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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."
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!
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.
When thermodynamics is wrong, you've missed something.
Ever notice that Cobra Commander sounds an awful lot like Star scream?
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.