This post originally appeared on xkcd.com.
'Uhhh ... how sure are we that everything is made of these?'" alt="==COSMOLOGY==> 'Uhhh ... how sure are we that everything is made of these?'" /> 'Uhhh ... how sure are we that everything is made of these?'" alt="==COSMOLOGY==> 'Uhhh ... how sure are we that everything is made of these?'" />