So, you have this computer on your desk at work. You look at stuff on the monitor, you type on the keyboard, you move the mouse, you do stuff. It’s happy, your spreadsheets spread, and your words are processed. One day the computer gets upgraded: all of your data and stuff is migrated to a terminal server. Since you don’t bother to look under the desk much, you don’t notice that your data and everything you hold dear is no longer under your desk, but is now on the far end of a network connection. Your keyboard, monitor and mouse behave very much as they always did, and you are none the wiser. Later, the terminal server is moved out of its place under the staircase to a data centre in the middle of town (that’s why it’s called a data centre). You don’t notice that the response time has dropped from 2 milliseconds to 7 milliseconds. A few months down the line, the data center suggests that the terminal server be virtualised. Everything that was on the terminal server’s disks gets copied bit by bit to some large storage array, and scattered in multiple shards across a set of 17 different devices running diverse operating systems. The CPU power of your terminal server is, for the first week of deployment, running on blade 17 in rack 2, but because Suzy really used a lot of CPU power, the entire terminal server was moved to blade 34 in rack 5. That particular computer doesn’t have hardware that looks like your original computer or your terminal server, but it simulates it instead. Nobody tells you about this, because it’s really not relevant. Later, during a storage upgrade, your data is moved away from the center of town to two different locations, connected by fibre optic links. For reasons of security, the data is encrypted too, and no longer resembles the data you think you have, except by the application of the esoteric mathematics of cryptography. This means that there is no objective reality anywhere that is your computer … and yet you continue to use it every day.
At this point, you send a rather ill-advised e-mail to someone with a litigious frame of mind. The police arrive at your place of work with a warrant to seize your computer and search it for evidence of your terrible crime. You step back from your keyboard, monitor and mouse, and look in horror as they take it all away – but they soon return. The forensics expert says there’s a problem. Please would you be so kind as to explain exactly what this computer thing is that they should seize?
The point of this story (a cautionary tale of desktop virtualisation) is that the computer looks just the same to the user even when its form changes radically. We believe in it as a computer, because that’s what it behaves like. We don’t care how long the bits of string are that make it do its thing – whether they are nanometres or kilometers. We don’t care about the complex mathematics that brought it to us. There is no straightfoward way of telling whether you are dealing with a computer, or with a simulation of a computer. As long as it performs the function of a stand-alone computer, to us, it is a stand-alone computer.
Now, about this universe thing that we see and observe, and count as a true fact. What is it made of? Apparently, it is made out of a few fundamental particles, such as electrons, neutrons and protons, and these interact via electromagnetic waves, when they are not too busy being waves themselves. These interactions are governed by mathematical rules. These rules are such that the absorption spectrum of a hydrogen molecule on earth can be seen in the light coming from the sun, and also in the light coming from distant stars. Now how is it that atoms know how to interact with light according to mathematical laws? Why would something as tiny as an atom spend its time doing mathematics?
James Clerk Maxwell, the physicist said this,
“A molecule of hydrogen, for example, whether in Sirius or in Arcturus, executes its vibrations in precisely the same time. Each molecule, therefore, throughout the universe, bears impressed on it the stamp of a metric system as distinctly as does the metre of the Archives at Paris, or the double royal cubit of the Temple of Karnac … the exact quality of each molecule to all others of the same kind gives it, as Sir John Herschel has well said, the essential character of a manufactured article, and precludes the idea of its being eternal and self-existent.”
Maxwell agreed with Herschel that molecules look manufactured, and did not manufacture themselves. There is, however, another possible explanation for the similarity of atoms that comes from computer science: a simulation.
If we were to manufacture an article such as a hydrogen molecule today, and have it interact with other hydrogen molecule according to mathematical laws, how would we do it? In Maxwell’s time you could manufacture something of wood with a few magnets stuck on and get an approximation of some of the qualities. In our time, you manufacture such articles in a simulation. The articles are identical because the same rules are applied to each article by the simulation. The rules are not inherent to the article itself, but are externally impressed on it by the simulation.
A virtual computer believes itself to operate on real hardware that functions according to predictable principles. It doesn’t matter how these principles are implemented – whether by hardware under your desk, or by something vastly more complex than you would expect.
We live in a universe that operates according to mathematical rules. For the purpose of observation and general use, it does not matter how the rules are implemented – whether they are fundamental to the stuff of the universe, or by something vastly more complex than you can conceive.
If we are living in a high quality simulation (as some interpretations of quantum mechanics propose), then the question should be whose simulation we are living in.
Paul, explaining the concept of the creator to the pagan Athenians, saw fit to quote this line from their own (pagan) poets:
Yet he is actually not far from each one of us, for
‘In him we live and move and have our being’; as even some of your own poets have said,
‘For we are indeed his offspring.’
It’s probably worthwhile to note that every simulation that has been done by man has used equipment that is vastly more complex than the thing being simulated. The stuff in the simulation does exist – it’s just virtual.
Update: The reason we don’t notice that the machine under our desk no longer exists is because we experience only the results of its mathematics – just like everything else we experience which is the result of mathematics. Any process that calculates the same results from the inputs we provide is essentially equal. We don’t care much whether the calculations in question are done by local electronics, or by remote electronics (or by by enslaved gnomes with pencils, if they can work fast enough).