If complete and total silence and nothingness existed, how would we recognize them? Just by the mere fact that we would, or could, know they're there cancels out their existence. While I think it's admirable to want to experience both or either...your being itself is constantly doing something, even if your mind is "still." So - when you sit in silence, the sounds of the functioning of your body continues - even if you can't, or won't, hear them. To paraphrase the gentleman in the film "The 11th Hour," within 10 seconds more things are happening in your body than there are stars and galaxies in the universe. Silence and nothingness are, on the surface, viable possibilities - but...when one goes deeper - they are both impossible for us as beings to live in and/or enjoy.
The sounds of silence is an oxymoron (as we all know), as is the sight of nothingness. If you can imagine it, some say, than it can be. However, in this case...you can imagine it, yet - it cannot be. Your imagination is not silent and it certainly isn't nothing. So, I think we must come to grips with the fact that we can enjoy some "form" of silence, or perhaps a better way of saying it is...almost no noise. And - maybe we can long to "be in the nothingness." But for now, while we may understand both concepts, we'll just have to live in their shadows.