you can imagine that--but for our purposes we use the word
“ether”to mean “something” which will exist after all atoms
have been removed from a position which the atoms occupied.
There is no known method for removing the “ether” itself.
Therefore, the existence of a material ether is convenience
adopted by many scientists to help imagine a medium in which
these infintely small particles exist. It is what is left in a light
bulb after the air (molecules) has been pumped out.
Then we would notice something else. No matter how many
electrons there were in the atom each would be at a definate
distance from each other. If one were to be harred ever so
slightly, immediately many of the others would shift so that the
original position would be maintained. Some of these electrons,
however, remain close to the nucleus and cannot be removed
by any known electrical or chemical means. There are always
Fig. 1
many more electrons which hold their positions close to the
nucleus than those which move when they are forced to do so
by electrical means. The electrons which can move away from
the nucleus are called “free electrons” and are exactly like the
“fixed” ones in every other respect.
What will this mean to us? It will mean that the electron
is “alive,” that is, it has a certain energy or force in it which
affects other electrons.
You are no doubt familiar with the common horseshoe magnet
as shown in Fig. 2. You have often seen a nail or a small
piece of iron drawn to the open end of a magnet. What is there
about a magnet which causes a piece of iron to move toward it?
We say it has an attracting force of energy. Exactly what this
is in the case of the magnet we will take up in a later lesson.
It is enough now to understand what we mean by the word
“force.”
