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Silence is a relative or total lack of sound. But it is possible for real? Is there any way to achieve this?

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If you are willing to take a high pedantic, microscopic view of these things sound is pressure waves in a material, and therefore molecules in motion.

Any particular set of molecular motions can be decomposed in Fourier space and to obtain a non-zero (but often absurdly low energy) sonic environment just from the random motions of the molecular component.

The only way to make this go away would be to cool the material to absolute zero.

That said, even in this overly pedantic view you can make things as quite as you want.


To learn more about practical construction and applications of very quite spaces search on "acoustically dead" and "anechoic".

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or by creating a perfect vacuum –  anna v Oct 1 '11 at 14:09
    
@georg: there is no movement at absolute zero which you should call "sound". –  Ron Maimon Oct 1 '11 at 15:54
    
Our ears (at 37 °C for good reasons) produce such theoretical sound irrespective of environment. As any microphone (any meter) our ears procduce some thermal noise. –  Georg Oct 1 '11 at 16:30
    
@Ron, I corrected for that meanwhile . –  Georg Oct 1 '11 at 16:32
    
Leaving aside the "tree falling in a forest" philosophical conundrum, the issue of the detector's contribution to the detected signal (i.e. how small a signal can be detected) is usually treated separately from the question of how small the signal can be. And, yes, I've dodged the quantum mechanical issues related to the absolute ground state. I'm going to claim that this is not because I'm lazy but because I assumed the reader understood the thermodynamic limits on reaching very low energy states. Yeah, that it. Yeah! –  dmckee Oct 1 '11 at 16:37
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