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By Lawrence M. Krauss
4.3
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The podcast currently has 158 episodes available.
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John Gertz is a Renaissance Man. One might think that the President of Zorro Productions might be the last person to talk with about the Search for Extraterrestrial Intelligence (SETI), and the last person to chair SETI’s governing board. But as is clear from our discussion, and from the material in his recent book, Reinventing SETI, John has not only mastered all of the relevant technical issues, he has thought deeply about the motivation for SETI, and the likelihood of its success. Treating the issue as a businessman rather than a scientist, he has tried to anticipate what signals other civilizations might send, and what we might listen for. He also takes a realistic view of what we might actually be able to detect. The net result of our conversations is that the prospects are not good for detecting anything out there. Distant aliens are likely not broadcasting in a way we could be sensitive to. And as he points out, we should probably do the same. His great hope is that alien civilizations have instead installed probes in other solar systems, including ours. However, this possibility too, as I emphasized with him, is also rife with difficulties. I have thought a lot about SETI since I wrote The Physics of Star Trek. I don’t think anyone has affected my thinking on the issue since then more than John. I was pessimistic before. Now I think the whole effort is probably misguided. Though, if someone other than the government is willing to pay for it, what the heck. As I often tell experimentalists. Do what you can do, no matter what us theorists say. We may be wrong. I hope you find our discussion as informative and provocative as I did. I will be interested to hear if it changes your perspective on SETI as well. As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe

There has been a lot of doom and gloom combined with excitement, if that is possible, about AI in the science news lately. Sabine and I tried to deconstruct the hype associated with the highly touted Open AI solution of one of the Millennium Problems in Mathematics, as well as explore the real concerns and imaginary concerns associated with both the recent Open AI agent hacking of Huggy Face, and the blog post by the CEO of Anthopic arguing for a pause in AI development because of the potential for disaster—a statement endorsed by both Elon Musk and Sam Altman. As usual, things are neither as bad, nor as good as they might seem. We also tackled two other stories of interest. A single data point might signal the discovery of particle dark matter in an underground detector! Sabine and I come at this from different perspectives—she has always been suspicious of the claimed need for dark matter, and I have not only explored and proposed a number of the prime candidates, but I also helped propose and promote the kind of technologies that led to LZ/LUX, the collaboration making the current announcement. Nevertheless both Sabine and I agree that it is premature to celebrate. And while Sabine won’t bet, I am betting that this single point will not be substantiated when more data comes in. Stay tuned. Finally we discuss a sad development—Scientific Paper Mills. Apparently you can buy your way to a first authorship, or just an authorship, on a scientific paper that can eventually be published somewhere, even if the results might not be completely kosher. While this is a disturbing new possibility, it seems like it is just affecting science at the margins. We need to try and stamp it out, but it is not undermining the bulk of scientific research. In any case, as they used to say on a famous TV show, after all the AI world-ending hype, happy to say: See you next time.. if there is a next time! As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe

This lecture, recorded before lecture 5, which was released a month ago, actually more naturally follows it, which is why releasing it after lecture 5, while unintended, actually makes sense. In the last lecture I described the most important unification in all of physics, the unification of electricity and magnetism, a unification into electromagnetism by James Clerk Maxwell in the 19th century. Because of its elegance, and its overpowering utility, the theory of electromagnetism has provided the prototype for all modern physical theories that have followed it. As I show in this lecture, the form of electromagnetism is governed by a new mathematical symmetry in nature, called gauge symmetry. It turns out the existence of this symmetry is profoundly important, and it not only governs the exact form of the theory, it turns out to govern the form of all the known forces of nature. Before we get to gauge symmetry, I want to explore more generally what is meant by symmetry in physics, and then I want to redo elementary physics by thinking about symmetry. In my mind, the fact that basic physics is introduced without reference to the symmetries of nature is perhaps the greatest failing in the teaching of modern physics. Concepts like energy and momentum have relevance because of fundamental symmetries of space and time. The facts that energy is ‘conserved’, and momentum is ‘conserved’ in systems, which rigorously fix determine the form of Newton’s laws of motion, are often introduced as if they are dictates on high, like the ten commandments. However, once one understands that these arise from symmetries of nature, the fact that these quantities exist and are conserved, becomes immediate, as the remarkable mathematician Emmy Noether showed at the beginning of the 20th century. Finally, as important as mathematical symmetries are in governing physical laws, it is equally striking that even if these fundamental symmetries exist in nature, they may not be manifest in particular situations. For example, gravity and electromagnetism don’t distinguish between left and right, but if I look around my room, the left side of my room looks very different than the right side. This is an example of what is called ‘broken symmetry’, one of the most subtle and impactful notions at the basis of what is now called The Standard Model of Particle Physics. In this lecture I review all of these ideas, which are essential if we are to go beyond the physics of the 19th century to understand the physics of the 20th and 21st centuries. Enjoy. As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe

Happy August! . Heading back to North America as we just concluded our Origin Project Adventure to Cyrpus and Greece, where we felt the heat, and avoided some wildfires while having some amazing positive experiences as well with an amazing group of 26 travelers. Please stay safe and try and stay cool this month. To help distract you from the heat, I hope you will enjoy this latest conversation about new discoveries in science with Sabine Hossenfelder. As always, we try and deconstruct the facts behind the headlines, and also explore new strange corners of our universe. This episode begins with some new observations of the Bullet Cluster of galaxies. This cluster contains two galaxies that have collided, and seems to have provided evidence for exotic dark matter that has passed through the collision unscathed. Not so, says a new analysis, which claims evidence for more dark matter in the form of black holes and other less visible normal matter. There are strong reasons to be skeptical however, as both Sabine and I agree. Speaking of black holes, a new analysis of collisions of black holes at the terrestrial gravitational wave detectors proposes a solution to the mystery of how black holes in a so-called forbidden gap between 10-20 solar masses and more than 50 solar masses have formed. They provide evidence that some of the black holes observed in collisions have been built up from earlier collisions with other black holes. This hierarchical growth could potentially explain how very large black holes in the early universe form, though it is a long way from 50 solar masses to 1 billion solar masses! Strange goings on at the largest scales of the universe continue to be claimed, as yet another study argues for an unexpected and unexplained cosmic spatial asymmetry. It is hard to reconcile this with the observed uniformity of the universe on the largest scales we can observe via the Cosmic Microwave Background. As a result, it is too early to get excited, even if newspaper reporters love to report on claims that fly in the face of the standard model of cosmology. The Vera Rubin Space Observatory has started its 10 year project to monitor a huge swath of sky every night looking for things that go bump in the night. On the first night, they found a few hundred thousand possible events. With a 10 year movie of the cosmos who knows what they will discover. Sabine introduced me to an article about Quantum Batteries. Are they going to be useful, or just another cute example of how quantum mechanics produces strange phenomena? Time will tell. Finally, I couldn’t resist introducing a story about cockroaches with nervous system implants that allow their motion to be remote controlled by experimenters, with tiny diving suits attached that allow them to breathe underwater for extended periods. It is claimed that they may help in undersea rescue.. Wow! Maybe so… What will they think of next? Until the next time.. enjoy! As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe

I began this lecture by saying I was daunted by what I was about to talk about. There are several reasons for this. First, I will lead you through the development of what was certainly most important theoretical development in the 19th century, and what could easily be considered the most important mathematical framework in all of physics. Second, this development affected our modern picture of the universe more than almost any other. Next, this development made our modern technological society possible. And finally, it allowed a calculation that ultimately unveiled the true nature of light. A calculation we will perform together during this lecture I am going to take you through what is often taught in a whole semester course in physics. So hold onto your hats. Take it step by step. I think the reward of understanding will be worth the effort. I hope at the end of this lecture you agree with me. This month I will be traveling with the Origins Project and a group of 27 intrepid travelers to Cyprus and Greece. So the next Origins podcast will not air until August. I hope your July is enjoyable. As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe
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