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| SCIENCE & TECHNOLOGY |
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Parallel universes Year of Astronomy Prof Yash
Pal
THIS UNIVERSE |
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CT scanning: safety issues ON December 19, the Committee on Medical Aspects of Radiation in the Environment (COMARE), UK, published a report on the impact of personally initiated X-ray computed tomography (CT) scanning for the health assessment of asymptomatic individuals. Everyone must read this 83-page report (www.comare.org.uk/documents/COMARE12thReport.pdf) which comprehensively deals with the safety issues of CT scanning. We are not far behind. Advertisements extolling the virtues of CT scanning have started appearing in India also. CT scans promise greater diagnostic accuracy and an increased range of clinical applications; there is also the potential for greater radiation doses to individuals, from interventional techniques and from changes of practice within X-ray computed tomography (COMARE, 2007). According to COMARE, a typical CT scan with an effective dose of 10 mSv is associated with a predicted average risk of fatal cancer induction of 1 in 2000 over a lifetime. (mSv is a unit of biologically effective radiation dose. A chest x-ray test exposes the patient to a dose of 0.02mSV) The harm associated with a medically necessary CT scan is below that considered to be unacceptable, compared to the spontaneous fatal cancer risk of approximately 1 in 4. “If 100,000 people undergo a CT scan every five years from age 40 to 70 years, receiving an effective dose of 10 mSv from each scan, then the estimated impact is approximately 240 excess fatalities…….. For scanning at higher frequencies (every two years or annually) this increases to 600 and 1200 fatalities, respectively.” COMARE cautioned. The risk from repeated scans is unacceptable. Physicians must consider the use of alternative techniques using lower doses of ionising radiation or non-ionising radiation. In any country, medical radiation exposure constitutes the major part of the radiation exposure from artificial sources of radiation. COMARE considered the detriment caused by radiation from the CT scan and also the subsequent psychological effects and potential physical detriment from further investigations. Commercial CT services should provide comprehensive information regarding dose and risk of the CT scan, as well as rates of false negative and false positive findings. False negatives will lead to wrong feeling of good health, while tests that provide false positives may cause psychological trauma followed by more diagnostic tests. The committee clarified that “it may not be possible to give an asymptomatic person a complete ‘all clear’ after a scan….It is also not clear whether CT imaging detects some cancers (eg lung) that are not as clinically as aggressive as those identified following presentation with symptoms”. Some cancers may be present at the individual’s death and would not have been life-threatening. COMARE recommended that any individual displaying symptoms and requesting a CT scan from a commercial service should not be scanned and should be referred back to their physician. The report considered in detail scanning of whole-body and three specific anatomical regions. COMARE asserted that it is not possible to optimise exposure parameters for CT scans of the whole of the body. Services offering whole body CT scanning of asymptomatic individuals should discontinue to do so. CT should not be used to assess spinal conditions, body fat and osteoporosis in asymptomatic individuals (COMARE Press release, December 19) COMARE concluded that there is no evidence that CT scanning for lung conditions is of benefit. However, cardiac CT scanning has been shown to have value for predicting cardiovascular risk and similarly CT colonography has the potential to detect small lesions. Both cardiac CT scanning and CT colonography should only be carried out in certain asymptomatic individuals. The report recommended that CT scanning should only be undertaken on individuals with intermediate risk identified by a comprehensive cardiovascular risk assessment, unless the referral is by a cardiac specialist. In view of the safety significance of CT scan units, they are subjected to licensing by the Atomic Energy Regulatory Board (AERB). It is illegal to operate a CT scan unit in India without obtaining a licence issued by AERB Dr K.S. Parthasarathy is former Secretary, AERB |
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IS the universe — correction: “our” universe — no more than a speck of cosmic dust amid an infinite number of parallel worlds? A staple of mind-bending science fiction, the possibility of multiple universes has long intrigued hard-nosed physicists, mathematicians and cosmologists too. We may not be able — as least not yet — to prove they exist, many serious scientists say, but there are plenty of reasons to think that parallel dimensions are more than figments of eggheaded imagination. The specter of shadow worlds has been thrown into relief by the December release of “The Golden Compass,” a Hollywood blockbuster adapted from the first volume of Philip Pullman’s classic sci-fi trilogy, “His Dark Materials”. In the film, an orphaned girl living in an alternate universe goes on a quest, accompanied by an animal manifestation of her soul, to rescue kidnapped children and discover the secret of a contaminating dust said to be leaking from a parallel realm. Talking bears and magic dust aside, the basic
premise of Pullman’s fantasy is not beyond the scientific pale. “The idea of multiple universes is more than a fantastic invention — it appears naturally within several scientific theories, and deserves to be taken seriously,” said Aurelien Barrau, a French particle physicist at the European Organisation for Nuclear Research (CERN), hardly a hotbed of flaky science. “The multiverse is no longer a model, it is a consequence of our models,” explained Barrau, who recently published an essay for CERN defending the concept. There are several competing and overlapping theories about parallel universes, but the most basic is based on the simple, if mind-boggling, idea that if the universe is infinite then logically everything that could possible occur has happened or will happen. Try this on for size: a copy of you living on a planet and in a solar system like ours is reading these words just as you are. Your lives have been carbon copies up to now, but maybe he or she will keep reading even if you don’t, says Max Tegmark, a cosmologist at MIT in Boston, Massachusetts.
— AFP |
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Year of Astronomy International Astronomical Union, an organisation that brings together about 1000 astronomers from all over the world, will act as the facilitating body. Contrary to common public perception, Galileo is not the inventor of the telescope. The invention was accidentally made in 1608 by a Dutch spectacle maker, Hans Lippershey, who by chance combined a convex lens and a concave lens and noticed the magnification of the image of an object. It should, however, be noted that Lippershey’s claim for a patent was turned down on the ground that the invention was in the air. The invention of the telescope belongs to the realm of romance of history. It would certainly make a good topic for a quiz contest. But it was its astronomical use the next year that constitutes a benchmark in the world history. As soon as the news of the chance discovery reached Galileo, at the time mathematics professor at the University of Padova, he worked out the scientific principles and made the world’s first designer telescope. Interestingly, Galileo did not immediately turn his sight on the heavens. He brought his telescope to the capital city of Venice; showed to the Senators how with its help enemy ships could be sighted hours before they became visible to the naked eye; presented it to them; and got a reward and a raise in pay. It is only then that he made use of it in astronomy The astronomical telescope initiated a revolution the impact of which has gone beyond astronomy and science. The 400th anniversary of the event provides us with an opportunity to renew interest in and enthusiasm for astronomy, which is truly a world science. So far, 99 nations and 14 organisations have signed up to participate in IYA2009.The event will highlight global cooperation for peaceful purposes and aims to convey to the citizens of the world , especially the youth, the excitement of personal discovery and the merits of the scientific method. Countries like India, with a long and well-respected astronomical tradition, should make a special effort to celebrate the year of astronomy . From Aryabhata’s time till that of Kepler, for about a thousand years Indian astronomers were probably the only ones anywhere in the world who could predict lunar and solar eclipses with an accuracy of a few hours that was remarkable for the time. The tradition was alive in Kerala as recently as 200 years ago. Sawai Jai Singh’s early 18th century masonry observatories in Delhi and Jaipur, commonly but wrongly dubbed Jantar Mantar, were inspired by Ulugh Beg’s Samarqand observatory, though they contain some original features also. These observatories were, however, never really used. The world’s first modern astronomical observatory outside Europe was set up in Madras in 1786. Meghnad Saha showed theoretically in 1920 that the spectra of light from far-off stars could be understood using the laws of nature as formulated on the earth, by postulating extreme physical conditions in stellar atmospheres, This work transformed the cosmos into a laboratory. Today, astronomy is a child of high technology , but as a cumulus, it represents the joint civilisational heritage of the humankind. It is hoped that the UN-sponsored Year of Astronomy will further the cause of science as well as of international cooperation. Dr Rajesh Kochhar is the Organising Secretary of the International Astronomical Union’s Commission on History of Astronomy. |
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THIS UNIVERSE Will life on Mars be possible in next 10 years? Human
beings might visit Mars in 10 years or so. But they will have to live in the capsules they go in or build up there. Building cities and colonies is a distant dream. Talking of dreams there are people who are
making plans for converting mars into an earthlike planet. It is not so different in size and does show evidences that at one time it had lot of water flowing on its surface. If human kind really wants to make mars into an earth like planet, with plants, atmosphere rain and clouds, it will have to use biological means and it might take a few centuries if not a few millennia. I am not sure we have enough patience or cooperation for projects like this. We only think in terms of military bases and ways of dominating and conquering others. I personally think there is a lot to be done here on earth if only we will. We have to remember that it is impossible to think of a habitat that contains only one species. Even we are not just one species alone. We would not be possible if we did not have within us a large number of other species inhabiting the world within us in a symbiotic relationship. All these would have to be sustainable in a planet that behaves like our earth. Just remember that even the earth had to be prepared by early life to come to a state where we became possible. For example oxygen in our atmosphere is a gift of that early life. This is not to say that there was a conscious attempt to prepare for our arrival. We just happened, that also very recently. Thus a lot will have to happen before mars becomes and autonomous earth like planet. Who knows it might even happen in a few thousand years. Why do pictures of big objects like mountains, rivers, buildings etc. on our small TV screens appear as big as in real life? To understand this all you have to remember is this. Ultimately the image you sense is that created on the tiny retina of your eye. The size you sense is in relation to other objects in the frame. What you see of a mountain five kilometres away is captured by the camera and transferred to a TV screen in front of you. The image on your retina is about the same
size as that you would get while seeing the mountain directly. |
The report noted that in UK, some commercial CT services market CT scanning of the asymptomatic individual directly to the public as a form of preventative medicine to give individuals some peace of mind! 
THE United Nations has declared the year 2009 as the International Year of Astronomy (IYA 2009) to commemorate the 400th anniversary of the astronomical use of telescope by Galileo Galilei. The proposal was formally submitted by Italy, Galileo’s home country. UNESCO has been designated the lead agency for IYA2009.