>the science of the day often becomes the BS of tomorrow

Only because much of what parades as science, isn't.

Scientific ideas and principles that are proven wrong probably shouldn't be
called bullshit (unless they were very poorly or irresponsibly put together
in the first place).  For example, all of Newton's laws of gravitation are
wrong.  But his system was thoroughly well thought out, documented by both
mathematical proof and empirical experimentation, and was the epitome of
good science.  (In fact, they were so good they're still in common use,
because for a lot of things, they work well and are simpler to deal with
than the more advance Einsteinian math--even though they're actually wrong.)

You can have really good, solid science that's not bullshit and still turn
out to be wrong in the end.  In real science, you advance a theory and test
it.  If you test it and test it and eventually falsify the theory, you've
still done something great.   You can have a very good, solid scientific
theory that's dead wrong.  The problem is when you announce prematurely
that a theory is a fact.  Then you're out of the world of science and
treading perilously close to BS.

But still, by comparison, telling me that I get tired because my astral
body is being disconnected from my somatic body by the evil spirits in meat
wreaking vengeance on my karma isn't science by any definition.  I'll leave
it to the reader to decide if it's BS or not.  ;-)