Shedding some light on the speed of darkness

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

22 January 2006

I eavesdropped on an interesting debate recently. The question was: scientists claim to know the speed of light, but do they know the speed of darkness? One person said that it must be equal to that of light, but his friend insisted that darkness doesn’t move therefore its speed is zero. Is anyone right, or are they both wrong?

Before going to light and darkness, let us first deal with objects. Darkness is the absence of light, what is the absence of an object? Emptiness? Can we then ask what is the speed of emptiness?

Think of someone holding on to a water hosepipe. If he released and closed the water continuously, you would see a trail of short jets flying through the air. In between the jets would be emptiness (OK, air, but who is counting?). The space between the jets would be moving at the same speed as the water.

The same can be said about light and darkness. If you switched a torch on and off continuously, short bursts of light would be emitted and, in between them, would be dark sections. The portions would move at the speed as light. Therefore, the speed of darkness is the same as the speed of light.

For this reason, if God turned off the sun at once, eight minutes would elapse before we notice anything. That is, the resulting darkness would take same amount of time as sunlight takes to get here.

Going back to objects and emptiness, suppose there are two glasses, one filled with water and the other empty. If you were asked to transfer the emptiness of the second glass to the first one, how would you go about it? Think, think, think… Simply pour the water from the first glass to the next one!

Now suppose that there are ten glasses in a line; the first nine filled with water and the last one empty. Now pour the water from the ninth glass into the tenth. Result: the emptiness in number 10 moves to number 9.

Next, pour the water from number 8 into 9, the emptiness is transferred to the eighth glass. Continue with this process until the liquid in the first glass is put in the second one. Result: the emptiness has been shifted, step-by-step, from the tenth glass to first.

Is there a point in all this? Yes: Silicon, the material used in the manufacture of electronic devices, conducts electricity in manner similar to the ten glasses in our example. When connected to a battery, electrons start flowing from the negative to the positive terminal. At the same time, the empty spaces left behind by the electrons move from the positive to the negative pole.

This queer process gives silicon and other so-called “semiconductors” very unique electronic properties. They conduct electricity in two currents – one by the electrons and the other by “emptiness”.

And don’t be quick to dismiss this as “unproven” theory. The design of your radio, TV, computer, mobile phone, calculator and all other electronic equipment is based on that fundamental principle. Since they work very well, then the theory is proven!