182 Chapter 3 The Universe Was Born With a Big Bang
If there are many extraterrestrial civilizations in the
galaxy, even if it is difficult to encounter their spaceships, we
should at least detect radio waves used in their communica-
tions. However, these traces have never been found.
Fermi was a “thought and action” person who not only
had many historical achievements in theoretical physics, but
also made many contributions in experimental physics. No
matter how likely it seems that aliens might exist, there is no
evidence of contact. This is the Fermi paradox.
Although many people have since tried to show the exis-
tence of extraterrestrial civilizations using methods such as
the Drake equation, all have run up against the question of
why there is no evidence of their existence. The Fermi para-
dox demands careful consideration.
Has Life Been Created Often?
Living creatures exist everywhere on Earth—but we have
come to know this only quite recently. In 1977, scientists who
had been investigating deep-sea hydrothermal vents in the
Pacific Ocean discovered strange creatures. One of these was
the tube worm.
A hydrothermal vent is an opening on the ocean floor
from which geothermally heated water gushes. Since the sur-
rounding area is often teeming with poisonous substances
such as hydrogen sulfide, it had previously been believed that
there were no living creatures there. However, tube worms
have a symbiotic relationship with chemosynthetic bacteria
living inside them—the bacteria use hydrogen sulfide as an
energy source, and they produce organic matter that the
tube worms use as nutrition. Thus, the tube worms have
propagated even in the ocean depths. Besides tube worms,
many living creatures such as fish or crabs that live near
hydrothermal vents comprise independent ecosystems. Such
ecosystems were a major discovery.
The study of these kinds of extreme creatures continues
even today, and many scholars claim that some kind of living
creature exists almost everywhere on Earth, from the tops of
the highest mountains to the depths of the oceans and even
underground. It is even said that microbes that ate lava existed
3.5 billion years ago.
The fact that living creatures can survive in such an
extreme environment is surely good news for people who
believe in the existence of extraterrestrial life. For example,
the surface of Europa (one of Jupiter’s moons) is covered with
ice, but since volcanic activity has been verified there, there
is a good possibility that there are oceans with hydrothermal
vents under the ice. If this is true, then there may be living
creatures such as tube worms there.
The Arecibo Message was an
attempt to broadcast news of
our civilization to aliens. Sent in
1973 to the Messier 13 cluster,
and written by Dr. Drake himself,
the message includes information
about elements and DNA, as well
as figures of a human, our solar
system, and the Arecibo radio