As one of my three-part series on the The Science Academies’ three-day lecture workshop on astronomy—which I am attending presently—here are the proceedings of the inaugural first day.
The Science Academies
The three day workshop focusing on undergraduate and graduate students of physics was convened by Dr R Srinivasan, a Fellow of The Science Academies—an association of the three leading science academies in India: the Indian Academy of Sciences, Bangalore; the Indian National Science Academy, New Delhi; and the National Academy of Sciences, Allahabad.
The Science Academies conducts regular Three-day Lecture Workshops all over the country, focusing on various disciplines; and this particular one was organised by the physics department of Yuvaraja’s College in Mysore, under the University of Mysore.
Eminent physicists will be taking part in the event, with Professors G Srinivasan and Biman Nath of the Raman Research Institute delivering four lectures on the first day. They will be continuing onto the second day when Prof Uday Shankar, also from the Raman Research Institute, and Dr Sreekumar from the Indian Space Research Organisation [ISRO] will be joining them.
Prof Srinivasan is scheduled to deliver a four lecture series on the birth and death of stars and Prof Nath is to speak on contemporary understanding of the universe. Prof Uday Shankar will be speaking on Radio Astronomy and Dr Sreekumar on X-ray astronomy.
Prof Srinivasan is a contemporary of the likes of Fermi and Chandrashekhar which necessarily makes it a privilege to interact with him. He is an alumnus of the University of Chicago and has worked at the IBM lab in Zurich and the Cavendish laboratory in Cambridge.
The start of the day
A little more had to be scheduled, understandably, on the first day because of introductory and inaugural speeches and formalities. While that took away a whole hour of what would otherwise have been scheduled as lecture time, it did not seem much because the entire event was started on the dot, at the strike of ten, as planned.
One particular statement in Prof Srinivasan’s introductory statement that appealed to me was his retelling of Rachel Carson’s words when Carson was asked in an interview what he would like to be born as if he were to be reborn:
“[If I were born again] I wish to be born with a sense of wonder.”
Four lectures were in for schedule today and they went on beautifully. The first was a lecture detailing the life of stars—their birth being still a debated, but unsettled issue, he did not want to begin by treading on softer paths. Titled ‘What are the stars?’ like his first book in his series, The Present Revolution in Astrophysics, the lecture began with man’s first look at the night skies. How we figured stars to be piercings in the sky and how we had but little idea about it until the 19th century. The common (and rather silly, as I thought) notion that it is the nature of things that one will never know what stars were.
A sort of history-of-physics-approach was taken, sprinkled with mathematics, all the way from Fraunhofer’s discovery of the solar spectrum in 1817 to Kirchoff’s laws of radiation to measuring the temperature, density and other physical parameters associated with the sun—indirectly—all the way to Sir Arthur Stanley Eddington’s explanation of how gravity exactly balances out the ideal gas and radiation pressures to stabilise a ball of gas: the first successful, scientific description of a star. Thus began the first part of our day.
Why even Superman cannot see inside a star
Then he discussed the Virial theorem and how one could use it to calculate the temperature of the sun without any experimentation whatsoever. Having detailed how the large temperature would push all electromagnetic phenomenon inside the sun towards the X-ray region, making it invisible to man, he put forth a rather interesting hypothesis: even Superman—who has X-ray vision—would not be able to see inside a star.
By this I mean, he cannot see anything; not even the tip of his nose. Prof Srinivasan then discussed Thomson scattering and how the high temperature would ionise the particles inside the sun, giving rise to an opportunity for the fine Thomson scattering which would in turn scatter particles so much (large scattering can occur even during the time period in which the X-rays strike the nose and reach your eyes) that it would be impossible for him to see even the tip of his nose!
The talk then entered the areas of luminosity and how it depended—almost strangely—solely on the mass and not even on the radius. Then he moved on to Eddington’s proposition of fusion inside a star a full decade before the idea came out prominently; the reasons why it is impossible to manually fuse two (let alone four) protons; the Maxwell-Boltzmann distribution; and George Gamow’s brilliant discovery of quantum tunneling. He ended on a historically peaking note, detailing Hans Bethe’s famed 1938 paper detailing—as he put it—the ‘start and end’ of the entire problem of proton fusion and its complete solution/explanation.
The expanding universe
In a knowledgeable second session that seemed to last shorter than an hour, but really went well past it, Prof Biman Nath went on to introduce the attendance to the comparisons of the cosmic scales he was about to delve into. From light minute distance between the Sun and earth to light hours to Neptue to light years between stars to billions of light years across the observable universe, Prof Biman Nath dedicated a lot of time into making the cosmic size apparent.
Then he proceeded to mathematically detail a homogeneous, isotropic universe of all possible curvatures (zero, negative, positive) sans gravity and one at the centre of which an observer was and then corrected all these assumptions to arrive at a more practical situation without involving too much of Einstein’s General Relativity. The final result was the astounding proof of how Hubble’s constant—in an expanding universe which Hubble himself proposed—would not really remain constant!
To burn or not to burn? That is the question
We broke to luncheon but spent more time admiring—and buying—books (at discounted rates) from a small stall hosted by Universities Press showing well-researched, almost revered books, in the subject. Having gone past schedule by half-an-hour owing to extensions in the lecture times, the lot of us decided to spend as little time as possible in filling our stomachs and, in its stead, head back to exercise our minds with a lot more physics.
Prof Srinivasan’s second lecture on the principles of statistical mechanics—designed to prepare the audience for the third and fourth lectures—took off from where the first talk ended: the contraction hypothesis. He explained how the apparent perpetual expansion-contraction/heating-cooling phenomenon that was the strange hypothesis could be dealt with and then introduced the formation of heavier elements and its consequences.
Walter Adams’ problem of the density excess in the Sirius binary star system was next on hand and a deviation towards statistical mechanics was necessary. From here on he explored Fowler’s examination of the Eddington paradox and alongside this, explained the basics of quantum mechanics such as Heisenberg’s Uncertainty Principle and Pauli’s Exclusion Principle and the basic differences between the classical and quantum universes.
Having gone through Maxwell’s velocity distribution, zero-point motion, spin angular momentum, bosons and fermions, and once again—and this time more convincingly—re-examined Eddington’s paradox and Fowler’s alternative explanation to it, Prof Srinivasan ended his last lecture for the day.
The Darkness out there
The last lecture for the day was Prof Biman Nath’s once again, and he spoke of the history of the universe. Linking it to his previous talk with the curvatures of the universe and its expansion/contraction instances, Prof Nath went on to derive the shocking relationship between the time period, the Universal Gravitational Constant and matter density. This relation—as Prof Srinivas later explained to us—is simply shocking because it also relates the time periods of a body left to oscillate through a tunnel dug across the centre of the Earth, of the Earth itself vibrating on being struck and so on!
Then he arrived at the present situation and how we are facing a problem as the experimentally observed rate of expansion seems unlike any of the previously seen/expected circumstances. The universe had to either expand and contract or expand at deceleration up to infinity. The observed situation, however, happens to be that the universe, after having slowed down in its expansion, is now once again accelerating!
This was unforeseen and has been attributed to a mysterious Dark Matter and its associated Dark Energy. The required amount being derivable from the know value (as we have seen before) of the ratio of the present density of the universe to its critical density; the value thus attributed to Dark Matter becomes a good 0.73, which, in a ratio, equals about 73% of all the known mass of the observable universe. More about this, he promised, would be discussed the following day.
The talk was ended with an extensive look into Cosmic Microwave Background Radiations and neucleosynthesis.
Preparing for tomorrow
After the fourth lecture, a small discussion was held lasting about half-an-hour. Important, recommendable books such as Steven Weinberg’s The First Three Minutes were stated since we had just discussed close to the first two hundred seconds in complete detail.
The stage was set for tomorrow with the speakers inviting us an hour early for discussions before the actual lectures began. So my day would start at nine tomorrow and I will, perhaps, have more to share over the next two days.