2016 – 2020

  • Shifu Zhu, a graduate student in the Department of Astronomy & Astrophysics, had his research discoveries on radio-loud quasars featured in a 2020 October press release by the Chandra X-ray Center. Specifically, Shifu analyzed X-ray, optical, and radio data for a large sample of 729 radio-loud quasars, with powerful radio-emitting jets, to determine the nature of their nuclear X-ray emission. His data indicated, surprisingly, that most of their X-ray emission generally does not originate from the jets themselves, but rather comes from a coronal structure lying above the accretion disk. These results challenge 35 years of thinking about the basic nature of this X-ray emission, and they provide insights into the accretion and ejection physics of these systems. For more information, see
  • Celebrating Sir Roger’s Nobel Prize in Physics:
    Roger Penrose is a founding (visiting)member of IGC since 1993 and has served on its Scientific Advisory Board since 2009. He held the Francis R. and Helen M. Pentz Distinguished Professorship in Physics and Mathematics at Penn State from 1993 to 2012.  On 12th October 2020, IGC celebrated his 2020 Nobel prize in Physics for “the discovery that black hole formation is a robust prediction of the general theory of relativity” through a special event. B. Sathyaprakash and Don Schneider explained the Theoretical and Observational background behind the discoveries that led to the Nobel Prize. Abhay Ashtekar and Nitin Smarath spoke on Roger’s dazzling contributions to Physics, Mathematics and on how his regular visits enriched the  Penn State Community.  140-150 Colleagues and friends joined the event from all over the world.  See Announcement, PDF of Abhay’s talk, and YouTube Link
  • Roger Penrose was awarded half of the 2021 Nobel Prize in Physics. Roger has been a visiting member of IGC since it was founded and also serves on its External Scientific Advisory Board. From 1993 to 2012, he also held the Francis R. and Helen M. Pentz Visiting Professor of Physics and Mathematics at Penn State. Through regular visits during the first 15 years of this period, he enriched our intellectual lives tremendously through countless discussions (that often ran late into dinner times(!)), seminars and popular lectures. See the announcement from the Penn State Research Communication Office (PDF).
  • When Supernova fails…

Nuclear burning and gravity plays together to power most of the energetic events that we see in the universe. Slow and steady nuclear burning produces the light in most of the stars in the sky (including our Sun) that goes on for billions of years. When burning gets vigorous, life goes faster and gets more exciting.
Read Rahul Kashyap’s account of the exciting work by IGC researchers. PDF

  • LIGO-Virgo finds mystery object in ‘mass gap’
    On August 14, 2019, the two Advanced LIGO detectors in the US, at Hanford, Washington and Livingston, Louisiana, and the Advanced Virgo detector in Cascina, Italy, observed a gravitational wave signal produced by the inspiral and merger of two compact objects — one, a black hole, and the other of undetermined nature. The mass measured for the lighter compact object makes it either the lightest black hole or the heaviest neutron star ever discovered in a system of two compact objects, but we can’t be sure which it is. This is also the most asymmetric system observed in gravitational waves as of now. This event was detected in real time by the GstLAL inspiral pipeline which is developed and operated largely by the LIGO group at Penn State. See Full Article
  • Nature published a special collection of articles on Multi-Messenger Astrophysics. It contains a review by
    Peter Meszaros, Derek Fox, Chad Hanna and Kohta Murase Nature Reviews Physics volume 1, pages585–599(2019)
    Link PDF file

In an invited comment, Miguel Mostafa describes the Astrophysical Multimessenger Observatory Network (AMON), an online network that enables real-time coincidence searches using data from the leading multimessenger observatories and astronomical facilities.
The Astrophysical Multi-messenger Observatory Network
Nature Reviews; June 23rd, 2020.
See full article

  • Garrett Wendel, Luis Martínez, and Martin Bojowald discuss the fundamental nature of time in our universe from a novel perspective by modeling time as a universal quantum oscillator. The article, Physical Implications of a Fundamental Period of Time, was published in Physical Review Letters, 124, 241301 (2020); on19th June 2020. It was highlighted in Physics by Katherine Wright, a Senior Editor.
    See the Physics article
  • In support and solidarity with the Black community and #Strike4BlackLives, and to commit to eradicating systemic racism and discrimination especially in academia and science, IGC organized a Zoom meeting on Wednesday, June10th 2020. We had some 137 participants, also from the Physics and Astronomy & Astrophysics Departments and MERSEC at Penn State, and a few from other institutions. The discussion was led by Dr. Stephon Alexander, Professor of Physics at Brown University, who is the current President of the National Association for Black Physicists. Stephon has had close associations with IGC from the time he began his faculty career at Penn State 15 years ago. While we had benefited by reading thoughtful articles and dialogs on the subject prior to the meeting, Stephon’s comments, questions and suggestions provided direct insight into the issues that are central to the thinking of leadership in the Black academic community. IGC will continue the dialog both among ourselves and also with the members of this community for ongoing improvement. Thank you, Stephon!
    Watch Meeting
  • Cambridge University Press has released a paperback edition of “General Relativity and Gravitation: A Centennial Perspective”. This volume was commissioned by the International Society on General Relativity and Gravitation and is edited by A.Ashtekar(Editor in Chief), Beverly Berger, James Isenberg and Malcolm MacCallum. It contains 12 Chapters written by leading international experts that provide overviews of the spectacular advances that have occurred in the field over the past three decades or so. The material is divided into 4 parts: I. Einstein’s Triumph; II. Was Einstein right? A Centenary Assessment; III. Gravity is Geometry, Afterall; and IV. Beyond Einstein, each with a detailed general introduction written by the Editors. This volume should be an excellent resource both for graduate students as well as experienced researchers in cosmology, general relativity, gravitational waves, and quantum aspects of gravity.
    Flier describing the volume and offering a 20% discount till May 2021. PDF file
  • Gravitational waves detected on April 25, 2019, by the LIGO Livingston Observatory were likely produced by a collision of two neutron stars, according to a new study by an international team including Penn State researchers. IGC members Patrick Godwin, Ryan Magee, B. Sathyaprakash and Surabhi Suchdev explain why this discovery is so exciting. See Full Article
  • The Story of Loop Quantum Gravity- From the Big Bounce to Black Holes:  What happens at the centre black holes? What happened before the big bang? A quantum theory of gravity is needed to answer these questions . Many of the leading scientists who developed Loop Quantum Gravity, one of the most promising attempts, tell the story of how it was developed in this film. We also go on to explore how the theory may be tested via observations of black holes or probing the very early universe. The film tackles some of the biggest questions of existence.YouTube Video
  • Popular article by Peter Mészáros on High Energy Neutrinos – PDF
  • YouTube video by Phil and Monica Harper, on the Multimessenger Universe featuring interviews with leading figures in the field. It was filmed during the conference IGC@25: The Multimessenger Universe that celebrated the Silver Jubilee of the Institute for Gravitation and the Cosmos. YouTube Video
  • IGC celebrated its silver jubilee through an international conference igc@25: The multimessenger universe which was held at Penn State from June 23rd to 27th 2019. The scientific program has a dual goal: to assess the current status of our field in broad terms and to discuss future directions. The plenary talks by leading experts provided a broad overview of the field, with emphasis on developments that have occurred in the past ~25 years, while panels focused on developments over the past decade and, especially, the vision for the next decade or two. The after dinner speech, entitled “Multimessenger Astronomy and the Big Questions of the Cosmos: A Billion Light year View”, was given by the NSF Director Dr. France Cordova. PDF of Dr. Cordova’s Talk, Conference website, Photogallery of the conference
  • Black Holes, Dark Matter & Quantum Gravity, what’s new in Loop Quantum Gravity
    Are back holes related to dark matter? Do the observations of black holes by LIGO hint at a signature of quantum gravity ? Can we find evidence of black holes from a previous universe? In 2019 second place in the Buchalter Cosmology Prize was awarded to two of the speakers you will see in this film which explores some of the above themes. We filmed this at the Loop Quantum Gravity Conference in 2019 and plan to make a follow up film exploring the latest ideas in the field. Look out for the optical illusion around 8:128:25. YouTube Video prepared by Monica and Phil Halper. Filmed during Loops19 conference.
  • The Big Bounce, Signs in the CMB? A Loop Quantum Gravity updateIs there evidence of a cosmic Big Bounce in the sky? Can dark energy be solved by quantum gravity? In our second report from the most recent Loop Quantum Gravity Conference, we interview many of the leading physicists in the field to get an update on experimental searches for signs of Loop Quantum Gravity and Cosmology. YouTube Video prepared by Monica and Phil Halper. Filmed during Loops19 Conference
  • Loops’19, the most recent conference in a long tradition of biannual international meetings focused on loop quantum gravity and background independent approaches to quantum gravity was held at Penn State From June 17 through 21st, 2021. The scientific program highlighted recent developments in quantum gravity research, structural and computational aspects of loop quantum gravity, applications to black hole physics and cosmology. The conference is preceded by the Loops’19 Summer School held at Bard College (NY) on June 09 – 16, 2019. Conference Website, 51 Photos by Phil Halper
  • LIGO and Virgo observatories detect neutron star smash-ups. IGC researchers Cody Messick, Ryan Megge and Alexander Pace provide their perspectives.  See Full Article
  • Abhay Ashtekar was awarded the Albert Einstein Prize in Gravitational Physics during the April 2019 Meeting of the American Physical Society held at Denver, Co. PDF Article and Photo
  • Two new probable gravitational waves — ripples in the fabric of spacetime caused by cataclysmic cosmic events and first predicted by Albert Einstein over 100 years ago — have been detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo observatory in Italy in the first weeks after the detectors were updated. The IGC team of LIGO scientists, led by Chad Hanna, playeda critical role. See Full Article
  • Penn State recently invested in an upgrade to its portion of the data grid that will roughly quadruple the cluster’s capacity for conducting cutting-edge astronomy and astrophysics research. See Full Article
  • NSF held a press conference on Thursday, July 12, 2018 to announce the major discovery of the first high-energy neutrino detected from a distant cosmological source. IceCube and AMON researchers at Penn State played a prominent role in this major advance. The result is reported in two articles in the current issue of Science and featured on its cover: http://science.sciencemag.org/content/361/6398.   This discovery marks the beginning of a new branch of astronomy using high-energy neutrinos and, since it partly relied on the coincident detection of high-energy photons, places in sharp relief the critical importance of the multimessenger approach pioneered at IGC through our AMON project. An article for lay audiences published in “The Conversation” by Doug Cowen, Derek Fox and Azadeh Keivani was picked up by
  • Remembering Stephen Hawking: Eberly College of Science; March 14, 2018 – https://youtu.be/BxUkPKL7O9k
  • Penn State participates in Nobel-winning physics project. See Full Article
  • For the first time, three detectors have tracked the gravitational waves emitted by a merger of two black holes — a critical new capability that allows scientists to more closely locate a gravitational wave’s birthplace in space. Chad Hanna and B. Sathyaprakash explain why.  See Full Article
  • Gravitational waves produced by the birth of a massive black hole, a record-breaking billions of light-years from Earth, have been detected by the Laser Interferometer Gravitational-wave Observatory (LIGO). IGC researchers provided leadership in this discovery. See Full Article
  • Three non-technical articles from CQG+ on recent results in Loop Quantum Cosmology. These are accessible to beginning researchers:
  • New Cosmic Messengers: A popular article by Abhay Ashtekar on the discovery of gravitational waves appeared in the Science Section of the March 18 issue of Frontline. Full story
  • Miguel Mostafá recently participated in the 2016 TedX talks and spoke about ultra high energy cosmic waves, the highest energy particles in the universe. Watch the YouTube video “Catching the Fastest Particles in the Universe”
  • Several articles on the first detection of gravitational waves:
  • A video about the first detection of gravitational waves featuring Stephen Fairhurst and Patrick Sutton (past IGC members): https://www.youtube.com/watch?v=Lcxt097G4Ps

  • A less technical account of the first gravitational wave detection (a viewpoint article on the PRL by Emanuale Berti): http://physics.aps.org/articles/v9/17
  • The video “LIGO, A Passion for Understanding” explains the dedication of those who have worked for nearly 30 years on a single science experiment. A second video, LIGO Generations, shares the stories of those who invented a whole new branch of physics in order to prove the last piece of Einstein’s theory of general relativity.
  • Chad Hanna’s personal story on detecting gravitational waves in The Conversation.