Parallel universes, or alternative universes or mirror universes have had a long run of popularity in science fiction and science fantasy, in both print and visual formats. One need only look at an “Alice in Wonderland” or look no further than the “Star Trek” universe (our Universe in less than obvious disguise) to view the near endless plot variations that such parallel / alternative / mirror universes provide our heroes and heroines. Do they actually exist and do they explain anything?
There are apparently two theoretical counterparts in our real world, or in our physics. Firstly, there’s the idea that from the beginning, there’s an infinite number of parallel universes where all things that can happen, do happen. Our Universe is just one of that infinite set. In five of those universes, you 1) flip a coin – in one, it’s a heads you flip; in another, tails; in the third, the coin stands on edge! Or, in a fourth universe you decide not to flip a coin at all, or in universe #5 you decide to flip something else instead.
The other theoretical set of parallel universes is a set that ever increases, staring with just one. Universes split whenever an either/or choice is forced upon it, such that all results that can happen, happen. In this (our) Universe you decide not to flip a coin – but that decision results in a division, the universe splits and in that split, in the new universe, you do flip a coin. In that universe it comes up heads. But, that universe then splits into two and yet another universe where your flip has tails comes up. There’s also another universe where the coin lands on edge! There’s also a universe that originally splits off where you decide to flip something other than a coin. This is known as the ‘Many Worlds Interpretation’ theory, (which resulted out of a need to explain certain quantum phenomena). With every passing second, more and more universes branch off (actually trillions per second).
I’ve never been a fan of the Many Worlds Interpretation of all things quantum. That is, the universe keeps splitting each time it comes to a fork in the road. The question of where all the matter/energy comes from – created out of nothing apparently – I’ve yet to see addressed in the texts. But, many top notch scientists adopt it – perhaps as the least of all the evils certain quantum phenomena dish up. As to where they fit, all those extra universes, that’s not as much of a problem. A motel with an infinite number of rooms never has to put out a ‘no vacancy’ sign – if you get the analogy. Oh, the Many Worlds Interpretation also means that there’s no such thing as free will. You may think you have free will in deciding to wear your red dress instead of your green dress, but in the Many Worlds Interpretation, you do both – so no free will.
However, I myself go for the Copenhagen Interpretation* – when you come to a fork in the road, one and only one choice is made – the other possible choice(s) are never realised and ultimately never have any reality. But, if you start out from scratch with an infinite number of universes, or at least a vast number, then the issue of ‘where’ all the universes are is irrelevant, and the creation of all the stuff that makes them up is equally irrelevant. In the beginning, it was so!
You can have an infinite number of universes in an infinite amount of space. An analogy – there are an infinite number of whole numbers like 1, 2, 3, 4, 5, 6, etc. There’s also an infinite number of even numbers such as 2, 4, 6, 8, 10, 12, etc. Ditto an infinite number of odd numbers. Yet the infinite set of even numbers, plus the infinite number of odd numbers, equals the infinite set of whole numbers. Infinity + infinity = infinity! Or, if you like, think of your house (volume) with just one molecule (universe) in it. You’d agree there’s room for one hell of a lot more molecules (universes). If your house had infinite volume, then…
I had always assumed, and followed the assumptions of others infinitely more brilliant than I, that such theoretical constructions, such parallel / alternative / mirror universes, was forever beyond our actual reach – works of fiction aside of course. We could construct them as an intellectual exercise, but could never verify and understand the actual existence of these mental or thought experiments. That’s because these universes, if they exist, would not be part of our space-time continuum and thus we could never interact with them.
But what if that assumption is wrong? What if parallel / alternative / mirror universes not only exist, but can and do interact with ours, and thereby give some additional credence to the adventures of our “Alice in Wonderland” and “Star Trek” characters, not to mention the reputations of those physicists who propose infinite universes or Many Worlds Interpretation theories.
Micro & Macro Mysteries: Well, those assumptions just might now be put to the test. I’d love to be able to say I thought of this idea, even independently, it’s just that brilliant. Alas, I didn’t, and I’m kicking myself because it’s just so simple and elegant. The credit for this goes to physicist David Deutsch, and for a fuller and better outline of his proposals, see his book cited below**.
The basics are as follows and deals with the paradoxical and famous ‘double slit’ experiment with light – an experiment with photons.
If you shine a light (millions of photons worth) at a slit, you’ll get a blob of light on the surface behind the slit. No problems – the photon ‘bullets’ go through the slit and impact on the surface behind.
Now you shine the light (millions of photons) at two slits. Contrary to expectation, you don’t get two blobs of light – one opposite each slit – but a classic wave interference pattern of alternating light and dark areas on the surface behind. So photons aren’t ‘bullets’; light must be a wave.
Thus is demonstrated the classic wave-particle duality or paradox of light. Is light a continuous wave, or is it a collection of individual ‘bullet’ particles?
Instead of firing millions of photons at these slits at a go, redo the experiment by firing off photons one at a time – say one per hour. That can actually be done. If you fire the one per hour photons at a single slit, the picture that emerges over time is your blob of light behind the slit. Photons are behaving as ‘bullet’ particles as before.
Now, fire the photons – one per hour – at the two slits. Clearly, you’d expect two blobs of light to ultimately form on the (say photographically sensitive) surface that is behind each slit. Sometimes the single photon would go through one slit; sometimes the other. Alas, you still get a wave-like interference pattern! How can this be? What’s interfering in real time with the actual photons that you’re shooting off?
The only object capable of interfering with photons, to cause wave-like interference, an alternating light-dark pattern, is other photons. But there are no other photons in the vicinity if they are shot out at one per hour and your photon source is the only photon source!
The inescapable conclusion is that there must be other photons around that can’t be detected (seen). Call these photons virtual photons, or shadow photons or ghost photons. Where do they come from? The answer is from our parallel / alternative / mirror universes. There is therefore a form of weak interaction between universes.
How do they, parallel universe photons say, actually get here? Well, at the quantum level, all manner of virtual particles pop into and out of existence from what’s called the vacuum energy. At the extremely microscopic level, what’s often called the ‘quantum foam’, is a level seething with activity, including the popping into and out of existence of micro wormholes, wormholes that can connect one universe with another, even if only for nanoseconds. But, that’s enough to allow the transfer of micro objects, like photons, and electrons, etc. from one universe to another. It’s like seeing the ocean from space. It looks really smooth and tranquil. However, at rowboat level, there’s this twenty foot wave about to come crashing down on top of you.
As the collection of all universes is the Multiverse, and since the wave-particle duality is at the heart and soul of quantum mechanics, then it follows that perhaps quantum physics is just the physics of the Multiverse!
The double slit experiment can be (and has been) repeated with electrons, and neutrons and protons, etc. Same results! So, therefore, there must be virtual or shadow or ghost electrons and neutrons (or quark trios) and protons (or again quark trios). Now things get interesting! But before I get to that, David Deutsch never speculated above the level of shadow or ghost protons (or other elementary particles) as proof of parallel universes. The following extrapolations are my doing!
If there are virtual / shadow / ghost protons and neutrons, then there are (let’s just call them) ghost nuclei. Add your ghost electrons and you have ghost atoms, hence ghost molecules and on up the chain to… well, ghosts!
Now these parallel universe ghosts aren’t dead people, but people quite alive in said parallel universe. They could appear to us as dead acquaintances or even dead loved ones, but parallel universes aren’t of necessity identical copies of ours (recall the heads, tails and coin-on-edge example). Just because Mum is deceased in our Universe doesn’t mean she’s yet snuffed it in a parallel one.
These virtual or shadow or ghostly images don’t even have to be living things of course. There’s a long history of apparently sane and sober people seeing, quite unexpectedly, spectral images of non-living ‘things’, like a building appearing in a otherwise verified field-of-grass only.
There’s equally a long list of documented transient phenomena, unfortunately unpredictable and unverifiable - UFOs anyone?
Speaking of UFOs (as intelligently piloted vehicles from elsewhere and/or elsewhen), sceptics often will claim ‘it can’t be, therefore it isn’t’, where the ‘can’t be’ usually refers to the impossibility of interstellar spaceflight which would require faster-than-light velocities to make things practical and viable, blah, blah, blah…. Quite apart from the fact that that assessment is total nonsense as I’ve already elaborated on elsewhere, subluminal interstellar travel doesn’t, of necessity, violate any laws of physics, period. End of discussion. However, nobody, including me, says it will be easy, but that’s a different horse of another colour.
Anyway, if there can be some sort of now and again natural interaction between parallel universes, then it follows that an advanced technological race of beings (call them aliens if you will), might be able to artificially manipulate such ‘gateways’ and go exploring – not so much in time and space but as in crossing over from X-universe to a parallel Y-universe, which in distance terms might be as close to zero kilometres as makes no odds.
Cryptozoology is another ripe area potentially explainable in part at least by parallel dimensions. Take Loch Ness and its alleged monster, one of the most baffling of cases in all of cryptozoology. On the one hand, you’ve lots of seemingly credible witnesses with no axe to grind going back over many decades. Are they all lying, exaggerating, and being fooled or just hallucinating? The odds of that are poor for the collective of all sightings. On the other hand, you have a relatively small and confined area offering little hiding room to a relatively large animal. It’s an area that has been combed many times with all the sophisticated technology we can muster – no animal. However, it doesn’t stretch the imagination to breaking point and beyond to suggest that in some parallel universe(s), plesiosaurs (or equivalent) still exist and that for some reason there is, albeit just a rarely now and again, some sort of harmonic resonance between that world and our world, and presto, a sighting of the elusive Loch Ness Monster.
Perhaps a most likely interaction between parallel universes is evident in our dreams.
We often seemingly invent out of thin air quite unfamiliar people, places, and situations when dreaming, as well as finding ourselves in more familiar surroundings, albeit rarely something exactly parallel down to the Nth detail – at least that’s my experience. It’s maybe 90% familiar territory; never 100%.
If there is some sort of parallel universe interactions, your dreams could be, in a nebulous sort of way, a link with the lifestyle of your counterpart(s), and presumably said counterpart(s) now and again dream slightly unfamiliar scenarios that reflect your actual situations; your world and your lifestyle and relations.
It’s a sort of telepathy perhaps only achievable at the subconscious level when you’re asleep and all those day-to-day routines and constant mental activities can’t overwhelm that incredibly faint signal from a parallel universe(s).
Now that’s not to say all dreams are parallel universe related, but some might be.
Since the double slit experiment with one photon at a time, produces interference patters 100% of the time, yet things like ghosts, UFOs, the Loch Ness Monster, even dreams, aren’t reproducible on demand, I can only conclude that it’s much easier for micro bits like photons and atoms to crossover from X-universe to Y-universe (our Universe) than it is for macro objects. But, that’s not an uncommon experience within our own world. Bacteria are vastly more common than humans – bacteria are everywhere; humans aren’t. Small things or objects can wriggle through small spaces where larger objects can not fit. It takes exceptional circumstances, an exceptional large gateway or hole between universes for a UFO or a Loch Ness Monster to make its ever so brief and unexpected appearance. So, lots of small holes or ‘gateways’ allowing lots of ghost photons (and presumably other particle types – very, very, few large holes or ‘gateways’, so actual sightings of living ghosts, etc. are very, vary rare.
Now more likely as not, it’s only a relatively few parallel universes that have a real resonance with ours. There could be other universes with physics so different that they are totally out of sight, even if not out of mind.
Summary: The concept of parallel universes is a sound, yet novel way of explaining one of the (many) deep mysteries contained in the double slit experiment that illustrates the wave-particle duality of matter. From that, the concept can be extrapolated or expanded to explain possible other, but more macro, anomalous phenomena.
*But with one very, very important caveat. The Copenhagen Interpretation of the quantum requires that Nature makes up Her mind when, and only when an observer or an observer’s measurement is made. Until then all is probability and nothing has reality or actual existence. The Moon has no reality unless someone is observing or measuring it! To me, observers are irrelevant – reality is reality, with or without observers.
**Deutsch, David; The Fabric of Reality; Penguin Books, London; 1998: