## Is energy released in time travel?

A huge obstacle in time travel is the vast amounts of energy needed to power it. What if we could borrow and pay back energy by moving it through time?

## A thermodynamic conundrum

One of the biggest obstacles in time travel is summoning the vast amounts of energy required to power it. I’ve often wondered whether we could use the energy from one time and return it in another during the time travel expedition the same way as we move physical objects around according to our transient desires.

So far it would seem not; the laws of thermodynamics mean that there cannot be a creation (or destruction) of energy and moving it from one time to another (forwards or backwards) is essentially the same thing (removing it from one time is ‘destruction’ and replacing it in another time is ‘creation’).

Looking at it another way, does time travel imply that there is a creation or destruction of energy? Perhaps thermodynamics hints at the importance of direction, at least in the temporal field.

## A matter of direction

Most of us have probably heard about the direction of time, or time’s arrow. In these cases the direction is linear, that is to say, forwards, backwards or if we’re being creative, sideways.

Equally creative, but perhaps more conventional given the motion of hands on a clock, have we ever considered a rotational direction of time?

In H. G. Wells’ The Time Machine (or was it that b***dy Baxter’s The Time Ships), the Time Traveller talks of a twisting of the spatial and temporal dimensions so that all 4 dimensions are transposed and travelling through time could be done so as easily as easily as travelling through space. Give or take a bit of nausea.

(Yes, it was Baxter. I remember now; he [appears to have] nicked the idea of rotating of the 4 dimensions (and inducing sickness from centrifugal and Coriolis forces from Poul Anderson, or at least the rotational aspect from Michael Moorcock’s Flux. )

It seems to me that if we’re going to play about with thought experiments and how time moves (or at least, how we move through an otherwise static time), then we should at least pay a bit of homage to the idea that it might twirl about!

Indirectly, my wife and I recently had a conversation which lead to these kind of musings.

I’ll say upfront that the conversation wasn’t directly related to time travel or even about time…but it did involve a clock. Note the manly pink colour, but please recall that I am a father of 2 daughters!

A few nights ago my wife exclaimed surprise that the bedside clock still worked even when the battery is put in with the knobbly bit on the wrong way reversed polarity. “Even the light comes on!”

Why wouldn’t it? In a general and simple electrical case (e.g. one without diodes), it’s not the direction of flow of electricity that makes light light or clocks tick (that’s an expression…digital ones don’t!) – rather, it’s the flow itself.

[Aside: an economist friend of mine once told me that the value of money is unimportant – it’s that it changes hands. Not spending a million dollars is the same as not spending 1 dollar. Movement, or flow, of money is important…though in this case the direction is important too…we’d rather receive a million dollars than part with it!]

My wife (who I should add, didn’t marry me for my money!) said that given all the warnings in the instruction manual about taking care to observe the correct polarity, she’d expected the clock to simply not work. Or blow up spectacularly.

At the very least, that it might run backwards.

Whilst this wouldn’t explain the workings of Edward Page Mitchell’s The Clock that went Backwards (which was a wind up Grandfather clock), the comment did lead to the usual cart-before-the-horse question: was our hypothetically backward running pink clock marking a backward motion of time, or was it actually driving it?

And if I can milk the driving metaphor, was our reverse polar battery the equivalent of the flux capacitor in the Back to the Future DeLorean time machine?

Now that the horse is well and truly trailing the cart, my wife and I turned to thinking about the local effect of a backward trip in time. As local as the battery squeezed in its compartment with the knobble against the spring.

In the usual case, the battery discharges and powers the clock. The corollary, if we’re going back in time, is that the battery is now charging – electricity is coming out of the clock and into the battery.

But if the battery isn’t discharging, then it can’t be powering the clock to drive the time backwards, and that means it should be discharging. We have the classic Grandfather Paradox…nullifying our speculative thought experiment!

Well! Paradoxes such as these are common place in time travel, so perhaps we’re on the right track…

But something else is at odds here – power is required to push time forwards (or to maintain it’s ambient rate of natural progression), and now it looks like energy is released in time travel when we go backwards!

This sounds counter-intuitive, but I wonder if it’s something else entirely…I think the clue is in the battery not being charged but recharged – the energy it spent in pushing time forwards is now being paid back.

It’s a subtle difference, but this idea of a return can be taken further in the case of time itself in that it’s not a backward motion of time but a return to some state of equilibrium, like an aeroplane doesn’t expend energy to fly downwards, but returns to the ground and gives up energy doing so.

This seems to be more in line with thermodynamic principles where energy is required to bring order and expended to return to chaos, and indeed…we have a battery with increasing energy.

A reversal of time is an increase in order(!)…the matter of the universe, going back in time, will become more ordered. Perhaps, into a singularity rather than an expanding universe.

So what’s all this got to do with rotational time?

Well OK, you got me! Clock hands rotating the wrong way doesn’t signify a rotational time direction any more than a digital clock counting backwards signifies time going backwards. Does it?

Maybe we’ll never know. If time is going (or rotating) backwards now how would we know? It would be normal to us; the definition of a direction would be a matter of convention.

I can’t help thinking though, that a time might introduce some twirling about, some seemingly random changes in direction, or loops or somersaults to avoid those pesky time travel paradoxes we’d have with a linear motion in time. And it would be a much cleaner solution that just making up a new multiverse to get out of the conundrum.

Don’t you think?

Well, we’ve talked and thunk ourselves into a tighter and ever decreasing circle, and like the Time Traveller, probably feeling quite dizzy and nauseous from it!

Paul