Pondering Big Cosmology Questions Through Lectures and Dialogues

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Pondering big questions in Cosmology:

What We Know & What We Don’t Know?

Cosmology in the 21st Century:

Shedding New Light on Black Holes

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In this one-hour public lecture, Josh Frieman, director of the Dark Energy Survey, presents an overview of our current knowledge of the universe and describes new experiments and observatories.

Forget what you think you know about dark matter. After a 30-year search for a single, as yet unidentified, species of dark matter particle that would make up some 25% of the mass of the universe, physicists are starting to consider novel explanations.

PI Public Lecture Series with a talk about the remarkable simplicity that underlies nature. Turok discusses how this simplicity at the largest and tiniest scales of the universe is pointing toward new avenues of physics research and could lead to revolutionary advances in technology.

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CMB radiation is one of the most important discoveries in the 20th Century, it traces the origin of the Universe from its early very hot, dense epochs famously known as the Big-Bang.

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LSST DESC Seminar May 22, 2019 by Jo Dunkley from Princeton University - The Hubble constant, \(H_{0} \) Discrepancy: Evidence for New Physics?

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Cosmology: Galileo to Gravitational Waves - with Hiranya Peiris

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"Robert P. Kirshner, the Clowes Research Professor of Science in the Harvard Faculty of Arts and Sciences, set out to find the deceleration of the expansion of the universe, only to find something else: amazingly, the measurements showed the expansion of the universe to be speeding up. The astonishing (un)discovery of cosmic acceleration has now been confirmed from many directions—and attributed to a “dark energy” that dominates the universe, whose nature is a deep mystery at the heart of physics."

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"After matter decouples from the afterglow radiation of the Big Bang at z~150, the primordial gas cools adiabatically, becoming cooler than the cosmic microwave background (CMB). Atomic collisions are effective at coupling spin and gas temperatures while the universe is dense, leading to a 21 cm absorption signal at high-redshift. Collisional coupling becomes ineffective as the Universe expands, diluting the gas, and the spin temperature slowly re-equilibrates with the CMB. However, once the first stars form, they produce a background of UV photons that again couple spin and gas temperatures leading to a second absorption regime at z~20. After the first stars die, they leave behind compact objects, such as black holes and neutron stars that, through accretion, generate X-rays. Along with emission from early quasars and stars, these X-rays travel long distances depositing their energy as heat. This raises the IGM temperature (around z~15) and eventually leads to a 21 cm emission signal. As further galaxies form, ionizing radiation leads to large ionized bubbles that begin the process of reionization (z < 15). Ultimately, all neutral hydrogen in the diffuse IGM is ionized and the 21 cm signal ends (z~6)." Reference: EDGES Science

See also MIT news: http://news.mit.edu/2018/astronomers-de ... verse-0228

Cosmological scale

Source: MIT Haystack Observatory, see also
EDGES