A Unified Theory of Time Travel: Part Two

There’s still one very nasty loose end here. What’s to prevent those from a parallel universe meddling and altering our time stream? It’s not enough for them to have a Prime Directive against that – we all know Prime Directives are meant to be broken! So, it looks like Hawking’s Chronology Protection Conjecture must apply to those visitors from parallel universes to our Universe as well. I mean what difference does it make to your existence whether you travel back in time within your own universe and kill your mother before you were conceived, or some serial killer escaping from a parallel universe to our Universe who kills your mother before you were conceived – even though in the latter case there’s no paradox, you still wouldn’t have been conceived of here in anyone’s philosophy!

OK, so relativity allows time travel back in time, but only to parallel universes. The Hawking Chronology Protection Conjecture not only prevents time travel paradoxes in general, but it also prevents parallel universe time travelers meddling and altering our timeline; ditto we humans time traveling to someone else’s parallel universe. But how would the Hawking Chronology Protection Conjecture actually accomplish this? My best guess is that parallel universes aren’t in phase – they aren’t polarized or synchronized in-phase like a laser beam, or the light that passes through your polarized sunglasses – otherwise we’d have some rather hard evidence of them; certainly way more than we do now.

So, if we go to parallel universe B or those from parallel universe B visits us, we’ll, or they’d be respectively out of phase with respect to the universe they are now in. Translated, they, or we, could look, but not touch for all practical purposes. I say for all practical purposes as now and again what’s out of phase (high probability – the usual state of affairs) will sync into phase (that’s rare). But the in-phase times are so few and far between, and last for such a brief duration that it’s unlikely to result in any inadvertent or deliberate timeline alterations. That’s my rendering of the Hawking Chronology Protection Conjecture – he could well have other ways and means in mind.

So another way of putting this is that time travelers would be spectral or ghostlike in their host universe, and maybe that’s where our traditions of ghosts and other things that go bump in the night come from! This is much like the parallel universe ghost or shadow photons that are conjectured to explain some highly mysterious aspects or phenomena contained within the famous quantum double slit [1] experiment. Now an obvious question is how do all the parallel universe ghost photons get into our physics labs where double slit experiments are carried out? I mean there are no local macro Black Hole or wormhole exits present – are there? Yes in fact there are! Not a macro wormhole, but a micro wormhole – actually wormholes. Theoretically, micro wormholes should exist all around you. It’s just that they are at quantum levels – incredible tiny; way subatomic in size. And they exist for just nanoseconds before collapsing. They are just part of the quantum foam [2] reality at super microscopic levels, a reality at the level where all things exhibit the quantum jitters or quantum fluctuations. Thus, every second of every day, everywhere, there are little quantum gateways – quantum sized wormholes connections between universes which quantum sized particles – like photons – can traverse! From the standpoint of the double slit experiment, it doesn’t matter whether the parallel universe’s ghost photons came from the past, future or present – just as long as they are, indeed, present!

Now you may think it would be easy to detect these ghostly photons. Just put a photon detector in a totally dark and sealed room. Well, not quite so easy. Some photons can pass through ‘solid’ matter. X-Ray photons anyone? Radio wave photons pass through the walls of your home. If you look at a bright light, you’ll still see light even if you close your eyes. So, your photon detector in your dark and sealed room could easily detect our local variety.

The ghostly bits aside, parallel universe time travelers (or even ordinary time travelers from within our Universe assuming Hawking is wrong)) might explain the sometimes uncanny, often incredible look-a-likes that we all seem to have. A long shot to be sure, but something interesting to ponder.

There’s still one more problem on the horizon. Just because a macro Black Hole or wormhole plunks you into a parallel universe (and of course you’ve got to be able to survive the trip itself which might be problematical), doesn’t mean you’re going to be with spitting distance of your ultimate destination(s) – say a parallel Earth(s). So, time travelers might also need more conventional transport – like Flying Saucers (okay, forget the saucers – like spaceships with fins and rocket motors). But then what’s really there to distinguish a visiting time traveler from a parallel universe from say a run-of-the-mill extraterrestrial from within our own Universe? Maybe you could just put out the welcome mat for both options!

One final thought. Could there be a Clayton’s time travel? - Time travel without traveling in time? At the risk of making Einstein turn over in his grave; I’m going to propose a universal NOW across all universes. Now I know that NOW, when it comes to observers, is a relative thing. An observer in Martian orbit sees Mars’ NOW somewhat before you on Planet Earth sees the same Mars’ NOW because the speed of light is finite. And relative motions and velocities complicate what is NOW. But, I propose (a thought experiment remember) to instantaneously freeze-frame the entire collection of universes’ NOW. Everyone and everything everywhere comes to an instant standstill. Right! We now have a universal NOW that we can study at our leisure (the freeze doesn’t apply to you and me – we’re outside the space-time continuum).

Let’s focus on that subset of all parallel universes – all parallel Earths and time travel between them. Now there’s no reason to assume that all parallel Earths are identical in all aspects. Indeed, some parallel universes may not even contain a parallel Earth! There maybe some parallel Earths identical or so close to identical to our Planet Earth as makes no odds – abodes you’d feel right at home in. Other Earths would differ in various ways, some minor, some major. Still others might be really weird and alien, as in having evolved a dinosaur society, civilization and technology. There was no parallel asteroid impact 65 million years ago; thus no human beings around the traps 65 millions later.

Your subset of parallel Earths would show near infinite diversity in infinite combinations. I say ‘near’ because you can only stretch the term ‘Earth’ or ‘Earth-like’ so far and no farther, before it’s not Earth or Earth-like. A 100% oceanic world is not Earth. If a parallel ‘Earth’ has Venus-like temperatures, it is not Earth-like. If it has a density approaching that of a neutron star, it is not Earth-like. If it has no life on it, even though in all other respects it is a near carbon copy of our Earth, it is not Earth-like.

Now it’s back to the NOW subset of parallel Earths and Earth-like abodes. There’s no reason to assume that evolutionary development; that evolutionary development rates would proceed in each and every case in an identical fashion. Some parallel Earths would still be in the dinosaur era (if they had dinosaurs of course). In some parallel Earths, cavemen and saber tooth tigers rule. In others, it’s Biblical times, or Medieval times or the era when Britannia ruled the waves. Others in our absolute NOW, on yet other parallel Earths, or parallel earthlings, might have just invented the wireless or landed on their Moon (if they have one). On some parallel Earths it may already be what to us will be the 23rd or 24th Century with interstellar warp drive capabilities at hand – and even way beyond that. So, you could seemingly travel to the past and future while actually remaining in our NOW. You’ve traveled in time without really traveling in time, or, time travel without the paradoxes – but maybe that spoils all the intellectual fun of contemplating time travel in the first place!

[1] The problem solved here is how can you get a classic wave interference pattern behind two slits you fire photons through; even when you fire the photons at say a rate of one per hour? Who you gonna call – ghost photons of course to the rescue.

[2] Quantum foam – the world may look pretty smooth from a distance, but as you keep magnifying the finer details, the micro world gets ever so slightly bumpier. Close in some more and things get rougher still, until at quantum level everything is a seething cauldron of tumultuous activity. It’s like the sea that looks perfectly smooth and tranquil from Earth orbit, but at rowboat level, you’re terrified as that 50 foot wave comes crashing down on you.

Further recommended readings about time travel:

Gott, J. Richard; Time Travel in Einstein’s Universe: The Physical Possibilities of Travel Through Time; Phoenix, London; 2002:

Hawking, Stephen W. et al.; The Future of Spacetime; W.W. Norton and Company, N.Y.; 2002:

Randles, Jenny; Breaking the Time Barrier: The Race to Build the First Time Machine; Paraview Pocket Books, New York; 2005:

Toomey, David; The New Time Travelers: A Journey to the Frontiers of Physics; W.W. Norton & Company, New York; 2007: