Decoding Nobel Prize for Physics, Medicine & Chemistry

Half the Nobel Physics prize for 2019 was awarded to James Peebles of Princeton University for his seminal contributions which enabled understanding of the evolution of the universe after it originated in a very hot dense phase dubbed as the “big bang”. Along with others like George Gamow, he along with Robert Dicke independently predicted the existence of the cosmic microwave background radiation (CMBR), the so-called afterglow of the Big Bang. This background radiation — which has now cooled to a temperature of about three degrees kelvin with the expansion of the universe — was detected serendipitously by Penzias and Wilson in 1965, which won them the Nobel Prize in 1978. Over the past decades, four prizes have been given for cosmology, starting from Penzias and Wilson, then in 2006 to Smoot and Mather for their detailed study of the CMBR using the COBE satellite and the 2011 prize for the discovery of dark energy (Perlmutter, Schmidt and Riess) and now the 2019 prize.

The paper accompanying the Penzias and Wilson paper was authorized by Dicke, Peebles and others, predicting the existence of such radiation. Subsequent theoretical work of Peebles has enabled wonderful high precision measurements of the CMBR over the last three decades. He helped develop the theoretical frameworks for cosmic structure formation which describes how galaxies and other large scale structures emerged from the primordial density structures in the universe. With his theoretical tools and calculations, Peebles was able to interpret the trace radiation from the infancy of the universe, discovering new physical processes in the CMBR structure as also the synthesis of light elements in the very early phase of the universe. Among other things, his work led to the paradigm that the familiar matter of which we are made and that surrounding us like stars, planets and living systems constitutes only five per cent of the matter in the universe. This implies that 95 per cent of the matter in the universe is unknown dark matter and dark energy which poses future challenges to fundamental physics. His is a lifetime work, his books Principles of Physical Cosmology and Large-Scale Structure of the Universe are like a bible in the subject.

The other half of the 2019 Physics prize is shared by Michel Mayor and Didier Queloz of the University of Geneva. They made the groundbreaking discovery of the first exoplanet, a hot Jupiter orbiting the star 51 Pegasi, in 1995 just 25 years ago. Prior to their discovery astronomers have been debating the existence of exoplanets for several decades. They detected this using the so-called radial velocity method, wherein the planet tugs gravitationally on its host star causing it to wobble periodically with a small velocity which can be detected by the Doppler Effect. Jupiter for instance, makes the Sun wobble by 13 metres per second.

It is remarkable that in the 25 years since this pioneering discovery, over four thousand exoplanets have been found orbing other stars, proving that our solar system is by no means unique and there may be as many as a billion earth-like planets in our galaxy. A larger fraction of these planets were discovered by the Kepler satellite which employs the transit method. New spacecraft like the TESS are continuing to find more and more new planets. These exoplanets come in all sizes, masses, temperatures, compositions, etc. Many are smaller than the earth. Some are water dominated while others have toxic gases like Venus. In short a whole menagerie of planets. The physics and chemistry underlying these objects are of much current interest with the James Webb Space Telescope looking for possible biosignature to detect life on these exotic worlds.

The 2019 Nobel Prize for Physiology or Medicine was awarded to Sir Peter J Ratcliffe of Oxford, William Kaelin Jr of Harvard and Gregg L Semenza of Johns Hopkins. They share the prize for their discoveries concerning how body cells sense and adapt to varying oxygen levels. The fundamental importance of oxygen in our body metabolism has been known for long. For instance, oxygen attaches to the haemoglobin molecule in our blood enabling it to be transported to different organs for various building processes. However, the way cells adapt to changes in oxygen levels has not been understood until their important work. Oxygen levels in the body can vary during exercises, at high altitudes or when blood supply is disrupted during injuries. When the levels drop, the cells have to rapidly adjust their metabolism. The oxygen sensing ability of the body plays a role in immune systems, in anaemic (lack of iron) cancer and even the earliest stages of natal life. It can trigger the production of erythrocytes (red blood cells) or constrict blood vessels. So drugs mimicking the process can effectively treat anaemia.

Again tumours can create new blood vessels and grow. Drugs that reverse this process may help halt the growth of cells. The work of these scientists and their team has led to a better understanding of this common life-threatening conditions leading to novel methods of treatments. Levels of the hormones erythropoietin (EPO) were shown to rise as oxygen levels fall. They found that this occurred due to a cluster of proteins called hypoxic inducible factor (HIF) changing the behaviour of the DNA, the genetic code. When oxygen levels were normal, cells constantly produced HIF only for it to be destroyed by another protein VHL. When oxygen levels fell, VHL will no longer tag the HIF leading to the build-up of oxygen levels. Thus, we have an elegant self-sustaining mechanism by which our cells sense oxygen levels and respond. So the above molecular ‘switches’ regulate how cells adapt to fluctuating oxygen levels leading to new techniques to treat heart failure, strokes, etc.

In short, their discoveries are being used by medical resources to treat various diseases by either actively or blocking the cellular oxygen sensing molecular machinery. Oxygen is vital for survival for every cell. Understanding how evolution has equipped cells to respond to fluctuating oxygen levels (during exercise, high altitudes, diseases, injuries, etc.) enables us of those processes for our health.

The 2019 Nobel Prize in Chemistry was shared by John B Goodenough, M Stanley Whittingham, and Akira Yoshino. At 97, Goodenough becomes the oldest Nobel Laureate, while the other two are septuagenarians. They were pioneers in the development of Lithium-ion batteries which among other things led to the mobile phone revolution. These batteries find ubiquitous use in the telecom and communication industry, transportation (electric vehicles), energy storage from renewable sources as also in medical applications like pacemakers along with a plethora of other applications.

In a sense, they have revolutionised our social set up; entering all areas of human existence. Whittingham laid the foundation for the development of these batteries when he researched fossil-fuel-free energy technologies during the oil crisis of the 1970s. Indeed the work is an offshoot of endeavours to find fossil-fuel-free energy-producing and storing devices arising from the 1973 oil crisis that leads to a vast increase in petroleum prices. Whittingham came up with an innovative cathode that could host lithium ions. But the voltage was low. Goodenough built on this research in the 1980s by doubling the voltage output demonstrating a battery holding 4V of charge. Subsequently, in 1985, the Japanese chemist Yoshino developed the first commercially viable Lithium-ion battery. This lightweight, rechargeable, powerful battery is also used in devices to store a significant amount of energy from solar and wind power, making possible the reality of a fossil fuel society. Indeed in the face of increasing ecological threats from extreme climate change, this year’s prize is particularly appropriate.

Whittingham discovered an energy-rich material, titanium disulphide, which he used to make a cathode. He made the anode from metallic lithium. This arrangement showed a strong preference for releasing electrons making it very suitable for use in batteries. Goodenough showed that the cathode could be improved if made of a metal oxide rather than sulphide. In 1980, after searching for the ideal material, Goodenough used cobalt oxide to boost or double the battery voltage. Using this cathode as the basis, Yoshino created first commercial Lithium-ion battery in 1985, while working for Asahi Kasei Corp and Meijo University. The resulting high powered, high energy-efficient battery is the one which now has universal application. Yoshino remarked that he was glad to help the environment with this invention, free of any fossil fuels.

However, in future, a shortage of lithium, now mainly produced in Chile and China, is already leading to research in alternate battery power systems.