong interactions, was instead the fundamental theory - the theory that unifies gravity with other forces.
The way this works is engaging, to say the least. The gravitons arise from the vibrations of closed strings; that is, the photon bosons are the vibrations of open strings, but when the two ends of a vibrating string are joined together, to form a closed loop, the vibrations correspond to graviton bosons. In the case of open strings, the boson vibrations are connecting the two opposite ends of the string, just as the photon “connects” the electron and positron. Smolin explains:
The ends of the open string can be seen as charged particles. For example, one end could be a negatively charged particle, such as an electron; the other would then be its antiparticle, the positron, which is positively charged. The massless vibration of the string between them describes the photon that carries the electrical force between the particle and the antiparticle. Thus you get particles and forces alike from the open strings, and if the theory is designed cleverly enough, it can produce all the forces and all the particles of the standard model.
Whoa, no wonder this gets people excited, but, then, again, on top of all this, when the ends of the string are joined together, the theoretical graviton boson is born. Again, Smolin explains:
If there are only open strings, there is no graviton, so it seems as though gravity is left out. But it turns out that you must include the closed strings. The reason is that nature produces collisions between particles and antiparticles. They annihilate, creating a photon. From the string point of view, this is described by the two ends of the string coming together and joining. The ends go away and you’re left with a closed loop.
Here, Smolin concentrates on the inflexibility of the theory’s consequences, something that is most desirable in a physical theory, but he doesn’t explain very well why “gravitons come only from vibrations of closed strings.” This is unfortunate, but probably due to the fact that to Smolin, and to many, many, others, the most significant part of the development of string theory is that it must include gravitons, while particle theory cannot be made to include gravity, in spite of all efforts to find a way to do so. He writes:
…the difference between gravity and the other forces is naturally explained, in terms of the difference between open and closed strings. For the first time, gravity plays a central role in the unification of the forces.
Isn’t this beautiful? The conclusion of gravity is so compelling that a reasonable and intelligent person might easily come to believe in the theory based on this alone, whether or not there was any detailed experimental evidence for it. Especially if that person has been searching for years for a way to unify the forces, and everything else has failed.
But the beauty and strength of the “unification of the forces” in this concept are not to be understood simply in the straightforward logic of open strings becoming closed strings, by joining the two ends together, a mechanical action that all of us are familiar with, in one way or another, but rather in the deeper significance of the implication that there exists an underlying law of nature that requires the process to take place. “But what gives rise to it?” Smolin asks, “Is there a law that requires the ends of strings to meet and join?” His answer is positive. It describes a deeper meaning, or a deeper unification of fundamental concepts, if you will.
He writes, “Herein lies one of the most beautiful features of the theory, a kind of unification of motion and forces.” Now, readers of this blog know that one of the primary tenets of Larson’s RST is that force cannot exist as an autonomous entity, apart from motion. Force is necessarily a property of motion, by definition, as Larson explains at length in his Neglected Facts of Science, but the LST community, following Newton’s program of research, interpreted as a dictum to focus on the forces of interaction, has treated them as something fundamental, existing autonomously and independently of motion, but here, Smolin is delighted that string theory has now lead to “a kind of unification of motion and forces.” Perhaps we would prefer to characterize it as a “reunification of motion and forces.” Unfortunately, however, that point would be lost on those not familiar with Larson’s works. Smolin continues:
In most theories [i.e. LST theories], particle motion and the fundamental forces are two separate things. The law of motion tells how the particle moves in the absence of external forces. Logically, there is no connection between that law and the laws that govern the forces.
In string theory, the situation is very different. The law of motion dictates the laws of the forces. This is because all forces in string theory have the same simple origin - they come from the breaking and joining of strings. Once you describe how strings move freely, all you have to do to add forces is add the possibility that a string can break into two strings. By reversing the process in time, you can rejoin two strings into a single string. The law for breaking and joining turns out to be strongly prescribed, to be consistent with special relativity and quantum theory. Force and motion are unified in a way that would have been impossible in a theory of particles as points.
Well, that might be so, but then, as we have been discussing below, and also in the New Math blog, the whole idea of points in the continuum, and the assumption of a correspondence of these with real numbers, has been confused from the beginning. Given the assumptions of the RST, the concept of a point charge changes, from the enigmatic one of an object with no spatial extent, to one of a spherical vibration, or change, a displacement, in the rates of an eternal space/time progression, at a given location in the progression. One of these, formed by the “direction” reversals in the space aspect of the universal progression, at that location, is the dual of the other, formed by the “direction” reversals in the time aspect of the universal progression.
When these two join together, and the probability that they will do so exists, because of the progression, the combination forms a one-dimensional object, consisting of two “points” separated by a “length” of magnitude. We refer to the space vibration as a SUDR (space unit displacement ratio) and the time vibration as a TUDR (time unit displacement ratio). When the two are joined together, they become the SUDR|TUDR combo (or S|T), which is analogous to the string vibration of string theory, in that it has two end terms and a middle term, but these are space/time magnitudes of motion, not an undulating object. Hence, while there is a useful comparison of the two concepts, they are vastly different.
Nevertheless, it is clear that what the three or four decades of research has revealed about string theory, that it “automatically” provides tremendous theoretical advantages in terms of the standard model and quantum gravity theory, is also an indication of the potential of the new system’s theory. Obviously, we can describe forces in terms of the joining and separating of the S|T entities in a similar manner, as the string theorists have done with their strings. However, we can expect much more than that as well, because, with the new math forming the basis of analysis, in the context of the Chart of Motion, the inductive aspect that string theory so conspicuously lacks becomes a big part of the new theory.
Just as the algebra of the new math is necessarily ordered, distributive, commutative and associative, in all dimensions, the rules of combining the discrete units of motion in the new physics follows the same straightforward, well understood, principles of discrete numbers. This means that the only thing needed to form the initial units of the system is a universal space/time progression, which, while we must assume it exists, and that too in a suitable form of a workable hypothesis, it is clearly observable for all to see: We know that both time and space are inexorably marching forward, do we not? We also observe no more than three dimensions of magnitude, do we not? Finally, while some may think that a “smooth” continuum of discrete points is possible, it’s clear that a non-divisible length cannot be imagined anymore than can a non-extendable length. Is this not so, surely?
Therefore, we conclude that string theory is giving us a valuable glimpse of the way forward. However, if we are to understand what it is telling us, we need to go back and correct the misguided concepts of the past. We need to recognize that ad hoc inventions, while they are certainly useful in the short run, will always come back to bite us in the long run.