When Does the Universe Compute? 182
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 don't think encoding/decoding are fundamental (Score:3, Interesting)
Why can we not think of the information as being embodied in "some aspect or other of" the matter and energy undergoing evolution. It is only some observer that needs to see the information as having been encoded or decoded.
Metrics of computations, or measurements of information flows, may be a productive way of describing (and predicting) complex physical evolutions, regardless of whether the physical system itself is identifiably encoding and decoding information explicitly. You just have to establish your own observer convention for how you think the information is represented in the matter and energy under discussion, or you can even just think about "the maximum amount of information" that could be contained in that matter/energy/spacetime region, and the maximum possible amount of information flow there.
Different types of computation (Score:5, Interesting)
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.
Adventures in epistemology (Score:5, Interesting)
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".
BS (Score:4, Interesting)
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.