What Is Outside the Universe?

What is outside the universe? Physics gives three answers: more universe, nothing at all, or other universes. One of them says the question doesn't even make sense. We sort every claim into what we know, what we infer, and what is pure speculation — the cosmic horizon, the 94% of galaxies already out of reach, how we measured that space is flat, the search for matching circles, why expansion isn't into anything, and bubble universes. ⏱ Chapters 0:00 Three answers 0:29 Seven steps to the edge of knowledge 0:48 The cosmic horizon: what we can see and reach 2:10 Just beyond the horizon 3:02 Finite or infinite? Flatness and matching circles 4:36 Expanding into nothing 5:48 Bubble universes (speculative) 6:45 Copies of you, cycles and many worlds 7:42 Known, inferred, speculative 8:20 Is there an outside? 📚 Sources Planck 2018 results VI: Cosmological parameters (A&A 641, A6) — https://arxiv.org/abs/1807.06209 Vardanyan, Trotta & Silk 2011 — the universe is at least ~250× the observable volume — https://arxiv.org/abs/1101.5476 Cosmic topology — matched-circle searches (2024) — https://arxiv.org/abs/2409.02226 Feeney et al. 2010 — first observational tests of eternal inflation (bubble collisions) — https://arxiv.org/abs/1012.1995 Max Tegmark 2003 — Parallel Universes — https://arxiv.org/abs/astro-ph/0302131 Davis & Lineweaver — superluminal recession velocities — https://arxiv.org/abs/astro-ph/0011070 Lineweaver & Davis — Misconceptions about the Big Bang (Scientific American) — https://www.astronomynotes.com/cosmol... Ethan Siegel (Big Think) — how much of the universe is out of reach — https://bigthink.com/?p=491629 NASA WMAP — tests of the Big Bang: the CMB — https://map.gsfc.nasa.gov/universe/bb... NASA SPHEREx completes its first all-sky map (EarthSky) — https://earthsky.org/space/nasa-spher... Observable universe / Cosmological horizon — overview — https://en.wikipedia.org/wiki/Observa... 🎙 Narration: AI-generated voice. Visuals: original animation by Lumavisor; astronaut illustration by Mohamed_hassan (Pixabay). 🎵 Music (Pixabay Content License): "Late Hours" by GuilhermeBernardes · "Duendo" by amurich · "Science beautiful" by LCMsounds · "Calm Smooth Flowing Mixed Emotions" by UniqueCreativeAudio · "quiet night_2" by Tomomi_Kato ▶ More from the Cosmos playlist:    • Cosmos   #Universe #Space #Lumavisor