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