For anyone who has seen the film The Matrix, they will know that the basic premise of the film is that reality is simulated in our minds by the means of a computer intelligence. The idea that reality is a simulation is not a relatively new idea. The essence of the idea can actually be traced back to around 300 BC in ancient China. The influential Chinese philosopher Zhuangzi famously asked the question, now translated as, “Am I a man dreaming I am a butterfly or a butterfly dreaming I am a man?” Since dreams are basically a simulation of reality (since the content of a dream is a product of the mind alone and not the outside world) Zhuangzi struggled with the question of whether reality, as we experience it, is merely the product of a dream.
The French mathematician Rene Descartes would later reinterpret this problem in his infamous Evil Demon Hypothesis. This hypothesis states that everything we experience, perceive or believe could be data fed into us by a powerful, malignant demon whose only aim is to deceive us.
Beyond these simple and supernatural versions of the Simulation Hypothesis, more modern philosophers have repackaged the idea. Hilary Putnam, for example, has argued that it is possible that each individual is merely a brain in a vat, being fed sense-data by electrodes attached to a computer. This is very similar to the basic premise of The Matrix.
So in effect, every time we experience the pleasure of sex or food, the sensation of heat, the smell of a flower or the sight of someone, the only external source for these experiences is the information stored in the computer which is then fed into us. On the other hand, just because this scenario is possible, does not mean that it is true, or even plausible. To believe in it would mean to make a number of assumptions: that computers could simulate reality in this way and that the designers of these computers would want to simulate reality in this way.
In any case, if this kind of simulation scenario is possible, it is interesting for that fact alone. Some thinkers have taken the kind of reasoning employed by Putnam and the creators of The Matrix to a new extreme. They have suggested that reality is not necessarily simulated in minds of individual brains, but that the universe (the universe which is visible to us and therefore everything we know) is a computer simulation generated by some other, more advanced civilisation.
The philosopher Nick Bostrom has said that in all likelihood, because of the vastness of the universe, there must be civilisations which are more technologically advanced than ours; civilisations which have the computing power to simulate universes (see his paper Are You Living in a Computer Simulation?) Perhaps these civilisations have harnessed the power of quantum computers which can carry out calculations infinitely quicker than classical computers. However they manage to simulate universes, Bostrom claims that if a civilisation can do it (because it’s easy) then they will. Bostrom reasons that even if such civilisations are rare, they will certainly create many simulations of universe and simulations within simulations, so that, in the end, simulated universes far outnumber real universes.
This kind of reasoning would certainly apply to the human race as we know it – whenever we are curious about something, we need to satisfy our curiosity, and at any cost. We have burrowed into reality at the depth of the atom, but with this came the invention of the atomic bomb. So even if simulating a universe would lead to human suffering, this moral issue would be outweighed by the curiosity of the advanced civilisation. One crucial (and possibly mistaken) assumption is made here, however. That is, that a hyper-evolved civilisation will think in much the same way we do. Perhaps a highly evolved civilisation would be morally minded enough not to simulate a universe in which beings like ourselves must suffer. But that’s just me being optimistic.
On the other hand, these sorts of claims have received some criticism from a number of physicists. John Barrow, for example, in his book The Infinite Book, says that if our universe is a simulation there should be clues for this in the form of glitches, errors or gaps in the programming, since even a super-civilisation may not know everything there is to know about the laws of physics. So far it seems we have not come across any of these ‘glitches’.
Well, according to string theorist James Gates, the fact that we have not encountered any ‘errors’ in the programming might actually tell us that we are living in a computer simulation. Gates has reported that ‘error-correction codes’ (a string of 0s and 1s, which make web-browsers work for example) have been found in the equations of super-string theory. Gates has proposed that if there really is computer code embedded in the equations which describe reality, then this could confirm whether we live in a computer simulation or not. What’s left to be seen is whether string theory becomes verified in the future and whether the ‘computer code’ in its equations is actually computer code.
The popular science writer, John Gribbin, has argued that if we are discussing the most likely origin of our universe, it is more likely that the universe was born from a black hole than from a computer simulation. Gribbin points out that it would be much easier for a super-civilisation to design our universe by creating a black-hole (which our current civilisation is nearly able to do) than to simulate the energy, position and velocity of every particle in our entire universe. The computing power necessary for that feat is beyond our imagination. Therefore, according to Gribbin, it is possible that a super-civilisation may have designed and created our universe, but if they did, in all likelihood they would have used black holes and not computers.