Seventeenth Marcel Grossmann Meeting

Public lectures

	Wendy Freedman	Is There Something Missing from our Current Understanding of the Cosmos? In 1929, Carnegie astronomer Edwin Hubble discovered  that the universe is expanding, and revolutionized our perspective on the universe. Decades of discovery followed. The launch of the Hubble Space Telescope (HST)  in 1990 enabled astronomers to make measurements of the universe of unprecedented accuracy. Professor Freedman will describe how astronomers measure how fast the universe is expanding, a quantity known as the Hubble constant, which gives a measure of the size and the age of the universe.  Recently, a new debate has emerged about the Hubble constant, potentially calling into question the standard model of cosmology, and raising the question of whether there is more exotic physics yet to be uncovered. Professor  Freedman will present some new data from the recently launched James Webb Space Telescope that promises to resolve many of the issues currently confronting cosmology.
	Katherine Freese	The Mystery of Dark Matter in the Universe The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5% of all matter and energy in the cosmos. The remaining 95% is made up of a recipe of 25% dark matter and 70% dark energy, both nonluminous components whose nature remains a mystery. Freese will recount the stories of the dark matter puzzle, starting with the discoveries of visionary scientists from the 1930s who first proposed its existence, to Vera Rubin in the 1970s whose observations conclusively showed its dominance in galaxies, to the deluge of data today from underground laboratories, satellites in space, and the Large Hadron Collider. Theorists contend that dark matter most likely consists of new fundamental particles; the best candidates include WIMPs (weakly interacting massive particles), axions, light or fuzzy dark matter, or even primordial black holes. Billions of them pass through our bodies every second without us even realizing it, yet their gravitational pull is capable of whirling stars and gas at breakneck speeds around the centers of galaxies, and bending light from distant bright objects. In this talk Freese will provide an overview of this cosmic cocktail, including the evidence for the existence of dark matter in galaxies. She will also talk about Dark Stars, early stars powered by dark matter, that may have already been discovered by the James Webb Space Telescope.  Solving the dark matter mystery will be an epochal moment in humankind's quest to understand the universe.
	Annapurni Subramaniam	Thirty Meter telescope – India’s participation In Late 2014 India joined the International consortium for building and operating next generation mega ground based optical and infrared astronomy facility known as the “Thirty Meter telescope (TMT) International Observatory (TIO).   India's in-kind contributions include Primary mirror Segment Support Assembly (SSA), Actuators, Edge Sensors, Primary mirror Segment Polishing, Observatory Software (OSW) and Telescope Control Software (TCS), M1/M2/M3 segment coating plants and Science Instruments. India is participating in the first light science instrument WFOS and leading the effort for the second-generation instrument HROS – a high resolution spectrograph. I will present the science goals and the current status of the activities.