Replacing Electricity With Sound or Light?

Most recent answer: 05/08/2013

I have been reading the questions on light vs. sound waves and I was wondering how unlikely it would be to use sound as an energy force, to light a bulb, for example. Would that even be efficient? Also, is it true that thermal energy isn't actually "hot" until it is touching something?
- Elizabeth (age 17)

Hi Elizabeth,

Interesting question. Here are my thoughts on the matter.

Electricity is carried throughout our power grid in the form of a current of electrons. We harness this current to provide light, heat, mechanical motion (through motors), computational resources (through computers), etc. Electrons are versatile enough to satisfy all of these needs mostly because we have powerful ways of controlling them.

Metals provide great methods of transporting electrical current at immense speeds across the entire world. Capacitors let us store energy, resistors let us create light and heat, and various other electrical elements let us control the flow and use of electrons. Within computers, electrons are shuffled through various logic gates to perform calculations for us.

In principle, nothing that we do with electrons needs to be done with electrons. In fact, modern communication systems are switching to using particles of light, or photons, instead of electrons. This change is motivated completely by how well we can control the particles involved; fiber optic cables can carry a lot more information with very low losses.

Modern experiments are also using photons to do quantum calculations. Eventually we hope to make entire computers which run on light, instead of electrons as in today's processors. I see no reason in principle why you couldn't also use sound waves to do similar computations, but in practice, sound waves are more difficult to manipulate.

If you wanted to use sound waves to directly illuminate a light bulb, I'm not sure of a good way to do it. All I can think of is blasting a piece of absorbing material with sound waves until it got hot and began to glow. I'm not sure if this has ever been done experimentally; it certainly doesn't sound efficient. (There is an effect, called sonoluminescence, , by which sound energy converts directly to light, without much overall heating. It's not very efficient./mw)

As you may know, lasers (invented many decades ago) are extremely useful for thousands of industrial and technological applications. In contrast, "phasers" (which emit sound, not light) were invented only recently, and are still too complicated to be useful.

We'll see what the future brings!

David Schmid

(published on 05/08/2013)

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