Important step toward computing with light

http://web.mit.edu/newsoffice/2011/optical-computing-diode-1123.html

by GvS • 15 years ago

20 5 15 years ago

web.mit.edu

Wha? "Light travels much faster than electrons." But electrons aren't 'traveling' when signalling in silicon circuits - its just photons of a different wavelength, right?

sudont• 15 years ago

http://en.wikipedia.org/wiki/Speed_of_electricity#Electromag...

beloch• 15 years ago

Electrical signals are actually more like waves in water. A conductor contains many loose electrons that behave like the water. Sending an electrical signal is like one person dropping a rock at one end of a glassy lake and another person watching for ripples at the other end. The signal gets through pretty fast, but all that motion dissipates a lot of energy. This is why wires heat up when you put current through them. Electrons moving about = heat.

Photons do not require a medium to propagate through. They go through vacuum just fine (while electrical signals don't). Photons are incredibly good at traveling vast distances without interacting with matter. If we can see a star in the sky that is a billion light-years away, that's because at least some of the photons emitted by that star have traveled that distance without being absorbed by anything other than the rods and cones in your eye.

teilo• 15 years ago

Electrons actually travel very slowly, and in AC current, electrons don't do anything more than vibrate in place.

Picture a straw full of BBs. Push a BB into one end, and another instantly comes out the other end. That's a loose analogy to what's happening with electricity and its perceived speed.

nitrogen• 15 years ago

I hope that one day this same (or a similar) diode material is made into a privacy-protecting glass, so light can get in but not out.

Important step toward computing with light

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