10۔ انسان كب سے زمين پر هے
ڈاكٹر ڈونالڈ جانسن(پیدائش 1943)، ميوزيم آف نيچرل هسٹري، كليولينڈ، اوهايو: يورپ افريقه اور ايشيا ميں جو فوسلز (fossils) برآمد هوئے هيں، وه انسان كي ابتداكو اور زياده پيچھے كي طرف لے جارهے هيں۔ بهر حال يه بات دن بدن نماياں هوتي جارهي هے كه ارتقا كامعامله (سابقه تصور كے خلاف) كهيں زياده پيچيده هے۔ وه مدت جس كا تعين ايك مسئله هے، وه تين ملين سے لے كر دس ملين سال پيچھے تك هے۔ انسان كے امكاني آباواجداد ميںبہ ظاهر بهت زياده فرق رها هے، اور هم كو نهيں معلوم كه ان كے درميان باهمي رشته كيا تھا (اس كي وجه جزئي طورپر ڈاكٹر جانسن كي حبش ميں دريافتيں هيں۔ نيز اس سے بھي زياده قديم فوسلز پاكستان ميں ملے هيں)۔
THE TOP TEN SECRETS OF SCIENCE
In The Encyclopaedia of Ignorance, to be published next Thursday, some 60 well-known scientists survey different fields of research, trying to point out significant gaps in our knowledge of the world. They write at very different levels, at very different lengths. However, last week we contacted some of the authors dealing with major branches of science and asked them to name a single unsolved problem which they personally found especially important or interesting. They give their choices below, together with those of two - Professor John Maynard Smith and Dr. Francis Crick - who could not be contacted, and which have been taken directly from the book.
1: Why is the universe so uniform? Ian Roxburg, Professor of Applied Mathematics, Queen Mary College, London: "the universe is astonishingly uniform. No matter which way we look, the universe has the same constituents in the same proportions. The laws of physics discovered on earth contain arbitrary numbers, like the ratio of the mass of an electron to the 'mass of a proton, which is roughly 1840 to one. But these turn out to be the same in all places at all times. Why? Did a creator arbitrarily choose these numbers? Or must these numbers have the particular uniform value we observe for the Universe to exist?"
2: Is there a, Z-particle? Abdul Salam, Professor of Theoretical Physics, Imperial College, London. '' In the fleet decade we need to confirm or disprove the existence of the so-called Z-particle. If it does turn out to exist as predicted by current theory, it will clinch the unification of two of the four forces we know in nature. [The four forces are gravity, electro-magnetism, the strong nuclear force that binds the atomic nucleus together, and the weak nuclear force involved in radioactivity. Recently, Professor Salam and others have made some progress towards unifying the weak nuclear force and electromagnetism. The discovery of the Z-particle would lend strong experimental support.]
3: What preceded DNA? Dr Graham Cairns-Smith, lecturer in chemistry, University of Glasgow. "We need to discover a new genetic material as different as you like from DNA. [The double helix structure of DNA was discovered by Francis Crick and James Watson in Cambridge in 1953.] I do not believe that DNA could have been made on the primitive earth. Life must have started with something else and DNA evolved later."
4: How are genes switched on and off? Sir John Kendrew, Chairman of the European Allender Biology Organisation, Heidelberg. " We know something about how genes are switched on and off in bacteria, but next to nothing about how it is done in higher animals? [It is by switching genes on and off that the cells of a single organism, which all contain the same set of genes, are able to do such different jobs, and become constituents of nerves, skin, etc.]
5: Why do we have an immune system? The body's immune system defends us against infection, is responsible for allergies, and makes organ transplant so difficult. But according to Dr. H. S. Micklem of the University of Edinburgh, "The most interesting question is not how the immune system works, but why it is there at all: Invertebrates seem to get along quite well without one, but it is incredibly complicated in vertebrates. The idea that it was needed to detect small changes in the cell surface which might lead to cancer has been popular in the last ten years but there is a lot of data to suggest it is not good enough."
6: How can we measure evolution? John Maynard Smith, Professor of Biology, University of Sussex, thinks that the theory of evolution has a built-in problem. "The essential components of the theory of evolution are mutation (a change in a gene), selection (differential survival or fertility of different types) and migration. The theory tells us that each of these processes, at a level far too low to be measurable in most situations, can profoundly affect evolution. Thus we have three processes which we believe to determine the course of evolution, and we have a mathematical theory which, tells us that these processes can produce their effects at levels we cannot usually hope to measure directly. It is as if we had a theory of electromagnetism but no means of measuring electric current or magnetic force."
7: How is the nervous system built? Francis Crick, Salk Institute, California. "Perhaps the most challenging problem in the whole of developmental biology is the construction of the nervous system of an animal. Many years ago it was shown by Roger Sperry that if a newt's eye was removed, so that the optic nerve from its eye to its brain was broken, then even if, the eye was replaced upside down, the optic nerve would regenerate from the retina, grow towards the brain and connect up again. After a period, the animal could see again with this eye, but it always saw upside down. In other words, the new connection had been made 'correctly ' except that the eye did not know it had been inverted. The results show that fairly precise processes are at work to make the correct, rather intricate, connections needed between one set of nerves and another but exactly what these mechanisms are we do not yet know." [In other words, the very fact that it was upside down shows how specific the links are.]
8: Does the quantum theory apply to gravity? Sir Herman Bondi, Chief Scientist, Department of Energy. "If we follow Einstein's widely accepted theory of gravity then any rapid change in the source of a gravitational field —two stars orbiting round each other, for example-. should radiate gravitational waves at the spend of tight. All other forms of recitation are ‘quantised,’ that is to say they are not continuous but come in discrete but minute packets. It is hardly conceivable that gravitational waves are quantised too, but nobody has yet succeeded in establishing the equations, though Many have tried."
9: How do different parts of the brain link up? Professor Horace Barlow, Cambridge. " We are almost totally ignorant about how different parts of the brain communicate with one another. For example, what goes on between the parts of the brain concerned with hearing and the rest when we recognise a familiar voice? You can draw an analogy with speech. It is carried by sound waves, but it is far more meaningful than the babbling of a baby which is carried by sound waves, too. In the brain nervous' impulses are the equivalent of soundwaves, but we have no idea of how they become meaningful."
10: How old is man? Dr Donald C. Johnson, Museum of Natural History, Cleveland, Ohio. "Fossil discoveries in Europe Africa and Asia are pushing human origins further back in time. However, it is becoming increasingly clear that the scenario of human evolution is much more complex. The probable time is three to ten million years ago. There appears to have been a great diversity of possible human ancestors and we don’t know how they were related. [This is due partly to Johanson's discoveries to Ethiopia and others, of even older fossils, made in Pakistan]
(Sunday Times, London, December 4, 1977, p. 13)
