Is this world real?
Already in ancient times philosophers imagined that there is no way of telling that the world around us is real or that other people have a mind of their own. Perhaps I am the only one who is real while the rest of the world is my imagination. This could all be a dream. Some major religions claim that gods created this universe and that we are like them. In the Bible it is written that God said: “Let us make mankind in our image, in our likeness.”
For a long time it was impossible to clarify why this world might not be real or how the gods might have created it. More recently advances in information technology changed that. This universe could be a virtual reality. We are inclined to think that what our senses register is real, so we may ignore evidence to the contrary. For instance, you may think you see a pipe when watching an image of a pipe. The caption of the picture makes you notice: this is not a pipe.
Do we live inside a computer simulation?
In 1977 science fiction writer Philip K. Dick was the first to claim that we do exist in a computer-generated reality. This is the simulation hypothesis. He came to this insight after experiencing a psychosis. If he is right then his name suggests that our creators do like to joke around. Professor Nick Bostrom explored the probability the simulation hypothesis being true in the simulation argument. It states that we almost certainly live inside a computer simulation if certain conditions are met.
According to science this universe started off fourteen billion years ago with a big bang. Ten billion years later life on this planet began to develop out of chemical processes. It took another four billion years for life to evolve into what it is today. The first humans arrived on the scene 400,000 years ago. Agriculture started 10,000 years ago. Modern science began only 500 years ago. There is no evidence of an intelligent creator, the laws of physics always apply, and we are biological organisms made out of carbon and water.
For the purpose of the argument this universe and our civilisation can be called real if the above is all true. If this is all appearance, and we only exist inside a computer, this universe can be called a simulation.
Bostrom argues that there may be many different real human civilisations as there might be parallel real universes containing human civilisations. The humans in those civilisations may at some point enhance themselves with bio-technology and information technology, live very long and acquire capabilities ordinary humans don’t have. For that reason these beings aren’t humans but are called post-humans. These post-humans may run simulations of human ancestor civilisations. In that case we may be living in one of those simulations ourselves. Bostrom argues that at least one of the following must be true:
- Nearly all real human civilisations end before enter the post-human stage.
- In any post-human civilisation only an extremely small number of individuals are interested in running simulations of a human ancestor civilisations.
- We almost are certainly living inside a computer simulation.1
It comes with the following assumptions that appear realistic to many experts in the relevant fields, but are not proven:
- The available computing power in post-human civilisations is sufficient to run a very large number of simulations of human ancestor civilisations.
- The human consciousness needs not to reside in a biological organism, but can be implemented in a computer, perhaps in a limited form that appears realistic.1
Bostrom then concludes that if you believe that our civilisation will one day become post-human and will run a large number of human ancestor civilisations then you must believe we are currently living inside such a simulation.1 That is because we don’t know at what point in time we are, before or after the invention of virtual reality universes. If every year has an equal probability of this technology being invented, and we are going to create this technology in the next 10, 100 or 1,000 years then it will not happen later than that. By then we will have done it. But what are the odds of it happening in the next 10, 100 or 1,000 years compared to the billions of years that already have passed?
Bostrom doesn’t try to guess the likelihood of the options. There are too many uncertainties. The available computing power of post-human civilisations might be insufficient. Or perhaps nearly all civilisations will die out before becoming advanced. Or perhaps post-humans will differ from us to the point that they will not be interested in running simulations of humans. Bostrom further assumes we have no information as to whether this universe is real or not. But that may not be true.
These simulations may be realistic in many ways but may not be realistic in some aspects. If that is somehow noticeable then we may be able to know. To see why a simulation may not be realistic in some respects, we have to look at the possible motivations for post-humans to run simulations of human ancestor civilisations. Even though it is not at all certain, post-humans may have similar motivations as humans. Hence, these simulations might be made for research or for entertainment.
A research application could be running what-if scenarios. So what if a giant meteor hits the surface of the planet? What if China never became unified? What if there never were religions like Christianity and Islam? Or what if a deadly infectious disease breaks out? Countless scenarios can be imagined. Post-humans might be interested in running them and see how humanity would cope. In that case the simulations may be realistic.
Possible entertainment applications for simulations are playing games or making your imaginations come true. Such a simulation may not be realistic in some aspects because it reflects someone’s imagination. Chaos theory suggests that even small changes in the initial conditions can have a dramatic impact on future developments so in order to guarantee a particular outcome you might need complete control over what happens. This doesn’t apply to games as unpredictable outcomes is what makes games interesting.
Real or fake?
If the simulation is in some ways not realistic, that may be noticeable. In order to notice it, we need to have an idea of what is realistic and what is not. We only have our universe and our state of knowledge about its past, its laws of physics, and our human nature, to make such a guess. If this universe is indeed real, then it must be realistic by definition. If we have sufficient knowledge about reality, it may be possible to discover that we live inside a simulation. If this universe is real, then the following seems to apply:
- There is no evidence of an intelligent force coordinating events in this universe.
- The laws of physics are always the same and cannot be breached.
- We are biological organisms made out of matter and our consciousnesses reside in our bodies.
Evidence to the contrary may indicate that we do live inside a simulation. Meaningful coincidences suggest that there is an intelligent force directing the events in this universe. The paranormal seems to flout the laws of nature. Evidence for reincarnation suggests that we are not biological organisms. But meaningful coincidences can happen because of chance. And there may be laws of physics we do not know of. And there is plenty of evidence of the consciousness residing in the body while only a few people remember a previous life. Making a convincing case for the simulation hypothesis requires clarifying why simulation is a more plausible explanation for these phenomena.
1. Are You Living In a Computer Simulation? Nick Bostrom (2003). Philosophical Quarterly (2003) Vol. 53, No. 211, pp. 243-255.