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If (when) we could figure out a way to do computations with light as opposed to electrons within circuits, how much faster would our computers be?

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I studied optical computing in undergrad. From that, certain categories of problems would be solved MUCH faster. For instance, do some research on 4-f optical correlators. These kinds of operations can perform at the propagation velocity of light through the media (so essentially the speed of light).

In terms of computing as we know it (logic gates, stateful gates which hold charge interpreted as '1' or '0'), I do not know if the advantages are there.

That said, consider the economic momentum of "traditional" computer development with silicon chip fabrication. It's about 50+ years or so old. So (like other technologies), until any other technology is cheaper or in more demand, it will be a while until optical computing becomes a commodity.

In any case, it's as cool as heck!

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  • \$\begingroup\$ Supercool as heck! But since I'm so ignorant if these things, I was wondering how much faster the speed of light is than our way of computing now (logic gates?)... \$\endgroup\$ – Wapiti Aug 10 '15 at 1:30
  • \$\begingroup\$ Well, I don't know of any store that sells optical transistors (yet), but if that were the case, I would look at a property called "propagation delay" that is either directly in or can be derived from a logic chip datasheet. I don't know if the comparison can be made right now due to the lack of commercial availability of optical logic gates, but that's how you would do it. Remember, one can't just take the speed of light and say that is how fast an optical computer is. (Electrons theoretically travel at the speed of light too). \$\endgroup\$ – cowboydan Aug 10 '15 at 1:37
  • \$\begingroup\$ Thanks, I I'll look into those things. On a side note though, electrons have mass-- how could they travel at light speed even theoretically? \$\endgroup\$ – Wapiti Aug 10 '15 at 1:40
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    \$\begingroup\$ Technically electrical signals can travel slightly slower than the speed of light, called the 'velocity factor'. This is typically about 67% for something like co-ax (it depends on the medium). That is the signal (electric field) not the electrons travelling that fast. Electrons move much slower in the electric field, at a speed called the 'drift velocity'. \$\endgroup\$ – Tom Carpenter Aug 10 '15 at 2:34
  • \$\begingroup\$ @TomCarpenter, true, but the speed of light through glass is also only about 67% of c. \$\endgroup\$ – The Photon Aug 10 '15 at 2:46

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