How can we tell if we are real and not a simulation that we perceive to be real. Given we know not what the universe is except what we perceive it to be.

What if galaxies are just but other probabilities, where we exist in other forms, and it so happens that earth is where we are because it is where the probability placed us.

  • Totally unclear... maybe "probabilities" are real. Oct 11, 2018 at 14:29
  • @MauroALLEGRANZA Hoping I did not imply so, what makes you think probabilities are real?
    – stomogaka
    Oct 11, 2018 at 14:51
  • What is "real" about ? Physical objects, numbers, souls ? If we "are not real and we are only a simulation" ... a simulation by whom ? Oct 11, 2018 at 14:53
  • The background that could be helpful to you may be "true" metaphysics. You can do a search for Michael Loux I think there are some PDF's of his books around. I can also recommend this book by him. amazon.com/…
    – Gordon
    Oct 11, 2018 at 16:39
  • Because they impinge on us, resist our whims and persist in time, isn't that enough? And if it is real enough why should we care if it is simulated?
    – Conifold
    Oct 11, 2018 at 17:52

4 Answers 4


Google defines simulation as, "Imitation of a situation or process." In that sense, whether the universe is a simulation depends not only on whether it is a nested universe, but also on whether the prime universe is similar. If the prime universe is different (that is, has a super-set of our physical laws), then our universe could be said to be real simply because it is an object in the prime universe. However if the prime universe is the same, our universe must be said to be a simulation, because it is an imitation of the prime in a sandbox.

Either way, the universe is an algorithm. While we say it is real, it clearly follows certain mathematical and logical principles, and so could be said to be a program in the sense that it follows its predefined algorithm.

There is, however, another possibility. If mirror universes are real (think Star Trek), then our universe could be created with an infinite number of a particular mirror soul who likes to act like an atom. If that is the case, the universe is very real indeed, but could be said to be imaginary in that it is the machinations of a person. Or mirror people, as it were. In this case, there could be no such thing as something that is not alive.

As for existing on Earth, I for one have no problem with the idea that it was selected at random. See Constitutional Luck. Wherever we were placed, we would have a world for it (not necessarily Earth).

  • Would you have any references for the reader to go for more information about these views? This would also strengthen the answer. Welcome to this SE! Oct 21, 2018 at 11:01

What does it mean for something to be real? Our idea of reality is brought to us mostly by our senses. If this is a simulation, our senses are still reporting what they would if this were "real". If it's a good simulation, there's no way for us to tell.

We can intelligently speculate on the possibility of simulation by computers such as we have in this reality, and it turns out that some natural processes are not possible to compute at all efficiently. If we are in a simulation, it's a simulation based in a universe where the laws of computation are different, despite the fact that most of them are mathematically based.

I don't follow the idea of galaxies being other probabilities. We only have the concept of galaxies from observation (in fact, the concept is about a century old), and the observations are of the sort that rely on assuming the laws of physics and astronomy work the same there as here. We know they're different from ours by the same observations that make us think they exist, and so another galaxy isn't going to be ours with different details of history (perhaps the lizardmen actually won the battle of Waterloo). It's going to be similar in some ways, but not a reflection of ours.


I'd argue that we assume our senses strongly reflect reality because it is the only framework with explanatory power. We could just be brains in a jar, but that isn't a useful idea. It allows to make no predictions whatsoever. Ok, so I'm a brain in jar, how does that help me achieve orbit around the Earth, cure a disease, or plan my trip to Florida? It doesn't. It doesn't help with anything. It's just an unfalsifiable statement.

Further in-depth reading: https://plato.stanford.edu/entries/skepticism-content-externalism/


One good reason to believe that humans are not simulations is the fact of human reproduction. A new baby resembles its parents both physically and cognitively. This would be unlikely in a simulated universe.

One good reason to believe that humans are not manifestations of one indivisible and invisible reality is the fact of harm. Harmful things hurt, and major harmful things (like wars and genocide) hurt a lot. This would be unlikely if all humans were actually one identity.

  • Why is a baby that resembles its parent unlikely in a simulated universe?
    – syntonicC
    Oct 11, 2018 at 16:56
  • In appearance, that's easy to simulate. But in cognition, a natural resemblance in simulation strains the idea that the baby's mind is actually unrelated to the genetic-biological body. Oct 11, 2018 at 17:42
  • I'm not sure I completely understand. But I don't see why the relationship between the mind and genetic body could not also be coded into the simulation. More broadly, since we are speaking of a hypothetical simulated universe, how do we even know what properties are possible or not possible at all?
    – syntonicC
    Oct 12, 2018 at 0:44
  • That's a bad argument. Everything is possible in a simulation, it all depends on the resources of the creator. Traits can be inherited as the developer decides (even in common programming languages); a unified reality does not imply that all people should feel the same feelings.
    – RodolfoAP
    Oct 12, 2018 at 4:25
  • @RodolfoAP - Correct ! In a simulation everything is possible; thus, is a complete waste of time to speculate about "simulated universes". Oct 12, 2018 at 10:40

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