

Things we can't compute - aycangulez
http://www.alexstjohn.com/WP/2013/10/07/things-cant-compute/

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nmc
TL;DR: _" If we can build a big enough computer we can understand anything"_
is a delusion, but _" If we can build a big enough computer we can compute
anything"_ is scientific fact.

* * *

There are many valid points in the article. Sadly, they are shadowed out by
misconceptions and/or wrong phrasing.

Since Turing's 1936 paper, we have proof that _computation is universal_. That
means any computation in the universe, including the one occurring in your
brain while you read this, can be implemented on a Turing machine.

So, yes, we have proof that _a big enough computer_ can compute the human
brain, the global climate, and any other physical phenomenon.

And the argument about indetermination in physics (ping-pong ball in the
rapids) is about getting the information, not computing it — computation is
universal, but information is sometimes impossible to obtain.

* * *

Universal computation does not mean that a computer can understand itself, and
I like that the author suggests such a thing should be impossible.

Universal computation does not mean that building _a big enough computer_
should always be the priority, and I like how the author addresses that.

~~~
philosophus
Not quite. We can compute any determinate process, perhaps. (Although as
Gödel‎ showed, self-reference introduces computational paradoxes even in
closed, limited, artificial, formal systems: how do we compute "this statement
is false?") You seem to believe that consciousness is essentially computation,
and perhaps you're right. You may be wrong though -- the nature of
consciousness is one of the trickiest, most intractable problems. It's an open
question. Again as with Gödel‎, self-reference introduces problems. If we
believe that consciousness is a mechanical/chemical operation without innate
intelligence, then any statement about consciousness is itself a product of a
certain balance of chemicals in the brain only. So the whole idea of getting
to the truth about such things is a pointless endeavor.

"does not mean that a computer can understand itself" \-- not sure I entirely
agree here either. My computer seems pretty good at understanding itself:
right now it's telling me its internal temperature, what programs it's
running, CPU and memory utilization, and so forth. In fact, it probably
understands itself much better than I do -- at billions of computations per
second, I certainly can't keep up. I'm being cute, yes, but I'm also
suggesting you seem to implicitly accept that there's a certain type of self-
understanding or consciousness that computers don't have, but living beings
(in particular, humans) do. Whereas before you said your brain is just a
computer ... ?

~~~
nmc
Let us make a distinction, shall we?

Determination is not an issue. Any non-deterministic Turing machine has an
equivalent deterministic Turing machine.

Consciousness is an issue. Indeed, if consciousness is pure computation, then
its self-referencing character make it vulnerable to Gödel's incompletude
theorem. However, maybe consciousness is more than mere computation — maybe it
cannot be reduced to an axiomatic system. Anyway, as far as neuroscience goes,
I think consciousness mostly remains a philosophical debate.

* * *

You misinterpreted my sentence. What I meant is: _" universal computation is
not, in itself, a proof that a computer can understand itself"_. This relates
to my above remark: maybe consciousness is not pure computation.

Also, a system monitoring its own status is not necessarily _understanding
itself_.

------
hnisnotreddit
Just for a bit of perspective, Alex St. John is the "Father of DirectX", and
created the first video game company that streamed games over a web browser.

