1. Almost all civilisations at our level of development become extinct before becoming technologically mature.

2. The fraction of technologically mature civilisations that are interested in creating ancestor simulations is almost zero.

3. You are almost certainly living in a computer simulation.

See FAQ for the details of the simulation argument. If the simulation argument is correct, at least one of these three propostitions is true (it does not tell us which).

See Usenet debate for a lively discussion. The thread was started by me and has contributions by author Greg Egan - among others.

Isn't the simulation argument-hypothesis untestable?

There are clearly possible observations that would show that we are in a simulation. For example, the simulators could make a "window" pop up in mid air in front of you with the text "YOU ARE LIVING IN A COMPUTER SIMULATION" - think Greg Egan here - but the hypothesis is not testable in the sense that we can make an experiment that could show us either way? That you don't have signs popping up in midair is not evidence that you are not living in a simulation.

What kind of computer could do the simulation?

Seth Lloyd calculates an upper bound for a 1 kg. computer of 5*10^50 logical operations per second carried out on 10^31 bits - compare that we would need 10^14 operations per second to simulate a human mind - perhaps as much as 10^17 . For a complete simulation of a human history , society and surroundings, Nick Bostrom speculates that we would need 10^36 operations (100 billion humans x 50 years/human x 30 mill secs/year x 10^17 flops in human mind/sec = app. 10^36) - which is far from the teoretical limit, but close to speculations of a planet size computer doing 10^42.

Finding a suitable energy source for all of this information processing is another problem. One could englobe the sun with sun collectors, this way the suns energy output could be used for information processing - or one could use some other kind of fusion.

A quantum computer, some kind of black hole computer would be great. Frank Tipler suggest modifying the universe (or the simulation or whatever it is?) - In Tiplers model the universe is closed (engineered so) and experiences an anisotropic collapse. Usable energy grews faster than temperature and allows a divergence of information processing. Subjective time (information) goes to infinity as the singularity is approached (and all there ever was in the universe can the be resurrected based on the information gathered from the things, light, that is on its way to collapsing in the singularity - heaven so to speak in the omega point).

In Tiplers world the argument is: Any mental life, any stream of consciousness, can be repliacated on a computer. Total number of human like streams of consciousness is finite. The processing power of this end of the world computer is effectively infinite. The end of time computer will be able simulate every possible human consciousness there ever was. Hence our resurrection is inevitable.

Still the conclusion is : Post human civilisations would have enough computing power to run hugely many ancestor simulations even while using a tiny fraction of their resources for the purpose.

Is it ethical to start a human race in a simulation?

Maybe advanced civilisations ban all ancestor civilisations with humans as unethical because of the suffering that is inflicted on the inhabitants of the simulations. And maybe the scientific value of an ancestor simulator is neglible - and for pleasure they, inhabitants of advanced civilisations, could just as well address their brains pleasure centers directly.

The existence of (unnecessay) evil is a huge problem in theology. But it is only a problem if one assumes that the world was created by an all powerful, all knowing and all perfectly good being. With the creator being less than these things, it should be no surprise if the simulation is less that perfect.

And, is it acceptable to stop a simulation just because it cost a lot of money - when you have the results you want - if people are actually living in this world? When a person dies in the simulation is it necessary for you (ethically speaking) to uplift/resurrect this person to another simulation where he can live forever with his simulated friends? Or should the uplift depend on how the person did in the simulation?

Or is it only "the conscious" part we should worry about? The conscious mind that consistently misattribute behaviour and perception to itself, even when they are done by lower levels and occur several hundred milliseconds before they become conscious? The conscious mind that experience itself as unitary, despite internal delays or obvious parts? Is it only that weird thing we should be nice to and treat with respect?

Maybe some humans in the simulations are real and others are zombies

And are all parts of the simulation equally important?

Maybe you populate you simulation with a few "real like people" and the rest are just zombies to make it a credible universe? This leaves the question how to treat a zombie person when you meet such in the simulation? Is it ok to kill a zombie? And how will you know the difference? We must assume zombies are put into the simulation because they are computational less expensive?

Substrate independence and superintelligence

Given (brain) simulation you also have super intelligence!

Substrate independence - is the idea that conscious minds could in principle be implemented not only on carbon-based biological neurons - but also on some other computational substrate such as silicon based processors.

Implementing a human brain in silicon obviously works if technology is available that can take a very detailed scan of a human mind, which can be uploaded to a computer. But if that exists one is close to superintelligence - say the upload will be identical to the original brain, but you will able to run at much higher speeds - years of results from the scanned brain could then be fed back to the original brain as instant knowledge. The same memories, skills, values and consciousness is then enough for superintelligence.

It follows that the morals in running simulations (brains and worlds) might be flawed, but we cant assume it is without benefits? Actually, we can assume that a simulation that contains consciousness, is pretty close to breaking into superintelligence.