The Riddles
of Science
By Dr Syed Amir
Bethesda, MD
In the mid-fourteenth
century, the greater part of Europe was ravaged
by a deadly pandemic, the plague, also known as
Black Death. This disease wiped out nearly a third
of the continent’s population. No one knew
what caused it, nor was there a known cure. Since
then, medical science has been revolutionized. Plague
is now a rare disease, readily amenable to antibiotics.
Similarly, other dreaded diseases, smallpox, polio,
tuberculosis and many others, that used to be common
infectious ailments have been controlled by modern
medicine. Aside from medical advances, humankind,
in a span of less than a hundred years, has uncovered
the secrets of the atom, and is in the process of
exploring the outer reaches of space and the solar
system. The advent of the Internet and information
technology has spawned a global culture, connecting
people as never before. The advancement of human
knowledge during the past century has been truly
breathtaking.
For all the impressive progress made by modern science,
there remain a number of questions for which scientists
have as yet no answers. The American journal, Science,
one of the world’s most prestigious scientific
magazines, recently celebrated its 125th centenary
and, as part of it, it polled its readers and editors
to identify the most compelling unsolved scientific
puzzles of our time. The journal received many submissions,
out of which it selected 25 questions to highlight
in its special issue published on July 1, 2005.
The editors believe that these riddles have some
realistic chance of being resolved during the next
25 years. Following are a selected few that appear
the most baffling.
What is the maximum human lifespan? The human life
span has been increasing steadily. For example,
a hundred years ago, people expected to live to
only about 50 years, but now the figure has climbed
to 76 years. There are variations among countries,
of course. While in Japan, the expected life span
is 81 years, in Pakistan it is twenty years shorter,
around 60 years. The person who is known to have
lived the longest life was a French woman who died
at the age of 122 in 1997, but even a careful study
of her life style could not yield definitive clues
to her longevity. The age-old question is: what
is the maximum limit of human life; the answer is
unknown. Some scientists believe that we are already
reaching the upper limit of our longevity, while
others disagree, contending that the normal lifespan
of humans will stretch to 100 or 120 in the future.
Most agree, however, that there is an upper limit
to the human lifespan, whatever ultimately it might
prove to be. Studies on the aging process, conducted
on worms and fruit flies, have shown that when they
are placed on a sharply reduced diet, they live
longer. Mice on a starvation diet lived 50 percent
longer than those on normal diet. It is unknown
whether the results derived from animals can be
applied to humans. Human studies are difficult as
they take a long time, and few of us are willing
to starve for years. The crucial question is, even
if a successful treatment can be found, would it
add fruitful years to our life or would it mere
prolong the sufferings of old age.
Will there ever be a vaccine against the AIDS virus?
No other disease has received so much attention
and investment of money for prevention and treatment
as AIDS has. The National Institutes of Health alone
spends $500 million per year in the quest for a
vaccine or a cure for this scourge. Nevertheless,
prospects for a preventive vaccine are not very
bright. The major problem is that the virus causing
AIDS (HIV) has the remarkable ability to change
itself continuously and deviously. Therefore, antibodies,
proteins that normally defend us against infection,
designed exquisitely to fight one form of HIV are
powerless when faced with another variant of it.
The virus thus successfully outmaneuvers and evades
our defenses every time. There are some promising
leads that scientists are pursuing. While AIDS remains
an incurable disease, in some cases people infected
with the virus have for mysterious reasons been
able to resist its progression to full-blown disease.
An understanding of the enigmatic factors that confer
immunity against AIDS on such people might lead
to an effective vaccine against this disease or
so the scientist hope.
What makes us different from other animal species?
The answer is not simple as no single trait can
fully define our uniqueness as human beings. The
famed anthropologist, Dr. Louis Leakey, proposed
that it was our ability to use tools that made us
unique, but then it was shown by Dr. Jane Goodall
that some chimpanzees, our closest cousins in the
evolutionary ladder, can also do so. Other traits
such as ability to develop culture, think and use
language have also been shown to be shared by other
animals to some degree or the other. While these
features may not define our distinctiveness, it
is unquestioned that we possess a unique set of
genes not shared by other animals, even chimpanzees.
Whereas the genetic make up of humans and chimps
differs by only 1%, this tiny difference apparently
was sufficient to set the two species on a separate
evolutionary route. Although the human genetic map
has been worked out, that of primates is still not
complete; only that of chimpanzees has just been
published. When this information becomes available,
it might be possible to analyze the exact nature
of differences at the genetic level that set us
apart from primates, indeed all other species. It
is unlikely, however, that genetic variations alone
will account for all the empirical differences readily
observable.
Are we alone in the universe? Until the mid-sixteenth
century when Galileo pointed his telescope to the
heavens and observed the moon and other planets,
it was believed that the earth was situated at the
center of the universe and all celestial bodies
-- the sun, the moon and the fixed stars -- revolved
round it. His observations afforded experimental
support for the theory of the Polish astronomer
and mathematician, Nicholas Copernicus, that the
earth revolved round the sun. These affirmations
earned him much hostility from the Orthodox Church
which regarded his teachings as inimical to religious
doctrine. Astronomers now believe that the universe
comprises hundreds of billions of galaxies like
our own Milky Way, with each galaxy populated by
billions of stars like our sun. They postulate that
there are countless planets like our earth surrounding
these stars. Scientists have observed and mapped
at least 150 planets in the vicinity of the earth
alone. While the vastness of the universe is mind-boggling,
the greater unsolved mystery is whether in this
immense cosmos intelligent life, much like that
found on earth, exists. The Institute for Extraterrestrial
Intelligence at Mountain View, California, has for
years been diligently scanning outer space with
its giant radio telescopes for any sign of life.
They have searched 710 star systems on 28 million
channels, but discerned only deathly silence. In
addition, billions of radio sources in our own Milky
Way have been analyzed for any intelligible messages
from outer space. Again, no signs of intelligent
life were detected. It needs to be emphasized that
these findings are preliminary and a vast amount
of space remains to be scanned before even a tentative
conclusion can be reached.
What is the universe made of? In the ancient times,
the universe was believed to be unchanging, a close
space surrounded by a spherical envelope, with nothing
beyond it. In the late Middle Ages, the ideas about
the nature of the universe were still evolving,
when in the sixteenth and seventeenth century physicists,
Copernicus, Kepler, and then Newton demonstrated
that the earth was just one planet among many orbiting
around one star, our sun. The question of what the
cosmos is made of has remained a major puzzle in
astronomy. On the face of it, the answer seems simple;
it is made of visible matter, such as stars, planets,
and all living creatures. Cosmologists, however,
have calculated that visible matter accounts for
less than 5% of the total matter that exists in
the cosmos. It raises another problem. All the matter
visible is not sufficient to exercise the gravitational
pull needed to keep the star and other heavenly
bodies in their orbits. What is the other invisible
matter? Theories abound as to the nature of this
mysterious dark matter that suffuses the universe,
yet is not detectable. Cosmologists believe that
it may in fact be five times as much as ordinary
visible matter and may be holding the galaxies together.
Currently, there is a heated debate going on in
this country as to whether the universe and life
on earth evolved through some intelligent design
or came into being through a relentless process
driven entirely by forces of evolutions and selection.
Neither side is willing to concede any points to
the other. It seems inconceivable, however, that
the beautiful cosmos, the unceasing motions of galaxies
and stars and the orderly evolution of life on earth
could have been possible without the will and design
of a supreme being, whatever we would like to call
him.
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