2014 04 16 Mike Polioudakis Forces, curved space, messenger particles, waves, interacting forces I use the term "work" not technically but usually to mean “operates”, “comes out”, or “comes out well”. A The question here reflects “fields” versus “particles” but not exactly. It is like what Einstein struggled with before he died but not exactly. How do we understand influences between bits of matter? Since Einstein, we understand gravity as operating by curving space-time (not exactly, but close enough). That is not the quantum view of force. In the quantum view, force works through exchange of messenger particles such as photons. The quantum view has been successful with the forces other than gravity: electro-magnetic, weak, and strong. Instead of the quantum view, can we understand the other major forces in terms of curving space? Einstein tried to do something like this in his unification of gravity and electro-magnetism, and failed. Forget about unifying any of the forces. Concentrate on one force. Can we have a "curved space-time" theory of the strong force or weak force or electro-magnetism alone similar to the relativistic theory of gravity? I don't know of any analysis of one force other than gravity in terms of curved space-time or any kind of space-time. I don't think quantum field theory can be taken as a theory of how space-time works. If it could, then we would have had a quantum theory of gravity long ago. But, then, I am not a physicist. I will search the literature more thoroughly some day, but I don't expect to find a depiction. B I am confused about the unification of forces, and how unification might affect seeing the forces in terms of curved space-time or in quantum terms. Evidence is good for the unification of forces at particular energies. At high enough energy, the weak force combines with electro-magnetism to form one electro-magnetic-weak (electroweak) force, and so on with the electroweak and strong forces. I am not sure if physicists in general think the strong-weak-electro-magnetic force combines with gravity at high enough energy. I am also not sure about the separation of forces at low energies. At the energies that prevail in most situations in the universe now, the four forces are separate, but electricity and magnetism are usually together. It is hard to generate electricity without magnetism, and vice versa, but not impossible. We can imagine static electricity without magnetism, and this is a kind-of electricity-separated-from-magnetism-at-a-low-energy (forgetting about moving observers or any relativistic effects). At this low energy, we can imagine electrons just sitting there. It is harder to imagine magnetism without electricity. We have all had magnets as children, and the magnets did not obviously depend on some electric current, but later we learned that explanations of the magnets did depend on electric particles within the magnets. And, as of yet, there is no magnetic monopole as there are electric monopoles. The issue of unification or separation of forces is relevant to "curved space versus quantum messenger particle" accounts of force because it is not clear at what energy levels which accounts might be expected to best apply. C The following sections are based on an analogy between electro-magnetism and the other forces. The issues here bear on the relation of waves and particles, and, so, bear on the nature of space-time. Although we are used to thinking of electro-magnetism now as one force, it might be useful to remember that sometimes it is not, as, for example, static electricity without obvious relativistic effects. That is why I write here “electro-magnetism” instead of “electromagnetism”. Electro-magnetism only works because it is two forces, and one force induces the other. Unless there were two forces, there would be no electro-magnetic waves and there would be no waves to serve as the basis for the messenger particle of electro-magnetism (or unless the one united force necessarily had different spatial components). The two forces are united-yet-distinct. The two forces are necessarily orthogonal (right angles) or else mutual induction would differ much from what it is now. Mutual induction at orthogonal angles causes a transverse-and-longitudinal wave that serves as the wave basis for the carrier particle (photon) of the combined force. Do the two forces have to induce orthogonally? Could they induce at other angles? If they tried to induce at another angle, would they wind up inducing orthogonally anyway? What does the fact that they (must) induce orthogonally say about space-time? Electricity and magnetism are distinct-but-inseparable forces because of relativity. They keep distinct only if the observer is not moving relative to the source of the force. What about the other forces? Is the weak force only one distinct force if an observer is not moving relative to the source or could not be moving relative to the source? What about the strong force? Does relativity require that the weak force be two distinct-but-united forces or that the strong force be two-distinct-but-united forces? “Observer” can mean not just a physicist in a lab but another particle in the same nucleus, an electron outside the nucleus, or a passing neutrino. I don’t know enough about the electroweak theory to answer this question but, from what I have read, relativity does not seem to play a key role in unifying the three forces. D The wave basis for the carrier particle (photon) in electro-magnetism is two united-but-distinct forces, orthogonal to each other, mutually inducing each other. What is the wave basis for the carrier particles in the other forces? As far as I know, the other forces are not two united-but-distinct forces inducing each the other. So what is the basis for the waves? If there is no basis for the waves in two united-but-distinct forces mutually inducing each other, then what is the wave basis for the carrier particles? Just invoking the Schrodinger wave equation here is not enough of an answer. As far as I can recall from what I have read, in the standard treatments of the forces other than electro-magnetism, the forces don’t induce within themselves, and don’t induce each other, and so don’t form transverse-longitudinal waves on the basis of any induction. If so, then what is the significance that one force, electro-magnetism, works through mutual induction of two separate-but-unified forces while the other forces do not? I know about gravity waves. As far as I know, those cannot be the basis for any waves in gravity that in turn are the basis for gravitons. Similarly, there might be pulses in the weak force or strong force, but those pulses would not be the basis for any waves that in turn are the basis for the carrier particles. Does the analogy between electro-magnetism and the weak force, and strong force, break down? What is the basis for the waves that in turn form the basis for the carrier particles? E In electro-magnetism, the forces are combined yet distinct, and are orthogonal. In the combined version of other forces, are the forces still distinct somewhat? If so, are the combined-yet-still-somewhat-distinct forces orthogonal to each other in some space? If so, would their orthogonal orientation promote some kind of wave and-or particle in the combined force? Is the electroweak force composed of two (or more) united but distinct forces, somehow orthogonal to each other, that produce waves, and are the waves the basis for the carrier particles of the electroweak force? Somewhat the same can be asked of the strong force except that I don’t know what other force it might mutually induce with orthogonally to form the basis for the waves that form the basis for the messenger particles. I know of the W-minus, W-plus, and Z bosons, and I know of the eight gluons. What I don’t know is the wave basis for them, and if the wave basis has a basis in the interaction-induction of forces. Because it is a transverse-longitudinal wave with the components orthogonal, an electro-magnetic wave needs four dimensions: electric flux, magnetic flux, direction of travel, and time. Assume the other waves for the other forces are also transverse-longitudinal (don’t know). Assume electricity, magnetism, and the weak force are in the same relation to each other in the electroweak force that electricity and magnetism are to each other in electro-magnetism, that the electroweak wave is transverse-longitudinal, and that the wave is made of the three component forces inducing each other while orthogonal. In that case, we would have a five-dimensional wave, with time as one of the dimensions. That is fine with me but it means we need another dimension. I want to stay away from the many dimensions of string (M) theory. If we do, five dimensions still are fine with me. Now assume the same with a combination of electricity, magnetism, weak force, and strong force. In this case, we need six dimensions. As long as we can stay away from many dimensions, six dimensions are still fine with me. Now assume the same with gravity in the mix. Now we need seven dimensions, and that is still fine with me. Maybe we can't find any gravitons because, at the energy levels we see, gravity does not work with any other force to produce waves made up of two forces as electro-magnetic waves are made up of two forces. Assume that forces, once combined, make one force. The electro-magnetic force is the electromagnetic force. The electro-magnetic-weak force is the electroweak force. The electroweak-strong force is the electroweakstrong force. If we assume the electro-magnetic force is one force, then can it interact with the weak force to make a transverse-longitudinal wave in which the electromagnetic force is one component and the weak force is another component, and both still orthogonal? This is simply a “dodge” to get rid of one dimension. It requires a “kind of” merging of electricity and magnetism that is not clear. If we allow this situation, what if the electroweak force is one force, and it mutually induces with the strong force to make one transverse-longitudinal wave in which the electroweak and strong forces are the two components orthogonal to each other? This is the same dodge, with the same issues; I merely state it be explicit and clear. Now we can ask the same of the electroweakstrong force and gravity. F I do know of the messenger particles for the various forces, and for the combined electroweak force. I don’t know of any messenger particles for the combined electroweakstrong force. Suppose that the messenger particles for the weak force and the strong force do not have a wave basis like the electro-magnetic force, that is, a wave basis that is made up of the combination of two forces that mutually induce and that are orthogonal. Then what is their wave basis? Again, it is not enough just to invoke the Schrodinger equation and say that they have a wave basis even if we don’t feel like specifying the wave basis. What makes up the wave basis? How can there be a wave basis if there are not two (or more) forces mutually inducing? G This section is even more far-fetched but fun. It is natural to think of the electro-magnetic force combining with the weak force because that is the tendency at higher energies. It is the down-to-up approach that we naturally get as we ascend the energy ladder. Why not forget about climbing energy thresholds, and go the other way? Why can’t the weak force combine with the strong force? Would that form the basis for a wave? Would that wave form the basis for a particle? Have no idea. Because this scenario skips over the weak force, it is even less likely: What about a combination of the electro-magnetic and strong forces? H Some of these issues might be useful in thinking about fractional charges, and the fact that we have qualitatively different charges in the four forces.