Is it real? Physicists propose method to determine if universe is a simulation

[grondilu]

This thread reminds me of a theory from Nikodem Poplawski according to which the universe might be inside a black hole (and that black holes are actually alternate universes).

I have to dig into his work one of this days because it's much more credible than one might think.

Did you know that apart from neutron stars and black holes, the only thing whose radius is of the same order of magnitude than its Scharzchild radius is the observable universe itself??

If you link this to the holographic principle, then a black hole's horizon is kind of a 2D quantum-computer which simulates its own universe.  And we would be the result of such a simulation.

I don't think the proposed test in this thread could be applied though.  From what I understand, they imagined kind of an inferior type of computer.  Not as powerful as a black hole horizon.

[grondilu]

Just watched "the 13th floor" for the first time.  It was nice.  Funny it came out the same year Matrix did.

It made me think of the following dialog:

«
- Damn those simulated human beings are so annoying.  They keep exploring the artificial world we create for them.
- So? That's good right?  It means they have curiosity and initiative.
- Yeah, but eventually they always manage to find out the limit of the domain and then they realize they are not real.  It's messed up.  So we have to make an other world and reboot the whole thing.
- Can't you make a bigger world?  Or a world topologically round?  Like a sphere?
- We did.  We made a round planet for them to live on, with a force that attracts them to the center, so that people on the lower half don't fell off.
- Makes sense.  Did that work?
- Nope, they did explore the whole planet but those morons also started to look at the sky.  Like, "with a telescope" look.
- What's the problem with that?
- The problem is that it gave them the idea of exploring space as well.
- Jeez.  And now you need to make a closed-curved universe as well?
- Screw that.  I don't have enough energy and resource to do something like that.  I'll make it simpler.   I'll make it look like the universe is extremely big and that stars are separated by huge distances, like light-years distances.
- Won't work:  at some point they'll manage to increase the speed of their spaceships and they'll reach your limits again.
- Yeah, that's why I'll add a rule saying that mass increases with speed, so that one needs an infinite amount of energy to accelerate above the speed of light.
- I see.  With such a rule, interstellar space travel will never be possible for them so whatever they do they'll never encouter the limits of your data.  Good work.
»

[thebaron]

:-)

[herzmeister]

From Plato's Cave to the 13th Floor and the Matrix in 1999 it was all just fun and games and curious thought experiments, but Nick Bostrom's paper a while later in 2003 really quite hardened this idea. The argument is so strong that there's hardly a way around it actually.

[grondilu]

The argument is so strong that there's hardly a way around it actually.

I would have much difficulty to explain why, but I have a strong belief that the kind of simulation he's talking about can not run faster than reality.  Therefore, It is not possible for evolved conscious beings to simulate their evolutionary history up to their current level of consciousness, as it would take way too much time.  So they would not do that, either because it would be pointless (who wants to wait a billion years for the result of a computation?), or because they would just have no time to do it in the universe they live in (considering their universe might have a finite lifespan for cosmological reasons).

So I think amongst his three hypothesis, it's the second which is true:

« any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); »

It doesn't mean they can not gather enough computing power.  It just means that having an infinite computing power does not mean you can simulate anything as fast as you want.

It's a very interesting paper though.  Thanks.  I'll read it more thoroughly some day.

[herzmeister]

They can run simulations with different degrees of faithfulness and different physical laws, which would result in different computational complexity, i.e. different frame rates of time (from the simulator's perspective, not from the inhabitants).

The dialog you quoted from the 13th Floor already suggests they use different complexities of physical laws in different simulations, and of course (I've seen the movie once but I don't remember much of it) they would have to ask the question if they're living in a simulation themselves.

[grondilu]

They can run simulations with different degrees of faithfulness and different physical laws, which would result in different computational complexity, i.e. different frame rates of time (from the simulator's perspective, not from the inhabitants).

True.  Kind of like Conway's game of life, but in more complicated I guess.  Haven't thought about that.

The dialog you quoted from the 13th Floor

It's not from the 13th floor.  I imagined it.  

[Deafboy]

The real question is, if we're in a simulation, are we simulated, too, or are we "jacked in" somehow?

From now on I'm going to feel terrible for killing the processes . What if thew were self conscious?

[myrkul]

The real question is, if we're in a simulation, are we simulated, too, or are we "jacked in" somehow?

From now on I'm going to feel terrible for killing the processes . What if thew were self conscious?

Look at it as mercy killings. They were locked up or otherwise misbehaving, or you wouldn't have needed to kill them.

[lebing]

Could you elaborate a little on that "we are just 3D projections of the 2D surface reality" part?

Google "holographic principle".

Basically, imagine a sphere. On that sphere, draw a complex pattern. Shine a light through that pattern. Now, imagine standing at the center of that sphere. If the pattern is complex enough, and drawn in the right manner, the interplay of light and shadow causes you to see an image projected around you. It's grossly oversimplified, but that's the idea.

Myrkul is now explaining the holographic theory?!!!

We have to be living in a simulation because this would never happen in the real world.

 

[myrkul]

Could you elaborate a little on that "we are just 3D projections of the 2D surface reality" part?

Google "holographic principle".

Basically, imagine a sphere. On that sphere, draw a complex pattern. Shine a light through that pattern. Now, imagine standing at the center of that sphere. If the pattern is complex enough, and drawn in the right manner, the interplay of light and shadow causes you to see an image projected around you. It's grossly oversimplified, but that's the idea.

Myrkul is now explaining the holographic theory?!!!

We have to be living in a simulation because this would never happen in the real world.

 

One can understand something without agreeing with it. In fact, it is necessary to understand something in order to disagree with it.

[thebaron]

Seeing pictures is on thing, feeling them is another.

[flynn]

- Won't work:  at some point they'll manage to increase the speed of their spaceships and they'll reach your limits again.
- Yeah, that's why I'll add a rule saying that mass increases with speed, so that one needs an infinite amount of energy to accelerate above the speed of light.
- I see.  With such a rule, interstellar space travel will never be possible for them so whatever they do they'll never encouter the limits of your data.  Good work.
»

It would not stop exploration.

A traveller would see the space in front of him getting contracted (and behind too) and he can go at any distance of the universe in any timelapse (if he can go fast enough, i.e. close enough to c)

Once he stops, space is not contracted anymore, and if he divides the mesured travelled distance by the (local) time it took to travel that distance, he'll find a value > c

It's no paradox, this speed is not a physical speed, but that value is all what matters to the traveler ! The only thing to remember is that this is a one-way ticket.

[myrkul]

- Won't work:  at some point they'll manage to increase the speed of their spaceships and they'll reach your limits again.
- Yeah, that's why I'll add a rule saying that mass increases with speed, so that one needs an infinite amount of energy to accelerate above the speed of light.
- I see.  With such a rule, interstellar space travel will never be possible for them so whatever they do they'll never encounter the limits of your data.  Good work.
»

It would not stop exploration.

Uh, yeah. It would. Barring something like the Alcubierre drive, you cannot get anywhere, even to our nearest stellar neighbor, within a human lifetime.

This is because in order to get something to go faster, you have to push it harder. In order to push it harder, you need more fuel. The more fuel you have, the more weight you need to push, and the harder you have to push it to get going the same speed. The faster something moves, the heavier it gets, meaning to push it faster, you need more fuel to push harder, which in itself is getting heavier, requiring more fuel to push it harder....

And around and round we go.

It would not stop expansion, assuming you were willing to hop on a colony ship and either freeze yourself for centuries or resign yourself to the fact that it's going to be your distant descendents that actually colonize the new world (if you can find one), and you'll die before you're really even on your way. Exploration, on the other hand, requires explorers that can go out, check several places, and get back to make reports before they die. Not going to happen with slowships. Probes, with radios that can reach back home, are an option, but not technologically feasible at the moment.

[goodlord666]

So, theoretical physics isn't "real work," is it?

Go ahead, call Stephen Hawking a slacker. [...]

Yeah I know it's mean

[grondilu]

It would not stop exploration.

A traveller would see the space in front of him getting contracted (and behind too) and he can go at any distance of the universe in any timelapse (if he can go fast enough, i.e. close enough to c)

Damn, you're right.   Ok, then I'll also create something I'll call "dark energy" and this thing will have the power of expanding the universe at an ever-accelerating rate.

I know it sounds totally lubricious but for some reason I'm sure they'll buy it.  

[flynn]

It would not stop exploration.

A traveller would see the space in front of him getting contracted (and behind too) and he can go at any distance of the universe in any timelapse (if he can go fast enough, i.e. close enough to c)

True.  But it won't matter as this traveler won't be able to come back to earth.  So he will travel a few light years, encounter the limits of the data, realize he is inside a simulation, and then we'll just destroy it.  It will be a negligible loss.

Kind of like the Bermuda triangle.  For the hidden puppet master, it does not matter if the explorers of the Bermuda triangle meet him there, as long as they don't come back and tell others.

He can come back the same way he went there, and it will take him the same time. The only problem is a long loooong time would have passed on (virtual)-Earth ; quite a challenge for the simulation to stay accurate IMO. (During my physics classes, we were warned that the biggest opportunity to make a mistake with SR is to behave like you have the gift of ubiquity and to be at every point of your thought experiment at a time. That is exactly the position of the simulation engine, sooo ...)

But anyway, the Lorentz equations. may not be part of the simulation

[grondilu]

That is exactly the position of the simulation engine, sooo ...

Interesting point.   Simulating a Lorentz invariant world got to be tricky.  I don't quite see how the simulator's clock could fit when compared to those of the simulation.

[quasarbtc]

If it is a simulation, would it be reasonable to assume the entity that generated or that is running the simulation is going to be at least a step or two ahead of the intelligence within the simulation?

[grondilu]

If it is a simulation, would it be reasonable to assume the entity that generated or that is running the simulation is going to be at least a step or two ahead of the intelligence within the simulation?

This entity does not need to have any intelligence, conscience or whatever.  For instance in the holographic principle, the simulation is realized by the very particular physics occuring at the horizon of a black hole.  And there is no need to imagine that a black hole is some kind of self-aware being.