“Simulating an entire universe with all of its elementary particles, elements, molecules, solar systems, and galaxies would require a tremendous amount of computing power. The same is true even for the simulation of just one single human brain. It may be hard to believe that this can ever be done.”
“The Relative Reality Simulation Hypothesis (RRHS), however, suggests to take a different road. It is based on the idea to simulate what we will call "Virtual Minds" (VMs) – instead of simulating an entire universe, the world experienced by such a Virtual Mind will be an emergent phenomenon.”
The simulation argument
In 2006, Nick Bostrom (University of Oxford) published a paper named "The Simulation Argument", which leads to the conclusion that we most certainly live inside of a computer simulation, unless it will be technically not possible to create such simulations.
“The simulation hypothesis or simulation theory is the proposal that all of reality, including the Earth and the rest of the universe, could in fact be an artificial simulation, such as a computer simulation. Some versions rely on the development of a simulated reality, a proposed technology that would be able to convince its inhabitants that the simulation was "real". The simulation hypothesis bears a close resemblance to various other skeptical scenarios from throughout the history of philosophy. The hypothesis was popularized in its current form by Nick Bostrom. The suggestion that such a hypothesis is compatible with all of our perceptual experiences is thought to have significant epistemological consequences in the form of philosophical skepticism. Versions of the hypothesis have also been featured in science fiction, appearing as a central plot device in many stories and films.” – Wikipedia
Criticism and counter arguments
The main counter argrument is probably the problem of limited computing resources – it is, in fact, hard to imagine how a computer could simulate an entire universe (note that the Relative Reality Hypothesis will try to solve this problem, and the resulting simulated universe should be similar to ous, featuring the same physical laws and paradoxes).
Right now, even the fastest supercomputers have are hardly fast enough to simulte single molecules, so let's first illustrate how difficult a simulation of an entire universe would be, by presenting some numbers:
There are 1080 atoms in the visible universe. To some, 1080 may not look like a big number, but it IS a lot, it's a 10 followed by 80 zeroes. A computer simulating the entire universe would have to be bigger than entire universe itself.
But even if we'd only have to simulate a small part of the universe, the required computing power would still lie far beyond any imagination.
There are 100 to 400 billion stars in our galaxy, that's about 1067 atoms.
There are 1056 atoms in solar system.
There are about 7*1027 atoms in a human brain.
So even simulating a single human brain with all of its atoms and connections is not possible for today's supercomputers, and it will take at least another 100 years until we will be able to simulate much simpler brains of small mammals.
An average human brain features 100 billion neurons and 100 billion nonneuronal cells, each of these neurons can have up to 15,000 connections with other neurons via synapses, all of which will make up over 100 trillion synapses in total.
The world's fastest supercomputer (as of 2020) is named Fugato (Japan), it's running a total of 158,976 A64FX processors by Fujitsu. The A64FX is 64 bit ARM processor offering 48 cores, so the entire Fugato supercomputer uses a total of 7,630,848 CPU cores.
Fugatu may be the fastest supercomputer on the planet, but it could never run a simulation of the entire universe.
To simulate the entire universe, each of Fugatu's CPU cores would need to simulate 10,000 to 20,000 galaxies.
To simulate our galaxy, the Milky Way, each of Fugatu's CPU cores would need to simulate 10,000 to 40,000 solar systems.
To simulate the human race on Earth, each of Fugatu's CPU cores would need to simulate about 1,000 human bodies including their brains.
To simulate a single human brain, each of Fugatu's CPU cores would need to simulate 7*1020 atoms, 26000 cells, or 13 million synapses.
As of today, none if this would be possible, and none of this will be possible in the next 100 years either. Even using the power of all computers in the world combined would not be enough, and connection speeds would be way to slow.
The solution: a lightweight simulation
The Relative Reality Simulation tries to solve the problem mentioned above by introducing a new way of simulation, inspired by today's networked multiplayer computer games:
Instead of simulating an entire universe, the RRS will only simulate the world's inhabitants' experiences (not even their entire brains).
Each inhabitant / observer within the simulating will technically be a "process" running on a CPU core.
If we only count humans for the moment, and leave animals aside, then the supercomputer running the simulation will need to run 7,8 billion such "Virtual Minds".
In Fugatu's case, this will mean that the computer will need to run about 1,000 such processes per core.
Running that much processes is possible on today's computer hardware, but only if we speak of quite simple processes, not of conscious exeriences that would be as details as what we exerience in our lives.
Nevertheless, it is now already possible to run quite detailed virtual reality games on single CPU cores, even without 3D hardware graphics acceleration. Today's supercomputers sould be able to run a virtual world simulation with 7 million non-conscious AI players in a quality similar to 1991's DOOM for example. If Moore's law will still be valid in future, then we could be able to run such simple simulations with 8 billion players within the next 20 years.
But this still wouldn't be conscious players of course, and even if only a fraction of the players would be conscious at all, while most other players would be "robots" or "philosophical zombies", then the computing requirements will still unmatchable for any supercomputer we may build within the next 50 years, at least.
So maybe we should agree that it won't be possible to create such a simulation in the near future, even if we would combine the resources of all computers on Earth.
Please note the following, however:
Some people will say that the required computing power will become available as soon as quantum computers will become common. This is an unproven argument however, and it is not clear how exactly quantum computers will be useful when it will come to simulations. They may accelerate things, but right now it's still way too early to make any good guesses.
Others will tell you that the hardware isn't the problem at all, it's the software that's the biggest issue, as we just don't know how and why brains and consciousnesses work. This is true, of course, but even if we'd manage do create the software, then it will surely be complex enough to require vast amounts of resources.
Another possibility is that some artificial intelligence will take over the world, and will then create the required computer infrastructure and "enslave" all humans in it (think of The Matrix, 1999). While we can't exclude the danger of an AI taking over power on Earth, it's still questionable, however, why such an AI should create a virtual world, and why it would emprison humans in it.
We have to acknowledge that building creating such a simulation will be a very difficult task, even for the generations to come, and even if we're talking about building the most simple version imaginable.
As mentionend before, the RRS will try to keep resource requirements as low as possible, by avoilding to simulate an entire world, by only simulating individual experiences using so-called "Virtual Minds".
The biggest problem, however, will then be to share information between those "Virtual Minds", as that they will be able to interact in their world, and this is where "Relative Reality" will become important.
If you play a networked first-person computer game, then all players will need to be inter-connected, so that actions in the shared world will remain consistent for all players. One major problem is that the number of required connections will grow exponentially with every player you will add. This is why most networked games use a "game server", which is gathering and distributing all data in real-time.
While is may work well for most computer games, it will become very difficult to implement if we talk about a realistic world featuring conscious minds, where each and every action will influence thousands of variables simultaneously.
Relative Reality uses a different approach:
Each "Virtual Mind" features its own, simplified representation of the world. Actions will at first only affect the VM's own reality, and changes will only be shared if necessary. Dedicated sync processes will make sure that the VM's experiences will be synchronized, but only if necessary.
Synchronzing the present
“Reality is, what most people will agree on to be real.”