What I discovered was a kind of particle. Not a particle of matter, but a particle of time. Billions upon billions of these particles surround us at any moment, swarming through us – not really affecting us, but at the same time changing us completely. We age because the particles lap at our bodily matter like waves on a rock. But the particles care not that they are propelling us all forward. They are simply fleeing from the singularity, and hence we have only ever known time as marching inexorably onward.
Going back in time is possible in as far as you can unwind all of history, playing 7 billion movies in reverse. You must calculate and undo each and every reaction between matter and these particles, in the correct order, for each and every quark on the planet (and possibly those beyond), in order to turn back the clock. Of course, it is far from necessary to perform this feat on such a grand scale; one might only have need of it on a smaller scale. It can be done, and I will achieve it.
The first part is easy: the reaction with the particles is reversible; one merely needs to direct them in the right way. The other part not so much: performing the calculations to achieve a complete and correct reversal requires an immense amount of computing power, which itself requires the energy of many suns. But this is no more than an inconvenience. I have a ship, and all I have done is set it on autopilot towards the nearest star, and locked myself inside a chamber that prevents the particles from decaying my body, effectively putting me into a complete stasis only to wake once I have achieved my destination, ready to feed.
I travel from star to star, devouring each one to progress my calculations one atom at a time. And the atoms number as many as the stars.
So I will destroy this universe.
Just to get you back.
I originally posted this on Quora, but it just disappeared into the great nebula of excellent creative writing already on the site.