c 600 BCE Greek "scientists" (eg Thales) started to wonder about the
nature of matter.
c 450 BCE Empedocles postulated that matter was composed of
"elements." He proposed the elements earth air fire and water --
Aristotle thought in terms of dry, cold, hot, wet
c 440 BCE first Leucippus and then
c 420 BCE his colleague Democrius proposed that there were many
elements and called them atoms (molecules???)
Admirable progress in 30 years!
BUT
c 100 AD Hero of Alexandria was trying to explain that the four
elements consist of atoms and
c 800 AD Jabir ibn Hayyan, later known as Geber, was trying to teach
that only two elements were needed: sulpher (which is hot and dry)
and mercury (which is cold and wet) -- so all _four_ elements are
present. And as late as
c 1660 "... they were STARTING to believe that matter is made of
atoms instead of the old alchemical essences -- earth, air, fire, and water."
TWO MILLENNIA after the fact!
Q1: When did the idea of "earth, air, fire and water" finally go
away? Who last refers to this philosophy in serious scientific discourse?
Q2: Why did it take so long, >2000 yrs, to shake the four-element philosophy?
Q3: What other concepts in physics persist to this day even tough we
know they are wrongish?