Logically Speaking

ttab adder fullIf it hasn’t been apparent, I’ve been giving a bit of a fall semester in some computer science basics. If it seems complicated, well, the truth is all we’ve done is peek in some windows. From a safe distance. And most of the blinds were down.

I thought we’d finish (yes, finish!) with a bang and take a deep dive down into the lowest levels of a computer, both on the engineering side and on the abstract logic side. When they say, “It’s all ones and zeros,” these are the bits (in both senses!) they mean.

Attention: You need to be at least this geeky for this ride!

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Turing’s Machine

state diagram 1aNo, sorry, I don’t mean the Bletchey Bombe machine that cracked the Enigma cipher. I mean his theoretical machine; the one I’ve been referring to repeatedly the past few weeks. (It wasn’t mentioned at the time, but it’s the secret star of the Halt! (or not) post.)

The Turing Machine (TM) is one of our fundamental definitions of calculation. The Church-Turing thesis says that all algorithms have a TM that implements them. On this view, any two actual programs implementing the same algorithm do the same thing.

Essentially, a Turing Machine is an algorithm!

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Transcendental Territory

transcendent mindLast time we considered the possibility that human consciousness somehow supervenes on the physical brain, that it only emerges under specific physical conditions. Perhaps, like laser light and microwaves, it requires the right equipment.

We also touched on how Church-Turing implies that, if human consciousness can be implemented with software, then the mind is necessarily an algorithm — an abstract mathematical object. But the human mind is presumed to be a natural physical object (or at least to emerge from one).

This time we’ll consider the effect of transcendence on all this.

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No Ouch!

no ouch

“Ouch!”

Over the past few weeks we’ve explored background topics regarding calculation, code, and computers. That led to an exploration of software models — in particular a software model of the human brain.

The underlying question all along is whether a software model of a brain — in contrast to a physical model — can be conscious. A related, but separate, question is whether some algorithm (aka Turing Machine) functionally reproduces human consciousness without regard to the brain’s physical structure.

Now we focus on why a software model isn’t what it models!

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Spider Tech


Sideband #59: Running Hot

running hotAs a diversion for the weekend: Have you ever wondered why computers run so hot? No? Okay, I’ll tell you. It’s actually kind of a hoot. (We’ll get back to the more serious topic of algorithms and AI, and wrap up that series, next week.)

You kind of have to wonder. Humankind has gone from oil and gas lamps to incandescent copper filaments, then to fluorescent lights, and now to LEDs. The trend here seems towards cooler more efficient light sources. But computers seem to need bigger and bigger fans!

The short answer: It’s all those short circuits!

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Four Doors

four doorsLast time I introduced four levels of possibility regarding how mind is related to brain. Behind Door #1 is a Holy Grail of AI research, a fully algorithmic implementation of a human mind. Behind Door #4 is an ineffable metaphysical mind no machine can duplicate.

The two doors between lead to physical models that recapitulate the structure of the human brain. Behind Door #3 is the biology of the brain, a model we know creates mind. Behind Door #2 is the network of the brain, which we presume encodes the mind regardless of its physical construction.

This time we’ll look more closely at some distinguishing details.

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Model Minds

mind modelLast week we took a look at a simple computer software model of a human brain. (We discovered that it was big, requiring dozens of petabytes!) One goal of such models is replicating consciousness — a human mind. That can involve creating a (potentially superior) new mind or uploading an existing human mind (a very different goal).

Now that we’ve explored the basics of calculation, code (software), computers, and (computer software) models, we’re ready to explore what’s involved in attempting to model a (human) mind.

I’m dividing the possibilities into four basic levels.

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World Series 2015

Congrats to the Kansas City Royals, winners of the 2015 World Series!

World Series 2015

They beat the New York Mets in just five games and completed the unfinished business from last year when they lost the 2014 WS in the final out of the final inning of the final game.

Go Royals!

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The Human Connectome

brain connectomeLast time we looked at the basic requirements for a software model of a computer and put a rough estimate on the size of such a model (about 2.5 terabytes). This time we’ll consider a software model of a human brain. Admittedly, there’s much we don’t know, and probably need for a decent model, but we can make some rough guesses as a reference point.

We’ll start with a few basic facts — number of neurons, number of synapses — and try to figure out some minimal requirements. The architecture of a viable software brain model is likely to be much more complicated. This is just a sketch, a Tinkertoy® or LEGO® version.

Even so, we’re gonna need a lot of memory!

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