If we live in a simulation, what does that imply?

The laws of physics in the basement level universe make it relatively easy to run lots (perhaps an infinite number) of simulations.

If there is a stack of simulators, with one world simulating another, the "basement level" is the world in which the stack bottoms out, the one which is simulating and not simulated.

This short story comes to mind.

Just for fun a recent paper:

Constraints on the Universe as a Numerical Simulation

Silas R. Beane, Zohreh Davoudi, Martin J. Savage (Submitted on 4 Oct 2012) Observable consequences of the hypothesis that the observed universe is a numerical simulation performed on a cubic space-time lattice or grid are explored. The simulation scenario is first motivated by extrapolating current trends in computational resource requirements for lattice QCD into the future. Using the historical development of lattice gauge theory technology as a guide, we assume that our universe is an early numerical simulation with unimproved Wilson fermion discretization and investigate potentially-observable consequences. Among the observables that are considered are the muon g-2 and the current differences between determinations of alpha, but the most stringent bound on the inverse lattice spacing of the universe, b^(-1) >~ 10^(11) GeV, is derived from the high-energy cut off of the cosmic ray spectrum. The numerical simulation scenario could reveal itself in the distributions of the highest energy cosmic rays exhibiting a degree of rotational symmetry breaking that reflects the structure of the underlying lattice.

http://arxiv.org/abs/1210.1847

What evidence is there for us being in a simulation? I've never heard of humans wanting to "simulate" history. Civilization doesn't play even remotely like a simulator and never claimed to be. The information equivalent to an entire world would have to be converted into data storage for such a project and what possible motive could there be for that? I'll follow Occam's Razor on this one- the more assumptions you make, the more likely you are to be wrong unless you have some sort of evidence.

Today, we often simulate our human ancestors' lives, e.g., Civilization. Our descendants will like want to simulate their own ancestors, namely us, and they may have much-improved simulation technology which support sentience. So, our simulators are likely to be our (post-)human descendants.

This sounds a lot like "If our simulators are like us then they are like us" or (more fairly) "if our simulators are like us in respect X, then they are also likely to be like us in respect Y,Z..."

Do we have any reason to think the simulators will be like us in respect to the issue of wanting to simulate beings like themselves?

Our simulators want to trade with us.

Acausal trade confuses me. Is the following right?

Humanity should simulate other agents who (a) would value being simulated and (b) would simulate us

Because it isn't clear to me that humanity is the type of agent that would value unconnected copies being simulated. (this is distinct but dependent on the assertion that simulated humans are entitled to moral consideration regardless of whether actual humans are sufficiently causally connected to the simulated humans).

The simulators are much like us, or at least are our post-human descendants.

No, they probably have a much greater desire to run simulations than we do or ever will.

Today, we often simulate our human ancestors' lives, e.g., Civilization. Our descendants will like want to simulate their own ancestors, namely us, and they may have much-improved simulation technology which support sentience. So, our simulators are likely to be our (post-)human descendants.

• People like us like to simulate people like themselves.
• Therefore, if the simulators are like us, then they simulate people like them.
• They simulate us.
• Therefore, if the simulators are like us, then we are like them.

That argument seems a bit empty, to say the least.

Now I suppose your argument is more like "We exist, therefore our descendants are more likely to exist than the average mind; and we want to simulate stuff, therefore our descendants are more likely to be simulators than the average mind. Therefore, a simulator is more likely to be one of our descendants than to be any random mind.", which is valid. But I deny the premise; we like to simulate some things about our ancestors, but not our ancestors themselves.

Our simulators clearly don't care about morality, for general reasons of theodicy. If they are like our descendants, then our descendants are likely to be unspeakably evil. This implies that we should destroy humanity now, to avoid birthing a race that will simulate matryoshka atrocities.

Thanks for starting this discussion!

If we are in a simulation, then (a) at least one universe, ours, is a simulation; and (b) at least one world includes a simulation with sentience. This gives some evidence that being simulated or being a simulator are not too unusual, and the stack may lead way down to the basement world, the ultimate unsimulated simulator.

...

[1] If there is a stack of simulators, with one world simulating another, the "basement level" is the world in which the stack bottoms out, the one which is simulating and not simulated. This uses a metaphor in which the simulators are below the simulated. An alternative metaphor, in which the simulators "look down" on the simulated, is also used.

Or maybe there isn't a basement universe. Maybe the stack never bottoms out. Think about it do you actually need one of those or are we just assuming you do because we assumed we lived in an unsimulated universe for most of our lives?

The basement universe if it exists seems likely to have certain odd traits.

I was expecting a post along the lines of "what are the tests that would falsify the hypothesis that we're in a simulated world?"

I recently came across a pertinent thought experiment. It's pretty entertaining (it's a short story) and it really makes you think.

If we are in a simulation, then (a) at least one universe, ours, is a simulation; and (b) at least one world includes a simulation with sentience. This gives some evidence that being simulated or being a simulator are not too unusual, and the stack may lead way down to the basement world, the ultimate unsimulated simulator.

In a Tegmark level IV multiverse there is no basement universe but every universe is simulated by some other universe.

[Added] The simulations are stacked.

Just a few question for this proposal:

• Wouldn't the infinitely stacking simulations lag and further increase the costs to support the simulation in the level below it.?

• Is it more likely that, if we are in a simulation, we are "close" to "basement level" rather than far out in an infinitely stacking simulation because the basement level will find it too costly to run an infinitely stacking simulation?

The simulators are much like us, or at least are our post-human descendants.

I estimate this particular proposal to be very low. We might just be the by-product of, or one of many civilizations of, a simulation. Humanity and its time of existence might just be a blip on the way to the real reason of the simulation – a civilization that will exist billions of years from now. In other words, perhaps we are merely the extras in a movie in which the audience have come to watch the stars.

Everything outside our vicinity, e.g., outside our solar system, will be calculated planetarium-style, and not from the level of particle physics.

If the physics on which ultra-high-energy cosmic ray sources run is not the same physics on which we run but only an approximation thereof, we might eventually notice weird things with them.

Our simulators want to trade with us.

Acausal trade confuses me. Is the following right?

Humanity should simulate other agents who (a) would value being simulated and (b) would simulate us

Because it isn't clear to me that humanity is the type of agent that would value unconnected copies being simulated. (this is distinct but dependent on the assertion that simulated humans are entitled to moral consideration regardless of whether actual humans are sufficiently causally connected to the simulated humans).