Understanding the Universe From Quarks to the Cosmos

One hot summer day in July of 392 BC, it might have been a Tuesday, the Greek philosopher Democritus of Abdera asserted that everything we see is made of common, fundamental, invisible constituents; things that are so small we don’t see them in our everyday experience. Like most great ideas, it wasn’t exactly original. Democritus’s teacher, Leucippus of Miletus, probably had the same atomistic view of nature. The concept of atomism remained just a theory for over two millennia. It wasn’t until the 20th century that this exotic idea of “atoms” proved to be correct. The atomistic idea, that there are discernable fundamental building blocks, and understandable rules under which they combine and form everything we see in the universe, is one of the most profound and fertile ideas in science.