11.01.2010

Perspective.

Perspective - What engineering and a lot of curiosity can teach you.

(Dedicated to the ultra strong coffee that just made my morning today. You'd better have one too, in case this gets too much on your nerves and you end up like this.)

I'm gonna take the example of the modern day machine - the aircraft. A teeny weeny bit of its HUGE system. A tiny bit of the whole stuff that happens during operation, the take-off. Even more particularly, one operation - the engines pushing you forward. I might not be exactly technically correct to every detail, I wish I was, but I'm kinda not far off. Now you've fastened your seatbelt after repeated requests from the pretty hostess, looked around and are tapping your fingers. The plane has taxied away from the base and is RIGHT NOW, about to take off.

The pilot up front, after receiving clearance, enables the necessary switches, checks that the gauges and instruments are all right, and in one fluid move, moves the thick lever (that sits between the pilot and the co-pilot) forward.

Pause.

Now. Moving the big bad lever forward. The lever is connected via a cable to a sensor system. The sensor is simply a device that 'reads' how much the lever has moved forward and in turn, sends an electrical signal to another system. (Warning: For the uninitiated, this is gonna be like Inception, only with a lot more levels)

Zoom in on the electrical signal. It is just a potential difference (in layman's words, Voltage) that exists between the wire and parts that are not connected to it.

The cable goes through a lot of other systems (filters, digital signal processors, etc which one needn't bother about), and reaches the main control computer. The computer, in turn is made up of a couple of hundreds of integrated circuits (ICs), connected together via metallic wiring etched onto a circuit board or as normal cables. Our voltage signal that set off from the sensor attached to the Big bad lever, has reached one of these ICs in the tiniest fraction of a second.

Zoom in to one of the ICs. The signal is processed and the computer now knows the pilot has engaged the lever. Now, during the time the IC was made, it has been taught to do its job, by programming a lot of code into it. This code now resides INSIDE the IC and is continuously running, monitoring any incoming signals and doing what must be done. Zoom in, fellas.

The code that we talked about, was written in some programming language, compiled and finally 'burnt' onto the IC in a way the machine can understand. Zooming in again, you see a tiny slab of Silicon on which a lot of etching, metallisation and doping is carried out. Now, on this slab are billions of transistors, which are the building blocks of an electronic circuit. To give you an indication of size, each transistor is around a few nanometres (that's one 100,000,000th of a metre) across. Zoom in. These transistors store a tiny bit of charge in a part of their body called the 'floating gate'. Depending on whether this charge exists or not, each transistor is considered to be on or off, and thus, (lo and behold) comes the 1 and 0 that we know in binary. No it's not over yet.

When the program was written, by a geek sitting miles away in some airconditioned office, he did it in something like C. The thing got translated from all those "int main(void)" stuff to hexadecimal code that looks like rows of rows of something like like 0xABCD12340. And THIS code is stored as BINARY, as those little ones and zeroes indicated by the thousands of electrons that store the charge in each transistor.

(Remember, it is just a few hundreds of microseconds since the pilot moved the Big bad lever high up in the cockpit..)

ZOOM IN.

Inside each transistor are thousands of electrons, flowing across 'junctions' that came into being when they were being 'fabricated'. (The beauty of the whole thing is, all this is exactly under our control). Now, once the signal had reached one of our computer's ICs, a part of the signal goes through these transistors, and automatically, a particular piece of the IC, which handles what must be done when the lever is being engaged, gets activated. This is how the code works, deep inside.

Plane --> Pilot --> Lever --> Sensor --> cables --> Computer --> IC --> flip flops --> Transistors --> gate-charge --> electrons.

Zoom out (whew).

A couple of hundreds of transistors actually form the inside of a few dozen flip flops, which are set to perform what the computer wants to do. The flip flops have been triggered, and they generate a control signal that (zoom out) goes out of the IC we talked about, through a lot of cables, onto the actuator system.

The actuator system has a lot of electrical power circuits connected to the engine to control its firing. The signals that reach the actuator undergo a similar electron-driven transistor-poking, and a few microseconds later, a power signal hits the engine control unit. The engine control unit now assumes power, and begins conducting its own show... Zoom out to watch!

The drama begins. The compressor sucks in air, as millions of air-molecules from outside. The fuel is drawn from the pipes, and the valves are instructed to open, admitting a spray of fuel into the jet turbine engine. Simultaneously, the control unit has initiated (think electron-transistor-powerAmplification again) the sparking system in the same engine to fire. The spark happens. A chemical reaction between the hydrocarbon in the fuel and the air, molecule-by-molecule, happens.. and the highly charged aviation fuel ignites, sending a mass of hot gases out through the engines back.

Zoom right out. Out and out, to the first layer.

*static* "You have control."

ONE SECOND or so after the lever has been moved forward, the pilot smiles smugly hearing the whirr of the engine slowly building up, gaining amplitude, to what is pretty loud inside and definitely a deafeningly friggin LOUD roar outside. Every fraction of a second is being monitored and controlled by the onboard computer, and the maze of wires, cables and copper strips are kept ever busy by the (deafening?) sea of electrons that are sent from one place to another, in some way, completely under human control.

The engines build on power and a few seconds later, the aircraft is pushed forward by one giant invisible hand of hot gases, rapidly building speed till the tyres lift off the ground and the big bird is airborne.

All this in a few seconds of your life.

So the next time my dad gets started onto me about "looking at life in the proper perspective", I'm gonna get him to read this post.