LECTURES AND TALKS
COSMIC DAWN
As first light from the first stars transforms the universe from the dark ages into cosmic dawn, the history may be traced in redshifted 21-cm from neutral hydrogen in the gas. Efforts to build precision radio telescopes to detect this faint signal are beginning to yield results of significance to the theory, thus constraining the starlight of the earliest galaxies.
14 JANUARY 2020
UNDERSTANDING THE UNIVERSE
Telescopes give panoramic visions of galaxies and stars in our present day nearby universe. We live in an expanding universe; therefore, light from early times in the history of the universe arrives on Earth shifted to the red as far as radio waves, and radio telescopes on ground and in space have given us a vision of the time when the first atoms formed and the universe was a very uniform hot gas. Understanding the transformation from that primordial gas to stars and galaxies is an unsolved problem.
13 JANUARY 2020
THE SOUTH AFRICAN LARGE TELESCOPE
The Southern African Large Telescope (SALT) is the largest single optical telescope in the southern hemisphere and among the largest in the world. It has a hexagonal primary mirror array 11 metres across, comprising 91 individual 1m hexagonal mirrors. SALT is situated at the South African Astronomical Observatory (SAAO) field station near the small town of Sutherland, in the Northern Cape province, about 400 km from Cape Town.
20 NOVEMBER 2019
SCHRODINGER'S CAT AND EINSTEIN'S SPACE TIME
Quantum mechanics works beautifully in the realm of elementary particles, atoms and molecules. But it seems to fail for large objects, even though large objects are made of particles which by themselves obey quantum mechanics. What is the reason for this failure? Einstein's theory of relativity works beautifully for space-time and large objects, but seems to fail in the realm of particles and atoms. What is the reason for this failure?
10 NOVEMBER 2019
BARYON ACOUSTIC OSCILLATIONS
The lecture began with a look at humanity’s approaches at map making through the ages, beginning with the assumption of a flat circular earth atop a cylinder to the globe-like shape we know today. The lecture went on to cover the correlation between Cosmic Microwave Background (CMB) radiation, its fluctuations and the expansion of the universe. He then discussed the dragging effect of photons on baryons (particles composing of three quarks, such as protons and neutrons). He explained the angular fluctuations observed due to this phenomenon can be used to understand and map the geometry of the universe. He finally explained the phenomenon of Baryon Acoustic Oscillations (BAO), which is, according to him, cosmology from the same physics imprinted in the galaxy distribution at different distances from us.
9 NOVEMBER 2019
FAULT IN OUR PHYSICS
The combination of escapism and delving into wonderful worlds with infinite possibilities, brought to us by science fiction sure does entertain our minds. Along with inspiring ideas and methods, it allows us to look at the bigger picture. This particular lecture takes it a step forward by analysing the way in which various sci-fi movies managed to break the boundaries of physics and for what purpose. In what other ways could a particular stunt be done and what else could be achieved in a universe with such laws.
9 NOVEMBER 2019
NUMERICAL RELATIVITY
Numerical relativity allows us to recreate cataclysmic cosmic phenomena that are otherwise inaccessible in the conventional laboratory – like gravitational collapse to black holes and neutron stars and the generation and propagation of gravitational waves. With supercomputers, it is now possible to tackle these equations numerically and explore these scenarios. That is the main goal of numerical relativity, the science of developing computer algorithms to solve Einstein’s equations for astrophysically realistic, high-velocity, strong-field systems.
22 OCTOBER 2019
ICE CUBE
The IceCube project at the South Pole melted eighty-six holes over 2.5 kilometers deep in the Antarctic icecap to construct an enormous astronomical observatory. The experiment recently discovered a flux of neutrinos reaching us from the cosmos, with energies a million times those of neutrinos produced at accelerator laboratories. The observation launches an entirely new way to study the universe because these cosmic neutrinos are astronomical messengers reaching us from some of the most violent processes in the early universe since the Big Bang.