What Is Time? The Question Physics Still Can't Answer

What Is Time? Does Time Really Flow? A clock doesn't measure time. It measures change. So what is time, really? In this series, we explore Einstein's relativity, black holes, entropy, quantum gravity, and the human brain, and look at what physics knows about time, and what it still doesn't. In this series: Part 1: What We Think Time Is Part 2: When Einstein Broke Time Part 3: Why Does Time Only Move Forward? Part 4: What If Time Doesn't Really Exist? Part 5: Living Inside Time Key books: Carlo Rovelli, The Order of Time · Sean Carroll, From Eternity to Here* · Julian Barbour, The End of Time· Brian Greene, *The Fabric of the Cosmos· Stephen Hawking, *A Brief History of Time Note: This video is educational. Ideas like "time may not be fundamental" are open scientific questions, not settled facts. 2. Complete Reference List (Parts 1 to 5) Books Augustine, Confessions (Book XI) Newton, Principia (1687) Einstein, Relativity: The Special and General Theory (1916) Eddington, The Nature of the Physical World (1928) Hawking, A Brief History of Time Rovelli, The Order of Time Sean Carroll, From Eternity to Here Julian Barbour, The End of Time Lee Smolin, Time Reborn Roger Penrose, The Emperor's New Mind*, *Cycles of Time Brian Greene, The Fabric of the Cosmos Kip Thorne, Black Holes and Time Warps Alan Lightman, Einstein's Dreams Paul Davies, About Time Huw Price, Time's Arrow and Archimedes' Point David Albert, Time and Chance Schrödinger, What Is Life? (1944) Prigogine, The End of Certainty Feynman, The Character of Physical Law Ernst Mach, The Science of Mechanics (1883) Frank Wilczek, A Beautiful Question Kant, Critique of Pure Reason (1781) Carl Sagan, Cosmos (1980), The Dragons of Eden (1977) Marc Wittmann, Felt Time William James, The Principles of Psychology (1890) Seneca, On the Shortness of Life Michel Siffre, Beyond Time Jo Marchant, Decoding the Heavens *Papers and experiments* Michelson & Morley (1887) Einstein (1905), On the Electrodynamics of Moving Bodies Minkowski (1908), Space and Time McTaggart (1908), The Unreality of Time Langevin (1911), twin paradox Rossi & Hall (1941), muons Frisch & Smith (1963), muons Pound & Rebka (1959-60) Hafele & Keating (1972, *Science*) Vessot & Levine (1976), Gravity Probe A Chou et al., NIST (2010, *Science*) Bothwell et al., JILA (2022, *Nature*) Uggerhøj et al. (2016), The young centre of the Earth Gödel (1949) Event Horizon Telescope, M87 (2019) Clausius (1865), Loschmidt (1876), Boltzmann (1870s) Wang et al. (2002, *PRL*), fluctuation theorem Cronin & Fitch (1964), BaBar (2012, *PRL*) Maxwell (1867), Landauer (1961), Bérut et al. (2012, *Nature*) Stetson, Fiesta & Eagleman (2007, *PLoS ONE*) Penzias & Wilson (1964-65) Wheeler-DeWitt (1967), Page & Wootters (1983), Connes & Rovelli (1994) Moreva et al. (2014, *Physical Review A*) Anderson (1972, *Science*), "More Is Different" Bekenstein (1973), Hawking (1974, *Nature*) Maldacena (1997), Ryu & Takayanagi (2006), Van Raamsdonk (2010) Sorkin, causal sets (1987, 1990) Hartle & Hawking (1983) Wilczek (2012), Zhang et al. and Choi et al. (2017, *Nature*), time crystals Rovelli, "Forget Time" (2009) Burbidge, Burbidge, Fowler & Hoyle (1957) Wells (1963, *Nature*), fossil corals Freeth et al. (2021), Antikythera mechanism Nobel Prize, circadian clock (2017) CGPM (2022), leap 🌌 Welcome to Cosmic Files — Explore the Universe! Discover the mysteries of space, astronomy, and science through fascinating stories, cosmic discoveries, and mind-blowing facts. From black holes and distant galaxies to mysterious planets and the secrets of the universe, we bring you the wonders of space in engaging, cinematic videos. 🚀 Explore the unknown. 🔭 Discover the extraordinary. 🌠 Unlock the secrets of the cosmos. Subscribe to Cosmic Files and join us on a journey beyond the stars! #CosmicFiles #Space #Astronomy #Science #Universe