It’s a saying that’s been quoted by others, usually scientists and science writers, thousands of times by now, yet it retains the element of a profound insight. And that is ‘the Universe is not only far stranger than we imagine, it’s far stranger than we can imagine’. Every time you turn a corner, there’s an unexpected and rather shocking surprise staring you in the face! Mother Nature never seems to run out of curve balls. Anyway, one such imagination could have our Universe’s strangeness level increased a notch or so in that it allows for micro (quantum) time travel and that perhaps can lead to a Universe that consists of way less stuff than that contained in the smallest speck of dust.
Symmetry: The Yin and the Yang:
Symmetry, or two ways of looking at things, or dual solutions or just plain duality is quite familiar in our world and has lots of parallels in mathematics and physics too. I mean we have wave – particle, forward - back, left - right, east - west, top - bottom, north - south, push - pull, either – or, positive charge - negative charge, matter – antimatter, spin-up – spin-down, mass (matter) – energy, clockwise – counter clockwise, for every action there is an equal and opposite reaction, the irresistible force vs. the immovable object, odd – even, zero – infinity, male – female, mind – body, alive – dead, black – white, night – day, dawn – dusk, right down to heads or tails, old vs. new, war and peace, a glass half full vs. a glass half empty, perhaps Coke vs. Pepsi in that glass!
We’re aware that there are mathematical equations that have two solutions. For an easy example, what is the square root of four? There are two solutions: +2 and -2. Of course the concept of -2 is usually considered to be irrelevant or nonsense (can something be minus two feet in height?), so normally only the positive values are considered justified. One tends to always assume and use +2, which, when squared, is four.
Likewise, the general form of a quadratic equation always has two solutions at its core, again, one that is usually a plus value, one that is usually a minus value, but in any event dual solutions.
Symmetry and the Flow of Time:
So, with all this symmetry and dualism in our lives, in physics and in mathematics, why not add in one more – say the flow or arrow of time. But surely time can only flow in one direction, from past to present to future. Or then again, maybe that’s an unwarranted assumption.
At the micro (quantum) level, there is no physical law or principle equivalent to the one-way macro ‘arrow’ of time. Every micro (quantum) action in what we would term the direction towards the future can be equally valid in what we would term the direction towards the past. If time has no significance at the micro (quantum) level, then all particles and all antiparticles can go both backwards and forwards in time, and in doing so, become pseudo-antiparticles or pseudo-particles respectively. The concept that the arrow of time can reverse must be among the most difficult of ideas to wrap your grey matter around if for no other reason than that our grey matter has only ever actually experienced a unidirectional time’s arrow.
Translating what a dual-solution, a minus or a positive value solution, could mean in real physics, Maxwell’s equations predict the existence of two sorts of light waves, a (positive value) ‘retarded’ light wave (the normal kind that travels from past to present to future), and (you guessed it) a (negative or minus value) ‘advanced’ light wave (a decidedly un-normal variety that would in theory travel from future to present to past).
In physics, one normally has something called CPT symmetry, where C = charge, P = parity (left vs. right), and T = time. To conserve symmetry, if a particle is assumed to be travelling backwards in time, then its handedness is reversed, and so is its charge. It takes on the appearance of that particle’s antimatter counterpart.
In other words, you have to reverse the charge, reverse left-right handedness, and reverse the arrow of time to conserve symmetry. When this is done, an electron, going backwards in time, must take on the appearance of, and be interpreted as, a positron – but of course it’s a pseudo-positron in that’s it’s a normal electron wearing a Halloween mask even though it’s indistinguishable from the real positron McCoy.
Feynman’s Idea:
When (future) Nobel Laureate Professor Richard P. Feynman (albeit starting this track while in his graduate days) looked at physicist Paul Dirac’s equation for electrons, he noticed that if one reversed both the electron’s charge and the time element, then there was perfect symmetry. An electron with normal negative charge going forward in time (one solution), seemed to be identical to an electron with positive charge – a positron – going backwards in time (a second solution)!
A positron is termed an electron’s antiparticle, or equally an electron could be termed a positron’s antiparticle, but in common terms, an electron and a positron are examples of matter and antimatter.
Now all matter particles have an antimatter twin. Their charges are opposite. Particles having no overall charge (like a neutron** or a neutrino) are their own anti-particles (in that their charge is the same – zero). Even so, these particles and their antimatter counterparts differ in other respects, have differing quantum numbers, so particle physicists still talk about such things as an anti-neutron** or anti-neutrino, and you’ll find references to them in the antimatter literature. Antimatter isn’t an ivory tower fairy tale concept. Positrons have been created; Mother Nature can create antimatter. In fact, gram for gram, antimatter is the most valuable stuff in existence, worth hundreds of times its weight in gold or diamonds because it’s both naturally rare and can only be manufactured in minuscule quantities at exorbitant costs in particle accelerators. And, as we all are aware, when matter meets antimatter it’s annihilation time – ka-boom – electromagnetic energy (photons) is given off***.
The upshot of all this is that Feynman proposed that antimatter was just ordinary matter but ordinary matter going in the opposite time direction! Perhaps at this juncture I’d be better off to quote Feynman directly:
“We begin with a photon and an electron, and we end up with a photon and an electron. One way this event can happen is: a photon is absorbed by an electron, the electron continues on a bit, and a new photon comes out. This process is called the scattering of light. When we make the diagram and calculations for scattering, we must include some peculiar possibilities. For example, the electron could emit a photon before absorbing one. Even more strange is the possibility that the electron emits a photon, then travels backwards in time to absorb a photon, and then proceeds forward in time again. The path of such a “backwards-moving” electron can be so long as to appear real in an actual physical experiment in the laboratory.
The backwards-moving electron when viewed with time moving forwards appears the same as an ordinary electron, except it’s attracted to normal electrons – we say it has “positive charge”. … For this reason it is called a “positron”. The positron is a sister particle to the electron, and is an example of an “anti-particle”.
This phenomenon is general. Every particle in Nature has an amplitude to move backwards in time, and therefore has an anti-particle.”
[Feynman, Richard P.; QED: The Strange Theory of Light and Matter; Penguin Books, London; 1990; p.97-98.]
Or, in the words of British science writer Jenny Randles:
“Indeed, it is now widely accepted that the best way to interpret a positron – which is the antimatter version of the electron with identical mass but opposite charge – is to view it as an electron that moves backwards through time.”
[Randles, Jenny; Breaking the Time Barrier: The Race to Build the First Time Machine; Paraview Pocket Books, New York; 2005; p.116.]
So, here’s my understanding of what happens, and apparently there are two ways of looking at the picture. What if an electron is going forward in time and for some reason emits or absorbs a photon which would cause it to alter direction, perhaps to the extent of reversing direction in time as well thus taking on the appearance of a pseudo-positron (because charge is reversed). At some later time, the pseudo-positron emits or absorbs a photon, and reverses time direction again turning back into your everyday electron. That’s one way of looking at things.
The other way is to abandon time reversals and just assume that all electrons and all positrons go forward in time, full stop. In either scenario, you have no physical contradictions – two solutions to the same equation as it were. But if you accept the time reversal concept, it’s a sort of micro Dr. Jekyll and Mr. Hyde transformation.
Let’s run that by again.
Reality one: A real electron travelling forward in time absorbs a photon, bounces back in time as a pseudo-positron (because charge has to be reversed) and absorbs a photon and reverses time direction again, back to that of an electron moving forward in time.
Equally, a real positron travels forward in time, absorbs a photon, goes back in time as a pseudo-electron (charge goes from plus to minus), absorbs a photon and reverses time direction. In this picture there is no matter-antimatter annihilation.
Reality two: A real electron (or positron) going forward in time meets its opposite number (caused by an earlier forward time travelling photon energy that disintegrated producing a matter-antimatter particle pair) and that annihilation produces (emits) a photon (energy) also travelling forward in time which can then disintegrate back into an electron-positron pair travelling forward in time. In this view there is annihilation (matter meets antimatter), and energy (photon) producing a matter-antimatter particle pair, but no time travel. In either picture, the total number of electrons, positrons and photons remain the same.
The One Electron Universe:
So here is where things get interesting. According to Michio Kaku* (and other sources – see further readings), Feynman speculated (whether seriously, or tongue-in-cheek I know not) that perhaps the Universe consisted of only one electron (and presumably one proton**, one neutron, etc.). The logic goes something like this – at 10 AM an electron travels in the normal future direction. At 10 PM the electron reverses its time direction and heads back towards the past. At 10 AM it bounces back towards the future. At 4 PM, you freeze-frame and ‘see’ three particles, two travelling from the past to the future; one travelling from the future to the past. But in reality, all three are the same particle, two are matter electrons, one appears as a pseudo-positron. Now multiple that zigzag by zillions and extend some of the time frames from the Alpha to the Omega. One can reach the conclusion that the Universe consists of just one each of all the elementary particles!
This electron/pseudo-positron pair, bouncing forever forward and backward in time between Creation and Armageddon, is in fact the sum total of electron-ness in the Universe, which explains why all electrons are identical clones; ditto positrons since one travelling backwards would then appear to be a pseudo-electron.
The same would apply to a proton. There’s only one bouncing forward in time (as a proton) and backwards in time (as a pseudo-anti-proton**) between the Alpha and the Omega. And real anti-protons, going backwards in time would appear as pseudo-protons.
In short, the Universe (including you), from beginning to end, consists of just a very few (one of each) particles and antiparticles, which makes the Big Bang event more believable! Any ‘now’ moment is just one slice of that forever ping-pong ball back-and-forth endless journey. It all happens so fast that for all practical purposes, one particle is everywhere at once. You think you consist of zillions of particles – alas, it’s only a few going zip, zigzag, zoom, zigzag, zip, zigzag, zoom, zigzag, zip, zigzag, zoom, zigzag, zip, zigzag, zoom, zigzag, zip, zigzag, zipping & zigzagging & zooming, etc. – back and forth – so rapidly it’s the illusion of many.
Now, personally, I think it’s one of the biggest crock-o-shit ideas I’ve come across (the lone particle idea, not the antimatter or the time reversal concepts – but then again Feynman may have been just shooting the bull and tossing out ideas just for the sake of speculating). I have to admit however, it’s a damn appealing idea in its simplicity! The cosmos all of a sudden is a lot less complex and perplexing. But…
The problem, as I see it, is that the zip/zoom time for electrons/pseudo-positrons (and positrons and their pseudo-electrons), or protons/pseudo-anti-protons (and anti-protons and pseudo-protons) is relatively slow (less than light speed) because they have mass. Even if they travelled at light speed, be it backwards or forwards in time, it would take, say zipping back to the Big Bang event, some 13.7 billions of years to do so (and another 13.7 billion years to return to our time). That would mean an awfully long duration when our ‘now’ was devoid of stuff and energy. The mirror of that is the time these few and far between particles would take to cross the Universe from side-to-side (assuming a finite Universe), even neglecting any further expansion while that crossing was going on. The crossing would take far longer than you could hold your breath for (and then some). Maybe that’s why the ‘one electron, one positron, one proton, one anti-proton, etc. Universe’ isn’t discussed much. As a science fiction idea, it’s great. As a practical example of how our Universe is constructed – well you don’t see it proposed in any astronomy textbooks!
Or could it? Keep in mind that the side-to-side and top-to-bottom (or ultimately volume) crossings of the Universe was easier/quicker in the past when the Universe was smaller (recall our Universe is not only expanding, but that the expansion rate is accelerating due to something we know nearly nothing about called ‘dark energy’). Alas, the time distance between Creation and Armageddon (assuming there is an actual final end which is doubtful given an ever ongoing expanding Universe) remains fixed, so there’s no way to compress that part of the journey. Now here I keep assuming that the maximum ‘velocity’ through time is one second per second in either direction.
Oh wait, I’ve neglected to take relativity theory or effects into account. The velocity of electrons and positrons (and protons and anti-protons) through space could affect their ‘velocity’ through time. However, I’ve no hard information on how fast in space electrons/positrons, protons/anti-protons will travel. Elementary particles can stand still – well wiggle and jiggle in places somewhat uncertain according to quantum principles. Or, they might really floor the petal to the metal and zip and zoom around – as opposed to being laid back. If they zip and zoom around at close to light speed, their ability to transverse the cosmos in quick-smart time is increased. Recall the so-called ‘twin paradox’ where the twin in the fast lane ages a lot slower than her stay-at-home laid back sister. Lacking hard information, I’ve really not neglected relativity; I just can’t figure it into the scenario.
An analogy in something less than cosmic terms, would be to think of a river which has length, depth, and width. Each fundamental particle, or let’s be generous and say one water molecule, would have to go from top to bottom, bank to bank, and headwaters to river mouth so quickly so as to give the illusion of a ‘solid’ continuously flowing river.
What ever so slight worries me here is that there is an actual known example of how Mother Nature presents us with an illusion. Solid matter (or liquid matter or gaseous matter for that matter) isn’t solid at all. Matter is nearly all empty space, be it an ice cube, a drop of water, or water vapor. Since that’s not an everyday common example, you’re more aware of how a film strip of individual images when moving rapidly create the illusion of a picture in motion, or a motion picture. Another common example is your TV screen or newspaper photograph. Those apparently solid continuous images are in reality just a composite of hundreds of individual dots.
Anyway, still, it’s a real stretch to imagine a river, far less our cosmos, as being composed of just a few bits and pieces! Actually that brings up a more fundamental problem in the case of one water molecule zipping and zapping so fast as to create an illusionary river – one water molecule, far less any single elementary particle or combination of particles has no property of wetness. So how could a one water molecule alone give a river its wetness property? [The same applies to other properties of matter – say colour, or texture. How could a one electron universe have colour?]
Ultimately it matters little if there is only one electron/positron (and proton/anti-proton) dual-particle or entity zipping and zooming and zigzagging back and forth, or an umpteenth zillion. There’s still an observational lack of antimatter and there should be near equal amounts of both matter and antimatter. That imbalance is strange in that with equal probability a photon should create both an electron and a positron (and electron-positron annihilation should create a photon – symmetry all around).
* Parts of this topic were sparked off by reading several pages in Michio Kaku’s chapter on Precognition, contained in his latest book Physics of the Impossible: A Scientific Exploration of the World of Phasers, Force Fields, Teleportation and Time Travel; Penguin Books, London; 2009:
** Old learning’s die hard. Of course both the neutron and the proton are no longer considered to be fundamental particles. Rather, both are composed of a trio of quarks, and thus it is proper to have quarks and anti-quarks rather than protons and anti-protons/neutrons and anti-neutrons.
*** I’ve never actually seen an explanation as to why matter and antimatter annihilate on contact giving off pure energy. It just does in the same, but opposite way (symmetry again) as pure energy can create matter and antimatter particle pairs. The annihilation and creation of matter – antimatter, to and from energy, is not the problem since matter (including antimatter) and energy are two sides of the same coin. [It’s interesting that you have matter and antimatter, but not energy and anti-energy.] So, I’ll just accept that when an electron meets a positron – ka-boom. Also ditto that in that a ka-boom can create an electron – positron pair. But presumably an electron and an anti-proton, if meeting up, won’t annihilate because the anti-proton is not the antimatter equivalent of an electron. Also ditto that in that energy cannot create an electron – anti-proton pair of particles.