A look into the past of our universe, wins this year’s Nobel Prize in Physics.

A look into the past of our universe, wins this year’s Nobel Prize in Physics.

The year 2019 has been an exciting year for global space enthusiasts, particularly in India. It happens to be the fiftieth year of the monumental ‘Giant Leap’ for mankind (Moon landing), the fiftieth year of the formation of the Indian premier Space research institution - the ISRO - and also the centenary year of Dr Vikram Sarabhai - the founding father of Indian space programmes. The icing on the cake came with yesterday’s announcement of this year’s Nobel Prize in Physics, which honoured the the discoveries of the early universe and the exoplanets.

From the dim millennium of prehistory, humankind’s quest for observation, particularly the heavenly bodies, clubbed with the evolutionary trait of opposable thumb and bipedalism helped man to scale up to the top of the evolutionary pyramid and it is this quest that enabled humankind to advance knowledge, stretching far beyond the realms of our physical world, to the origin of our universe and humanity’s position in this unending cosmos. This year’s Nobel prize in physics recognises the contributions of three scientists who helped in our understanding of the origin of our universe and the discoveries of Exoplanets. James Peebles, a physicist at Princeton University, won half the Nobel prize (9 Million Swedish Krona) for his contributions to the physical cosmology, while Michel Mayor, a physicist at the University of Geneva, and Didier Queloz, an astronomer at Geneva and at the Cavendish Laboratory in Cambridge, shared the other half, for their discovery of an exoplanet orbiting a sunlike star.

James Peebles - Bhishm peetamah in the field of cosmology -, professor emeritus at Princeton University, has helped us in understanding how from the Big Bang, the universe has swirled into galaxies and stars and other heavenlybodies, which we now see in the night sky, and so also other stars and galaxies that we cannot see. Michel Mayor and Didier Queloz, were the first to discover an exoplanet, or a planet circling around our sun-like star. James Peebles has been studying the cosmos and trying to understand about the formation of the universe and its constituents for more than six decades. From the beginning of the 1960s, when the information and knowledge available in the field of cosmology was sparse and imprecise, Peebles has been painstakingly trying to understand the origin of our universe. Although astronomers had observed the cosmos and its constituents - the stars, galaxies, clouds of gas etc . - through telescopes, unfortunately they were struggling to explain much about them - the constituents of the Universe. Even the fundamental knowledge of the cosmological distances between celestial bodies or the age of the universe were imprecisely defined and measured. In doing so, there was also a wide variance to such measurements. Dr. Peebles’s research laid the foundation for the subject of cosmology to be more precise and that it relied on mathematical foundations.

The first of the evidence for the contributions of Peebles came in 1964-65, when two radio astronomers, Arno Penzias and Robert Wilson, discovered - by serendipity - a background hiss of microwaves pervading the universe - Cosmic Microwave Background (CMG) -, which was an ancient light emitted when the universe was some 380,000 years old. The CMB provides a snapshot of the young universe. Penzias and Wilson were perplexed with the CMB, until they came across theoretical calculations of Peebles and others who had predicted this background radiation, which was a result of the universe cooling some 400,000 years after the Big Bang and thus producing the first of the chemical elements - the hydrogen and helium atoms - the forerunners to the world we know today. Peebles made detailed calculations (1966) of the abundances of difervent isotopes that would have been produced in this process, known as Big Bang nucleosynthesis. Ever since, Dr Peebles has been involved in most of the major developments, particularly post discovery of the CMB, in 1965. Later, in the 1970s, Peebles pioneered the theory of cosmic structure formation, which throw light into how the universe evolved into galaxies and dark matter and dark energy, which we now understand, what the entire universe is made up of in the present. Peebles work showed that the matter known to us only make up five percent of the universe, while the other 95 percent is made up of "unknown dark matter and dark energy".

It is for this reason that the Royal Swedish Academy of Science, while announcing the Nobel Prize said “ Dr. Peebles’s work on physical cosmology enriched the entire field of research and laid a foundation for the transformation of the science of cosmology over the past 50 years, from speculation to science.”

Are we alone in the unending universe and are is planet Earth and our solar system unique? This was one of the profound questions that was central to human curiosity. Fortunately astronomers had long presumed that there must be planets - similar to our solar system - in orbits around many other stars. But for several years, until 1992, astronomers could not locate any such planets. Whatever little claims of spotting planets that came up, could not stand closer scientific scrutiny to the exacting standards of science. But then in the year 1992, astronomers found the first planets outside the solar system, which orbited an exploded star, making them an unlikely place for life to exist. Three years later this year’s Nobel laureates - Dr. Mayor and Dr. Queloz - successfully found a planet around 51 Pegasus, a star similar to our sun, 50 light years away. Although this planet too was not habitable, it laid the foundation for the astronomers to study planetary systems that could be similar to our own. Dr. Mayor and Dr. Queloz did not see the planet directly. Rather, they looked at a ‘periodic wobble’ in the colors of light from the star. The gravity of the planet pulled on the star. The motion back and forth shifted the wavelengths of the starlight (Blue and Red Shift) much like what we experience when we hear a horn of a train or the siren of an ambulance, which rises in its pitch when approaching and falls when receding ( Doppler effect). This discovery was soon confirmed by other astronomers. This finding forms the basis for our modern understanding of the universe. The discovery of the first planet outside of our solar system, announced by Dr. Mayor and Dr. Queloz in 1995, has revolutionised astronomy. Now it is estimated that more than 4,000 exoplanets have been discovered in our Milky Way galaxy, some of which could be habitable. More and more planets are being spotted with more minds and money pooling into the search. With numerous projects planned to start searching for exoplanets, we may eventually find an answer to the eternal question, are we alone in the universe?

As we march towards our interplanetary exploration in which India too is actively involved with our plans for Chandrayaan, Gaganyaan and Mangalyaan, and we aim for those illusive years when man is likely to colonise outer planets, it is now time for us to celebrate and hail this year’s Nobel Laureates who paved way for this exploration.