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By Lawrence M. Krauss
4.3
496496 ratings
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

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

We usually begin the study of physics with a discussion of motion, not because it is easy, or because the modern understanding of motion began with Galileo hundreds of years ago. Rather, Galileo’s groundbreaking work provides a paradigm to understand how physics is done today. Extracting out the fundamental essence of motion from all the distractions associated with what turn out to be irrelevant complexities was a monumental intellectual leap for humankind—a leap we often take for granted. Without the leap, for example, Newton could never have made his profound discoveries about the relationship between force and movement, nor his discovery of the Universal Law of Gravitation. But too often we treat these remarkable achievements as something belonging in antiquity.. as if we have moved far beyond them in every way. Nothing could be further from the truth. Applying the very same ideas that Galileo and Newton developed leads us to the cusp of modern physics: the discovery of the dominant mass in the Universe, a vast invisible sea of dark matter. In this episode, we travel over 450 years of physics, from Galileo, to the threshold of our understanding of the cosmos today. Hang onto your hats. I’m also pleased to share a quick PSA. A reminder of our 2026 Origins expedition through the Greek archipelago (July 24 to 31), with a Cyprus add-on (July 17 to 22). If you’re interested, it’s worth raising your hand early. These trips tend to fill quickly. Express interest at https://originsproject.org/greek-adventure-2026-application/ 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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