Feynman’s Blunder—Part 1
Einstein is attributed to have stated: “Everyone should be respected as an individual, but no one idolized.” I often quote Feynman [pictured] because I consider him to be a giant of physics on whose shoulders I can stand to see further. And it seems that a reader might consider that I idolize him. So this article is to begin to correct such a consideration, if it exists. 
Feynman began The Feynman Lectures On Physics with an Introduction 1-1. But the actual lecture on physics began “1-2 Matter is made of atoms.” And I have often quoted the paragraph which followed. Now, I quote it again plus the next four paragraphs.
“If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that 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, is enormous amount of information about the world, if just a little imagination and thinking are applied.
“To illustrate the power of the atomic idea, suppose that we have a drop of water a quarter of an inch on the side. If we look at it very closely we see nothing but water—smooth, continuous water. Even if we magnify it with the best optical microscope available—roughly two thousand times—then the water drop will be roughly forty feet across, about as big as a large room, and if we looked rather closely, we would still see relatively smooth water—but here and there small football-shaped things swimming back and forth. Very interesting. These are paramecia. You may stop at this point and get so curious about the paramecia with their wiggling cilia and twisting bodies that you go no further, except perhaps to magnify the paramecia still more and see inside.
This, of course, is a subject for biology, but for the present we pass on and look still more closely at the water material itself, magnifying it two thousand times again. 
Now the drop of water extends about fifteen miles across, and if we look very closely at it we see a kind of teeming, something which no longer has a smooth appearance—it looks something like a crowd at a football game as seen from a very great distance. In order to see what this teeming is about, we will magnify it another two hundred and fifty times and we will something similar to what is shown in Fig. 1-1. [see right.]
This is a picture of water magnified a billion times, but idealized in several ways. In the first place, the particles are drawn in a simple manner with sharp edges, which is inaccurate. Secondly, for simplicity, they are sketched almost schematically in a two-dimensional arrangement, but of course that are moving around in three dimensions.
Notice that there are two kinds of “blobs” or circles to represent the atoms of oxygen (black) and hydrogen (white), and that each oxygen has two hydrogens tied to it. (Each little group of an oxygen with its two hydrogens is called a molecule.) The picture is idealized further in that the real particles in nature are continually jiggling and bouncing, turning and twisting around one another. You will have to imagine this as a dynamic rather than a static picture. Another thing that cannot be illustrated in a drawing is the fact that the particles are “stuck together,”—that they attract each other, this one pulled by that one, etc. The whole group is “glued together,” so to speak. On the other hand, the particles do not squeeze through each other. If you try to squeeze two of them too close together, they repel.
“The atoms are 1 or 2 X 10-8 cm in radius. Now 10-8 cm is called an angstrom (just as another name), so we say they are 1 or 2 angstroms (A) in radius. Another way to remember their size is this: if an apple is magnified to the size of the earth, then the atoms are approximately the size of the original apple.
“Now imagine this great drop of water with all these jiggling particles stuck together and tagging along with each other. The water keeps its volume; it does not fall apart, because of the attraction of the molecules for each other. If the drop is on a slope, where it can move from one place to another, the water will flow, but it does not just disappear—things do not just fly apart—because of the molecular attraction. Now the jiggling motion is what we represent as heat: when we increase the temperature, we increase the motion. If we heat the water, the jiggling increase and the volume between the atoms increases, and if the heating continues there comes a time when the pull between the molecules is not enough to hold them together and they do fly apart and become separated from one another. 
Of course, this is how we manufacture steam out of water—by increasing the temperature; the particles fly apart because of the increased motion.
“In Fig. 1-2 [ see right] we have a picture of steam. The picture of steam fails in one respect: at ordinary atmospheric pressure there might be only a few molecules in the whole room, and there certainly would not be as many as three in this figure. Most squares this size would contain none—but we accidently have two and a half or three in the picture (just so it would not be completely blank). Now in the case of steam we see the characteristic molecules more clearly than in the case of water. For simplicity, the molecules are drawn so that there is a 120oangle between them. In actual fact the angle is 105o3’, and the distance between the center of a hydrogen and the center of the oxygen is 0.957 A, so we know this molecule very well.”
I ask: What was Feynman’s blunder? This article was titled (Feynman’s Blunder—Part 1) because I want to give a reader an opportunity to comment as to what his blunder was. For it was a serious blunder which I will describe in Feynman’s Blunder—Part 2.
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