"It is man's greatest mistake to believe that all he perceives is all there IS to perceive."  I can't remember who said that, but it is a good watchdog for feelings of certainty.  I don't think either Lex or Martin feels 100% certain about many things, especially cosmological things or notions that explain "everything".  This admitted uncertainty, or reluctance to say things unequivocally, is what gives me a feeling of comfort.  The comfort science brings far outweighs the anxiety of the existential and unknown.  In fact, toiling with the unknown is a fascinating endeavor and one which a person could devote their entire life to and never want for more.