Decoding the cosmos - with Hiranya Peiris

Unravel the profound mysteries of the universe's explosive birth.

This talk was recorded at the Ri on 26 April 2024.

Just a century ago, observational evidence established the existence of other galaxies besides our own. Soon afterwards, it was discovered that the Universe is expanding, driving a profound change in our understanding of the cosmos. In 1998, the prevailing cosmological paradigm was again upended by the discovery that the Universe's expansion is accelerating.

Since then, the remarkable progress in cosmology, spanning Peiris's research career, has been driven by the close interplay between theory and observations. Observational discoveries have led to a Standard Model of cosmology with ingredients not present in the standard model of particle physics – dark matter, dark energy, and a primordial origin for cosmic structure. The physical nature of these ingredients remains a mystery. The race to unravel this cosmic puzzle is now underway, motivating a new generation of ambitious sky surveys across the electromagnetic spectrum and using new messengers such as gravitational waves.

Peiris describes some highlights from her journey through this rapidly changing cosmological landscape in this discourse. She also discusses how laboratory experiments are helping us test new fundamental physics paradigms developed to explain cosmological observations.

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00:00 Intro
1:30 How do we know about the universe?
7:55 Tracing the light of galaxies
13:00 The Legacy Survey of Space and Time (LSST)
16:53 Mapping dark matter with gravitational lensing
22:30 How do we know how far away galaxies are?
32:03 Using machine learning to explore galaxies
35:50 Detecting dark matter in the lab
46:31 The Universe on a table-top
54:58 Condensed matter experiment and cosmology

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Hiranya Peiris holds the Professorship of Astronomy (1909) at Cambridge, the first woman to do so in the 115-year history of this prestigious chair. As a cosmologist, she delves into cosmic mysteries at the edge of our understanding, reaching back to the very first moments of the Universe after the Big Bang, often treading the path of high risk and high reward. She is noted for interdisciplinary research bridging fundamental physics with astronomical data. Peiris recently contributed to the anthology “The Sky Is For Everyone” and works to reach beyond traditional audiences for public engagement, including through science/art collaborations and live science/music events. Her work has been recognised by awards such as the Max Born Prize of the German Physical Society and the Institute of Physics (2021), the Eddington Medal of the Royal Astronomical Society (2021) and the Breakthrough Prize in Fundamental Physics (2018).
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Discourses are one of the Ri’s oldest and most prestigious series of talks. Since 1825, audiences in the theatre have witnessed countless mind-expanding moments, including the first public liquefaction of air by James Dewar, the announcement of the electron by JJ Thomson and over 100 lectures by Michael Faraday. In more recent times, we have had Nobel laureates, Fields medal winners, scientists, authors and artists – all from the cutting-edge of their field. Discourses are an opportunity for the best and brightest to share their work with the world.

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[mkree]

Science is a role model on how to evolve as society. I am always impressed to see people talking with such a joy about what they do in live. These are the real heroes, not the people trying to spread hate and dissonnance!

[toma]

I'm impressed by the quality of presentations from the Royal Institution. Always top notch.

[ulrichmachtle]

Best visualization I've ever seen, this glass lens is awesome

[billyodonoghue]

Is anybody else staring at what im staring

[MrTobitobitobitobi]

This was a great presentation of a very complex subject!

[franciscogeorge]

FROM BRAZIL: WHAT A GREAT PRESENTATION!!! SHE WAS FANTASTIC. CONGRATULATIONS...

[troymosher]

I grasped the concept of using gravitational lensing to map dark matter. A very cool demonstration. Thank you for this work.

[jamiehenworth]

What a great presentation from an intelligent woman who understands how to explain very complex subjects to someone like myself.
I wish my science teachers at secondary school were as awesome as Hiranya

[karlstraub]

Lovely presentation overall. Just a gentle note, with respect, that your Tibetan singing bowl demo shows movement of water, yes, but that is not the same thing as phase change. There is no phase change as suggested in your demo. I presume that your viewers who already have basic physics knowledge will know that, but I hope you will correct this error in notes, and in future episodes to avoid misinforming the general public further. The rest of your talk was great. Best wishes on your continued inspiring lectures!

[horningjan]

This should become the standard of excellence against which all other RI lectures are measured.

[karagi]

So many lunatic cosmologists come to the comment section these days!

[chadb]

54:52 anyone who understands anything about the amount of energy water takes to change phase knows that that little, minuscule sound energy you put into that bowl changed, no phase. It caused waves that splashed, but there was no liquid water to water vapor phase change going on there.

[dadsonworldwide]

I'm proud that we are back to objectivism and not every object is physical.
That idealism & subjective systems can have eqaul sigma 6 measure on par with physicalism. .
And subjectivity Is not idealism or physicalism lol
96% of the universe is subjective properties like hamiltonian oscillating waves or feilds. Gravity is not idealism nor physicalism.
I understand the ease of access teaching everything is physicalism plus needs and demands of the era I grew up in but is was wrong, ugly and combative for those of us well connected to how we came to know.what we know think what we think, english orientation and direction that dictates all longitude and latitude that all the world adopted as our elusive prosperity

[TRGopalakrishnanNair]

Well, The concept of dark matter, the elusive expansion energy and its quantifications, formation of more than 2000 isotopes of 100 elements and its systematic periodicity, the why of formation of galaxy in the way in which they are today, does the gravitational lensing is curvature created or quantum field and its grids created? Etc and thousands of things are missing in this 20th century science projected through the lense of AI based generative correlation model. We need to say, yes, thoughts are good or reaching reality only at those points where possibility of origin with BE condensate pictures (rubidium)are shown., Wishing you the best to reach real 21 st century exposition of what constitutes universe and a unified field transforming in to all these multitudes of existence.

[GlassEyedDetectives]

Wow!...decoding the Universe!, a very ambitious endeavor indeed, with lots of 'imagine ifs'.

[robertbritt]

Brilliant, insightful and inspiring in a second language. We are so fortunate to have such a lovely soul to learn with.

[pebbleschan]

The Milky Way is missing from the doctored Planck CMB maps. 😂

[scott-hrhd]

Hmm. What has gravity but can’t be seen?

[TroyThomas-jd]

So gravity; would be the measurement of pressure?

[robdev]

I would watch this over Netflix any day! 🤓🍿