belong to the Milky Way. Accepting this very
plausible conclusion, the new star in Perseus must have been more than
five hundred times as far as the nearest fixed star. We know that it
takes light four years to reach us from Alpha Centauri. It follows that
the new star was at a distance through which light would require more
than two thousand years to travel, and quite likely a time two or three
times this. It requires only the most elementary ideas of geometry to
see that if we suppose a ray of light to shoot from a star at such a
distance in a direction perpendicular to the line of sight from us to
the star, we can compute how fast the ray would seem to us to travel.
Granting the distance to be only two thousand light years, the apparent
size of the sphere around the star which the light would fill at the
end of one year after the explosion would be that of a coin seen at a
distance of two thousand times its radius, or one thousand times its
diameter--say, a five-cent piece at the distance of sixty feet. But, as
a matter of fact, the nebulous illumination expanded with a velocity
from ten to twenty times as great as this.

The idea that the nebulosity around the new star was formed by the
illumination caused by the light of the explosion spreading out on all
sides therefore fails to satisfy us, not because the expansion of the
nebula seemed to be so slow, but because it was many times as swift as
the speed of light. Another reason for believing that it was not a mere
wave of light is offered by the fact that it did not take place
regularly in every direction from the star, but seemed to shoot off at
various angles.

Up to the present time, the speed of light has been to science, as well
as to the intelligence of our race, almost a symbol of the greatest of
possible speeds. The more carefully we reflect on the case, the more
clearly we shall see the difficulty in supposing any agency to travel
at the rate of the seeming emanations from the new star in Perseus.

As the emanation is seen spreading day after day, the reader may
inquire whether this is not an appearance due to some other cause than
the mere motion of light. May not an explosion taking place in the
centre of a star produce an effect which shall travel yet faster than
light? We can only reply that no such agency is known to science.

But is there really anything intrinsically improbable in an agency
travelling with a speed many times that of light? In co