Dark Flow

Why does the universe seem to be moving in one particular direction? Get your own Space Time t­shirt at Tweet at us! @pbsspacetime Email us! pbsspacetime [at] gmail [dot] com Comment on Reddit: Help translate our videos! Previous Episode: The Secrets of Feynman Diagrams Space is not static. Everything moves. Planets orbit stars, stars orbit within galaxies, galaxies whirl within the gravitational fields of giant clusters. And of course, the universe is expanding; distant galaxies are thrust apart from each other as the space between them grows. But there’s no preferred direction to any of this motion. Motion due to the expansion of the universe – what we call the Hubble flow – is equal in all directions. The random motion of galaxies – what we call their peculiar motion – should also have no preferred direction. On the largest scales of the universe, there should be no preference for up or down or left or right. At least that’s what we thought. Observations of the cosmic microwave background suggest that the galaxy clusters across the cosmos may be moving, ever so slightly, towards the same point beyond the cosmic horizon. We call this dark flow. Written and Hosted by Matt O’Dowd Produced by Rusty Ward Graphics by Kurt Ross Assistant Editing and Sound Design by Mike Petrow Made by Kornhaber Brown (www.kornhaberbrown.com) Comments answer by Matt: VacuumDiagrams Samuel Benda JoJoModding Squid Master Big Bang CoolAsCats David Nicklas Eugene Lawson Quasar Tambe Barsbay Max Levine Mayank M. Mehrota Mars Yentur Josh Mark Rosenthal Dean Fuqua Hypernova Chuck Zegar Jordan Young Ratfeast John Hofmann Joseph Salomone Martha Hunt Craig Peterson Science Via Markets Barry Hatfield Peter Durocher Michael Kers Chris Hicks Mark Vasile Patrick Murray Sultan Alkhulaifi Alex Seto Conor Dillon Jared Moore Michal-Peanut Karmi Bernardo Higuera Erik Stein Daniel Lyons Kevin Warne JJ Bagnell J Rejc Amy Jie Avi Goldfinger John Pettit Shannan Catalano Florian Stinglmayr Yubo Du Benoit Pagé-Guitard Nathan Leniz Jessica Fraley Loro Lukic Brandon Labonte David Crane Greg Weiss