The Heart of the Machine
You’ve likely heard the expression that the CPU (Central Processing Unit) is the “brain” of the computer. (Not so much lately, with machines commonly having dual and quad processors.) While this is a crude analogy, it is not altogether misleading. Yet, when you buy a machine, what you see most prominently promoted is not the size of this “brain” but its speed. The three-year old computer I’m writing on has an AMD Athlon™ 2.2 Gigahertz Dual Processor. The speed is represented by the 2.2 gigahertz reference, but exactly what does that number represent? Well, one gigahertz represents one billion cycles per second. Cycles of what? Cycles of the internal computer clock. If the CPU is the “brain,” then this clock is its “heart.”
By calling it the “brain,” we’re saying the CPU controls the computer—but the clock controls the CPU. The computer’s clock tells each component of the computer when to act. More importantly, it tells the CPU when to take the next step, the next programming instruction. But most importantly, it keeps all the parts in line, stepping to a constant beat.
Think about it: without a constant, regulated blood supply, our brain would not control anything. So it is with the computer. But the clock, as the “heart” of the computer, is even more important. The invention of the clock was the key invention of the machine age. Yes, there were machines before the invention of the clock, but they merely amplified man’s physical power. Until the invention of the clock, it was not possible to amplify, to control, man’s mental power. The clock was the first information machine—although the Information Age was still in the distant future.
The clock, contrary to the common view, did not measure time. Space had been measured (distances on the earth’s surface) and gave some small advantage to the machines of the day. With the clock, time went from noticing the seasons and waking with the sunlight, to marking the days, hours, minutes, and seconds. The clock didn’t measure time, but transformed natural durations into measurable manmade units.
The clock made a clear demarcation between the crude machines of the past (before clocks) and the new theory of machines that eventually lead to computers. The clock did one other thing that made it the basis of all future machines: the clock can run backwards. Unlike its human analogue (the heart), the clock—and all the machines based on this new theory—can run either forwards or backwards. The clock could not only define the time segments of the future, it could do the same for the past. So one key difference between the ultimate machine, the computer, and the entire biological world, is that the computer, too, can run backwards. Therefore, in answer to the question, “Can a machine think?” perhaps we should ask, “What does it mean to think backwards?”