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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