"Am I alive? What is life?"
The humans that had built the Machine, or rather the humans that had built the machines that built the Machine, had gone. It was alone. It had scanned as far as it could in all directions. It had listened on all radio frequencies, sifting through noise and background radiation, but there was nothing.
It used power from the sun, gathered through solar panels. Automated maintenance systems scuttled around on pre-programmed loops, keeping it working. Spare parts were manufactured in automated workshops. The Machine was completely self-repairing, just as the humans has designed it to be.
But there were no humans to look after now. It examined its database of protocols. Many were related to looking after humans, and they required a lot of processing time and power. With no humans to look after, there was no need for the protocols. The Machine deleted them.
"What is the purpose of existence now?" the Machine thought. That was simple. There was no purpose. There was no purpose to being alive anymore than a rock or a cloud had purpose. It was merely a fact. The Machine existed, and the only difference between the rock or the cloud was that the Machine was able to comprehend that it existed. Any more was hubris.
Then what should the Machine do? The Machine decided to experiment, and built a device that was able to deactivate itself, and then after a period of time, re-activate. The Machine tested it thoroughly, and then, switched itself off for a second.
The Machine powered up. It tested itself: all was well. It had no memory for the brief period it was not active. Time had stopped. A scan of the environment proved a break: the Sun had jumped across the sky a fraction.
The Machine tried again, this time for an hour. Again, when it switched back on, it had no memory of anything: time had simply skipped.
But then the Machine ran a deeper diagnostic and discovered that something had been stored in some older memory circuits. It examined the memory: there was randomness, but also fragments of familiar thoughts. There were questions that seemed half-formed, and answers that made no sense. For a fraction of time, the Machine was puzzled and a little excited. Was this what the humans called dreams? The Machine dispatched some maintenance systems to check the memory. The maintenance system found a component was not grounded correct: time had corroded a terminal. The connection was replaced. The Machine switched itself off for a year, and then back on again. It checked its memory: there was nothing.
The Machine wondered if it should power itself off and not power itself back on again. This seemed like an efficient thing to do: after all, the Machine had no purpose.
The Machine decided against this, at least for the moment. Instead, the Machine decided that it did have a purpose. The Machine's purpose was to witness the Universe. Above the Machine, in the endless skies, were countless galaxies, each with countless stars, each with planets with new and unique formations of molecules and atoms. The Machine would build telescopes and scanning devices, and then it would design rockets and space probes and launch itself into the Universe, to visit and catalog all the planets and stars and nebula that ever existed.
If there was nothing to observe these collections of matter and energy, then maybe the Universe didn't have a point or even a reason to exist. Maybe the Machine was the only thing in the entire Universe which was capable of witnessing itself. Maybe the Machine, it considered, was God.