t I am not
arguing that there actually is a thick wall of semi-plastic material
surrounding the earth through which a space flyer could not pass. If I
did, I would automatically bar myself from writing interplanetary
stories, a thing that is far from my desires. I do wish to point out,
however, that such a layer might exist, so far as we at present know.
The objections to which I wish to reply are two: first, "How do
meteors pass through that imaginary substance which is too much for a
powerful space flyer?" and second, "How about refraction?"

To reply to the first we must consider two things, kinetic energy and
resistance to the passage of a body. The kinetic energy of a moving
body is represented by the formula 1/2 mv^2 where m is the mass of the
body and v the velocity. The resistance of a substance to penetration
of a body is expressed by the formula A f_c where A is the area of the
body in contact with the resisting medium and f_c is the coefficient
of sliding friction between the penetrating body and the resisting
medium. Consider first the space flyer. To hold personnel the flyer
must be hollow. In other words, m must be small as compared to A. A
meteor, on the other hand, is solid and dense with a relatively large
m and small A. Given a meteor and a space flyer of the same weight,
the volume of the meteor would be much smaller, and as the area in
contact with the resisting medium is a function of volume, the total
resistance to be overcome by the space flyer would be much greater
than that to be overcome by the meteor. Again, consider the relative
velocities of a meteor and a space flyer coming from the earth toward
the heaviside layer. The meteor from space would have an enormous
velocity, so great that if it got into even very rare air, it would
become incandescent. As it must go through dense air, the space flyer
could attain only a relatively low velocity before it reached the
layer. Remember that the velocity is squared. A one thousand pound
meteor flying with a velocity 100 times that of the space ship would
have 100^2 or 10,000 times the kinetic energy of the space ship while
it would also have less friction to overcome due to its smaller size.

If my critic wishes to test this out for himself, I can suggest a very
simple experiment. Take a plank of sound pine wood, two inches thick
by twelve inches wide and four feet long. Support it on both ends and
then pile lead slabs onto it, covering the whole are