Why you can't simulate an universe - interesting paradox

[tikker]

  

2 hours ago, Wictorian said:

> That's why I said simulating the universe is impossible.

 .You are correct that simulating the Universe may be practically impossible. We would need to know the exact, and I mean exact initial conditions to infinite accuracy. For our understanding of the Universe it would be enough to create something with the same properties however.

2 hours ago, Wictorian said:

> The weather example is exactly why a simulation wouldn't work. For example to determine a baby's gender, you could choose one with 50% chance, but that's actually not how it works and with enough data, you could know it beforehand.

Weather is chaotic in nature, that's why simulations are hard. What do you mean "with enough data, you could know it beforehand"? We can't predict a baby's sex. We can only compile all known previous (regional) data and our knowledge about biology, and from that say it has X% change to be a boy and Y% change to be a girl.

21 hours ago, _princess_ said:

That is why when you try to measure something precisely, you cannot be sure of the outcome: the game's equations predict behaviors of large masses and lacks the computing power to make precise predictions of movement on the individual molecular level. This is why, theoretically you could have air particles fill only 1 side of a room due to random probability, but actually air particles will never fill only 1 side of a room.

This is why statistics and "bulk equations" are so important. It's extremely hard, if not impossible, to predict something about a single entity, but much much easier to say something about the general collection of things. This does not mean they are not realistic. That same theory still predicts an extremely extremely tiny chance (basically 0) of finding all air particles in one corner of a room, or it would not be a good theory.

3 hours ago, Wictorian said:

> That we are living in a simulation could be proven, but I don't think it could be disproven.

It's more the other way around. Truths can't really be proven. You try to prove something wrong instead.

12 minutes ago, _princess_ said:

yes but that was just one vague example. I think there might be some difference but I don't know what difference. And what other tests could we run also?

There being a difference is a crucial assumption you have to make. If we live in a simulation that is perfect and indistinguishable from reality, we would have no way of finding out, ever. So, if we were to find out, you'd need to think about what flaw our simulation would have that we could detect (for example, déjà vu or something repeating in The Matrix).

[_princess_]

12 minutes ago, tikker said:

  

 .You are correct that simulating the Universe may be practically impossible. We would need to know the exact, and I mean exact initial conditions to infinite accuracy. For our understanding of the Universe it would be enough to create something with the same properties however.

Weather is chaotic in nature, that's why simulations are hard. What do you mean "with enough data, you could know it beforehand"? We can't predict a baby's sex. We can only compile all known previous (regional) data and our knowledge about biology, and from that say it has X% change to be a boy and Y% change to be a girl.

This is why statistics and "bulk equations" are so important. It's extremely hard, if not impossible, to predict something about a single entity, but much much easier to say something about the general collection of things. This does not mean they are not realistic. That same theory still predicts an extremely extremely tiny chance (basically 0) of finding all air particles in one corner of a room, or it would not be a good theory.

It's more the other way around. Truths can't really be proven. You try to prove something wrong instead.

There being a difference is a crucial assumption you have to make. If we live in a simulation that is perfect and indistinguishable from reality, we would have no way of finding out, ever. So, if we were to find out, you'd need to think about what flaw our simulation would have that we could detect (for example, déjà vu or something repeating in The Matrix).

Yes this is what im saying. We cannot know things beforehand, this is the simulations trick. The simulation doesn't ever have to make accurate calculations since we lack the ability to measure anything accurately. Maybe it uses just a few KB's to simulate complex behavoir since we lack the instruments to predict complex behavoir accurately, and so the simulations calculations themselves do not have to be accurate to fool us.

 

Why planets are spheres? One explanation is gravity makes them into round balls. Another explanation is that gravity conveniently makes them into round balls since it makes solar trajectories easier to compute. Still though the earth is more of an ellipse than a perfect sphere. And there are comets. On the other hand our instruments lack the accuracy to predict the trajectories of comets with certainty. For instance there is an asteroid that might collide with earth. But we are not sure if it will collide or not because our instruments lack the precision. And this is how the simulation gets away with using just a few MBs to compute planetary gravity. Our instruments are not precise enough to prove otherwise.

 

Quote

 

It's more the other way around. Truths can't really be proven. You try to prove something wrong instead.

There being a difference is a crucial assumption you have to make. If we live in a simulation that is perfect and indistinguishable from reality, we would have no way of finding out, ever. So, if we were to find out, you'd need to think about what flaw our simulation would have that we could detect (for example, déjà vu or something repeating in The Matrix).

 

Yes. For all we know the simulation calculates planetary orbits the same regardless if we are looking at it or not. So we'd have to find other proofs. If people have magic powers does that prove a simulation? Someone could say the magic is just because there are beings in a dimension that is out of phase that we cant detect, or some energy substance we cannot detect yet, not proof that we live in a computer sim illusion.

 

[Craftyawesome]

Why are we assuming the hypothetical universe simulating ours even needs to save storage? Maybe our universe is much more simple than the universe that is simulating us, just like any simulation we run in this universe.

Spoiler

https://www.smbc-comics.com/comic/the-dimension-store

 

[tikker]

9 hours ago, _princess_ said:

f people have magic powers does that prove a simulation?

No it doesn't, because magic does irrefutably imply a simulation. You would make a theory "if we live in simulation X, people can use magic". Then we observe we can't use magic, so we have disproven that we live in simulation X.

9 hours ago, _princess_ said:

Yes this is what im saying. We cannot know things beforehand, this is the simulations trick. The simulation doesn't ever have to make accurate calculations since we lack the ability to measure anything accurately. Maybe it uses just a few KB's to simulate complex behavoir since we lack the instruments to predict complex behavoir accurately, and so the simulations calculations themselves do not have to be accurate to fool us.

The core of the problem to solve then becomes discovering what inaccuracies it has, so we can start measuring those. If something predicts what it should (whatever that may be), then by defnition it is accurate. The problem here is that we would somehow need to know these "higher order laws of nature" that exist beyond our current laws.

9 hours ago, _princess_ said:

 

Why planets are spheres? One explanation is gravity makes them into round balls. Another explanation is that gravity conveniently makes them into round balls since it makes solar trajectories easier to compute. Still though the earth is more of an ellipse than a perfect sphere. And there are comets. On the other hand our instruments lack the accuracy to predict the trajectories of comets with certainty. For instance there is an asteroid that might collide with earth. But we are not sure if it will collide or not because our instruments lack the precision. And this is how the simulation gets away with using just a few MBs to compute planetary gravity. Our instruments are not precise enough to prove otherwise.

The laws of physics would still be the laws of physics, because for the simulation to simulate them it has implemented exactly those laws. For simulating e.g. the present day Solar System it doesn't matter how the planets got their shapes, just that they have the shapes they have. Then you ask how did they get their shapes? And you would end up with our current understanding of planet formation, which would have to be how the simulation implemented it, because it is what we observe. We can predict orbits of planets and comets just fine. It's how Neptune was discovered. It was predicted to exist, because Newton's laws could not predict the orbit of Uranus accurately enough. Another planet would solve this.

 

I think the paradox with a simulation universe is that by constructions we cannot prove or disprove it. We derive laws of Nature based on what we observe. If we live in a simulation, what we observe will only ever be the laws of that simulation. If there were flaws in the simulation that did not match the theory, we would have derived different theories and again never known they were flaws. We would have to transcend outside the simulation (again like in "The Matrix") to realized there was a higher order existence.

We can't with 100% certainty rule it out of course, but in situations like this we typically invoke Occam's razor, i.e. don't make things unnecessesarily complicated unless we have reason not to.

[Wictorian]

10 hours ago, tikker said:

  

 .You are correct that simulating the Universe may be practically impossible. We would need to know the exact, and I mean exact initial conditions to infinite accuracy. For our understanding of the Universe it would be enough to create something with the same properties however.

Weather is chaotic in nature, that's why simulations are hard. What do you mean "with enough data, you could know it beforehand"? We can't predict a baby's sex. We can only compile all known previous (regional) data and our knowledge about biology, and from that say it has X% change to be a boy and Y% change to be a girl.

This is why statistics and "bulk equations" are so important. It's extremely hard, if not impossible, to predict something about a single entity, but much much easier to say something about the general collection of things. This does not mean they are not realistic. That same theory still predicts an extremely extremely tiny chance (basically 0) of finding all air particles in one corner of a room, or it would not be a good theory.

It's more the other way around. Truths can't really be proven. You try to prove something wrong instead.

There being a difference is a crucial assumption you have to make. If we live in a simulation that is perfect and indistinguishable from reality, we would have no way of finding out, ever. So, if we were to find out, you'd need to think about what flaw our simulation would have that we could detect (for example, déjà vu or something repeating in The Matrix).

I meant the particles in the room by weather example (my bad). But it also works for weather, if its chaotic, we cant simulate it with maths and we have to simulate it with more details ( even in atomic level to be precise)

 

Yes, but how can we disprove that we are in a simulation? 

[Wictorian]

10 hours ago, _princess_ said:

Yes this is what im saying. We cannot know things beforehand, this is the simulations trick. The simulation doesn't ever have to make accurate calculations since we lack the ability to measure anything accurately. Maybe it uses just a few KB's to simulate complex behavoir since we lack the instruments to predict complex behavoir accurately, and so the simulations calculations themselves do not have to be accurate to fool us.

 

Why planets are spheres? One explanation is gravity makes them into round balls. Another explanation is that gravity conveniently makes them into round balls since it makes solar trajectories easier to compute. Still though the earth is more of an ellipse than a perfect sphere. And there are comets. On the other hand our instruments lack the accuracy to predict the trajectories of comets with certainty. For instance there is an asteroid that might collide with earth. But we are not sure if it will collide or not because our instruments lack the precision. And this is how the simulation gets away with using just a few MBs to compute planetary gravity. Our instruments are not precise enough to prove otherwise.

 

Yes. For all we know the simulation calculates planetary orbits the same regardless if we are looking at it or not. So we'd have to find other proofs. If people have magic powers does that prove a simulation? Someone could say the magic is just because there are beings in a dimension that is out of phase that we cant detect, or some energy substance we cannot detect yet, not proof that we live in a computer sim illusion.

 

It depends on the purpose of the simulation, I don't think it is about us but rather the universe itself, then they can't use tricks like that. If it's about us they could as well delete the planets.

[Wictorian]

6 hours ago, Craftyawesome said:

Why are we assuming the hypothetical universe simulating ours even needs to save storage? Maybe our universe is much more simple than the universe that is simulating us, just like any simulation we run in this universe.

  Reveal hidden contents

https://www.smbc-comics.com/comic/the-dimension-store

 

That was actually my point

[Wictorian]

Also I think the time is faster in the simulation because whou would wait billions of years?

[tikker]

12 minutes ago, Wictorian said:

I meant the particles in the room by weather example (my bad). But it also works for weather, if its chaotic, we cant simulate it with maths and we have to simulate it with more details ( even in atomic level to be precise)

  We can simulate the air density in a room, just not really where exactly each single atom and molecule is (and we don't have to). The particles in the room are not chaotic. If you change their initial distribution slightly, it'll still settle in the same or similar distribution. It's not like, as a figure of speech, breathing to the left will just move the air and breathing to the right will dump all air in a single corner. For the weather that is the case. Rounding down or changing the starting point will have dramatic consequences for the outcome. It's not that you can't simulate chaotic things with math, it's that it is extremely sensitive to small changes.

 

12 minutes ago, Wictorian said:

Yes, but how can we disprove that we are in a simulation?

Excellent question. Nobody knows.

6 minutes ago, Wictorian said:

Also I think the time is faster in the simulation because whou would wait billions of years?

Of course it is. We can simulate 14 billion years of universe in a couple of weeks or months real time.

[Wictorian]

3 minutes ago, tikker said:

  We can simulate the air density in a room, just not really where exactly each single atom and molecule is (and we don't have to). The particles in the room are not chaotic. If you change their initial distribution slightly, it'll still settle in the same or similar distribution. It's not like, as a figure of speech, breathing to the left will just move the air and breathing to the right will dump all air in a single corner. For the weather that is the case. Rounding down or changing the starting point will have dramatic consequences for the outcome. It's not that you can't simulate chaotic things with math, it's that it is extremely sensitive to small changes.

 

Excellent question. Nobody knows.

Of course it is. We can simulate 14 billion years of universe in a couple of weeks or months real time.

Can't air density effect the weather? 

[tikker]

6 minutes ago, Wictorian said:

Can't air density effect the weather? 

I mean sure, but it's not like you farting in your room, increasing the local air density will cause a tornado on the other side of the planet. Things are sensitivey, but probably not that sensitive.