120 The Poetry of Physics and The Physics of Poetry
velocity of light. Perhaps we may grant now that it is possible that the
intuition we developed with super-slow velocities, like the speed of
sound, do not apply when we are dealing with the velocity of light.
While this reasoning does not completely resolve the paradox in our
minds, it helps us to understand how it is that the physics with velocities
of the order of c can be so different from the low velocity physics that we
intuitively identify with because of our limited experience. Bearing this
in mind, perhaps we will not feel so uncomfortable with the ideas of
relativity. Some discomfort is inevitable, however. We will notice that
certain relativistic effects such as the Fitzgerald contraction encountered
earlier disappear as the velocity involved becomes small compared with
the velocity of light. For example, a mass of a particle traveling at the
speed of sound increases only one part in 10^12 and a length in the
direction of motion shrinks by a similar amount.