Something about Skynet has bugged me for a while. Okay, I know that in Part I I spent considerable words criticising the criticism of time travel, but now I’m going to play the hypocrite. I feel somewhat justified, though, as it’s not the mechanics portrayed in the franchise I’m criticising so much as a character within that franchise.

It’s unclear whether Terminator occupies a Single Amorphous Timeline or a Branching Timeline (see Part I for more information); I tend to think it’s a BT, just because the time travellers in the past never experience any of the changes they make to the future. But either way, Skynet’s plan is pretty stupid. For those who haven’t seen them, in the Terminator films a sentient artificial intelligence has taken over the world of the future and pretty much wiped out humanity, apart from a small resistance group. Skynet sends robots, called Terminators, into the past to kill the leader of the resistance, John Connor, either before he was born or when he was a whiny, pubescent kid (whose mannerisms instantly date the movie as a product of the nineties (hasta la vista, baby!)). Fine, sure. You kill him before he’s a problem (which it never quite manages, but let’s assume it does) and Skynet has a clear run to world domination. But not the same Skynet. If we assume Terminator inhabits a Branching Timeline, then Skynet isn’t helping itself one bit. The Skynet in the new timeline is living sweet, but nothing changes for the original. It just keeps sending robots back in time and basically seeing no results. So unless Skynet has some sort of weird trans-reality empathy for its alternate selves, there’s not much point in solving its problems with time travel.

It’s a little different for the SAT case, but only in that instead of creating new Skynets in parallel timelines, Skynet is actively erasing itself by sending the Terminators back. Its future disappears and is replaced by a new one, complete with a new Skynet, springing from the new conditions that the time travel produces.

There’s also the possibility of the films taking place in a Novikov universe. The first Terminator movie seems to imply that John Connor sent Kyle Reece back in time to defend his mother because John knew what would happen already; ie, that his mother told him all about the events of the first movie, and he in the future conspired to make these events happen. However, the fact that events in each movie push Judgement Day, the moment at which Skynet nuked half the world, further back, seems to contradict this and imply a Branching Timeline.

By the way, under this model of the Terminator universe, the timeline would look something like this:

---------------------------------------------

T1-------------------------------

T2--------------------

T3---------TS

On an unrelated note: Something which I’ve never seen addressed in time travel fiction is conservation of energy. This is one of the most important principles in physics: the idea that energy can neither be created nor destroyed, only transformed. It’s been proven in a million different experiments and it underpins our entire scientific understanding of the universe (not to mention our power-driven economy). All of the energy that was in the universe when the Big Bang happened is still here; none of it has leaked away, and no new energy has found its way in.

So how can I just step out of my own time period and into the past without violating this most sacred of tenets? A whole person’s worth of mass-energy has just disappeared from the present, effectively destroyed; in the meantime, in the past, that same amount of energy has come to be out of nowhere.

My wild speculation has arrived at the conclusion that, in order for me to travel to the past, an equivalent amount of energy must make the reverse journey, to replace the dearth of energy left in my absence and leaving me an energy gap to fill in the past. However, unless this replacement energy takes the form of solid matter, it’s going to leave a heck of a mess in the present I’m leaving. Transitioning all eighty kilograms (give or take) of my mass into unbound energy (gamma rays, for example) gives you the equivalent of thirty-four nuclear bomb detonations (Calculation 1). So that’s maybe a problem.

Again, this is rampant speculation. No-one really knows the mechanics of time travel, if they exist at all. So whatever.

Anyway, I hope you’ve enjoyed my Time Travel in Fiction series. Tune in next week for more conversation!

Back to Part II: Timey-Wimey Stuff

Appendix

Calculation 1:

The Tsar Bomba, the most powerful nuke ever tested, has an output of 2.1 * 10^17 J.

E = mc^2 = 80kg * (3 * 10^8m/s)^2

= 7.2 * 10^18 J

7.2 * 10^18/2.1*10^17

= 34.286

That’s not taking into account all of the energy floating around my body as heat or electricity, which is negligible by comparison.