String Gas Cosmology: Challenging Inflation | Robert Brandenberger

"I view string theory as the most promising way to quantize matter and gravity in a unified way. We need both quantum gravity and we need unification and a quantization of gravity. One of the reasons why string theory is promising is that there are no singularities associated with those singularities are the same type that they offer point particles." — Robert Brandenberger In this thought-provoking conversation, my grad school mentor, Robert Brandenberger shares his unique perspective on various cosmological concepts. He challenges the notion of the fundamental nature of the Planck length, questioning its significance and delving into intriguing debates surrounding its importance in our understanding of the universe. He also addresses some eyebrow-raising claims made by Elon Musk about the limitations imposed by the Planck scale on the number of digits of pi. Moving on to the topic of inflation and its potential detectability, Robert sheds light on the elusive B mode fluctuations and the role they play in understanding the flaws of general relativity. He explains why detecting these perturbations at the required scale may be beyond our current technological capabilities. The discussion further explores the motivations behind the search for cosmic strings in the microwave sky and the implications they hold for particle physics models beyond the standard model. With his expertise in gravity and the quantization of mass, Robert Brandenberger emphasizes the need for a quantum mechanical approach to gravity. He discusses the emergence of time, space, and a metric from matrix models, offering new insights into the foundations of our understanding of the universe. The speaker's work challenges conventional notions of inflation and proposes alternative models, such as string gas cosmology, as potential solutions. Beyond the scientific aspects, Robert Brandenberger reflects on his role as a scientist and educator. He expresses his gratitude to a mentor and shares advice he received about navigating the academic world. Additionally, he discusses the evolution of being a professor over the past three decades and shares his thoughts on the profession as a whole. [00:03:46] Cosmology, inflation, and a new principle. [00:08:25] TransPlankian censorship conjecture based on Penrose's observations regarding black holes, unitarity, and untangled entropy [00:16:23] Super string theory suggests cosmological models without scalar fields. [00:26:30] String theory criticized for infinite possible ground states. [00:32:48] Summary: String theory, space-time, and evolving fields. [00:36:05] Quantum matrix model yields emergent time and space [00:43:09] Inflation; criteria for successful cosmology. [00:51:38] Planck length, mass, and inflation limitations. Inflation's role in general relativity questioned. [00:57:03] Motivation for studying cosmic strings and their effects. [01:05:10] Quantize gravity, use string theory for unification. [01:15:57] Einstein viewed time/space as illusory. [01:22:11] Passion for science, gratitude, moving institutions, evolving profession. [01:32:20] Science, relativity, culture, human uniqueness, preventing alien devouring, monoliths, ethical will. [01:38:29] Cosmic strings disproven, mistakes admitted, lessons learned. [01:40:39] Robert advises publishing with confidence. Strive for the impossible to go beyond limits. Advice to young self: have courage. [01:46:32] Thoughts on the life of a Professor Join this channel to get access to perks: https://www.youtube.com/channel/UCmXH_moPhfkqCk6S3b9RWuw/join 📺 Watch my most popular videos:📺 Neil Turok https://www.youtube.com/watch?v=Dt5cFLN65fI Frank Wilczek https://youtu.be/3z8RqKMQHe0?sub_confirmation=1 Eric Weinstein vs. Stephen Wolfram https://www.youtube.com/watch?v=OI0AZ4Y4Ip4?sub_confirmation=1 Sir Roger Penrose: https://youtu.be/AMuqyAvX7Wo Sabine Hossenfelder: https://youtu.be/g00ilS6tBvs Avi Loeb: https://youtu.be/N9lUceHsLRw Follow me to ask questions of my guests: 🏄‍♂️ Twitter: https://twitter.com/DrBrianKeating 🔔 Subscribe https://www.youtube.com/DrBrianKeating?sub_confirmation=1 📝 Join my mailing list; just click here http://briankeating.com/mailing_list ✍️ Detailed Blog posts here: https://briankeating.com/blog.php 🎙️ Listen on audio-only platforms: https://briankeating.com/podcast #universe #podcast #briankeating #intotheimpossible #science #astronomy #cosmology #cosmicmicrowavebackground