Dr Who should have written this but he didn’t so I have to. We keep seeing those cute little tears in space-time in episodes of the BBC’s Dr Who, that let through Daleks and Cybermen and other nasties. (As an aside, how come feminists never seem to object to the term Cybermen, even though 50% of them are made from women?). Dr Who calls them rifts, and it allegedly needs the energy of entire star systems to open and close them. So, not much use as a weapon then, but still a security issue if our universe leaks.
Sci-fi authors have recognized the obvious dangers of time-space rifts for several decades. They cause problems with causality as well. I got a Physics degree a long time ago (well, Applied Mathematics and Theoretical Physics, but all the maths was EM theory, quantum mechanics and relativity, so it was really a physics degree), but I have never really understood fully why causality is such a big deal. Sure it needs a lot of explaining if it fails, but why would an occasional causal error cause such a huge problem? The Daleks are far more worrying. **Politically incorrect joke censored**
I just wrote about time travel again. All competent physicists rightly switch on their idiot filters automatically on hearing any of the terms ‘cold fusion’, ‘telekinetic’, ‘psychic’, ‘perpetual motion machine’, ‘time travel’ or ‘global warming catastrophe’. Sorry, that last one just sort of crept in there. Time travel is not really possible, unless you’re inside a black hole or you’re talking about a particle shifting atoseconds in a huge accelerator or GPS relativistic corrections or something. A Tardis isn’t going to be here any time soon and may be impossible and never ever come. However, there is a quite real cyberspace route to quite real time travel that will become feasible around 2075, a virtual rift if you like, but no need to activate idiot filters just yet, it’s only a virtual rift, a rift in a sandbox effectively, and it won’t cause the universe to collapse or violate any known laws of physics. So, hit the temporary override button on your idiot filter. It’s a fun thought experiment that gets more and more fun the more you look at it. (Einstein invented thought experiments to investigate relativity, because he couldn’t do any real experiments with the technology of his time. We can’t verify this sort of time travel experimentally yet so thought experiment is the only mechanism available. Sadly, I don’t have Einstein’s brain to hand, but some aspects at least are open to the rest of us to explore.) The hypothesis here is that if you can make a platform that stores the state of all the minds in a system continuously over a period from A to B, and that runs all those minds continuously using a single editable record, then you can travel in time freely between A and B. Now we need to think it through a bit to test the hypothesis and see what virtual physics we can learn from it, see how real it would be and what it would need and lead to.
I recognized on my first look at it in
that cyberspace offers a time travel cheat. The basic idea, to save you reading it now that it’s out of date, is that some time soon after 2050 – let’s take 2075 as the date that crowd-funding enables its implementation – we’ll all be able to connect our brains so well to the machine world that it will be possible to share thoughts and consciousness, sensations, effectively share bodies, live electronically until all the machines stop working, store your mind as a snapshot periodically in case you want to restore to an earlier backup and do all sorts of really fun things like swapping personalities. (You can see why it might attract the required funding so might well become real). If that recording of your mind is complete enough, and it could be, then, you really could go back to an earlier state of yourself. More importantly, a future time tourist could access all the stored records and create an instance of your mind and chat to you and chat and interact with you from the future. This would allow future historians to do history better. Well, that’s the basic version. Our thought experiment version needs to go a bit further than that. Let’s call it the deluxe version.
If you implement the deluxe version, then minds run almost entirely on the machine world platform, and are hosted there with frequent restore points. The current state of the system is an interactive result of real-time running of all the minds held in cyberspace across the whole stored timeline. For those minds running on the deluxe version platform, there isn’t any other reality. That’s what makes up those future humans and AIs on it. Once you join the system, you can enjoy all of the benefits above and many more.
You could actually change old records and use the machines to ripple the full system-wide consequences all the way through the timeline to whenever your future today is. It would allow you to go back to visit your former self and do some editing, wouldn’t it? And in this deluxe version, the edits you make would ripple through into your later self. That’s what you get when you migrate the human mind from the Mk1 human brain platform into the machine world platform. It becomes endlessly replicable and editable. In this deluxe version, the future world really could be altered by editing the past. You may reasonably ask why we would allow any moron to allow that to be built, but that won’t affect the theoretical ability to travel in time through cyberspace.
It is very easy to see how such a system allows you to chat with someone in the past. What is less obvious, and what my excuse for a brain missed first time round, is that it also lets you travel forwards in time. How, you may reasonably ask, can you access and edit records that don’t exist yet? Well, think of it from the other direction. Someone in the future can restore any previous instance of you from any time point and talk to them, even edit them. They could do that all in some sort of time-play sandbox to save money and avoid quite a few social issues, or they could restore you fully to their time, and since the reality is just real-time emulation all rippled through nicely by the machine platform, you would suddenly appear in the future and become part of that future world. You could wander around in a future android body and do physical things in that future physical world just as if you’d always lived there. Your future self would feel they have travelled in time. But a key factor here is that it could be your future self that makes it happen. You could make a request in 2075 to your future self to bring you to the future in 2150. When 2150 arrives, you see (or might even remember) the request, you go into the archives, and you restore your old 2075 self to 2150, then you instruct deletion of all the records between 2075 and 2150 and then you push the big red button. The system runs all the changes and effects through the timeline, and the result is that you disappear in 2075, and suddenly reappear in 2150.
There would be backups of the alternative timeline, but the official and effective system reality would be that you travelled from 2075 to 2150. That will be the reality running on the deluxe system. Any other realities are just backups and records on a database. Now,so far it’s a one way trip, far better if you can have a quick trip to the future and come back. So, you’re in 2150, suppose you want to go back again. You’ve been around a while and don’t like the new music or the food or something. So before you go, you do the usual time mischief. You collect lots of really useful data about how all the latest tech works, buy the almanacs of who wins what, just like in Back to the Future, just in case the system has bugs that let you use them, and you tweak the dials again. You set the destination to 2075 and hit the big red button. The system writes your new future-wise self over your original 2075 entry, keeping a suitable backup of course. The entry used by the deluxe system is whatever is written in its working record, and that is the you that went to 2150 and back. Any other realities are just backups. So, the system ripples it all through the timeline. You start the day in 2075, have a quick trip for a week’s holiday in 2150, and then return a few minutes later. Your 2075 self will have experienced a trip to 2150 and come back, complete with all the useful data about the 2150 world. If you don’t mess with anything else, you will remember that trip until 2150, at which time you’ll grab a few friends and chat about the first time you ever did time travel.
All of the above is feasible theoretically, and none of it violates any known physics. The universe won’t collapse in a causality paradox bubble rift if you do it, no need to send for Dr Who. That doesn’t mean it isn’t without issues. It still creates a lot of the time travel issues we are so familiar with from sci-fi. But this one isn’t sci-fi – we could build it, and we could get the crowd-funding to make it real by 2075. Don’t get too excited yet though.
You could have gone further into the future than 2150 too, but there is a limit. You can only go as far as there exists a continuous record from where you are. You basically need a road that goes all the way there. If some future authority bans time travel or changes to an incompatible system, that represents a wall you can’t pass through. An even later authority could only remove that wall under certain circumstances, and only if they have the complete records, and the earlier authority might have stopped storing them or even deleted earlier ones and that would ruin any chances of doing it properly.
So, having established that it is possible, we have to ask the more serious question: how real is this time travel? Is it just a cyberspace trick with no impact on the real world? Well, in this scenario, your 2075 mind runs on the deluxe system using its 2075 record. But which one, the old one or the edited one? The edited one of course. The old version is overwritten and ceases to exist except as a backup. There remains no reality except the one you did your time travel trip in. Your time trip is real. But let’s ask a few choice questions, because reality can turn out to be just an illusion sometimes.
So, when you get home to 2075, you can print off your 2150 almanac and brag about all the new technologies you just invented from 2150. Yes?
Yes… if you implement the deluxe version.
Is there a causality paradox?
Will the world end?
But you just short-circuited technology development from 2075 to 2150?
So you can do real time travel from 2075? You’ll suddenly vanish from 2075, spend some time in 2150, and later reappear in 2075?
Yes, if you implement the deluxe version.
Well, what happens in 2150?
You’ll do all the pushing red button stuff and have a party with your friends to remember your first time trip. If you set the times right, you could even invite your old self from 2075 as a guest and wave goodbye as you* goes back to 2075.
Or you* could stay in 2150 and there’d be two of you from then on?
OK, this sounds great fun. So when can we build this super-duper deluxe version that let’s you time travel from 2075 to 2150 and go back again.
And what happens to me between 2075 and 2150 while I wait for it to be built?
Well, you invest in the deluxe version, connect into the system, and it starts recording all its subscribers’ minds from then on, and you carry on enjoying life until 2150 arrives. Then you can travel from 2075 to 2150, retrospectively.
Well, you can travel from 2075 to whatever date in the future the deluxe system still exists. And your 2075 self will fully experience it as time travel. It won’t feel retrospective.
But you have to wait till that date before you can go there?
Yes. But you won’t remember having to wait, all the records of that will be wiped, you’ll just vanish in 2075 and reappear in 2150 or whenever.
What *insert string of chosen expletives here* use is that?
Erm…. Well…. You will still have enjoyed a nice life from 2075 to 2150 before it’s deleted and replaced.
But I won’t remember that will I?
No. But you won’t remember it when you’re dead either.
So I can only do this sort of time travel by having myself wiped off the system for all the years in between after I’ve done it? So the best way of doing that is not to bother with all the effort of living through all those years since they’re going to be deleted anyway and save all the memory and processing by just hibernation in the archives till that date arrives? So I’ll really vanish in 2075 and be restored in 2150 and feel it as time travel? And there won’t be any messy database records to clean up in between, and it will all be nice and environmentally friendly? And not having to run all those people years that would later be deleted will reduce storage and processing costs and system implementation costs dramatically?
OK, sounds a bit better again. But it’s still a fancy cyberspace hibernation scheme really isn’t it?
Well, you can travel back and forth through time as much as you like and socialize with anyone from any time zone and live in any time period. Some people from 2150 might prefer to live in 2075 and some from 2075 prefer to live in 2150. Everyone can choose when they live or just roam freely through the entire time period. A bit like that episode of Star Trek TOS where they all got sent through a portal to different places and times and mixed with societies made of others who had come the same way. You could do that. A bit like a glorified highly immersive computer game.
But what about gambling and using almanacs from the future? And inventing stuff in 2075 that isn’t really invented till 2150?
All the knowledge and data from 2150 will be there in the 2075 system so you won’t have anything new and gambling won’t be a viable industry. But it won’t be actually there until 2150. So the 2075 database will be a retrospective singularity where all of the future knowledge suddenly appears.
Isn’t that a rift in the time-space continuum, letting all the future weapons and political activists and terrorists and their plans through from 2150 to 2075? And Daleks? Some idiot will build one just for the hell of it. They’ll come through the rift too won’t they. And Cyberpersons?
It will not be without technical difficulties. And anyway, they can’t do any actual damage outside the system.
But these minds running in the system will be connected to android bodies or humans outside it. Their minds can time travel through cyberspace. Can’t they do anything nasty?
No, they can only send their minds back and connect to stuff within the system. Any androids and bodies could only be inhabited by first generation minds that belong to that physical time. They can only make use of androids or other body sharing stuff when they travel forwards through time, because it is their chosen future date where the android lives and they can arrange that. On a journey backwards, they can only change stuff running in the system.
And that’s what stops it violating physics?
So let’s get this straight. This whole thing is great for extending your mind into cyberspace, sharing bodies, swapping personalities, changing gender or age, sharing consciousness and some other things. But time travel is only possible for your mind that is supported exclusively in the system. And only that bit in the system can time travel. And your actual 2075 body can’t feel the effect at all or do anything about it? So it’s really another you that this all happens to and you start diverging from your other cyber-self the moment you connect. A replica of you enjoys all the benefits but it thinks it is you and feels like you and essentially is you, but not in the real world. And the original you carries on in parallel.
Correct. It is a big cyberspace bubble created over time with continuous timeline emulation, that only lets you time travel and interact within the bubble. Like an alternative universe, and you can travel in time in it. But it can only interact with the physical universe in real time at the furthermost frontier of the bubble. A frontier that moves into the future at the same speed as the rest of the local space-time continuum and doesn’t cause any physics problems or real time paradoxes outside of the system.
So it’s not REAL time travel. It’s just a sort of cyber-sandbox, albeit one that will be good fun and still worth building.
You can time travel in the parallel universe that you make in cyberspace. But it will be real within that universe. Forwards physical time travel is additionally possible in the physical universe if you migrate your mind totally into cyberspace, e.g. when you die, so you can live electronically, and even then it is really just a fancy form of hibernation. And if you travel back in time in the system, you won’t be able to interact with the physical stuff in the past, only what is running on the system. As long as you accept those limitations, you can travel in time after 2075 and live in any period supported after that.
Why do all the good things only ever happen in another universe?
I don’t know.
No physics or mathematics has knowingly been harmed during this thought experiment. No responsibility is accepted for any time-space rifts created as a result of analytical error.