(a small break from explaining myself.)

we know some things, and one of the things we know is that we have brains in which knowledge must somehow be instantiated. and we detect activity there-- we can talk, for example, about neurons and how they fire. but we don't know how knowledge is instantiated in brains-- what the physical state is that equals knowing your childhood address during all of that time you spend not consciously saying it to yourself. and we can calculate the energy of the entire universe, but what we find is that: seventy percent of the universe is something that isn't matter. we don't know what it is. we call it dark energy, or quintessence or the cosmological constant, but we might as well call it 'other people's hearts' for all we know about it. and of the thirtyish percent of the universe composed of matter, the vast majority is dark matter. what is dark matter? well, it's the kind of matter that we can neither observe nor know the composition of. another term we use to bracket off the inexplicable in our mathematical models. and the matter that we know, that small percentage of a percentage that we've got a handle on (minus brain matter), when we look at it down as far as we can look, is a matter of quantum mechanics, of which the physicist richard feynman said "if you think you understand quantum mechanics, you don't understand quantum mechanics." [as a small taste: if you are interested in making sense of quatum theory you'll have to get used to assuming that we live in one of many possible worlds existing in four dimensions.]

i look in and i look up and i see what i sort of know and i'm in awe, but it's a thin film on the surface of what i don't know, which is almost everything.