QUESTION: Why is it impossible to see an atom in a really powerful microscope?

ANSWER: First we should establish that when we say we are "seeing" someone, what we really mean is that photons are entering our eyeballs after having bounced off the physical manifestation of the person we are looking at.The problem with seeing with light is that light is kind of big. Repeat: Light is big. It comes in waves with several hundred nanometers in between the crests while the average atom is only about a fifth of a nanometer across. So the atom is like a grain of sand washed to and fro in a tsunami-sized surf of light.

That's where electron microscopes are handy. Electrons can bounce off an object and leave an image on a piece of film. This image can show objects only a few dozen atoms across. Why can't electron microscopes make images of individual atoms? Because these electrons pack quite a wallop, and when they hit one lonely atom they can easily obliterate it. Or change it drastically.

James Trefil, coauthor of the new book "Science Matters: Achieving Scientific Literacy," told us, "It's like you have a long dark tunnel, and you want to see if there's a car down at the end of it, and the only way you can find out is by sending another car down the tunnel and listening for a crash."

In the past decade, a new device, the scanning-probe or scanning-tunneling microscope, has made it possible to make images of atoms themselves. The tip of a teensy wire floats over the even smaller object and picks up the electrical charge at its surface. When the probe is directly above an atom, the current is stronger, and when it is to the side or between two atoms, the current is weaker. From this it is possible to make an image showing the contour of the object.

Of course, atoms aren't the smallest objects known to man. Smaller still are quarks and things collectively known as leptons, including muons, neutrinos and electrons. But these are "point particles" (this is the official word) that have no physical dimensions. No width, no breadth, no depth. Let's meditate on that for a while. Also, let's all consider naming our firstborn child "Muon."

QUESTION: Why do we stare into space when we daydream?


Oh, yeah. We stare into space, obviously, because we don't want to focus on anything. To focus on something tangible is to be distracted from the deeper metaphysical mystery of existence.

The real question is: How far into space are we staring when we daydream, on average? It varies, depending on whether you are near-sighted or far-sighted. For the average person, though, it's about one meter. That is, if someone stuck their hand in the air one meter from your glazed expression, it would be in perfect focus.

Washington Post Writers Group