Showing posts with label Astronomy. Show all posts
Showing posts with label Astronomy. Show all posts

Tuesday, June 23, 2009

Are we witnessing the end of science?


Dark matter

(http://www.guardian.co.uk/science/blog/2009/jun/22/end-science-unified-theory-mavericks)

Physicists only really understand 4% of the universe's constituents – the rest is mysterious dark energy and dark matter (represented here in purple, flanking the Bullet colliding galaxy clusters). Photograph: AP

Wired magazine is well known for its catchy cover lines. I won't forget one from 2007. Alongside a mocked-up image of a yellowing lab notebook and magnifying lens, it proclaimed: "The end of science: The quest for science used to begin with grand theories; now it begins with massive amounts of data."

Scientists and science commentators often say that if yesterday's science needed outstanding individuals such as Darwin and Einstein, tomorrow's theories will be shaped by the vast quantities of data pouring forth from networked computers and from the labours of big research teams working in areas such as particle physics, the human genome and astronomy.

The End of Science was also the title of a book published in 1996 by science writer John Horgan, though Horgan thought the pursuit of science was coming to an end for different reasons. He claimed that the basic scaffolding of the natural world is now mostly understood – the big bang theory, the structure of DNA and evolution by natural selection and the periodic table of elements are not going to change. Yes, many refinements are needed in our understanding of how things work, but as we are closer to reality in so many fields, the chances of seeing revolutionary new thinking will be that much less.

Will we never witness a scientific revolution again? And will tomorrow's theories be guided by big data rather than revolutionary ideas?

I recently put these questions to particle physicist Alison Wright, chief editor of the journal Nature Physics and to Lewis Wolpert, pioneering biologist from University College London, when I chaired a debate on the future of science.

Lewis's view is that fundamental biology is now unlikely to throw up any new surprises: there is much we don't know, but the fundamental architecture won't change. Alison takes a similar view for physics and says that we shouldn't expect any new shocks to the system, though, unlike Lewis, she recognises that you can never say never.

I'm with Alison on this – something tells me that physics has the potential to take off in directions that we cannot predict. Many physicists would like to see a single theory explain all of the fundamental forces of nature, or at the very least see experimental verification of the Standard Model of particle physics.

There are good reasons for this. Unification in physics has a long history – electricity and magnetism were unified in the 1800s, and later mass and energy were found to be interchangeable. In the latter half of the 20th century, two further forces were unified: electromagnetism and the "weak" force. But for the past 30 years, experimental verification of theory in physics has been more limited. This may well be because scientists have lacked the right equipment – results from the Large Hadron Collider at Cern could break the logjam.

But you do see something similar going on in physicists' attempts to unpack the composition of the universe. According to the big bang model, our universe is made up of around 4% of normal (atomic) matter; 22% dark matter and 74% dark energy. Some research groups claim to have found a signature for dark matter – but their results have not been corroborated by others. As for the idea of dark energy, Alison describes it as a "sticking plaster" that masks the fact that we don't really know what it represents.

But if we assume for a minute that physics holds the potential for a revolution in thinking, would we be able to see one coming?

Revolutions in scientific thinking are always difficult – but perhaps one reason why we may see fewer of them in the future is because of the highly professional way in which modern science is organised. It takes a lot of courage to challenge conventionally accepted views, and it needs a certain amount of stamina to constantly battle those who want to protect the status quo. Mavericks do not do well in large organisations, which is what some scientific fields have become.

Progress in science needs researchers who are not afraid – or who are encouraged and rewarded – to ask awkward and difficult questions of theory and of new data. It is easier to question mainstream views if you are independently wealthy, as many scientists in previous ages tended to be. But I wonder how many of us would do so if we were employed by the state and our career progression depended on the validation of our peers?

Ehsan Masood is a science writer and chaired Nature's Big Science Debate on the future of physics and biology, which took place on 8 June


Sunday, February 10, 2008

"The Cosmic Connection" by Carl Sagan

From earliest times, human beings have pondered their place in the universe. They have wondered whether they are in some sense connected with the awesome and immense cosmos in which the Earth is imbedded.

Many thousands of years ago a pseudoscience called astrology was invented. The positions of the planets at the birth of a child were supposed to play a major role in determining his or her future. The planets, moving points of light, were thought, in some mysterious sense, to be gods. In his vanity, Man imagined the universe designed for his benefit and organized for his use.

Perhaps the planets were identified with gods because their motions seemed irregular. The word "planet" is Greek for wanderer. The unpredictable behavior of the gods in many legends may have corresponded well with the apparently unpredictable motions of the planets. The argument may have been: Gods don't follow rules; planets don't follow rules; planets are gods.

When the ancient priestly astrological caste discovered that the motions of the planets were not irregular but predictable, they seem to have kept this information to themselves. No use unnecessarily worrying the populace, undermining religious belief, and eroding the supports of political power. Moreover, the Sun was the source of life. The Moon, through the tides, dominated agriculture-especially in river basins like the Indus, the Nile the Yangtze, and the Tigris-Euphrates. How reasonable that these lesser lights, the planets, should have subtler but no less definite influence on human life!

The search for a connection, a hooking-up between people and the universe, has not diminished since the dawn of astrology. The same human needs exist despite the advances of science.

We now know that the planets are worlds more or less like our own. We know that their light and gravity have negligible influence on a newborn babe. We know that there are enormous numbers of other objects-asteroids, comets, pulsars, quasars, exploding galaxies, black holes, and the rest-objects not known to the ancient speculators who invented astrology. The universe is immensely grander than they could have imagined.

Astrology has not attempted to keep pace with the times. Even the calculations of planetary motions and positions performed by most astrologers are usually inaccurate.

No study shows a statistically significant success rate in predicting through their horoscopes the future or the personality traits of newborn children. There is no field of radioastrology or X-ray astrology or gamma-ray astrology, taking account of the energetic new astronomical sources discovered in recent years.

Nevertheless, astrology remains immensely popular everywhere. There are at least ten times more astrologers than astronomers. A large number, perhaps a majority, of newspapers in the United States have daily columns on astrology.

Many bright and socially committed young people have more than a passing interest in astrology. It satisfies an almost unspoken need to feel a significance for human beings in a vast and awesome cosmos, to believe that we are in some way hooked up with the universe-an ideal of many drug and religious experiences, the samadhi of some Eastern religions.

The great insights of modern astronomy have shown that, in some senses quite different from those imagined by the earlier astrologers, we are connected up with the universe.

The first scientists and philosophers-Aristotle, for example - imagined that the heavens were made of a different sort of material then the Earth, a special kind of celestial stuff, pure and undefiled. We now know that this is not the case. Pieces of the asteroid belt called meteorites; samples of the Moon returned by Apollo astronauts and Soviet unmanned spacecraft; the solar wind, which expands outward past our planet from the Sun; and the cosmic rays, which are probably generated from exploding stars and their remnants-all show the presence of the same atoms we know here on Earth. Astronomical spectroscopy is able to determine the chemical composition of collections of stars billions of light-years away. The entire universe is made of familiar stuff. The same atoms and molecules occur at enormous distances from Earth as occur here within our Solar System.

These studies have yielded a remarkable conclusion. Not only is the universe made everywhere of the same atoms, but the atoms, roughly speaking, are present everywhere in approximately the same proportions.

Almost all the stuff of the stars and the interstellar matter between the stars is hydrogen and helium, the two simplest atoms. All other atoms are impurities, trace constituents. This is also true for the massive outer planets of our Solar System, like Jupiter. But it is not true for the comparatively tiny hunks of rock and metal in the inner part of the Solar System, like our planet Earth. This is because the small terrestrial planets have gravities too weak to hold their original hydrogen and helium atmospheres, which have slowly leaked away to space.

The next most abundant atoms in the universe turn out to be oxygen, carbon, nitrogen, and neon. These are atoms everyone has heard of. Why are the cosmically most abundant elements those that are reasonably common on Earth-rather than, say, yttrium or praseodymium?

The theory of the evolution of stars is sufficiently advanced that astronomers are able to understand the various kinds of stars and their relations-how a star is born from the interstellar gas and dust, how it shines and evolves by thermonuclear reactions in its hot interior, and how it dies. These thermonuclear reactions are of the same sort as the reactions that underlie thermonuclear weapons (hydrogen bombs): The conversion of four atoms of hydrogen into one of helium.

But in the later stages of stellar evolution, higher temperatures are reached in the insides of stars, and elements heavier than helium are generated by thermonuclear processes. Nuclear astrophysics indicates that the most abundant atoms produced in such hot red giant stars are precisely the most abundant atoms on Earth and elsewhere in the universe. The heavy atoms generated in the insides of red giants are spewed out into the interstellar medium, by slow leakage from the star's atmosphere like our own solar wind, or by mighty stellar explosions, some of which can make a star a billion times brighter than our Sun.

Recent infrared spectroscopy of hot stars has discovered that they are blowing off silicates into space-rock powder spewed out into the interstellar medium. Carbon stars probably expel graphite particles into surrounding cosmic space. Other stars shed ice. In their early histories, stars like the Sun probably propelled large quantities of organic compounds into interstellar space; indeed, simple organic molecules are found by radio astronomical methods to be filling the space between the stars. The brightest planetary nebula known (a planetary nebula is an expanding cloud usually surrounding an exploding star called a nova ) seems to contain particles of magnesium carbonate: Dolomite, the stuff of the European mountains of the same name, expelled by a star into interstellar space.

These heavy atoms-carbon, nitrogen, oxygen, silicon, and the rest-then float about in the interstellar medium until, at some later time, a local gravitational condensation occurs and a new sun and new planets are formed. This second-generation solar system is enriched in heavy elements.

The fate of individual human beings may not now be connected in a deep way with the rest of the universe, but the matter out of which each of us is made is intimately tied to processes that occurred immense intervals of time and enormous distances in space a way from us. Our Sun is a second or third-generation star. All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star stuff.

Our atomic and molecular connection with the rest of the universe is a real and unfanciful cosmic hookup. As we explore our surroundings by telescope and space vehicle, other hookups may emerge. There may be a network of intercommunicating extraterrestrial civilizations to which we may link up tomorrow, for all we know. The undelivered promise of astrology-that the stars impel our individual characters - will not be satisfied by modern astronomy. But the deep human need to seek and understand our connection with the universe is a goal well within our grasp.



From The Cosmic Connection: an Extraterrestrial Perspective. Copyright 1973 by Carl Sagan. Published by Anchor Press / Doubleday.

Wednesday, April 25, 2007

Enigma of ancient computer solved

antikythera"The computer is so advanced in its mathematics and technology that the history of ancient Greece may have to be rewritten, contends Edmunds. 'We now must ask: What else could they do? That's a difficult thing, because this is really the only surviving metallic artefact of its kind. Who knows what else may be lost?'

It was not until the end of the first millennium AD and the golden age of Islamic science that anything so technologically wondrous surfaced again..."


Here's the rest

Earth-like planet found outside solar system

newplanet-eso-070424"Astronomers in Europe have discovered the most Earth-like planet to date outside our solar system, one they say could potentially hold liquid water, a necessary ingredient to support life.

Scientists with the European Southern Observatory say the planet, discovered orbiting a red dwarf star 20.5 light years away, is the smallest of those found outside our solar system."


Here's the rest

Monday, April 16, 2007