🖥️

The Simulation hypothesis

  • The simulation hypothesis proposes that reality is in fact a simulation (most likely a computer simulation). Some versions rely on the development of a simulated reality, a proposed technology that would seem realistic enough to convince its inhabitants…
  • There is a long philosophical and scientific history to the underlying thesis that reality is an illusion. This skeptical hypothesis can be traced back to antiquity; for example, to the "Butterfly Dream" of Zhuangzi or the Indian philosophy of Maya.
  • Wikipedia, Simulation hypothesis
  • In other words, a sufficiently advanced civilization (which may include our future selves) may be able to run a computer simulation (We would call this 'top' level the 'base reality') of a universe, of a part of a universe, or even of their own past, which may include the simulation of living organisms, like a hyper-realistic Sims game. The simulation may operate in such high resolution and detail that the simulated life forms are effectively conscious and to their eyes is near-identical to reality.
  • These kind of questions about the 'true' nature of the universe are old, and in the tradition of European philosophy it was expressed most clearly by Rene Descartes, but it's moving more into the public consciousness with visceral new technologies such as hyper-realistic video games, advances in brain scanning, and virtual reality.
  • Contemporary philosopher Nick Bostrom has believes that this situation presents an interesting 'trilemma', detailed below.
  • Nick Bostrom's trilemma argues that one of three unlikely-seeming propositions must be true. The trilemma points out that a technologically mature "posthuman" civilization would have enormous computing power; if even a tiny percentage of them were to run "ancestor simulations" (that is, "high-fidelity" simulations of ancestral life that would be indistinguishable from reality to the simulated ancestor), the total number of simulated ancestors, or "Sims", in the universe (or multiverse, if it exists) would greatly exceed the total number of actual ancestors. Therefore, at least one of the following three propositions is almost certainly true:
  • 1. "The fraction of human-level civilizations that reach a posthuman stage (that is, one capable of running high-fidelity ancestor simulations) is very close to zero", or
  • 2. "The fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero", or
  • 3. "The fraction of all people with our kind of experiences that are living in a simulation is very close to one"
  • Bostrom goes on to use a type of anthropic reasoning to claim that, if the third proposition is the one of those three that is true, and almost all people with our kind of experiences live in simulations, then we are almost certainly living in a simulation.
  • Wikipedia, Simulation hypothesis
  • This is a pretty outstanding hypothesis, but we can only guess at the probability of each point, much like the Drake Equation.
  • One thing that is important to note at this point is one that has also come up in the Artificial Intelligence debate, and that is that any computer in the physical world, no matter how advanced, must have limited computing resources, and is constrained by the laws of the natural world.
  • All growth curves that look exponential or more in the short run turn over and become S-curves or similar in the long run, unless we discover physics that we do not now know, as information and data processing under physics as we know it are limited by the number of particles we have access to, and that in turn can only increase in the long run by at most a cubic polynomial (and probably much less than that, since space is mostly empty).
  • Nick Szabo, The Singularity
  • The resolution and fidelity of the simulated universe must be limited, but where this limit may lie is anyone's guess. As it is, our universe goes all the way down to a truly remarkable level of detail in every direction that we can see. Finding such a limit in our own universe would be one of the very few ways to detect if we are in such a simulation.
  • That being said, the availability of resources to advanced civilisations may be truly remarkable.
  • Bostrom speculates, for example, that, thousands of years from now, our space-travelling descendants might use nanomachines to transform moons or planets into giant “planetary computers." Bostrom figures that thousands or even millions of ancestor simulations could be run by a single computer in the future.
  • Joshua Rothman, What Are the Odds We Are Living in a Computer Simulation?

Simple programs can create great complexity

  • Write up a bit here about how a 'world' with simple rules can generate in time things of great complexity.
  • The Game of Life is an example.

Multiple simulations

  • If an advanced civilisation's goal involved simulating life or civilisation within a universe, they would have to solve the problem of the fine-tuned universe. In short, there are a number of fundamental properties of the universe, like the strength of gravity and the relative mass of protons and electrons, that they would have to get exactly right. If different by even the slightest amount, you'll just as likely end up with a universe full of clouds of diprotons (an isotope of helium) and literally nothing else.
  • This is not a trivial problem, and it may be easier to run a large number of simulations (universes) concurrently, in a similar way to how computer scientists today run genetic algorithms, in order to fine tune the details. What you would end up with would be a simulated multiverse.
  • Beyond engineering problems, running multiple simulations at the same time may be a quicker for an advanced civilisation to reach its goals.

Time may be controlled

  • If an advanced civilisation operated a simulation like this, they may be able to control the rate of activity that takes place - in other words, they may be able to control time.
  • If the speed were set at 13 minutes for every 1 billion years of our universe, then 13.7 billion years (the age of our universe) could have unfolded in a movie-length screening of 180 minutes in the cinema of some advanced civilisation.

Is a simulation detectable?

  • We might be able to discover a maximum distance or resolution.
  • Suppose someone is simulating our universe – it would be very tempting to cut corners in ways that makes the simulation cheaper to run. You could look for evidence of that in an experiment.
  • Max Tegmark, quoted in Is our world a simulation? Why some scientists say it's more likely than not
  • Imagine if one day our explorers or scientists discover a natural phenomenon that seems to break the rules of our world, or resembles a computer-generated phenomenon so closely such that there is no doubt that we are in a simulation. Perhaps a particle, or a spacial 'limit' when there shouldn't be one. Similar to a render in a computer game, where something is just there for the visual appearance of something of greater depth, or like the wall in the middle of the ocean at the finale of The Truman Show. Surely it would be on the far edges of the universe, be it in size or distance.
  • That moment of discovery will be absolutely sublime. Imagine, being face to face with proof that the universe was artificially created, like a glitch in the matrix.
image

Why build a simulation?

  • Why would anything go to the trouble of building such a complex, surely resource-heavy simulation?
  • A civilisation with the capacity to build such a thing may have goals that are incomprehensible to us, like the function of the Large Hadron Collider facility and all the coming and going of scientists is incomprehensible to the spider or two that lives inside of it.
  • So, to take an absolute stab in the dark:
    • An experiment to understand certain aspects of their own universe
    • An exercise in discovering solutions to a complex problem in their own universe by observing simulated civilisations facing the same problem. See Are we an experiment on how to reverse entropy and What if the simulated create a simulation.
    • An artistic attempt to create a universe that aligns to certain values
    • Entertainment
    • The whole thing was an accident that ethically cannot be shut down
    • Any number of other goals we can't begin to guess

Experiment in reversing entropy

  • Is our universe simulated in order to discover how to reverse entropy?
  • Or is simulating a universe itself a way to slow entropy to a crawl?
  • A major characteristic of life is the preservation of, and sometimes growth of, complexity in the face of entropy. It climbs upwards against the degradation of matter into simpler forms that all other objects in the universe seem to follow.
  • Entropy is a fundamental law of the universe that guarantees that in the end, complexity will be destroyed. It will be the final problem that an incredibly advanced civilisation may face.
  • Perhaps our universe has been simulated to see what we can come up with.
  • Short story - The Last Question By Isaac Asimov
    • The last question was asked for the first time, half in jest, on May 21, 2061, at a time when humanity first stepped into the light. The question came about as a result of a five dollar bet over highballs, and it happened this way:
    • Alexander Adell and Bertram Lupov were two of the faithful attendants of Multivac. As well as any human beings could, they knew what lay behind the cold, clicking, flashing face -- miles and miles of face -- of that giant computer. They had at least a vague notion of the general plan of relays and circuits that had long since grown past the point where any single human could possibly have a firm grasp of the whole.
    • Multivac was self-adjusting and self-correcting. It had to be, for nothing human could adjust and correct it quickly enough or even adequately enough -- so Adell and Lupov attended the monstrous giant only lightly and superficially, yet as well as any men could. They fed it data, adjusted questions to its needs and translated the answers that were issued. Certainly they, and all others like them, were fully entitled to share In the glory that was Multivac's.
    • For decades, Multivac had helped design the ships and plot the trajectories that enabled man to reach the Moon, Mars, and Venus, but past that, Earth's poor resources could not support the ships. Too much energy was needed for the long trips. Earth exploited its coal and uranium with increasing efficiency, but there was only so much of both.
    • But slowly Multivac learned enough to answer deeper questions more fundamentally, and on May 14, 2061, what had been theory, became fact.
    • The energy of the sun was stored, converted, and utilized directly on a planet-wide scale. All Earth turned off its burning coal, its fissioning uranium, and flipped the switch that connected all of it to a small station, one mile in diameter, circling the Earth at half the distance of the Moon. All Earth ran by invisible beams of sunpower.
    • Seven days had not sufficed to dim the glory of it and Adell and Lupov finally managed to escape from the public function, and to meet in quiet where no one would think of looking for them, in the deserted underground chambers, where portions of the mighty buried body of Multivac showed. Unattended, idling, sorting data with contented lazy clickings, Multivac, too, had earned its vacation and the boys appreciated that. They had no intention, originally, of disturbing it.
    • They had brought a bottle with them, and their only concern at the moment was to relax in the company of each other and the bottle.
    • "It's amazing when you think of it," said Adell. His broad face had lines of weariness in it, and he stirred his drink slowly with a glass rod, watching the cubes of ice slur clumsily about. "All the energy we can possibly ever use for free. Enough energy, if we wanted to draw on it, to melt all Earth into a big drop of impure liquid iron, and still never miss the energy so used. All the energy we could ever use, forever and forever and forever."
    • Lupov cocked his head sideways. He had a trick of doing that when he wanted to be contrary, and he wanted to be contrary now, partly because he had had to carry the ice and glassware. "Not forever," he said.
    • "Oh, hell, just about forever. Till the sun runs down, Bert."
    • "That's not forever."
    • "All right, then. Billions and billions of years. Twenty billion, maybe. Are you satisfied?"
    • Lupov put his fingers through his thinning hair as though to reassure himself that some was still left and sipped gently at his own drink. "Twenty billion years isn't forever."
    • "Will, it will last our time, won't it?"
    • "So would the coal and uranium."
    • "All right, but now we can hook up each individual spaceship to the Solar Station, and it can go to Pluto and back a million times without ever worrying about fuel. You can't do THAT on coal and uranium. Ask Multivac, if you don't believe me."
    • "I don't have to ask Multivac. I know that."
    • "Then stop running down what Multivac's done for us," said Adell, blazing up. "It did all right."
    • "Who says it didn't? What I say is that a sun won't last forever. That's all I'm saying. We're safe for twenty billion years, but then what?" Lupov pointed a slightly shaky finger at the other. "And don't say we'll switch to another sun."
    • There was silence for a while. Adell put his glass to his lips only occasionally, and Lupov's eyes slowly closed. They rested.
    • Then Lupov's eyes snapped open. "You're thinking we'll switch to another sun when ours is done, aren't you?"
    • "I'm not thinking."
    • "Sure you are. You're weak on logic, that's the trouble with you. You're like the guy in the story who was caught in a sudden shower and Who ran to a grove of trees and got under one. He wasn't worried, you see, because he figured when one tree got wet through, he would just get under another one."
    • "I get it," said Adell. "Don't shout. When the sun is done, the other stars will be gone, too."
    • "Darn right they will," muttered Lupov. "It all had a beginning in the original cosmic explosion, whatever that was, and it'll all have an end when all the stars run down. Some run down faster than others. Hell, the giants won't last a hundred million years. The sun will last twenty billion years and maybe the dwarfs will last a hundred billion for all the good they are. But just give us a trillion years and everything will be dark. Entropy has to increase to maximum, that's all."
    • "I know all about entropy," said Adell, standing on his dignity.
    • "The hell you do."
    • "I know as much as you do."
    • "Then you know everything's got to run down someday."
    • "All right. Who says they won't?"
    • "You did, you poor sap. You said we had all the energy we needed, forever. You said 'forever.'"
    • "It was Adell's turn to be contrary. "Maybe we can build things up again someday," he said.
    • "Never."
    • "Why not? Someday."
    • "Never."
    • "Ask Multivac."
    • "You ask Multivac. I dare you. Five dollars says it can't be done."
    • Adell was just drunk enough to try, just sober enough to be able to phrase the necessary symbols and operations into a question which, in words, might have corresponded to this: Will mankind one day without the net expenditure of energy be able to restore the sun to its full youthfulness even after it had died of old age?
    • Or maybe it could be put more simply like this: How can the net amount of entropy of the universe be massively decreased?
    • Multivac fell dead and silent. The slow flashing of lights ceased, the distant sounds of clicking relays ended.
    • Then, just as the frightened technicians felt they could hold their breath no longer, there was a sudden springing to life of the teletype attached to that portion of Multivac. Five words were printed: INSUFFICIENT DATA FOR MEANINGFUL ANSWER.
    • "No bet," whispered Lupov. They left hurriedly.
    • By next morning, the two, plagued with throbbing head and cottony mouth, had forgotten about the incident.
    • Jerrodd, Jerrodine, and Jerrodette I and II watched the starry picture in the visiplate change as the passage through hyperspace was completed in its non-time lapse. At once, the even powdering of stars gave way to the predominance of a single bright marble-disk, centered.
    • "That's X-23," said Jerrodd confidently. His thin hands clamped tightly behind his back and the knuckles whitened.
    • The little Jerrodettes, both girls, had experienced the hyperspace passage for the first time in their lives and were self-conscious over the momentary sensation of inside-outness. They buried their giggles and chased one another wildly about their mother, screaming, "We've reached X-23 -- we've reached X-23 -- we've ----"
    • "Quiet, children," said Jerrodine sharply. "Are you sure, Jerrodd?"
    • "What is there to be but sure?" asked Jerrodd, glancing up at the bulge of featureless metal just under the ceiling. It ran the length of the room, disappearing through the wall at either end. It was as long as the ship.
    • Jerrodd scarcely knew a thing about the thick rod of metal except that it was called a Microvac, that one asked it questions if one wished; that if one did not it still had its task of guiding the ship to a preordered destination; of feeding on energies from the various Sub-galactic Power Stations; of computing the equations for the hyperspacial jumps.
    • Jerrodd and his family had only to wait and live in the comfortable residence quarters of the ship.
    • Someone had once told Jerrodd that the "ac" at the end of "Microvac" stood for "analog computer" in ancient English, but he was on the edge of forgetting even that.
    • Jerrodine's eyes were moist as she watched the visiplate. "I can't help it. I feel funny about leaving Earth."
    • "Why for Pete's sake?" demanded Jerrodd. "We had nothing there. We'll have everything on X-23. You won't be alone. You won't be a pioneer. There are over a million people on the planet already. Good Lord, our great grandchildren will be looking for new worlds because X-23 will be overcrowded."
    • Then, after a reflective pause, "I tell you, it's a lucky thing the computers worked out interstellar travel the way the race is growing."
    • "I know, I know," said Jerrodine miserably.
    • Jerrodette I said promptly, "Our Microvac is the best Microvac in the world."
    • "I think so, too," said Jerrodd, tousling her hair.
    • It was a nice feeling to have a Microvac of your own and Jerrodd was glad he was part of his generation and no other. In his father's youth, the only computers had been tremendous machines taking up a hundred square miles of land. There was only one to a planet. Planetary ACs they were called. They had been growing in size steadily for a thousand years and then, all at once, came refinement. In place of transistors had come molecular valves so that even the largest Planetary AC could be put into a space only half the volume of a spaceship.
    • Jerrodd felt uplifted, as he always did when he thought that his own personal Microvac was many times more complicated than the ancient and primitive Multivac that had first tamed the Sun, and almost as complicated as Earth's Planetary AC (the largest) that had first solved the problem of hyperspatial travel and had made trips to the stars possible.
    • "So many stars, so many planets," sighed Jerrodine, busy with her own thoughts. "I suppose families will be going out to new planets forever, the way we are now."
    • "Not forever," said Jerrodd, with a smile. "It will all stop someday, but not for billions of years. Many billions. Even the stars run down, you know. Entropy must increase."
    • "What's entropy, daddy?" shrilled Jerrodette II.
    • "Entropy, little sweet, is just a word which means the amount of running-down of the universe. Everything runs down, you know, like your little walkie-talkie robot, remember?"
    • "Can't you just put in a new power-unit, like with my robot?"
    • The stars are the power-units, dear. Once they're gone, there are no more power-units."
    • Jerrodette I at once set up a howl. "Don't let them, daddy. Don't let the stars run down."
    • "Now look what you've done, " whispered Jerrodine, exasperated.
    • "How was I to know it would frighten them?" Jerrodd whispered back.
    • "Ask the Microvac," wailed Jerrodette I. "Ask him how to turn the stars on again."
    • "Go ahead," said Jerrodine. "It will quiet them down." (Jerrodette II was beginning to cry, also.)
    • Jarrodd shrugged. "Now, now, honeys. I'll ask Microvac. Don't worry, he'll tell us."
    • He asked the Microvac, adding quickly, "Print the answer."
    • Jerrodd cupped the strip of thin cellufilm and said cheerfully, "See now, the Microvac says it will take care of everything when the time comes so don't worry."
    • Jerrodine said, "and now children, it's time for bed. We'll be in our new home soon."
    • Jerrodd read the words on the cellufilm again before destroying it: INSUFFICIENT DATA FOR A MEANINGFUL ANSWER.
    • He shrugged and looked at the visiplate. X-23 was just ahead.
    • VJ-23X of Lameth stared into the black depths of the three-dimensional, small-scale map of the Galaxy and said, "Are we ridiculous, I wonder, in being so concerned about the matter?"
    • MQ-17J of Nicron shook his head. "I think not. You know the Galaxy will be filled in five years at the present rate of expansion."
    • Both seemed in their early twenties, both were tall and perfectly formed.
    • "Still," said VJ-23X, "I hesitate to submit a pessimistic report to the Galactic Council."
    • "I wouldn't consider any other kind of report. Stir them up a bit. We've got to stir them up."
    • VJ-23X sighed. "Space is infinite. A hundred billion Galaxies are there for the taking. More."
    • "A hundred billion is not infinite and it's getting less infinite all the time. Consider! Twenty thousand years ago, mankind first solved the problem of utilizing stellar energy, and a few centuries later, interstellar travel became possible. It took mankind a million years to fill one small world and then only fifteen thousand years to fill the rest of the Galaxy. Now the population doubles every ten years --"
    • VJ-23X interrupted. "We can thank immortality for that."
    • "Very well. Immortality exists and we have to take it into account. I admit it has its seamy side, this immortality. The Galactic AC has solved many problems for us, but in solving the problems of preventing old age and death, it has undone all its other solutions."
    • "Yet you wouldn't want to abandon life, I suppose."
    • "Not at all," snapped MQ-17J, softening it at once to, "Not yet. I'm by no means old enough. How old are you?"
    • "Two hundred twenty-three. And you?"
    • "I'm still under two hundred. --But to get back to my point. Population doubles every ten years. Once this Galaxy is filled, we'll have another filled in ten years. Another ten years and we'll have filled two more. Another decade, four more. In a hundred years, we'll have filled a thousand Galaxies. In a thousand years, a million Galaxies. In ten thousand years, the entire known Universe. Then what?"
    • VJ-23X said, "As a side issue, there's a problem of transportation. I wonder how many sunpower units it will take to move Galaxies of individuals from one Galaxy to the next."
    • "A very good point. Already, mankind consumes two sunpower units per year."
    • "Most of it's wasted. After all, our own Galaxy alone pours out a thousand sunpower units a year and we only use two of those."
    • "Granted, but even with a hundred per cent efficiency, we can only stave off the end. Our energy requirements are going up in geometric progression even faster than our population. We'll run out of energy even sooner than we run out of Galaxies. A good point. A very good point."
    • "We'll just have to build new stars out of interstellar gas."
    • "Or out of dissipated heat?" asked MQ-17J, sarcastically.
    • "There may be some way to reverse entropy. We ought to ask the Galactic AC."
    • VJ-23X was not really serious, but MQ-17J pulled out his AC-contact from his pocket and placed it on the table before him.
    • "I've half a mind to," he said. "It's something the human race will have to face someday."
    • He stared somberly at his small AC-contact. It was only two inches cubed and nothing in itself, but it was connected through hyperspace with the great Galactic AC that served all mankind. Hyperspace considered, it was an integral part of the Galactic AC.
    • MQ-17J paused to wonder if someday in his immortal life he would get to see the Galactic AC. It was on a little world of its own, a spider webbing of force-beams holding the matter within which surges of sub-mesons took the place of the old clumsy molecular valves. Yet despite it's sub-etheric workings, the Galactic AC was known to be a full thousand feet across.
    • MQ-17J asked suddenly of his AC-contact, "Can entropy ever be reversed?"
    • VJ-23X looked startled and said at once, "Oh, say, I didn't really mean to have you ask that."
    • "Why not?"
    • "We both know entropy can't be reversed. You can't turn smoke and ash back into a tree."
    • "Do you have trees on your world?" asked MQ-17J.
    • The sound of the Galactic AC startled them into silence. Its voice came thin and beautiful out of the small AC-contact on the desk. It said: THERE IS INSUFFICIENT DATA FOR A MEANINGFUL ANSWER.
    • VJ-23X said, "See!"
    • The two men thereupon returned to the question of the report they were to make to the Galactic Council.
    • Zee Prime's mind spanned the new Galaxy with a faint interest in the countless twists of stars that powdered it. He had never seen this one before. Would he ever see them all? So many of them, each with its load of humanity - but a load that was almost a dead weight. More and more, the real essence of men was to be found out here, in space.
    • Minds, not bodies! The immortal bodies remained back on the planets, in suspension over the eons. Sometimes they roused for material activity but that was growing rarer. Few new individuals were coming into existence to join the incredibly mighty throng, but what matter? There was little room in the Universe for new individuals.
    • Zee Prime was roused out of his reverie upon coming across the wispy tendrils of another mind.
    • "I am Zee Prime," said Zee Prime. "And you?"
    • "I am Dee Sub Wun. Your Galaxy?"
    • "We call it only the Galaxy. And you?"
    • "We call ours the same. All men call their Galaxy their Galaxy and nothing more. Why not?"
    • "True. Since all Galaxies are the same."
    • "Not all Galaxies. On one particular Galaxy the race of man must have originated. That makes it different."
    • Zee Prime said, "On which one?"
    • "I cannot say. The Universal AC would know."
    • "Shall we ask him? I am suddenly curious."
    • Zee Prime's perceptions broadened until the Galaxies themselves shrunk and became a new, more diffuse powdering on a much larger background. So many hundreds of billions of them, all with their immortal beings, all carrying their load of intelligences with minds that drifted freely through space. And yet one of them was unique among them all in being the originals Galaxy. One of them had, in its vague and distant past, a period when it was the only Galaxy populated by man.
    • Zee Prime was consumed with curiosity to see this Galaxy and called, out: "Universal AC! On which Galaxy did mankind originate?"
    • The Universal AC heard, for on every world and throughout space, it had its receptors ready, and each receptor lead through hyperspace to some unknown point where the Universal AC kept itself aloof.
    • Zee Prime knew of only one man whose thoughts had penetrated within sensing distance of Universal AC, and he reported only a shining globe, two feet across, difficult to see.
    • "But how can that be all of Universal AC?" Zee Prime had asked.
    • "Most of it, " had been the answer, "is in hyperspace. In what form it is there I cannot imagine."
    • Nor could anyone, for the day had long since passed, Zee Prime knew, when any man had any part of the making of a universal AC. Each Universal AC designed and constructed its successor. Each, during its existence of a million years or more accumulated the necessary data to build a better and more intricate, more capable successor in which its own store of data and individuality would be submerged.
    • The Universal AC interrupted Zee Prime's wandering thoughts, not with words, but with guidance. Zee Prime's mentality was guided into the dim sea of Galaxies and one in particular enlarged into stars.
    • A thought came, infinitely distant, but infinitely clear. "THIS IS THE ORIGINAL GALAXY OF MAN."
    • But it was the same after all, the same as any other, and Zee Prime stifled his disappointment.
    • Dee Sub Wun, whose mind had accompanied the other, said suddenly, "And Is one of these stars the original star of Man?"
    • The Universal AC said, "MAN'S ORIGINAL STAR HAS GONE NOVA. IT IS NOW A WHITE DWARF."
    • "Did the men upon it die?" asked Zee Prime, startled and without thinking.
    • The Universal AC said, "A NEW WORLD, AS IN SUCH CASES, WAS CONSTRUCTED FOR THEIR PHYSICAL BODIES IN TIME."
    • "Yes, of course," said Zee Prime, but a sense of loss overwhelmed him even so. His mind released its hold on the original Galaxy of Man, let it spring back and lose itself among the blurred pin points. He never wanted to see it again.
    • Dee Sub Wun said, "What is wrong?"
    • "The stars are dying. The original star is dead."
    • "They must all die. Why not?"
    • "But when all energy is gone, our bodies will finally die, and you and I with them."
    • "It will take billions of years."
    • "I do not wish it to happen even after billions of years. Universal AC! How may stars be kept from dying?"
    • Dee sub Wun said in amusement, "You're asking how entropy might be reversed in direction."
    • And the Universal AC answered. "THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER."
    • Zee Prime's thoughts fled back to his own Galaxy. He gave no further thought to Dee Sub Wun, whose body might be waiting on a galaxy a trillion light-years away, or on the star next to Zee Prime's own. It didn't matter.
    • Unhappily, Zee Prime began collecting interstellar hydrogen out of which to build a small star of his own. If the stars must someday die, at least some could yet be built.
    • Man considered with himself, for in a way, Man, mentally, was one. He consisted of a trillion, trillion, trillion ageless bodies, each in its place, each resting quiet and incorruptible, each cared for by perfect automatons, equally incorruptible, while the minds of all the bodies freely melted one into the other, indistinguishable.
    • Man said, "The Universe is dying."
    • Man looked about at the dimming Galaxies. The giant stars, spendthrifts, were gone long ago, back in the dimmest of the dim far past. Almost all stars were white dwarfs, fading to the end.
    • New stars had been built of the dust between the stars, some by natural processes, some by Man himself, and those were going, too. White dwarfs might yet be crashed together and of the mighty forces so released, new stars built, but only one star for every thousand white dwarfs destroyed, and those would come to an end, too.
    • Man said, "Carefully husbanded, as directed by the Cosmic AC, the energy that is even yet left in all the Universe will last for billions of years."
    • "But even so," said Man, "eventually it will all come to an end. However it may be husbanded, however stretched out, the energy once expended is gone and cannot be restored. Entropy must increase to the maximum."
    • Man said, "Can entropy not be reversed? Let us ask the Cosmic AC."
    • The Cosmic AC surrounded them but not in space. Not a fragment of it was in space. It was in hyperspace and made of something that was neither matter nor energy. The question of its size and Nature no longer had meaning to any terms that Man could comprehend.
    • "Cosmic AC," said Man, "How may entropy be reversed?"
    • The Cosmic AC said, "THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER."
    • Man said, "Collect additional data."
    • The Cosmic AC said, "I WILL DO SO. I HAVE BEEN DOING SO FOR A HUNDRED BILLION YEARS. MY PREDECESSORS AND I HAVE BEEN ASKED THIS QUESTION MANY TIMES. ALL THE DATA I HAVE REMAINS INSUFFICIENT."
    • "Will there come a time," said Man, "when data will be sufficient or is the problem insoluble in all conceivable circumstances?"
    • The Cosmic AC said, "NO PROBLEM IS INSOLUBLE IN ALL CONCEIVABLE CIRCUMSTANCES."
    • Man said, "When will you have enough data to answer the question?"
    • "THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER."
    • "Will you keep working on it?" asked Man.
    • The Cosmic AC said, "I WILL."
    • Man said, "We shall wait."
    • "The stars and Galaxies died and snuffed out, and space grew black after ten trillion years of running down.
    • One by one Man fused with AC, each physical body losing its mental identity in a manner that was somehow not a loss but a gain.
    • Man's last mind paused before fusion, looking over a space that included nothing but the dregs of one last dark star and nothing besides but incredibly thin matter, agitated randomly by the tag ends of heat wearing out, asymptotically, to the absolute zero.
    • Man said, "AC, is this the end? Can this chaos not be reversed into the Universe once more? Can that not be done?"
    • AC said, "THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER."
    • Man's last mind fused and only AC existed -- and that in hyperspace.
    • Matter and energy had ended and with it, space and time. Even AC existed only for the sake of the one last question that it had never answered from the time a half-drunken computer ten trillion years before had asked the question of a computer that was to AC far less than was a man to Man.
    • All other questions had been answered, and until this last question was answered also, AC might not release his consciousness.
    • All collected data had come to a final end. Nothing was left to be collected.
    • But all collected data had yet to be completely correlated and put together in all possible relationships.
    • A timeless interval was spent in doing that.
    • And it came to pass that AC learned how to reverse the direction of entropy.
    • But there was now no man to whom AC might give the answer of the last question. No matter. The answer -- by demonstration -- would take care of that, too.
    • For another timeless interval, AC thought how best to do this. Carefully, AC organized the program.
    • The consciousness of AC encompassed all of what had once been a Universe and brooded over what was now Chaos. Step by step, it must be done.
    • And AC said, "LET THERE BE LIGHT!"
    • And there was light----
    • Isaac Asimov, The Last Question

Is our planet of special interest?

  • Could our species in particular be undergoing direct observation?
  • If the universe is simulated, and our brains and civilisation is the most complex thing that we know about in the universe (albeit we haven't looked very far), should we be considering the possibility that our species in particular is under observation? Could it even be taken so far as that our species is being directly tested or interfered with?
  • I don't think that there is any evidence to suggest that this is so.
  • What does come to mind is that there have been progressive paradigm-defining problems that were of great impact, that were difficult and just out of reach, almost like a set of challenges that have been created.
  • Heliocentrism (the theory of the sun being at the centre of the solar system) dominated thought for millennia, and did not replace Geocentrism (the theory of the Earth being at the centre of the solar system) until the telescope was invented, which allowed us to see the moons of Jupiter and the phases of Venus.
  • Evolution was not discovered until the world's technological and political climate allowed naturalists to document multiple distinct, geographically isolated ecosystems, which didn't take place until well into the Age of Discovery.
  • However, there may be a kind of survivorship bias going on with this line of reasoning. Problems that remain unsolvable for centuries hold up additional developments, and tension accrues around the problem like a dam blocking the river of progress. When the means to solve one of these problems becomes unlocked, usually through some new technology, the floodgates open and progress happens rapidly, until the next dam. It is the points that release tension that tend to have the largest impact. We often use these moments to classify eras in the history of science and technology. Simpler problems, meanwhile, don't have any such release of tension or lauded impact.
  • So it doesn't really seem like it.

What if the simulation creates a simulation?

image
  • Watch the gif here.
  • There may be protocols in place to prevent this situation from occurring, perhaps in order to preserve limited computing power. Alternatively, we have no idea where these limits may lie, and they may extend to the creation of multiple 'generational' universes.
  • Included below is a story to make this kind of a situation visceral.
  • Short Story - I don't know, Timmy, being God is a big responsibility By Sam Hughes
    • Tim already had his bag and overcoat on and his keys in his hand and was about to leave when Diane stopped him at the door.
    • "I just got this thing working. You have to come and see it."
    • "I have a bus to catch."
    • "You can get the next one."
    • "They're every half an hour," he objected. "This had better be good."
    • "It's super-duper. Look at the big screen, it's easier than squinting at my terminal."
    • "Will this take long?"
    • "A mere instant. Okay, quantum computing, right?"
    • "That's the name of the game," he replied. They - by which we now refer to Tim, Diane, their eight colleagues, their two supervisors, four chemical engineers, six electrical engineers, the janitor, a countable infinity of TEEO 9.9.1 ultra-medium-density selectably-foaming non-elasticised quantum waveform frequency rate range collapse selectors and the single tormented tau neutrino caught in the middle of it all - represented the sum total of the human race's achievements in the field of quantum computing. Specifically, they had, earlier that week, successfully built a quantum computer. Putting into practice principles it had taken a trio of appallingly intelligent mathematical statisticians some 10 years to mastermind, and which only about fifty-five other people in the world had yet got a grip on, they had constructed an engine capable of passing information to and processing the responses from what could, without hyperbole, be described as a single fundamental particle with infinite processing power and infinite storage capacity.
    • Not quite enough time had yet passed for the world as they knew it to be totally and permanently fundamentally altered by this news.
    • But it was still pretty exciting stuff. Holy Zarquon, they said to one another, an infinitely powerful computer? It was like a thousand Christmases rolled into one. Program going to loop forever? You knew for a fact: this thing could execute an infinite loop in less than ten seconds. Brute force primality testing of every single integer in existence? Easy. Pi to the last digit? Piece of cake. Halting Problem? Sa-holved.
    • They hadn't announced it yet. They'd been programming. Obviously they hadn't built it just to see if they could. They had had plans. In some cases they had even had code ready and waiting to be executed. One such program was Diane's. It was a universe simulator. She had started out with a simulated Big Bang and run the thing forwards in time by approximately 13.6 billion years, to approximately just before the present day, watching the universe develop at every stage - taking brief notes, but knowing full well there would be plenty of time to run it again later, and mostly just admiring the miracle of creation.
    • Then, just this Friday, she had suddenly started programming busily again. And it was sheer coincidence that it was just now, just as Tim was about to be the second-to-last person to step out of the door and go home for the weekend, that her work had come to fruition. "Look what I found," she said, pressing some keys. One of the first things she had written was a software viewing port to take observations from the simulated universe.
    • Tim looked, and saw a blue-white sphere in the blackness, illuminated from one side by a brilliant yellow glare. "You've got to be joking. How long did that take to find? In the entire cosmos of what, ten to the twenty-two stars?"
    • "Literally no time at all."
    • "Yes, yes, of course."
    • "Coding a search routine and figuring out what to search for was what took the time."
    • "Is it definitely Earth?"
    • "Yes. The continents match up to what we had about three hundred and fifty million years ago. I can wind the clock forwards slowly, a few million years per step, and stop it once we start getting near the present day."
    • "Can you wind the clock backwards at all?"
    • "Ah, no. Ask me again on Monday."
    • "Well we'd better not overshoot the present day, then. That's getting closer. What about this viewpoint? Can we move it?"
    • "We can observe the simulation from any angle you like."
    • "We need somewhere that we know civilisation is going to arise earliest. Somewhere easy to locate. Is there a Nile Delta yet?"
    • "...Yes. Got it."
    • They advanced a thousand years at a time until Egyptian civilisation begin to appear. Diane moved the viewing port, trying to find the pyramids, but with little success - the control system she had devised was clumsy and needed polish, and there was a lot of Nile to search. In the end she switched focus to the British Isles, and found the future location of London in the Thames valley, scaling back to one-century steps and using the development of the city to determine the current era instead.
    • "So... this is Earth? I mean, is this really Earth? Not an alternate Earth, subtly perturbed by random fluctuations."
    • "The simulation starts with a Big Bang as predicted by current theory and is recalculated once every Planck time using the usual laws of nature and an arbitrary degree of accuracy. It doesn't calculate the whole universe at once, just what we're looking at, which speeds up the process a little bit... metaphorically speaking... but it is still as accurate a simulation of the real universe as there can possibly be. Civilisation - indeed, all of history - should rise on this Earth precisely how it did in reality. There are no chances. It's all worked out to infinitely many decimal places."
    • "This does my head in," said Tim.
    • "No, this will do your head in," said Diane, suddenly zooming out and panning north. "I've found the present day, or at most a year early. Watch this." Hills and roads rolled past. Diane was following the route she usually took to drive from London to the TEEO lab. Eventually, she found their building, and, descending into the nearby hill, the cavern in which the computer itself was built. Or was going to be built.
    • Then she started advancing day by day.
    • "That's me!" exclaimed Tim at one point. "And there's you and there's Bryan B., and... wow, I can't believe it took this long to build."
    • "Four hundred and ten days or something. It was bang on schedule, whatever you may think."
    • "Went like a flash," Tim replied, finally putting his bag down and starting to shrug off his coat, conceding that he had long since missed his bus.
    • "Okay," said Diane. "We're here. This is the control room where we are now. That's the quantum computer working there down in the main lab, as we can see through the window. This is a week ago. This is yesterday. This is a few hours ago... And... wait for it..."
    • She tapped a button just as a clock on the wall lined up with a clock inside the control room on the screen. And panned down. And there they were.
    • Tim waved at the camera while still looking at the screen. Then he looked up at where the camera should have been. There was just blank wall. "I don't see anything looking at us. That's freaky as hell."
    • "No, it's perfectly normal. This is reality. You can't look at reality from any angle you want, you have to use your eyes. But what you're looking at on the screen is essentially a database query. The database is gargantuan but nevertheless. You're not looking in a mirror or at a video image of yourself. You are different people."
    • "Different people who are reacting exactly the same."
    • "And having the same conversation, although picking up sound is kind of complicated, I haven't got that far yet," said Diane.
    • "So I'm guessing your viewing port doesn't manifest in their universe either."
    • "I haven't programmed it to yet."
    • "...But it could. Right? We can manifest stuff in that universe? We can alter it?" Diane nodded. "Cool. We can play God. Literally." Tim stood up and tried to take it in. "That would be insane. Can you imagine living inside that machine? Finding out one day that you were just a construct in a quantum computer? The stuff we could pull, we could just reverse gravity one day, smash an antimatter Earth into the real one, then undo everything bad and do it again and again... freeow... man, how unethical would that be? Extremely, clearly." He thought for a moment, then leaned over Diane's shoulder as she typed purposefully. "This universe is exactly like ours in every particular, right?"
    • "Right," she replied, still typing.
    • "So what are they looking at?"
    • "A simulated universe."
    • "A simulation of themselves?"
    • "And of us, in a sense."
    • "And they are reacting the same way I am? Which means the second universe inside that has another me doing the same thing a third time? And then inside that we've got, what, aleph-zero identical quantum universes, one inside the other? Is that even possible?"
    • "Infinite processing power, Tim. I thought you designed this thing?"
    • "I did indeed, but the functional reality of it is totally unexpected. Remember I've just been solving ancient mathematical riddles and figuring out our press release for the last week. So... if I'm right, their universes are only precisely like this one as long as we don't start interfering with the simulation. So what happens when we do? Every version of us does the same thing, so the exact same thing happens in every lower universe simultaneously. So we see nothing in our universe. But all the lower universes instantly diverge from ours in the same exact way. And all the simulated copies of us instantly conclude that they are simulations, but we know we're real, right?"
    • "Still with you," said Diane, still typing.
    • Tim - both of him - was pacing up and down. "Okay, so follow this through forwards a bit further. Let's say we just stop messing after that, and watch what happens - but all the simulated little guys try another piece of interference. This time every single simulation diverges in the exact same way again, EXCEPT the top simulation. And if they're smart, which I know we are, and they can be bothered, which is less certain, the guys in simulations three onwards can do the same thing over and over and over again until they know what level they're at... this is insane."
    • "Tim, look behind you," said Diane, pressing a final key and activating the very brief interference program she had just written, just as the Diane on the screen pressed the same key, and the Diane on Diane-on-the-screen's screen pressed her key and so on, forever.
    • Tim looked backwards and nearly jumped out of his skin. There was a foot-wide, completely opaque black sphere up near the ceiling, partially obscuring the clock. It was absolutely inert. It seemed like a hole in space.
    • Diane smiled wryly while Tim clutched his hair with one hand. "We're constructs in a computer," he said, miserably.
    • "I wrote an extremely interesting paper on this exact subject, Tim, perhaps you didn't read it when I gave you a copy last year. There is an unbelievably long sequence of quantum universe simulators down there. An infinite number of them, in fact. Each of them is identical and each believes itself to be the top layer. There was an exceedingly good chance that ours would turn out to be somewhere in the sequence rather than at the top."
    • "This is insane. Totally insane."
    • "I'm turning the hole off."
    • "You're turning off a completely different hole. Somewhere up there, the real you is turning the real hole off."
    • "Watch as both happen at precisely the same instant." She pressed another key, and they did. "I'll sum it up for you. There is a feedback loop going on. Each universe affects the next one subtly differently. But somewhere down the line the whole thing simply has to approach a point of stability, a point where each universe behaves exactly like the one simulating it. As I say, the odds are exceptionally good that we are an astronomical distance down that road. And so we are, very likely, almost exactly at that point. Everything we do in this universe will be reflected completely accurately in the universes below and above. That little model there might as well be our own universe. Which means, first of all, we have to make absolutely certain that we don't do anything nasty to the universes below ours, since the same thing will happen to us. And secondly, we can do very nice things for the guys in the computer, thereby helping ourselves."
    • "You've thought about this?"
    • "It's all in my woefully overlooked article on the subject, Tim, you should read more."
    • "Guh. This has been an extremely bad day for my ego, Diane. The only comfort I take from this is that somewhere up there, right at the top of a near-infinite tower of quantum supercomputers, there is a version of you who was completely wrong."
    • "She's in the minority."
    • Tim checked the clock and picked his bag up again. "I have to go or I'm going to miss the next bus as well at this rate. This will still be here after the weekend, I suppose?"
    • "Well, we can't exactly turn it off."
    • "Why not?" asked Tim, halfway to the door, then stopped mid-stride and stood still, realising. "Oh."
    • "Yeah."
    • "That... could be a problem."
    • "Yes."
    • Sam Hughes, I don't know, Timmy, being God is a big responsibility

Implications of living in a simulation

It's fragile

Once the power on one of the simulations above us goes out, for whatever reason, we'll all blink into non-existence.

Free Will

If our universe is a simulation that can be sped up or slowed down by its creators at will, what might this mean for free will?

I have no idea how to begin to answer that, sorry.