Today, I’m happy to host my father, Dean Zollman, for a monthly series of blog posts on the history of the theory of atoms. I asked my dad, a physics professor at Kansas State, to write history of science posts because he is a great storyteller and an excellent teacher. His posts will be published the first Friday of the month.—Kim
By Dean Zollman
In his Lectures on Physics, Richard Feynman asks his students rhetorically, “If all scientific knowledge were lost to a cataclysm, what single statement would preserve the most information for the next generation of creatures? How could we best pass on our understanding of the world?”
He answers his questions with, “I believe it is the atomic hypothesis that all things are made of atoms—little particles move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.”
An early 20th century model of the atom. (Image from Wikimedia Commons, used under the terms of the GNU Free Documentation License)
These atoms which Feynman (and most of us) consider so important have not always existed in the universe. For about 380,000 years after the Big Bang (start of the universe, not the TV series) the amount of energy in the universe was too great for atoms to form. At that time, an electron was too energetic to be held to a proton and thus form a hydrogen atom.
But eventually the universe expanded and cooled enough that hydrogen and helium atoms were formed. Then later, stars and eventually the elements that we know today formed. The story of how all of this happened is an interesting one. Perhaps even more interesting are the ways in which we have been able to learn that it happened. (NASA has some good websites for that information.)
However, the stories of the Big Bang and our understanding of the evolution of the universe are not the stories that I wish to tell. An equally interesting tale is humankind’s views of atoms and how we came to understand them.
Much of this history is part of Western thought and began about 2,500 years ago in Greece. However, it is not exclusively Western (more about that in some future posts). And of course, there is the time period in which Alda and Hruodland lived (at least lived in the fictional world of The Cross and the Dragon). For an eighth and ninth century ruler, Hruodland’s uncle, Charlemagne, was relatively enlightened about intellectual endeavors. However, thinking about matter as being made of lots of objects too small to see did not sit well with early Christianity. (Again, more later.) So, Charlemagne’s “science advisors” were more likely to think about the stars than the constituents of matter.
A theory of atoms did not return to Western scientific thinking until the beginning of the 19th century. At that time John Dalton used the concept to explain experiments in chemistry. However, it was the discoveries of the late 19th and early 20th century that put atomic theory on firm ground. (We will get to those ideas later.)
In the next post, we will start at the beginning—not the beginning of atoms, but the beginnings of humankind’s understanding that they may exist. We will discuss briefly how Leucippus and Democritus concluded that something like atoms exists. Then, we will look at why Aristotle thought they were wrong even though without Aristotle we, today, would probably not know about Leucippus’ and Democritus’ ideas.
Dean Zollman is university distinguished professor of physics at Kansas State University where he has been a faculty member for more than 40 years. During his career he has received three major awards—the National Science Foundation Director’s Award for Distinguished Teacher Scholars (2004), the Carnegie Foundation for the Advancement of Teaching Doctoral University Professor of the Year (1996), and American Association of Physics Teachers’ Robert A. Millikan Medal (1995). His present research concentrates on the teaching and learning of physics and on science teacher preparation.