#DarkMatter #Astrophysics #Cosmology Self-interacting dark matter This talk will provide a summary of the key motivations, example particle physics realizations and robust predictions of the self-interacting dark matter (SIDM) model. I will focus the discussion on models with large cross-sections where the interplay of dark matter and baryons is simple to understand, and the possibility for gravothermal core collapse exists. I will show how SIDM models can explain the diversity of dark matter distributions in galaxies, and discuss the possibility of testing these models using satellite galaxies and black hole formation. ... https://www.youtube.com/watch?v=1Z_JIfS-mVg

From Aristotle to Einstein, scientists have long grappled with the seemingly elementary idea that time's arrow is fundamental to the universe. After all, physical processes are described by fundamental laws such as thermodynamics. But since thermodynamics is quantum mechanics applied to large systems, and since quantum systems exhibit time-independent evolution, how can a direction of time arise? How can time emerge from laws that are themselves time agnostic? A new perspective on clocks has provided a new way to think of time itself. By studying the simplest conceivable clocks researchers have discovered the fundamental limits of timekeeping. These researchers have discovered fsacinating relationships between accuracy, information, complexity, energy and entropy. But until this year, those relationships were merely theoretical when experimental physicists at the University of Oxford reported measurements of a nanoscale clock that strongly support the new thermodynamic theory. This video describes how these intriguing results could eventually lead to optimally efficient, quantum clocks for controlling future quantum computers and nanoscale devices. As upcoming guest Dr. Yunger Halpern said “This line of work does grapple, in a fundamental way, with the role of time in quantum theory,” ? Watch my most popular videos:? A New Contender is Here! https://www.youtube.com/watch?v=-6A6myur--c Frank Wilczek https://youtu.be/3z8RqKMQHe0?sub_confirmation=1 Weinstein and Wolfram https://www.youtube.com/watch?v=OI0AZ4Y4Ip4?sub_confirmation=1 Sheldon Glashow: https://youtu.be/a0_iaWgxQtA?sub_confirmation=1 Michael Saylor The Physics of Bitcoin https://youtu.be/CaN_CDKqXOg?sub_confirmation=1 Sir Roger Penrose, Nobel Prize winner: https://www.youtube.com/watch?v=AMuqyAvX7Wo?sub_confirmation=1 Jill Tarter https://youtu.be/O9K9OBd3vHk?sub_confirmation=1 Sara Seager Venus LIfe: https://youtu.be/QPsEDoOTU6k?sub_confirmation=1 Noam Chomsky: https://youtu.be/Iaz6JIxDh6Y?sub_confirmation=1 Sabine Hossenfelder: https://youtu.be/V6dMM2-X6nk Sarah Scoles: https://youtu.be/apVKobWigMw Stephen Wolfram: https://youtu.be/nSAemRxzmXM Be my friend: ?‍♂️ Twitter: https://twitter.com/DrBrianKeating ? Subscribe https://www.youtube.com/DrBrianKeating?sub_confirmation=1 ✍️Detailed Blog posts here: https://briankeating.com/blog.php ?️Listen on audio-only platforms: https://briankeating.com/podcast.php A production of http://imagination.ucsd.edu/ Support the podcast: https://www.patreon.com/drbriankeating Credits: Thanks to UCSD's StudioU's Treb Padula ... https://www.youtube.com/watch?v=09fSrhhfRwE

#OriginsOfLife #AssemblyTheory #LastUniversalCommonAncestor Sara Walker is an astrobiologist and theoretical physicist interested in the origin of life and how to find life on other worlds. She is most interested in whether or not there are “laws of life’ related to how information structures the physical world that could universally describe life here on Earth and on other planets. Will life be made in the lab before we discover it in the universe? Walker is deputy director of the pioneering Beyond Center for Fundamental Concepts in Science, which is devoted to confronting the big questions of science and philosophy. She is Associate Director of the ASU-Santa Fe Institute Center for Biosocial Complex Systems and Assistant Professor in the School of Earth and Space Exploration. She is also Co-founder of the astrobiology-themed social website SAGANet.org, and is a member of the Board of Directors of Blue Marble Space. She is active in public engagement in science, with appearances at the World Science Festival and on "Through the Wormhole" and NPR's Science Friday. Sara’s provocative paper: Origins of Life: A Problem for Physics Follow Sara on Twitter.com/Sara_Imari https://beyond.asu.edu Join my mailing list for twice monthly content from around the universe: http://briankeating.com/mailing_list.php 00:00:00 Intro 00:05:35 Why is the origin of life a problem for physics? 00:05:35 What is life and why did life arise? 00:10:49 What is emergence and how is it related to origin of life science? 00:11:10 The scales of the universe have a hierarchy 00:13:42 Life happens at multiple scales 00:16:17 How is the arrow of time essential to the origin and evolution of life? 00:27:32 What is the state of abinitio research into the origin of life? (Beyond the Urey-Miller Experiment). 00:30:09 What are the latest experimental approaches to origin of life research with cues from the physics world? 00:37:26 What are some of the most important origin of life research criticisms? 00:42:37 What do you think of “intelligent design” and is it a principle? 00:46:03 Explaining the LUCA - the Last Universal Common Ancestor 00:51:20 Why is chirality essential to life? 00:56:03 How can we see evidence of life with our advanced telescopes? Will JWST? 01:07:45 Can assembly theory discard the low value information? 01:09:49 what do you think of Avi Loeb's ideas on alien life and SETI? 01:15:23 Is there a shadow biosphere? 01:16:38 Could there be "alien" life on earth? The field of extremeophiles. 01:21:42 What are the chances of finding life beyond earth in our solar system? 01:25:50 What do you think about the idea that good physics must be "beautiful"? 01:30:45 What does fine tuning of initial conditions have to do with free will? Watch Sara’s conversation ... https://www.youtube.com/watch?v=0Iklfzmqz88

Recently, Bergner and Seligman explained the behavior of the first interstellar object, ‘Oumuamua, as a rare form of a quite common object, a comet. They claim it "began as an icy planetesimal that was irradiated at low temperatures by cosmic rays during its interstellar journey, and experienced warming during its passage through the Solar System. This explanation is supported by a large body of experimental work." But Avi Loeb disagrees: “In a new paper published recently in Nature -- https://www.nature.com/articles/s41586-022-05687-w Acceleration of 1I/‘Oumuamua from radiolytically produced H2 in H2O ice -- Jennifer Bergner and Darryl Seligman suggest that the peculiar acceleration observed by the first known interstellar object `Oumuamua, can be explained if `Oumuamua was made of water ice which was partly dissociated into hydrogen by cosmic-rays along its interstellar journey. In the abstract of the paper, the authors admit that past models involving a pure hydrogen iceberg or a pure nitrogen iceberg do not work due to theoretical or observational inconsistencies. In fact, the hydrogen iceberg model was proposed in a previous 2020 paper by Darryl Seligman himself. A few months later, I wrote a paper with Thiem Hoang, showing that heating by interstellar starlight would destroy hydrogen icebergs too quickly and not allow them to reach the solar system from their likely formation sites of giant molecular clouds. https://www.nature.com/articles/s41586-022-05687-w Read Hoang and Loeb's response paper: https://lweb.cfa.harvard.edu/~loeb/Hoang_Loeb_23.pdf Essay: https://avi-loeb.medium.com/oumuamua-was-not-a-hydrogen-water-iceberg-1dd2f7a6107f https://arxiv.org/pdf/2208.00092.pdf https://www.theguardian.com/world/2023/mar/24/harvard-physicist-pacific-expedition-first-interstellar-meteor Win a real meteorite if you have a .edu email address: briankeating.com/list In the new paper, Bergner and Seligman also point out that sublimation of a pure water iceberg cannot provide the full acceleration of `Oumuamua, as reported by Marco Micheli and collaborators in a 2018 Nature paper. Since the observed acceleration declined smoothly in inverse proportion to distance squared from the Sun, I suggested a few months later in a paper with my former postdoc Shmuel Bialy that `Oumuamua was a thin membrane, pushed by sunlight. Since nature does not make light sails, I suggested in follow-up papers and my book Extraterrestrial that `Oumuamua was possibly produced by an extraterrestrial technological civilization. Most recently, I proposed in a newly published paper that this form of thin space trash could represent a piece from a broken Dyson sphere, which was damaged by asteroid impacts. Since Bergner and Seligman admit that a pure water iceberg or a pure hydrogen iceberg are not viable models for `Oumuamua, it is unclear how mixing two failing models would make a successful solution. In particular, when hydrogen evaporates from a water iceberg, it would give less kick to the water than to a pure hydrogen iceberg because of the higher molecular weight of water. Moreover, if hydrogen evaporates easily from water ice, then it would not survive the journey, just as in the case of a pure hydrogen iceberg. These issues are not addressed in the new paper. Another concern is that comets often show jitter from jets as a result of uneven sublimation of ice on their surface, as well as a substantial evolution in their spin period as they evaporate, whereas none of these was evident in the case of `Oumuamua. This point was highlighted in a 2018 paper by Roman Rafikov, shedding doubt on a cometary origin for `Oumuamua’s excess acceleration away from the Sun.” ... https://www.youtube.com/watch?v=86E03OzQDCo