I knew I should have gone to Cal Tech rather than MIT. Lost in Math: How Beauty Leads Physics Astray Hello, Professor Carroll. Sean Carroll, theoretical physicist and one of this world’s most celebrated writers on science, rewrites the history of 20th century physics. 4.3 out of 5 stars 114. His latest book is The Particle at the End of the Universe: How the Higgs Boson Leads us to the Edge of a New World. 2. You know that once released the object will continue along an inertial trajectory. Carroll, while raised as an Episcopalian,[17] is an atheist, or as he calls it, a "poetic naturalist". So, R (curvature scalar) is the Kinetic Energy of the field, and the distribution of matter and energy is the potential. Furniture 3D Models: 10 Great Sources in 2020. He has written extensively on models of dark energy and its interactions with ordinary matter and dark matter, as well as modifications of general relativity in cosmology. Video of Sean Carroll's panel discussion, "Quantum to Cosmos," answering the biggest questions in physics today, This page was last edited on 19 February 2021, at 18:28. Spacetime and Geometry: An Introduction to General Relativity - Kindle edition by Carroll, Sean M.. Download it once and read it on your Kindle device, PC, phones or tablets. In 2012 he organized the workshop "Moving Naturalism Forward", which brought together scientists and philosophers to discuss issues associated with a naturalistic worldview. Audible Audiobook. In 2010 NIST reported on their ground based precision clock Relativity tests comparing clocks at differing relative speeds (SR) & comparing clocks placed at differing positions within the gravity potential (GR). "[32][33] Theoretical physicist Dr. Aron Wall also wrote a debate review. (sample questions: Does an infalling object have a future beyond the moment it hits the singularity? You are correct. He received his Ph.D. in 1993 from Harvard University. As in the example from the first question, the object affected by gravity is just following the path of least resistance/action, as higgs field is weaker in the direction facing the center of mass then in the opposite direction. How can we be sure this isn’t just a consequence of a bad choice of coordinates? Is it true that Gravitational potential energy is not defined in GR? Distinguished mostly by a deeper dive into black holes, including the information-loss puzzle. Hello, I have somewhat connected questions (i appoligize if they are nonsensical): 1. He received his Ph.D. from Harvard in 1993, and is now on the faculty at the California Institute of Technology, where … With over 1,900 citations, it helped pioneer the study of f(R) gravity in cosmology.[12]. I wonder (this is sheer speculation), is it the case that in your opinion GR does not need the concept of inertia? It is a great teaching. I have worked on questions involving dark matter and dark energy, modified gravity, violations of Lorentz invariance, extra dimensions, topological defects, cosmic microwave background anisotropies, causality violation, black holes, and the cosmological constant problem. This one’s sure to be a crowd-pleaser. Wonderful video. Carroll believes that many of his fellow physicists need to acknowledge gaps in the understanding of quantum mechanics—which seems … Related (I think) is when you say ” As Minkowski taught us, Tau^2 = t^2 – x^2″ where Tau is the “time elapsed. I assume that “small” means a different thing near a black hole than it does if you’re floating in the void between galaxy clusters? His dissertation was entitled Cosmological Consequences of Topological and Geometric Phenomena in Field Theories. By Sean Carroll. Before the debate stated s/he is not worried about Carroll. I have a few questions which may or may not be pertinent to the forthcoming gravity q & a as I’m only now catching up in the series. [23] Both Craig and Carroll had talked on each other before the debate. Awful things did happen in the Big Bang. You have to tell them where you are going to be – your location in space – but you also need to let them know when. I wonder if you would spend an hour or so on what may or may not turn out to be a great idea: induced gravity. Is there an intuitive understanding why space-time curvature can also be understood in terms of gravitons? https://arxiv.org/abs/1506.02853 Construct a space station that is large enough and with such an angular velocity that inhabitants of that Ehrenfest disk at a particular distance ‘r’ to the axis of rotation experience 1 G of centripetal acceleration. What is the significance of that? I very much appreciate you walking through the concepts and related equations. If a large mass falls into a black hole, is it done affecting the gravitational field around the black hole once it crosses the event horizon? Sorry, your blog cannot share posts by email. This is a question about changes in the rate of time & a potential ‘further’ test of General Relativity. He began a podcast in 2018 called Mindscape, in which he interviews other experts and intellectuals coming from a variety of disciplines, including "[s]cience, society, philosophy, culture, arts, and ideas" in general.[5]. Yikes! 2. Enter your email address to subscribe to receive notifications of new posts by email. (There might be partial effects due to frame dragging, but I suspect they would still be different.) Sean Carroll. In this video, and in recent ones, you referred to how the designation of “forces” is really just a vernacular shorthand and that the deeper you go into studying physics the less meaningful the term “force” becomes, that quantum specialists in particular talk in terms of fields, not forces. Why, for example, does the electromagnetic force need the photon as a force carrier rather than just the result of the curvature of the field? I extended that to include: nor does gravity. Of course, the whole thrust of your presentation is that objects subject only to gravitational interaction move along a _geodesic_ of GR spacetime. Quantum Space: Loop Quantum Gravity and the Search for the Structure of Space, Time, and the Universe Jim Baggott. Sean Michael Carroll (born October 5, 1966) is a theoretical physicist specializing in quantum mechanics, gravity, and cosmology. When you're designing a scene, using pre-existing 3D models can save time. Since gravity waves propagate at the speed of light, does that mean they also cannot escape a black hole? In 2017 Carroll presented an argument for rejecting certain cosmological models, including those with Boltzmann brains, on the basis that they are cognitively unstable: they cannot simultaneously be true and justifiably believed. But I think that it is actually not fully satisfied in GR, because the metric itself is a „thing“, relative to which we can e.g. (2003) was written with Vikram Duvvuri, Mark Trodden, and Michael Turner. Q: Would a clock comparison experiment that measures ONLY a difference in gravity be a ‘further’ test of General Relativity? Brett Ryder. I’m assuming you will do a video on Quantum Gravity? These NIST Relativity tests prove beyond any doubt that a clock moving at greater velocity ticks slower & that a clock ticks faster higher up within a gravity potential – BUT has it been experimentally proven that time ticks slower in the greater gravity field? Any chance you could talk a bit more about singularities? I think Einstein himself was a big fan of this idea, and even used it as a guiding principle to find GR. The event horizon seems like an exception to this, because it is possible for things to take a trajectory where they cross the event horizon going into the black hole, but if you reverse the trajectory it is impossible to cross the event horizon from inside. He is a research professor in the Walter Burke Institute for Theoretical Physics in the California Institute of Technology Department of Physics and an External Professor at the Santa Fe Institute. Sean Carroll is a Research Professor of Physics at Caltech and the Santa Fe Institute. Also related (I think) is the Spacetime Interval Equation that has a first term of -dt^2… then, the -1 in the Metric g mu, nu matrix…. Carroll has also worked on the arrow of time problem. Entanglement, Click to share on Facebook (Opens in new window), Click to share on Twitter (Opens in new window), Click to share on Reddit (Opens in new window), Click to share on Tumblr (Opens in new window), Click to email this to a friend (Opens in new window), Energy Conservation and Non-Conservation in Quantum Mechanics, The Biggest Ideas in the Universe | 24. Sean Carroll is an assistant professor in the Physics Department, Enrico Fermi Institute, and Center for Cosmological Physics at the University of Chicago. (think bigger galaxy). He has been a contributor to the physics blog Cosmic Variance, and has published in scientific journals such as Nature as well as other publications, including The New York Times, Sky & Telescope, and – Carroll vs Craig Review (Part 1)", "Carroll's five replies to the fine-tuning argument: Number 1", https://www.preposterousuniverse.com/blog/2011/04/05/debating-william-lane-craig/comment-page-2/, "Open thread for January 1-7, 2014 - LessWrong", "Thoughts on the Carroll-Craig Debate » Undivided Looking", "The Shelly Kagan debate on moral theory & the Sean Carroll debate on cosmology are William Lane Craig's two biggest losses", "2014 National Convention - Los Angeles - Freedom From Religion Foundation", "Royal Society Winton Prize for Science Books", Dark Matter, Dark Energy: The Dark Side of the Universe, Video introduction to Sean Carroll's lectures "The Biggest Ideas in the Universe", https://en.wikipedia.org/w/index.php?title=Sean_M._Carroll&oldid=1007744527, California Institute of Technology faculty, 21st-century American non-fiction writers, MIT Center for Theoretical Physics alumni, CS1 maint: bot: original URL status unknown, Wikipedia articles with CANTIC identifiers, Wikipedia articles with PLWABN identifiers, Wikipedia articles with SELIBR identifiers, Wikipedia articles with SUDOC identifiers, Wikipedia articles with WORLDCATID identifiers, Creative Commons Attribution-ShareAlike License. (I very much enjoyed the Schwartzschild explanations.) Albert Einstein’s theory of general relativity describes gravity as a geometric property of space and time. By Sean Carroll. Would you agree, and what are your thoughts about GR & Mach’s principle? My current interests include quantum mechanics, gravitation, cosmology, statistical mechanics, and foundations of … "[9] In 2015 he was awarded a Guggenheim Fellowship. Gravity is easier than QM. There was a remark, attributed to Neil Young: rust never sleeps. In every presentation of GR (except yours), a central place is given to the the concept of equivalence of inertial mass and gravitational mass. P.S. Why do things fall „downwards“ and not „upwards“ and what has time diletation to do with it? One thing I’d like to understand better about GR is its relation to Mach‘s principle, which states that there is no absolute motion, so in particular the effect of rotation on an object (which we can measure as a centrifugal force) would only exist because the object is rotating relative to other objects (like the earth, or distant galaxies). Does the GRW approach best adapt GR (because it’s a “gravitational collapse” model?) Finally, and this is neither here nor there, and as a physicist maybe you don’t care, but as I presume you value naturalness and elegance I wonder if you take a position on the pi vs. tau issue? Carroll has worked on a number of areas of theoretical cosmology, field theory and gravitation theory. [19] My favorite way of introducing the concept of equivalence principle is to present the case of pulling G’s onboard a slowly rotating Ehrenfest disk. So, because it (higgs field) has distributed much of its local energy to slow massive particles, the rate at which it is slowing them down gets lower localy, making the space “less dense” the more we get to center of mass, giving arise to an effect which we call curvature of space – gravity? How is this reconciled with time symmetry? 0:00:00 Sean Carroll: Hello everyone, and welcome to the Mindscape Podcast. That sounds counterintuitive to me. in The Blackwell Companion to Science and Christianity develops the claim that science no longer needs to posit a divine being to explain the existence of the universe. Sean Carroll, an acclaimed theoretical physicist, is determined to reintroduce this vital science to a new generation. Field. “The more you move in space, the less you move in time”… I think this is a key concept that I’m failing to grasp. My research goal is to obtain a better understanding of how Nature works, on various levels and in a number of different contexts. 1. 4.6 out of 5 stars 1,365. I have not been able to find any evidence of a clock comparison experiment conducted ‘anywhere’ that holds speed & centrifugal force equal for both clocks & ONLY a difference in gravity occurs. Excellent talk. Such a clear presentation. Finally, in an expanding universe, that matrix term turns positive +1…. He has also worked on the foundations of quantum mechanics, especially the Many-Worlds interpretation, including a derivation of the Born Rule for probabilities. Minkowski spacetime). Carroll enlisted Alan Guth, the G in BGV theorem, for help in this elaborate ruse. You’ve said the singularity doesn’t have a point in space, but it seems like you could attribute a point in spacetime to where a particular in falling particle hits the singularity? Aug 30, 2020. 1:24:48 can you explain why the bending of light is two times larger when calculating with GR compared to Newton Gravity? Gravity generally works in a way that is symmetric with respect to time. Re: the Einstein-Hilbert action, since it is a Lagrangian, it should be Kinetic Energy – Potential Energy. He has been a contributor to the physics blog Cosmic Variance, and has published in scientific journals such as Nature as well as other publications, … How you present these very fascinating and very difficult topics in physics is a usefully different supplement to what else is out there. The motion of the object with respect to the Ehrenfest disk is accelerated motion. Hardcover. I guess all bets are off at that point? Sean Carroll is a physicist and author. In 2004, he and Shadi Bartsch taught an undergraduate course at the University of Chicago on the history of atheism. Emergence, The Big Picture: On the Origins of Life, Meaning, and the Universe Itself, The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World, From Eternity to Here: The Quest for the Ultimate Theory of Time, Spacetime and Geometry: An Introduction to General Relativity, The Higgs Boson and Beyond (The Great Courses), Mysteries of Modern Physics -- Time (The Great Courses), Dark Matter and Dark Energy (The Great Courses). [34] Dr. Richard Carrier, a historian and a philosopher whose works focus on the historicity of Jesus, atheism and empiricism, referenced this debate as one of Craig's biggest two losses. The GR experiment incurs a difference in both speed (centripetal) & centrifugal force for the raised clock as well as a difference in gravity. Carroll showed a picture of Guth holding a sign that read “[The universe is] very likely eternal but nobody knows.” The picture had its desired effect on the debate. About the 22 minute point, you comment that gravity is not really a force it is a feature of the curvature of spacetime. "[21], In 2014, Carroll debated with philosopher and Christian apologist William Lane Craig as part of the Greer-Heard Forum in New Orleans. Criticality and Complexity, How to Make Educational Videos with a Tablet, The Biggest Ideas in the Universe | 22. 12 June 2013. [22] Dr. Luke Barnes, a postdoctoral cosmology researcher at Western Sydney University, has written 2 pre-views before the debate[23][24] and a review[25][26][27] and rebuttals[28][29] to Carroll's in-debate arguements after the debate was over. Use features like bookmarks, note taking and highlighting while reading Spacetime and Geometry: An Introduction to General Relativity. I opened the transcript and I searched for the word ‘inertial’. Blurbs. Sean Carroll is a theoretical physicist specializing in quantum mechanics, gravity, and cosmology. Cosmology, The Biggest Ideas in the Universe | 21. The SR experiment incurs a difference in centrifugal force for the gyrated clock as well as difference in speed. You briefly mentioned Kruskal coordinates that are well-behaved on the complete manifold near a black hole and thus prevent awfull things from happening. Wonderful talk as always. Thanks! What do you think may happen there? Download PDF Abstract: We investigate theories in which gravity arises as a consequence of entropy. At least one very good thing has come from the present difficulties. Any gravitational-interaction-trajectory is truly an _inertial trajectory_. The Biggest Ideas in the Universe | 6. Sean Carroll on how time and space began The Life Scientific Professor Sean Carroll tells Jim why he stopped trying to out-Einstein Einstein to focus on pure quantum quantumness. In 2010, Carroll was elected fellow of the American Physical Society for "contributions to a wide variety of subjects in cosmology, relativity, and quantum field theory, especially ideas for cosmic acceleration, as well as contributions to undergraduate, graduate, and public science education". He and Jennifer Chen posit that the Big Bang is not a unique occurrence as a result of all of the matter and energy in the universe originating in a singularity at the beginning of time, but rather one of many cosmic inflation events resulting from quantum fluctuations of vacuum energy in a cold de Sitter space. Sean Carroll – Preposterous Universe I'm interested in how the world works at the deepest levels, which leads me to do research in physics and philosophy. Could that be interpreted as if the object is just following the path of least action because the space is more streched (less dense) in the direction pointing to the center of planet then in the opposite direction? In 2012, he teamed up with Michael Shermer to debate with Ian Hutchinson of MIT and author Dinesh D'Souza at Caltech in an event titled "The Great Debate: Has Science Refuted Religion? I’m your host, Sean Carroll. Logical implication: equivalence of inertial and gravitational mass. His research ranges over a number of topics in theoretical physics, focusing on cosmology, field theory, and gravitation. *(by utilising NIST portable clocks at differing locations of same longitude & height above sea level to equalise centripetal speed/centrifugal force, but of differing geological density – or via placing clocks at existing grav.wave detectors – or via these similarly oriented proposals: 3. Would it be wrong to use the term “streched” instead of “curved” for space? Already hailed as a masterpiece, Something Deeply Hidden shows for the first time that facing up to the essential puzzle of quantum mechanics utterly transforms how we think about space and time.