In 400 B.C., the Greek thinker Democritus proposed that all matter was made of tiny indivisible particles, which he named atomos. But scientific investigation as we know it was not commonly practiced back then, and Democritus never carried out any experiments to see if his theory was correct. He had his supporters, and the Democritus University of Thrace was named in his honor, but lacking any solid evidence, his theory was rejected by Aristotle; and therefore the idea of atoms was likewise rejected by nearly everyone else for the next two thousand years.

     Then, in the early 1800s, an English school teacher named John Dalton took the old idea of atoms and made it into something useful to modern science. How did this happen? Why did Dalton's idea catch on, while Democritus's didn't?

     The fundamental principle behind what we call science today is the idea that we gain knowledge from evidence. We know something scientifically if we can point to some experience that proves it. What evidence did scientists of Dalton's time have that made it easier to accept Dalton's ideas? That's what we're going to find out in this WebQuest.


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Last updated:  May 21, 2008