For years now the debate as to whether it’s possible to create an artificial intelligence
by mimicking the human brain has raged. Last month, New Scientist
published an awesome feature titled Memristor Minds
, which has some interesting points to make about the AI debate.
The article tells the story of a chap named Leon Chua who, back in the early seventies, was an electronics engineer at the University of California, Berkley. He found it fascinating that no one had sat down and written a mathematical formula for electronics. Armed with his technical background and enthusiasm for mathematics, he was a fine candidate to have a stab at it. And that’s precisely what he did.
I’m not an electronics engineer so I’m going to quote New Scientist directly for this bit to make sure that I get it right.
" Back in 1971, Chua was examining the four basic quantities that define an electronic circuit. First, there is electric charge. Then there is the change in that charge over time, better known as current. Currents create magnetic fields, leading to a third variable, magnetic flux, which characterises the field's strength. Finally, magnetic flux varies with time, leading to the quantity we call voltage.
"Four interconnected things, mathematics says, can be related in six ways. Charge and current, and magnetic flux and voltage, are connected through their definitions. That's two. Three more associations correspond to the three traditional circuit elements. A resistor is any device that, when you pass current through it, creates a voltage. For a given voltage a capacitor will store a certain amount of charge. Pass a current through an inductor, and you create a magnetic flux. That makes five. Something missing?"
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Now, in mathematics there’s a rule which says that four interconnected variables can relate to one another in six different ways. When Chua started running the numbers, he found that there was something missing. Only five relations could be made using what we knew about electronics at the time. In a thought process the likes of which someone with my humble understanding of electronics could only muster after a good deal of study, Chua deduced that the sixth relationship would be a type of resistor that could some how remember the voltage that had previously passed through it. The Memristor was born.
Despite theory pointing towards the existence of the Memristor, at that point, no-one had actually made one. In the early 2000s, Leon Chua had the chance to pair up with Stan Williams, a researcher for Hewlett Packard, things started to get moving. The duo found a way to pass current through a semi-conductor called titanium dioxide in such a way that its resistance was altered. Crucially, when the current was switched off, the state of resistance at the time stayed the same and so the metal remembered and ‘woke up’ in the same resistance state.
While writing up his first paper on memristance, the ever-inquisitive Chua became fascinated with synapses in the human brain. While studying them, the electronics engineer realised synapses were beginning to appear startlingly familiar. He realised then that synapses were in fact, 'biological memristors’.
Research has already been begun by organisations such as DARPA
to put these findings to work in the AI field. It’s starting to look as though the reason we’ve been so far from recreating an artificial ‘brain’ is because we may have been missing an artifial alternative to one of the most crucial components. We may have just taken a massive step towards making Jonny Five come alive.