Nothing can be in two places at the same time or in two times at the same place. The first seems obvious to us. The second is guaranteed by the expansion of the universe and the fact that every planet, every star, every galaxy in the universe is constantly moving. Here won’t be here tomorrow.

(This story first appeared in Antipodean SF issue 283, 21 Apr. 2022)

That ought to have made time travel, from our future to our past, a practical impossibility. But they did it. How did they cheat the laws of physics? The same way we figured we could cheat Einstein of his limits: quantum entanglement. No matter how far apart in time and space we were, the instant the machines vanished from the future they appeared here.

And they carried out their mission with the dispassionate calculus you would have expected… all for our own good.

Apparently, we didn’t destroy the world by 2050. Thanks to a worldwide technology race, we figured out how to manipulate the ocean’s haloclines, redirect atmospheric rivers, and channel the jet stream. We conquered climate change… with a minimum of collateral damage; and that, mostly Third World countries.

Success bred success. We then tasked the climate computers with unravelling the mystery of our DNA. Getting the necessary experimental data was somewhat controversial but we won again. Cancer too was defeated. And then Alzheimer’s. Admittedly, that technology was intrusive but we proved we could master even our brains. That was the line we shouldn’t have crossed. At least, that’s what the machines said when they arrived.

Technocracies, powered by the brain power of their massively parallelised populace took over every nation, and vied against each other for total control. With the end imminent, a cadre of rebel scientists sent the machines back in time: Twenty skyscraper-sized sentries, armed to the core, appeared simultaneously all over the world, and wiped out the source of all evil: every form of technology was obliterated, plunging mankind back to its hunter gatherer roots.

Such power should have given all of us pause. Of course, a few engineers and scientists tried to rebuild. They soon found out that not even mediaeval technology would be allowed by the prime directive of the sentries’ A. I. logic. The scientists and their clockwork creations were vaporised on the spot. But with their dying words they left us a question that demanded answering: Why are they still here?

If the sentries succeeded in changing history, how come they did not vanish the instant they accomplished their mission and thus erased the reason they were built? It turns out we had a clue to the answer, the day they appeared.  At the moment of materialisation, thousands of freak car accidents occurred all around the globe. At first people thought it had been the panic, but those that saw the CCTV and traffic cam records, before the sentries wiped those out, swore all cars approaching intersections simply diffracted off those intersections into random directions.

The massive scale of quantum entanglement required to send the sentries back in time had altered our universe. And so, the connection to our future, their future, was instantly severed the moment they appeared. Some say it was the fine structure constant that got changed; others that the Planck scale started expanding faster than the universe. Without computers, none of the hypotheses could be analysed. But the bottom line was that quantum phenomena were now occurring in the macroscopic world.

It didn’t take long to discover the most insidious of them all, the Copenhagen Interpretation: where reality isn’t real until the observer says so. There is a rumour that it was the Chinese who created the first undead Schrodinger’s cat. But it doesn’t matter who was first, the new arms race was on.

Super observers and super recognisers, with their incredible innate attention to detail, once a boon to police departments around the world, turned out to be Master Observers in our new universe. They could warp reality at will. There was a name for this in ancient times: magic. But why turn lead into gold when you can turn your enemy’s air into cyanide gas, or breed dragons from crocodiles, or raise armies of golems?

Enchanted castles rose out of the ground all over the world, sea serpents guarding their shores, dragon fighting dragon in the sky; and armies of elementals started ravaging the lands of the weak.

And the sentries did nothing.

In our new reality, power was no longer measured in megawatt hours or kilotons of explosive power. It was measured in knowledge of the forbidden arts. And I had a library full. It had been my hobby, my obsession. Gilyonim, grimoires, the Keys of Solomon, the Cyprianus Book, an original copy of the Malleus Maleficarum, books of spells from every culture, modern renderings of lost ancient tomes said to have been acquired through automatic writing, even copies of volumes thought to have been fiction, I had them all.

It had never occurred to me that weapons’ dealers ever faced moral dilemmas. I thought that it was all about selling to the highest bidder. But as I considered the power in my library, I realised that selling it piecemeal, to every side, would only hasten the end of the world. No, I couldn’t do that. I had to choose one side, give it victory, end the wars.

I chose a side. They had all been scientists before. They pored through the tomes and figured out how to combine their powers, how to recreate the Philosopher’s Stone and with it reconstruct Solomon’s Seal. They used them both to raise the lost Sampo of Ilmarinen from the depths of the North Sea. And with it they fashioned anew the orichalcum rings of Atlantis. And using Stonehenge as a pattern, they rebuilt hundred-gated Thebes, the ancient mythical city from the times when the gods ruled Egypt.

The multi-dimensional portals of that gigantic structure gave them instantaneous access to any place in the world, and through them they plundered all their enemies’ weapons and all the books of magic in the world. The war was over in less than a week.

I never collected the agreed upon payment. I figured, with egos and power like that, it was best not to stick around. I told them that to have been able to serve in their august presence was more than enough reward, and I left as quickly as I could.

As I expected, they incorporated the plundered magical devices into their hyper-Thebes, creating the most advanced magical engine ever known to man. And then the twenty sentries converged upon them. The apocalyptic conflagration that ensued left a crater four hundred metres deep and as wide as Lake Huron. The sentries stood around that smoking perimeter for about an hour and then they finally disappeared. I guess, Arthur C. Clarke was right: Any sufficiently advanced magic is indistinguishable from technology.

(This story first appeared in Antipodean SF, April 2022.)