# God the Computer; The Universe's Code

1. Nov 27, 2007

### Orann

While learning secondary physics in high school I often used the idea of the entire universe being a computer program to help me better understand how some things (Strong atomic forces, for example) would work by visualizing how I would program them should I need to recreate the same effect in a computer program. Now that I have a lot of spare time, I was playing around with the idea of recreating some very basic, but perfectly realistic physics simulations via a computer program. This got me to thinking, what would I actually Need to program?
What I am really asking here is, how complex, in it's most basic form, is the universe? Aside from the 4 forces of the universe, what else is there coded into universal behavior?

Basically, is the diffraction of light a side-effect of the existing forces acting in unexpected ways, or is that a basic property of nature? Do atoms form out of electrons, protons and neutrons just due to the core forces, or is there something else at work?

Naturally I'd assume there would be plenty of quantum-level oddities to deal with too. Any insight into this would be appreciated, and any opinions.

2. Nov 27, 2007

### Mentz114

This is the most optimistic question I've ever seen. Modelling two bodies colliding inelastically ( for instance) is a difficult thing to do - never mind a whole universe.

I once took a whole week to model Brownian motion realistically - and I had to leave out 3 ( or more) body interactions or it would have taken another week.

Calculating is a good way to learn physics, but choose something do-able.

3. Nov 27, 2007

### Orann

Ah, you seem to misunderstand me, I don't actually plan to simulate an entire universe, or even a single atom. This question was mostly asked out of pure curiosity; I'd honestly like to know how much there is other than the forces, at work in the universe. I have a certain fascination with the way that things in the universe work in a way that is quite different to what we would expect.

A best case scenario would be for me to play with, perhaps 2 electrons and a proton simulated with all the physics forces working, but even then, what would that do? What would I need to add to get those particles to form into a hydrogen atom (Other than rig initial velocities)? Would it then have the properties of hydrogen?

At any rate, i'm looking for general answers to the question rather than solutions to programing such a thing, something that will likely never happen anyway.

4. Nov 27, 2007

### PhY

We can simulate the Universe through programming...although we can't now.
Unless you found a way to create a Yotta byte Computer.
Plus I heard the Universe is Infinite, which would mean a Yotta Byte Hard disk can't store all the files and a Cpu/Gpu performing Yotta Flops will never process/render the entire universe.

I think the Hypothetical God Computer you are talking about is way way beyond our time, because we haven't yet grasped the concept of what Infinite means (a really really large number is not good enough a concept)

Last edited: Nov 27, 2007
5. Nov 27, 2007

### Mentz114

Takes my breath away. You've hugely underestimated the complexity of things if you think there's a quick answer to that.

Gasp. Take a one-year course in QM and you'll realise how uninformed that question is.

I detect from your questions that you've made not much effort to find out about these things before asking. What you're asking is for someone to give you the entire state of physics in a few quick one-liners so you can play at calculation. If only it were possible.

Get an introductory book on quantum mechanics, you'll enjoy it.

Last edited: Nov 27, 2007
6. Nov 27, 2007

### pixel01

It does not depend only on how many bites you have in your super computer. To establish models and make them work, we need many things, of which high resolution observations are very important. Hubble images are not enough. We need more powerful telescopes. James Webb is going to come, and beyond.

7. Nov 27, 2007

### Mentz114

PhY:
Eh ? How can you possibly say that. By definition you can't simulate the universe. Would your simulation include the simulation which would include itself ...

Pixel01
like a working theory of everything !

Beam me up, Scotty !

8. Nov 27, 2007

### kokophysics

Once i heard in a documentary that a "program" of the universe could be made made only using the basic variables comprised in it. These are the mass of an electron, the charge of an electron, the gravitational constant... They actually said in that documentary the amount of these variables (about tweentysomething).

Indeed, they said that if you vary these variables, you would get another posible universe.

It was very interesting. It was a series of about 5 mini-documentaries about the string theory. You may find them.

PD: If you succeed in generating a universe and something in it destroys it, don't panic, it's not a bug, you would have created humans!

9. Nov 28, 2007

### vanesch

Staff Emeritus
These kinds of iconoclastic statements are unfortunately common in the infantile minds of certain (sometimes successful) physicists. But we're remotely not close to such position.
Physics is a science that tries to discover, through observation, experiment, generalisation and induction, theoretical deduction, and mathematics a model of (a part of) the behaviour of nature. It has been quite successful in that, and we have now several operational models of which we have good hope that they model quite well certain parts of nature. Some of these models are inherently limited, others "could be true" for all of nature, or at least for a very big chunk of it. As such, they create "theoretical toy universes" in which they are supposed to be absolutely valid, but that's just a mind game! It doesn't mean that the real universe behaves like that! So the situation is more like:

1) we know the postulates of some models of which we know that they describe quite well certain chunks of nature (and maybe bigger chunks than we think).

2) from these postulates we can create (in our mind) toy-universes in which these postulates are absolutely valid.

3) under these assumptions, we can, *in principle*, write down the mathematical problem of the exact behaviour of our toy universe. The problem is that we cannot do that in practice, because it becomes soon too complicated.

4) We don't know if we have a mathematical solution to the problem (not) written down in point 3). We have some potential techniques to solve approximately (say, numerically) certain simplified problems, but most of the time, we don't know any techniques to solve the general problem - and in many cases, we don't even know if the solution *exists*.

5) in any case, these potential techniques would break down for practical reasons, even on a very very powerful computer (that is, say, 10^50 times more powerful than the currently existing machines).

However, in sufficiently simple situations, we may try to do something, and come up with numerical results in which we can have a reasonable trust that they are close to the solution to the mathematical problem that describes the situation based upon the postulates we started out with. That's the kind of thing working physicists try to do.

So we are a far cry from being able to predict the behaviour of the universe!

10. Nov 28, 2007

### PhY

Just 40-50 years ago, if somebody said I will make a machine that inputs data, process information and give an output on a Screen, they would have laughed at him.

My simulation? Do i look like a Professor in AI to you?
We have simulations of the Earth already, of the Solar System, maybe even half the galaxy, its not impossible...

Obviously Right Now we cannot Simulate the Universe, just like back then a Computer was a box with Blinking lights, who would ever think that from printing binary code on to paper the computer would be simulating the Earth itself Graphically and Geographically on the Internet, Open to anybody with a Internet connection.

When I say simulation, I do not mean "The Matrix ".-_-

11. Nov 28, 2007

### zankaon

universe as computer or geometry?

celestrial mechanics- our way. But not nature's way. For example, if orbital parameters were calculated by nature, then their would have to be rounding off at a certain number of significant digits; but this would result in accumulative error. Now if the calculation never ends, (i.e. the Turing tape of generic computer never ends), then no result is ever attained. So geometry would seem better, from nature's perspective. A marble revolving around a saucer is an apt description i.e. a geodesic in curved spacetime. So the reality of the universe (or nature) as a computer, just wouldn't seem useful.

12. Nov 28, 2007

### Orann

I had realized initials when posting that such a simulation would no doubt be out of my reach, but it is clear to me now that it is out of humanity's reach altogether (possibly even possibilities reach). It seems I have a lot more physics to learn before I should start even thinking about this sort of thing. Thankyou all for your comments, I think I'll start looking into quantum mechanics.