Slashdot Mirror
When Does the Universe Compute?
KentuckyFC writes "The idea that every physical event is a computation has spread like wildfire through science. That has triggered an unprecedented interest in unconventional computing such as quantum computing, DNA computing and even the ability of a single-celled organism, called slime mold, to solve mazes. However, that may need to change now that physicists have worked out a formal way of distinguishing between systems that compute and those that don't. One key is the ability to encode and decode information. 'Without the encode and decode steps, there is no computation; there is simply a physical system undergoing evolution,' they say. That means computers must be engineered systems based on well understood laws of physics that can be used to predict the outcome of an abstract evolution. So slime mold fails the test while most forms of quantum computation pass."
"I'll get it," a wife said to her husband as the phone rang.
On the line a pervert, breathing heavily, said, "I bet you have a tight asshole with no hair."
"Yes," she responded. "He's sitting next to me watching TV."
We only don't see the encoding and decoding steps because we are inside the system that is doing the computation. If the universe were a simulation, those inside the simulation would see a ball trace a parabola with no encoding or decoding steps. Those who designed the simulation would be well aware of those steps.
Give me Classic Slashdot or give me death!
The type of computation discussed in this article is not the type of computation used in the phrase "every physical event is a computation". These physicists are trying to discern computation from physical processes by discerning whether the process can encode information in its initial conditions, and other information can be extracted from its results. This is good when trying to determine which processes lend themselves to building computers, but it does not address the question of whether the universe is a computer, and whether the laws of physics are merely closed form equations describing some of its operational semantics.
Higher Logics: where programming meets science.
Or that they're saying the universe doesn't need to do calculations to determine where a falling object is going -- it just falls according to the laws of physics and doesn't need to be calculated.
Does 'imagination' in this context actually tell us anything? We know that we need to do calculations for this stuff, but how does the assertion that the universe isn't doing the calculations limit our imagination? Stuff happens according to physical laws, the behavior is inherent to reality. Nobody has to do the math, it just happens.
Very meta, and equally meaningless. Yes, if we were in a simulation, we'd likely never know.
But given that we have no evidence to suggest we are, any assumptions around the notion that we are (or may be) are pretty much useless to us unless we can figure out the gaps in the simulation.
To me the suggestion we're living in a simulation serves no other purpose that throwing out something wacky to stump people at parties, but otherwise doesn't seem to have any application to understanding our universe.
Lost at C:>. Found at C.
For example, the processes that slime mould uses to solve a maze are largely unknown. For this reason it is not computation.
Don't we usually declare characteristics of things based on what we know about them, rather than on the basis of not knowing about them?
Seems like a strange kind of subjective solipsism--"what is, is dependent upon on what I currently know is".
~ Whence do you come, slayer of men, or where are you going, conqueror of space?
I RTFAed. Their theory is essentially that computation can only be said to have occurred if you know the physical nature / laws that allowed the computation to occur.
Which is BS. There are plenty of people who can add 2 numbers on a calculator without knowing anything about electrons, bits, electronics etc. You can extend that until the number of people who understand specific physical laws underlying a computation is zero.
Since when is human knowledge the test for whether any computation is happening? All they are saying is "If we don't understand it, we will not call it computation." Way to go with the semantic circus.
Entia non sunt multiplicanda praeter necessitatem.
Point particles come from the interaction of various waves which carry force. Points don't even take up space. The Universe is one giant 2D wave, and all 3D space is holographic illusion.
Look, seriously, Doom was DECADES ago at this point. The rest of the world's moved on, you really need to stop living in the past and base your universal theories on something OTHER than an engine Carmack made back in the DOS era.
doesn't seem to have any application to understanding our universe.
If we are a simulation, we may be able to discern exactly what we're simulating, and why. Theology aside, even discovering that our universe functions like a simulation may allow us to seek out and utilize aspects of the simulation that are useful to us.
Consider, for example, if we could simply access an information store outside our universe from anywhere within it. Even a single bit being accessible would offer the ability to have near-instant communications with other planets, or perhaps even other stars. If we could push matter out of or into the universe, we'd have an effective teleportation mechanism.
Science is all about figuring out the rules of our universe. Being inside a simulation means there are other, possibly different, rules outside, so breaking out means we have new capabilities that are impossible within our universe.
You do not have a moral or legal right to do absolutely anything you want.
Maybe not *your* balls.
Please give an example of such violation? Because I'm afraid I can't see this obvious flaw you posit.
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
Actually, he's right, and the analogy is quite good too. Newtonian physics is "wrong" in the sense that it doesn't hold for very massive, very fast or very small objects. However, for medium-sized objects moving at medium speeds, it holds very well.
Similarly, the second law of thermodynamics, that entropy always increases, can be derived in statistical mechanics by assuming that there are an infinite number of particles in your system. Thus, it holds for the entire universe, and it holds extremely well for any macroscopic system that I know of. However, for microscopic systems, it becomes quite probable that entropy decreases in small periods of time (the fluctuation theorem tells you the probability for this to happen.)
If you're interested in how this "makes sense": in statistical mechanics, it is shown that entropy is actually just a measure of microscopic disorder. There usually exists a lot more of possible disorderly states than orderly states for a system, so if no particular microstate is preferred (the probability of entering any microstate is equally probable), it's simply more probable that you will observe a transition from an ordered state to a disordered one, not the other way around. For a small system, the discrepancy is small, so you see transitions in both directions on small enough timescales. But as the number of particles in the system grows, the number of disordered states of the total system will grow far faster than the number of ordered states (the discrepancy is O(n!) for n particles in the system), so transitions from disordered to ordered states become extremely unlikely.