Science does not have all the answers. There are many things that science, perhaps, will never be able to prove or disprove. For example, the existence of God. However, there is a topic that is much more interesting in the current scientific and near-scientific realities. It was proposed by Swedish contemporary philosopher Nick Bostrom, as well as several other very prominent scholars. It sounds like this: are we living in computer simulation?
It should be recognized that even the desire to speculate on this topic can lead to almost rabies at least one person – Sabrina Hossenfelder. And no, this person is not a religious person. He is a theoretical physicist and popularizer of science from the Frankfurt Institute for Advanced Studies (Germany). This week, she decided to share her opinion on this topic on the pages of her personal blog Backreactions. The truth here is to point out that it is not the statement about “our life in computer simulation” that upsets her. She is upset by the fact that some prominent scientists and philosophers make statements that, if they are facts, must certainly be reflected in our physical laws. But they are not displayed.
“I’m not saying that this is impossible,” explains Hossenfelder. “But I want to hear not only words, but also see what can support them.”
Confirmation of this opinion will require colossal work and countless time for mathematical calculations. In general, the effort will have to spend so much that they are enough to solve most of the most difficult problems and gaps in theoretical physics.
So, you want to prove that the Universe is actually a simulation created by a certain “programmer”. No, you do not approach the issue from a religious point of view and do not say that God created the universe. You simply think that some “omnipotent higher power” has designed the universe according to its vision, and, saying that, you mean not God at all.
To begin with, to make it more understandable for people who have just joined us and do not understand at all, what we are talking about at all, the term “computer simulation of the universe” implies that we live in a universe where all available space and time are based on discrete Bits of data. That is somewhere there must exist some ultra-megasupercomputer with “units” and “zeros”, creating everything that surrounds us. But in this case absolutely everything that exists in the Universe, even on the smallest scales, should have its own specific properties, certain states or values - yes or no, 1 or 0. However, according to Hossenfelder, science already knows that this can not be.
Let us take quantum mechanics. There are some things in it that can really be distinguished by certain values, but the basis, the very basis of quantum mechanics, is not in the properties of objects. The basis of quantum mechanics are probabilities. Elementary particles, like the same electrons, have a property called spin (momentum). Quantum mechanics says that if we do not observe particles, then we can not say with precision what value their spin has at that moment. We can only assume. On this principle the parable of the cat of Schrödinger holds. If a certain process, like radioactive decay, for example, can be determined by quantum mechanics and is responsible for whether a cat is locked in the box or not, then in our current understanding of classical physics, the cat should in fact be in two states simultaneously – alive and dead, – until we open the box to look. Quantum mechanics and classical computer bits are based on different, unrelated things.
If you dig deeper, it turns out that some “programmer” will have to encode a lot of classic bits, whose values are fixed, into quantum bits, which is governed by the principle of uncertainty. Quantum bits, in turn, do not have definite values-not represented by zeroes and ones-but instead tell us about the probability of taking any of these values (including the so-called superposition state). Physicist Xiao-Gang Wen of the Institute of Theoretical Physics Perimeter tried to model all of this and to present the universe as something consisting of “qubits”. Hossenfelder says that Wen’s models seem to be largely consistent with our standard models of physics and mathematics, describing the properties of our particles, but still could not correctly predict relativity.
“But he did not say that we live in a computer simulation. He just tried to explain the probability that the universe could consist of qubits, “commented Hossenfelder.
The presence of any proof that we live in a simulation will require us to revise all our laws of elementary particle physics (general and special relativity) and use a different interpretation of quantum mechanics, on the basis of which its current laws are derived so that it can perfectly describe our universe . What is most interesting, there are people who dedicate this to their whole life, but they do not approach the cherished goal by a centimeter.
Scott Aaronson, a specialist in the theory of computers and systems, talks about the probability of existence of theories that can combine gravity with quantum mechanics. And if our universe really consists of quantum bits, then sooner or later these theories someone can pull out and correctly justify. Therefore, if among people there are those who would like to solve one of the most complicated riddles in theoretical physics, then you are welcome. Aaronson himself refers himself rather to the “camp of disinterested” in deciding whether our universe is virtual or not, but nevertheless his opinion on the subject matter also has:
“Why not take this hypothesis and simplify it, excluding from the equation” aliens “or anyone there at the head, if the presence of this factor is of no practical use in the solution of the hypothesis?” – asks Aaronson.
Definitely, whether it be “aliens” or some “main programmer” – they would all be in this case the highest “forms of life”, which we would most likely never have been destined to understand. And if our theories work without assumptions that we all can live in a simulation, then why try to find an explanation for what we do not really need?
And yet, being a computer specialist, Aaronson could not ask himself another equally interesting question: is it possible, according to our computer calculation rules, to create a simulation, a scale with the Universe? In the case of modeling our universe, according to Aaronson, according to the most rude and optimistic assumptions, it would take 10 ^ 122 qubits. (This number would represent a unit with 122 zeros, with some estimates that the approximate number of atoms in our universe is 10 ^ 80). No less interesting would be the question of whether this hypothetically created virtual universe is capable of bypassing the stopping problem and calculating its end in advance, that is, doing what ordinary computer programs can not do.
After all, those who believe in the “simulation model of the universe” can simply change the parameters in the simulation in order to ultimately confirm their assumptions. But this will no longer be science. It will be a religion, with aliens or some kind of “main programmer” instead of God. And yet neither Hossenfelder nor Aaronson argue that we all can or can not live in a simulation. They only say that if you can prove this, then you will need much more effort than simply shaking hands and conducting philosophical conversations. You will need irrefutable evidence, indicating that the architecture of the universe works as one giant computer and does not contradict the most complex laws of our physics.
“I do not convince anyone and do not force you to give up trying to prove it. Quite the opposite. I call to prove it, “Hossenfelder sums up.
“What irritates me most about all this is an attempt to renounce all the fundamental theories and laws that we already have in our hands.”
