Are We Living In A Simulation? - Sabine Hossenfelder

Sabine Hossenfelder is a theoretical physicist, research fellow at the Frankfurt Institute for Advanced Studies, quantum gravity researcher and an author. There are a lot of big questions in the world, like does the past still exist? Do particles think? Was the universe fine tuned for us? Does free will exist? Will we ever have a theory of everything? Are we living in a simulation? And given that we don't have answers yet, why not let a physicist have a crack at them? Expect to learn why physicists who say they know how the universe started aren't telling the truth, whether we can compute a human brain, why no one gets any younger, if maths is the ultimate basis of reality, why there might be copies of all of us out there in the universe, how your entire life could be the imagined history of a brain floating in space and much more... Sponsors: Get 15% discount on Craftd London’s jewellery at https://bit.ly/cdwisdom (use code MW15) Get a Free Sample Pack of all LMNT Flavours at https://www.drinklmnt.com/modernwisdom (discount automatically applied) Get 20% discount on the highest quality CBD Products from Pure Sport at https://bit.ly/cbdwisdom (use code: MW20) Extra Stuff: Buy Existential Physics - https://amzn.to/3Rqbk6F Subscribe to Sabine's YouTube Channel - https://www.youtube.com/c/SabineHossenfelder Get my free Reading List of 100 books to read before you die → https://chriswillx.com/books/ To support me on Patreon (thank you): https://www.patreon.com/modernwisdom #physics #simulation #freewill - 00:00 Intro 02:53 The Problem with the Simulation Hypothesis 11:15 How Physics Impacts Free Will 18:13 Misunderstanding the Universe’s Origins 27:09 Is There Something Better than Mathematics? 32:00 The Fine-Tuned Theory 37:45 Boltzmann Brains 45:10 Can We Compute Consciousness? 53:37 Where to Find Sabine - Get my free Reading List of 100 life-changing books here - https://chriswillx.com/books/ Listen to all episodes on audio: Apple Podcasts: https://apple.co/2MNqIgw Spotify: https://spoti.fi/2LSimPn - Get in touch in the comments below or head to... Instagram: https://www.instagram.com/chriswillx Twitter: https://www.twitter.com/chriswillx Email: https://chriswillx.com/contact/

Sabine HossenfelderguestChris Williamsonhost

Sep 3, 202254mWatch on YouTube ↗

WHAT IT’S REALLY ABOUT

Physicist Sabine Hossenfelder Dismantles Cosmic Myths About Reality And Free Will

Sabine Hossenfelder discusses why popular ideas like the simulation hypothesis, fine‑tuning, and many speculative cosmology stories are not genuinely scientific but often oversold as such. She stresses the limits of current physics: we cannot yet simulate the universe, explain the Big Bang, or reliably predict its ultimate fate, and honest answers often amount to “we don’t know.”
On free will and quantum mechanics, she argues that known laws combine determinism with randomness in ways that make traditional free will hard to reconcile with physics, regardless of the interpretation of quantum theory. She also explores questions about consciousness, artificial intelligence, mathematics as the “language” of reality, and thought experiments like Boltzmann brains.
Throughout, Hossenfelder pushes for evidence-based thinking, resisting comforting narratives and philosophical speculation that outruns what physics can currently justify.

IDEAS WORTH REMEMBERING

5 ideas

The simulation hypothesis is not a scientific theory without a concrete algorithm.

Claiming our universe is a computer simulation effectively claims to have a theory of everything implementable on a computer; without specifying how to compute chaotic, scale‑invariant systems like climate or fluids exactly, it remains unsupported speculation rather than physics.

Our current laws of physics make traditional free will very hard to defend.

Fundamental laws appear either deterministic or deterministic plus truly random quantum events; in neither case is there room for a kind of free will that lets us step outside those laws to influence outcomes, unless you redefine what you mean by ‘free will.’

We genuinely do not know how the universe began or how it will end.

General relativity breaks down at the Big Bang, and speculative add‑ons like bounces or pre‑Big‑Bang universes are mathematically allowed stories but not empirically required; similarly, extrapolating the universe’s fate trillions of years forward accumulates uncertainties we cannot eliminate.

Fine‑tuning arguments rest on unquantifiable probabilities and arbitrary choices.

Saying constants are ‘improbably’ suited for life assumes a probability distribution we can’t justify and arbitrary notions of ‘small’ changes; moreover, alternative sets of constants might still allow complex chemistry, weakening claims that our universe is uniquely fine‑tuned.

Boltzmann brain paradoxes hint at constraints on the laws of nature.

If the universe and its dynamics were fully ergodic over infinite time, random fluctuations would almost surely produce fleeting conscious brains; taking this seriously suggests the real laws (especially involving gravity or the strong force) may not be ergodic in that way.

WORDS WORTH SAVING

5 quotes

If you claim that it’s actually based on science, that’s when I get a problem.

— Sabine Hossenfelder (on the simulation hypothesis)

Basically, you just claimed that you have a theory of everything, and I want to see the algorithm.

— Sabine Hossenfelder

I think the honest answer we can give as physicists to the question ‘How did the universe begin?’ is, ‘We don’t know.’

— Sabine Hossenfelder

People should stop talking about [fine‑tuning].

— Sabine Hossenfelder

We’ve barely just begun to understand nature and to try to formulate our hypotheses about it in forms of mathematics.

— Sabine Hossenfelder

Critique of the simulation hypothesis and limits of computational modeling of realityFree will, determinism, and interpretations of quantum mechanics (e.g., many worlds)Origins and fate of the universe, Big Bang vs. bounces, and cosmological modelsFine‑tuning arguments, constants of nature, and the multiverse vs. creator narrativesBoltzmann brains, ergodicity, and implications for statistical mechanics and cosmologyMathematics, alternative ways of doing science, and universality across alien civilizationsConsciousness, computability, AI progress and limitations, and the arrow of time

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