LECTURES & TALKS

Is it possible to detect the merger of supermassive black holes throughout the universe? How can we use the regular clocklike flashes from distant pulsars to search for gravitational waves? Join us for a 30-minute lecture investigating these "pulsar timing arrays" and black holes, followed by a panel Q&A consisting of several astrophysicists who made this discovery to answer your questions. Timestamps below: 00:00 Announcements 04:03 Intro to Gravitational Wave Presentation 04:41 Gravitational Wave Presentation 27:04 Q&A for Gravitational Wave Presentation 27:27 "Does the black hole size change the gravitational waves?" 28:09 "Where are the pulsars located for this study?" 28:38 "How do the gravitational waves change with black hole characteristics?" 31:00 Intermission 34:23 Q&A Panel Introductions 38:42 Q&A Panel 38:45 "How does distance to pulsar affect the measurement?" 40:21 "And how does it impact the gravitational wave detections?" 42:00 "Why does the correlation curve look like that?" 44:18 "Is there an explosion when black holes merge!" 45:13 "Can a black hole consume itself?" 48:52 "Can we determine the distribution of black holes from this measurement?" 50:55 "Can we identify individual black hole mergers with this measurement?" 53:55 "How well do we need to know the location of our planets to make this measurement?" 57:09 "Did these gravitational waves originate in the early universe?" 59:13 "When can we identify individual black hole mergers with this measurement?" 1:00:53 "In this measurement, how do you account for undiscovered objects?" 1:05:20 "What makes black holes dark?" 1:06:25 "Do the funadmental particles in black holes change during a merger?" 1:11:24 "How important is quantum computing in this field?" 1:14:00 "If a black hole disappears, would it affect Earth?" 1:15:22 "How did Einstein predict gravitational waves?" 1:18:38 "How are mergers between black holes different from black hole-neutron star mergers?" 1:21:21 "Can black holes lose mass or energy?" 1:24:26 "What does Hawking Radiation look like when released?" 1:25:51 "If the universe expands at faster than light speed, how do we detect waves from it?" 1:26:48 "Can we estimate the number of black hole binaries from this measurement?" 1:28:43 "Can black holes consume a galaxy? Is there a maximum black hole mass?" 1:32:37 "Can exotic matter play a role in black hole theory?" 1:35:08 "Why are there supermassive black holes at the centers of galaxies?" 1:40:30 "What is actually measured at the radio telescope for this discovery?" 1:42:55 "Can we use radio telescopes in orbit to make better images of black holes?" 1:46:00 "Are pulsars observed on existing radio telescopes or new specialty telescopes?" 1:48:23 "What makes a black hole inactive or active?" 1:52:32 "Can we create black holes and gravitational waves in the lab?" 1:54:21 "What would a single black hole merger look like in the pulsar signal?" 1:55:58 Concluding Remarks Q&A Panelists from NANOGrav Team (Left to Right) Dr. Aaron Johnson - Postdoctoral Fellow, Caltech Dr. Patrick Meyers - Postdoctoral Fellow, Caltech Sophie Hourihane - PhD Candidate, Caltech Dr. Katerina Chatziioannou - Professor, Caltech Dr. Joseph Lazio - Chief Scientist, NASA JPL For a higher-level presentation at the level of professional scientists on this discovery, please see our Caltech Colloquium talk by Dr. Patrick Meyers: https://www.youtube.com/watch?v=b1GhSgC8wmw Title: Merging Supermassive Black Holes & Pulsar Timing Arrays Speaker: Aaron Johnson Abstract: Supermassive black holes lurk at the centers of most galaxies. When galaxies merge, their black holes are also predicted to merge, releasing vibrations in the surrounding spacetime known as gravitational waves. While we cannot directly see these gravitational waves, it may be possible to detect them by looking for irregularities in the clock-like flashes coming from distant rotating dead stars known as pulsars. By monitoring a large enough network of pulsars spread around our galaxy for these irregularities, astronomers may be able to detect supermassive black holes throughout the universe. Are the merging black holes really out there, and when will we find them? Join us to learn about these so-called "pulsar timing arrays" and how we can use them to study the most massive black holes in the universe.

The early space race between the United States and the Soviet Union not only encompassed humans to the moon but also encompassed a captivating competition to explore other planetary objects in our solar system. NASA's fervent interest in Mars and the Soviet Union's unwavering pursuit of Venus exemplified the excitement and determination among scientists. This competition fueled an unprecedented era of scientific discovery and innovation. It prompted rapid advancements in spacecraft technology, planetary science, and interplanetary exploration strategies. The excitement among scientists was exhilarating, as each successful mission unraveled new layers of knowledge about the neighboring worlds within our cosmic neighborhood. This early era also encompassed many mission failures and tremendous disappointments. This panel explores the captivating atmosphere of scientific pursuit of knowledge about the solar system that continues today.

High school students participating in the 2022–2023 Exploration of the Moon and Asteroids by Secondary Students (ExMASS) program give their final research presentations to a panel of judges. The ExMASS program is managed by the LPI's Center for Lunar Science and Exploration and funded by NASA's Solar System Exploration Virtual Institute.

Speaker: Dr. Fabian Schneider (Heidelberg Institute for Theoretical Studies) Date: May 16th, 2023 Abstract: Black holes are some of the most fascinating objects in the Cosmos. They can form when massive stars collapse at the end of their lives. However, it remains unknown which stars form black holes and which explode in supernovae. The first stellar-mass black holes were identified in Galactic X-ray binaries, and mergers of black holes and neutron stars are nowadays routinely observed thanks to gravitational-wave detectors. With almost 100 observations of compact-object mergers, the mass distribution of stellar-mass black holes is being revealed across cosmic time. This will help better understand many aspects relevant to their formation such as supernova explosion physics and pre-supernova evolution of massive single and binary stars. In particular, the progenitor stars of most of the observed black holes were subject to envelope-stripping by binary mass transfer. This has severe consequences for the explodability of stars and hence the question of which stars form black holes. I will show that envelope stripping gives rise to characteristic black hole masses of 9 and 16 solar masses, and that there are hints of such a bimodality in current gravitational-wave observations. Furthermore, I will show how some of the most massive stellar-mass black holes may form from stars that merged with a companion during their evolution.

May 10, 2023 Andrew Fraknoi (Fromm Institute, University of San Francisco) North America will be treated to two eclipses of the Sun in the 2023-24 school year: an annular eclipse on Oct. 14, 2023 and a total eclipse on Apr. 8, 2024. Some 500 million people will be in a position to see at least a partial eclipse on each date. Fraknoi discusses the cause of eclipses, the circumstances of each eclipse and where each will be visible, and how to view eclipses safely. He shows maps of the eclipse paths and provides URLs to where you can get free information materials to help you enjoy the eclipses, wherever you are.

The formation of our Solar System was a chaotic collapse of gas and dust into the Sun, planets, asteroids, and comets we have today, punctuated by catastrophic collisions between these forming bodies. Dr. Masiero will discuss how the asteroid families in the belt today are the last remnants of these massive collisions, and give us a window into the processes that shaped our Solar System. Joseph Masiero, Scientist & NEOWISE Deputy-PI, NASA Jet Propulsion Lab Carnegie Science Astronomy Lecture Series April 23, 2018 #AsteroidFam

The Lyman-α forest is a key diagnostic for the state of diffuse baryons in the intergalactic medium (IGM) and for fundamental cosmological parameters. At high redshift (i.e., z ≥ 2) the Lyman-α forest is observed in optical wavelengths from ground-based observatories and has been used to constrain small-scale cosmic structure, the dark matter distribution, the IGM gas temperature, and the evolution of the ultraviolet ionizing background (UVB) radiation. However, the low redshift (z~0.1) Lyman-α forest, observed from space-based UV instruments such as HST COS, has challenged the most advanced cosmological simulations. In this talk, I will show how active black hole (AGN) feedback can be at least as important (or more!) as the UVB for setting the amount and distribution of neutral gas in the low redshift IGM. The AGN feedback signatures appear in the neutral gas statistics beginning around z~1, thus possibly affecting 21-cm intensity mapping programs that target this redshift range (e.g., HIRAX). These findings herald a significant paradigm shift for cosmological simulations and observations that target the low redshift IGM and suggest that cosmological simulations should develop AGN feedback models with both galaxies and the IGM in mind.

From discovering the rarest astrophysical objects to mapping the large-scale structures of the cosmos, artificial intelligence is advancing our understanding of the universe. In this one-hour lecture, Dr. Aleksandra Ciprijanovic explains how artificial intelligence is transforming the field of astrophysics in unprecedented ways. Her lecture covers the latest breakthroughs and the potential for future developments at this exciting intersection. Ciprijanovic is a Wilson Fellow in the Data Science, Simulation and Learning Division at Fermilab, where she leads the Cosmic Artificial Intelligence group. She is a member of the Deep Skies Lab, the Rubin Observatory/LSST Science Collaborations, the Society of Astronomers of Serbia, the International Astronomical Union, and the European Astronomical Society. Her main research interests are artificial intelligence and machine learning in astrophysics and cosmology; working with big data from simulations and astronomical surveys; and studies of galaxies, galaxy clusters and gravitational lensing. She is also interested in astroparticle physics, high-energy physics, nucleosynthesis, gamma-ray astronomy and neutrino astronomy. Ciprijanovic loves working with students of all levels and strives to teach them not only how to solve scientific problems, but also how to navigate the job market and reach their career goals in or outside of academia. Ciprijanovic received her Ph.D. in astrophysics at the University of Belgrade, Serbia. Prior to moving to the United States, she worked as assistant research professor at the Faculty of Mathematics of the University of Belgrade and at the Mathematical Institute of the Serbian Academy of Sciences and Arts in Belgrade. To learn more about astrophysics research at Fermilab, please visit: https://www.fnal.gov/pub/science/particle-physics/experiments/dark-matter-and-dark-energy.html For information about the Fermilab Arts and Lecture Series, please visit: https://events.fnal.gov/arts-lecture-series/

Public lecture presented by Anu Ojha and David Wilkinson from the UK Space Academy

What's the deal with this "Green Comet" and why should you care? Cameron Hummels explains where comets come from, why they look the way they do, how this comet was discovered, and what will be its future! Timestamps below: 00:00 Introduction 01:12 What is our Solar System? 03:08 Where are the comets? 06:03 Why do comets look this way? 15:59 What about meteor showers? 17:22 How was Comet ZTF discovered? 22:09 Where is Comet ZTF going? 25:00 Summary 25:51 Which comets are visible next? Dr. Cameron Hummels is a computational astrophysicist and Director of Outreach for the Astronomy Department at Caltech. His research focuses on simulating how galaxies form and evolve over the billions of years since the Big Bang. Cameron is very passionate about public education and speaking with audiences about science, with the goal of inspiring people to be curious about the world around them.

January 10, 2023 meeting of Amateur Astronomers Association of Princeton (AAAP) featuring Alyssa Pagan, Science Visuals Developer at Space Telescope Science Institure (STScI)

Public Lecture from Nov 18th 2022 held at Columbia University.

Learn about the history and philosophy of astronomy from Professor Impey, a University Distinguished Professor of Astronomy at the University of Arizona, with our Knowing the Universe: History and Philosophy of Astronomy course here on YouTube. This video is part of module 2, Greek Science. Check out all courses taught by Professor Impey on Coursera: https://www.coursera.org/instructor/chrisimpey Have questions about the content? We host live Q&A sessions on our sister channel Astronomy: State of the Art and on Twitch at TeachAstronomy, come join us and get your questions answered! TeachAstronomy on Twitch: https://twitch.tv/teachastronomy Astronomy SOTA: https://www.youtube.com/AstronomySOTA #astronomy #history #philosophy

On which worlds and under what conditions can life begin? The new “urability” framework (places and conditions under which life can originate) is a new addition to Astrobiology, joining the term “habitability” (worlds where life as we know it can survive). Applying urability to exoplanet models will inform a key term in the Drake Equation enabling better estimation of the inventory of worlds where life might arise. The framework is based on a foundation of accumulating evidence by multiple international teams, which increasingly supports an origin of life on land in volcanic hot spring pools. David Deamer and Bruce Damer of UC Santa Cruz and the BIOTA Institute will introduce urability and the hot spring scenario and present a new twist, “the Drake Equation, in reverse,” along with a potentially controversial proposal that “microbes may be hard, not easy.” Senior researcher Franck Marchis moderates this talk. If you like science, support the SETI Institute! We're a non-profit research institution whose focus is understanding the nature and origins of life in the universe. Donate here: https://seti.org/donate Learn more about the SETI Institute and stay up-to-date on awesome science: - Subscribe to our YouTube channel at https://www.youtube.com/c/SETIInstitute/ - Watch our streams over on Twitch at https://www.twitch.tv/setiinstitute - Listen to our podcast, Big Picture Science http://www.bigpicturescience.org/ - Subscribe to our newsletter https://seti.org/signup - Buy merchandise from Chop Shop https://www.chopshopstore.com/collections/seti-institute/SETI Don't forget to like and subscribe! Ring the bell for notifications of when we go live. #setitalks #searchforlife #seti

Stephanie La Massa, Space Telescope Science Institute Black holes are the most enigmatic objects in the Universe, objects so dense that not even light can escape from them. A natural consequence of Einstein’s theory of general relativity, they have in the past been considered theoretical curiosities. However, observational evidence of black holes has become abundant over the past several decades. Though black holes give off no light, we can infer their presence based on the effect they have on their surroundings. Dr. La Massa will highlight the clues we use to discover black holes from within our Galaxy to the edges of the Universe. Recent ground-breaking observations from the Event Horizon Telescope and gravitational waves have pushed the boundaries of our knowledge about black holes. Still, many important questions remain, which the next generation of ground and space-based telescopes will help answer. - News from the Universe starts at 3:08 - Main talk starts at 12:22 Host: Frank Summers, Space Telescope Science Institute Recorded live on Tuesday, November 1, 2022 More information: www.stsci.edu/public-lectures

Take a guided tour of the invisible universe on Dark Matter Night. On October 26, dark matter researchers Katie Mack and Ken Clark shared insights into the ubiquitous, mysterious matter that makes up the majority of stuff in our universe. Dark Matter Night was a live webcast brought to you by Perimeter Institute and the McDonald Institute. Starting off the evening, Katie Mack discussed the theoretical and observational foundations of dark matter at Perimeter Institute, where she holds the Hawking Chair in Cosmology and Science Communication. Next, Ken Clark, an associate professor at the Arthur B. McDonald Canadian Astroparticle Physics Research Institute, shared experimental approaches that could help solve the riddle of dark matter. We also got a guided video tour of SNOLAB, the state-of-the-art underground laboratory two kilometres beneath Sudbury. Dark Matter Night is one of many ways you can explore the topic -- find lots more at https://www.interactions.org/dark-matter-day Perimeter Institute (charitable registration number 88981 4323 RR0001) is the world’s largest independent research hub devoted to theoretical physics, created to foster breakthroughs in the fundamental understanding of our universe, from the smallest particles to the entire cosmos. The Perimeter Institute Public Lecture Series is made possible in part by the support of donors like you. Be part of the equation: https://perimeterinstitute.ca/donate Subscribe for updates on future webcasts, events, free posters, and more: https://insidetheperimeter.ca/newsletter/ https://www.facebook.com/pioutreach https://twitter.com/perimeter https://www.instagram.com/perimeterinstitute/ https://www.linkedin.com/company/perimeter-institute/

Take a guided tour of the invisible universe on Dark Matter Night. In a hybrid event (in-person and live webcast) on October 26, dark matter researchers Katie Mack and Ken Clark will share insights into the ubiquitous, mysterious matter that makes up the majority of stuff in our universe. Dark Matter Night will be webcast live from two locations. Starting at 7:30 pm ET, Mack will discuss the theoretical and observational foundations of dark matter at Perimeter Institute, where she holds the Hawking Chair in Cosmology and Science Communication. Clark, an associate professor at the Arthur B. McDonald Canadian Astroparticle Physics Research Institute, will then share experimental approaches that could help solve the riddle of dark matter. Each speaker’s presentation will be simulcast to the live audience at the other institute, and the whole event will be available via free webcast. Dark Matter Night is one of many ways you can explore the topic -- find lots more at https://www.interactions.org/dark-matter-day

“The Divine Comedy” by Dante Alighieri is the story of a journey through the universe—a sort of ante litteram science fiction book, written as a poem. Dante had a good knowledge of astronomy and a great passion for it, traits shared with his descendant, astrophysicist Dr. Sperello di Serego Alighieri. As a medieval man, Dante straddled the beliefs of the ancients and modern knowledge. Dr. Alighieri will explore how his ancestor repeatedly anticipated later views on topics such as features of the Moon, our Milky Way galaxy—and the curved universe, unlimited but finite, which anticipates the hypersphere of Einstein. Join us for an invitation to reread Dante's poem with different eyes, ones turned upward. To be recorded live on Tuesday, October 4, 2022 More information: www.stsci.edu/public-lectures

Planet Venus is a hellish place and seemingly hostile to life, although recent measurements claimed the detection of biogenic signatures. Less than a billion years ago, Venus’s atmosphere underwent a dramatic runaway greenhouse effect rendering it likely to be uninhabitable. This lecture will consider what can be learned about the possibility of catastrophic climate change on Planet Earth, in the light of thermodynamics and of what has happened to Earth’s twin, Venus. A lecture by Professor Katherine Blundell OBE The transcript and downloadable versions of the lecture are available from the Gresham College website: https://www.gresham.ac.uk/watch-now/end-atmospheres Gresham College has offered free public lectures for over 400 years, thanks to the generosity of our supporters. There are currently over 2,500 lectures free to access. We believe that everyone should have the opportunity to learn from some of the greatest minds. To support Gresham's mission, please consider making a donation: https://gresham.ac.uk/support/ Website: https://gresham.ac.uk Twitter: https://twitter.com/greshamcollege Facebook: https://facebook.com/greshamcollege Instagram: https://instagram.com/greshamcollege

Cosmic rays are tiny particles traveling all over our Galaxy at almost the speed of light, and figuring out their origin is one of the biggest mysteries in astrophysics. Join us as we search for the genesis of cosmic rays, taking us on a tour of some of the strangest things in outer space: black holes, exploding stars, and even the tenuous shock waves of the Galactic wind. This 30-minute lecture will be followed by a panel Q&A consisting of several astrophysicists. Timestamps below: 00:00 Announcements 04:06 Intro to Cosmic Ray Presentation 04:50 Cosmic Ray Presentation 40:51 Intermission 47:41 Q&A Panel Introductions 49:48 How do we measure speed of cosmic rays? Why don't they go speed of light? 52:17 What is the magnetic field in the cloud chamber? 53:21 How do the Ice Cube results fit into cosmic ray detections? 55:14 What are differences between space- and ground-based cosmic ray detectors? 56:07 Can merging neutron stars or black holes create high-energy cosmic rays? 57:17 What are slowest cosmic rays? 58:08 Can we create cosmic rays? 59:37 Do cosmic rays emit radio waves? 1:00:31 Do cosmic rays consist of neutrons? Other particles? 1:01:50 How to use cosmic rays to see inside pyramids? 1:04:02 What is the flux rate of cosmic rays here? 1:05:07 How are cosmic rays different here than outside solar system? 1:06:27 Do cosmic rays transmutate elements? 1:07:30 What causes gamma rays from comets? 1:09:08 What is your favorite kind of explosion? 1:12:12 Can cosmic rays be used to map the interior of planets? 1:13:28 Why do supernovae not create elements more massive than iron? 1:16:00 Why do supernovae explode after implosion? 1:18:02 Are we using JWST for our studies? 1:22:50 How large are the Lagrange points in the Sun-Earth System? 1:25:23 Why is there a maximum neutron star / white dwarf mass? 1:31:33 Did the DART mission pulverize its asteroid target? 1:35:35 Is the DART impacted asteroid still visible? 1:40:38 Microphone problems 1:50:00 Do we understand the asteroid that came from another solar system? 1:55:31 Concluding Remarks