Summary
The discussion centers on the limits of human observation of the universe and the implications of cosmic expansion. It begins with the concept of light travel, explaining that when we observe distant celestial objects, we see them as they were in the past due to the finite speed of light. The cosmic microwave background radiation (CMB) serves as a crucial reference point, representing the oldest light we can detect, emitted shortly after the Big Bang. This light has traveled approximately 13.7 billion years to reach us, but due to the universe's expansion, the regions from which it originated are now much farther away.
As the conversation progresses, it delves into the concept of the particle horizon and the Hubble horizon, which define the limits of what we can observe. The Hubble horizon, currently about 14.5 billion light years away, marks the boundary where galaxies recede faster than the speed of light. However, light from beyond this horizon can still reach us due to the universe's expanding nature. The discussion highlights that while we can currently observe light from the CMB, the accelerating expansion of the universe poses a future limitation on our ability to see new cosmic events.
The episode concludes by introducing the cosmological event horizon, which represents the ultimate boundary beyond which no signals can ever reach us. This horizon is expected to shrink over time, ultimately merging with the Hubble horizon, thereby restricting our view of the universe. The conversation hints at future explorations of humanity's potential to influence and explore the cosmos, suggesting that understanding these limits is essential for contemplating our place in the universe.
Show Notes
Thank you to Brilliant for Supporting PBS. To learn more go to https://brilliant.org/SpaceTime/
PBS Member Stations rely on viewers like you. To support your local station, go to:http://to.pbs.org/DonateSPACE
Sign Up on Patreon to get access to the Space Time Discord! https://www.patreon.com/pbsspacetime
There’s an absolute limit to our access to the universe beyond our own galaxy. There’s a limit to what we can ever hope to explore or send signals to, and a very different limit to what we can ever hope to witness. Today we’re going to explore the latter. We’re going to figure out the absolute limit of our future view of the universe, and of the universe’s ability to influence us. Next time we’ll turn it around and ask: how much of the external universe can WE potentially influence, and even explore?
Check out the Space Time Merch Store https://www.pbsspacetime.com/shop
Sign up for the mailing list to get episode notifications and hear special announcements! https://mailchi.mp/1a6eb8f2717d/spacetime
Search the Entire Space Time Library Here: https://search.pbsspacetime.com/
Hosted by Matt O'Dowd Written by Matt O'Dowd & Euan McLean Post Production by Leonardo Scholzer, Yago Ballarini, & Stephanie Faria Directed by Andrew Kornhaber Associate Producer: Bahar Gholipour Executive Producers: Eric Brown & Andrew Kornhaber Executive in Charge for PBS: Maribel Lopez Director of Programming for PBS: Gabrielle Ewing Assistant Director of Programming for PBS: John Campbell
Spacetime is produced by Kornhaber Brown for PBS Digital Studios. This program is produced by Kornhaber Brown, which is solely responsible for its content. © 2023 PBS. All rights reserved.
End Credits Music by J.R.S. Schattenberg: https://www.youtube.com/user/MultiDroideka
Space Time Was Made Possible In Part By:
Big Bang Sponsors Ian Jones Bryce Fort Peter Barrett David Neumann Sean Maddox Alexander Tamas Morgan Hough Juan Benet Vinnie Falco Fabrice Eap Mark Rosenthal
Quasar Sponsors Glenn Sugden Alex Kern Ethan Cohen Stephen Wilcox Christina Oegren Mark Heising
Hypernova Sponsors Ivari Tölp Vyce Ailour Zachary Wilson Kenneth See Gregory Forfa Kirk Honour Joe Moreira Bradley Voorhees Marc Armstrong Scott Gorlick Paul Stehr-Green Ben Delo Scott Gray John R. Slavik
Donal Botkin John Pollock Edmund Fokschaner chuck zegar Jordan Young Daniel Muzquiz
Gamma Ray Burst Supporters Lucas Kazakevicius Massimiliano Pala Aaron Molina Thomas Nielson Joe Pavlovic Ryan McGaughy Mark West Chuck Lukaszewski Edward Hodapp Cole Combs Andrea Galvagni Jerry Thomas Nikhil Sharma Ryan Moser Jonathan Cordovano John Anderson David Giltinan Scott Hannum Paul Widden Bradley Ulis Craig Falls Kane Holbrook John Yaraee Ross Story teng guo Mason Dillon Matt Langford Harsh Khandhadia Thomas Tarler Susan Albee Frank Walker Michael Lev Terje Vold James Trimmier Andre Stechert Paul Wood Kent Durham jim bartosh Ramon Nogueira Paul Suchy Ellis Hall John H. Austin, Jr. Diana S Polijar Faraz Khan Almog Cohen Alex Edwards Endre Pech Daniel Jennings Cameron Sampson Russ Creech Jeremy Reed David Johnston Michael Barton Andrew Mann Isaac Suttell Bleys Goodson Robert Walter Yury Kitaev Mirik Gogri Mark Delagasse Mark Daniel Cohen Nickolas Andrew Freeman Shane Calimlim Tybie Fitzhugh Robert Ilardi Eric Kiebler Craig Stonaha Graydon Goss Frederic Simon Tonyface John Robinson Jim Hudson Alex Gan David Barnholdt David Neal John Funai Bradley Jenkins Cody Brumfield Thomas Dougherty Dan Warren Patrick Sutton John Griffith Dean Faulk Learn more about your ad choices. Visit megaphone.fm/adchoices
More from PBS Space Time
Learn more about Audible at: https://www.audible.com/spacetime or text spacetime to 500 500!Uploaded 09-05-19PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACEQuantum computing is cool, but you know what would be extra awesome - a quantum internet. In fact if we want the first we’ll need the latter. And the first step to the quantum internet is quantum cryptography.Check out the new Space Time Merch Store!https://pbsspacetime.com/Support Space Time on Patreonhttps://www.patreon.com/pbsspacetimeNeed a Black Hole Refresherhttps://youtu.be/vNaEBbFbvcY#cryptography #quantumcomputing #spacetimeHosted by Matt O'DowdWritten by Graeme Gossel and Matt O'DowdGraphics by Leonardo WilleDirected by Andrew KornhaberProduced By: Kornhaber BrownQuantum theory may seem like an obscure subject of questionable relevance to the average person. But in fact much of our technological world depends on our understanding of the quantum properties of the subatomic universe. And soon, perhaps very soon, we’ll be interacting with the weirdness of quantum mechanics even more directly – with the coming of quantum computing and the quantum internet. Quantum computing is a topic that’s that has been well covered, so we’re going to be talking about the quantum internet. Specifically quantum cryptography and quantum key distribution – the foundations of the prospective quantum internet. We may come back to quantum computer in detail – but for now let me show you why their advent will demand a quantum internet. Special Thanks to our Patreon Supporters!Big Bang Supporters:Anton LifshitsDavid NicklasFabrice EapJuan BenetQuasar Supporters:Mark RosenthalTambe BarsbayVinnie FalcoHypernova Supporters: Antoine BrugierChuck zegarDanton SpiveyDonal BotkinEdmund FokschanerHank SJohn HofmannJordan YoungJoseph SalomonekkmMark HeisingMatthewMatthew O'ConnorGamma Ray Burst Supporters: Adrien MoyneuxAlexander LazerevAlexey EromenkoAndreas NautschAntonio RuizBradley JenkinsBrandon LabonteBuruk AregawiCarlo MogaveroDaniel LyonsDavid BehtalaDustan JonesGeoffrey ShortJames FlowersJames QuinteroJohn FunaiJohn PollockJonahJoseph DillmanJoseph EmisonJosh ThomasKevin WarneKyle HoferMalte UblMark VasileNathan HitchingsNick VirtuePaul RoseRatfeastRyan JonesScott GossettSigurd Ruud FrivikTim StephaniTommy MogensenYurii Konovaliukسلطان الخليفي Learn more about your ad choices. Visit megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices
Viewers like you help make PBS (Thank you 😃) . Support your local PBS Member Station here: https://to.pbs.org/DonateSPACEUploaded 18-07-18Entropy and the second law of thermodynamics has been credited with defining the arrow of time.You can further support us on Patreon at https://www.patreon.com/pbsspacetimeGet your own Space Time t-shirt at http://bit.ly/1QlzoBiTweet at us! @pbsspacetimeFacebook: facebook.com/pbsspacetimeEmail us! pbsspacetime [at] gmail [dot] comComment on Reddit: http://www.reddit.com/r/pbsspacetimeHelp translate our videos!https://www.youtube.com/timedtext_cs_...Previous Episode:Quantum Invariance and The Origin of The Standard Modelhttps://www.youtube.com/watch?v=V5kgruUjVBsEntropy is surely one of the most intriguing and misunderstood concepts in all of physics. The entropy of the universe must always increase – so says the second law of thermodynamics. It’s a law that seems emergent from deeper laws – it’s statistical in nature – and yet may ultimately be more fundamental and unavoidable than any other law of physics. Hosted by Matt O'DowdWritten Matt O'DowdGraphics by Grayson BlackmonAssistant Editing and Sound Design by Mike PetrowMade by Kornhaber Brown (www.kornhaberbrown.com)Special thanks to our Patreon Big Bang, Quasar and Hypernova Supporters: Big BangCoolAsCatsDavid NicklasAnton LifshitsJoey RednerFabrice EapQuasarTambe BarsbayMayank M. MehrotaMars YenturMark RosenthalDean FuquaRoman PinchukColeslawPurdieVinnie FalcoHypernovaDonal BotkinEdmund FokschanerMatthew O’ConnorEugene LawsonBarry HatfieldMartha HuntJoseph SalomoneChuck ZegarCraig PetersonJordan YoungRatfeastJohn HofmannThanks to our Patreon Gamma Ray Burst Supporters: James HughesFabian OlesenKris FernetJane MeyersJames FlowersGreg AllenDenys IvanovNick VirtueAlexey EromenkoNicholas RoseScott GossettMark VasilePatrick Murrayسلطان الخليفيAlex SetoMichal-Peanut KarmiErik SteinKevin WarneJJ BagnellAvi GoldfingerJohn PettitFlorian StinglmayrBenoit Pagé-GuitardNathan LenizBrandon LabonteDavid CraneGreg WeissShannan CatalanoBrandon CookMalte Ubl Learn more about your ad choices. Visit megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices
Learn More about The Great Courses Plus: http://ow.ly/wvWC30o0QYVUploaded 20-03-19PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACECheck out the new Space Time Merch Store!https://pbsspacetime.com/Support Space Time on Patreonhttps://www.patreon.com/pbsspacetimeThe power of Dark Energy may be increasing as the universe ages. Subtle clues are emerging that the accepted model for the nature of dark energy and dark matter may not be all that. We saw the first such clue recently in our recent episode on the Crisis in Cosmology. Today we’re doing a Space Time Journal Club to reveal another clue. We’re looking at a new paper in Nature Astronomy, “Cosmological constraints from the Hubble diagram of quasars at high redshifts” by Risaliti and Lusso. It hints that the cosmological constant may not be so constant after all. In fact it may be increasing. If this is true, then our prediction for the future of our universe looks VERY different, and may involve the entire universe tearing itself to shreds at the subatomic level in the Big Rip.On this edition of Space Time Journal Club we look at:Risaliti and Lusso (2019) "Cosmological Constraints from the Hubble Diagram of Quasars at High Redshifts"https://www.nature.com/articles/s41550-018-0657-z#darkenergy #darkmatter #spacetimeMore about The Great Courses Plus: The Great Courses Plus is currently available to watch through a web browser to almost anyone in the world and optimized for the US, UK, and Australian markets. The Great Courses Plus is currently working to both optimize the product globally and accept credit card payments globally.Learn More About Dark Energy Here:https://www.youtube.com/playlist?list=PLsPUh22kYmNA6WUmOsEEi32zi_RdSUF4iHosted by Matt O'DowdWritten by Matt O'DowdGraphics by Aaron HalevyDirecting by Andrew KornhaberSpecial thanks to our Patreon Big Bang, Quasar and Hypernova Supporters: Big Bang:Anton LifshitscoolascatsDavid NicklasFabrice EapJuan BenetJustin LloydTim DavisQuasar:James FlowersMark RosenthalTambe BarsbayVinnie FalcoHypernova: chuck zegarDanton SpiveyDonal BotkinEdmund FokschanerJens TheisenJohn HofmannJordan YoungJoseph SalomonekkmMark HeisingMatthew O'ConnorThanks to our Patreon Gamma Ray Burst Supporters: Alexey EromenkoAntonio RuizBradley JenkinsBrandon LabonteBuruk AregawiCarlo MogaveroDaniel LyonsDavid BehtalaDavid CraneDavid SchmidtDustan JonesGeoffrey ShortGreg WeissJack FroschJames HughesJames QuinteroJinal DoshiJJ BagnellJohn WebberJon FolksJonahJoseph EmisonJosh ThomasKenneth F LeonardKevin WarneKyle HoferMalte UblMark VasileNathan HitchingsNicholas RoseNick VirtueRatfeastRichard BromanScott GossettSigurd Ruud FrivikTim CrookhamTim StephaniTommy Mogensenسلطان الخليفي Learn more about your ad choices. Visit megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices
PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACE↓ More info below ↓Uploaded 15-12-20Sign Up on Patreon to get access to the Space Time Discord! https://www.patreon.com/pbsspacetimeGood news everyone: it looks like the universe is going to end with a series of catastrophic explosions. The very, very long story short is that the universe ends in heat death, as it approaches maximum entropy, and its eternal exponential expansion drives it to effective utter emptiness and absolute cold. But new calculations have revealed we may be able to look forward to one last source of astrophysical cataclysms - a new type of supernova that can only happen at the end of the universe. Check out the Space Time Merch Storehttps://pbsspacetime.com/Sign up for the mailing list to get episode notifications and hear special announcements!https://mailchi.mp/1a6eb8f2717d/spacetimeHosted by Matt O'DowdWritten by Matt O'Dowd Graphics by Leonardo Scholzer, Yago Ballarini, Pedro Osinski, and Adriano Leal Directed by: Andrew KornhaberAssistant Producer: Setare GholipourExecutive Producers: Eric Brown and Andrew KornhaberEnd Credits Music by J.R.S. Schattenberg: https://www.youtube.com/channel/UCRl6-nb4iOnsij-vnpAjp0QSpecial Thanks to Our Patreon SupportersBig BangAhmad JodehAlexander TamasBrodie RaoClinton RobinsonDavid NicklasFabrice EapJuan BenetMark RosenthalMatthew MillerMorgan HoughRadu NegulescuScott GraySean MaddoxQuasarChristina OegrenHank SMark HeisingVinnie FalcoHypernovaAlec S-LBen Delochuck zegarDanton SpiveyDonal BotkinEdmund FokschanerJason FinnJohn HofmannJohn PollockJohn R. SlavikJordan YoungJoseph SalomoneJulian TyackeJustin JermynL. Wayne Ausbrooksm0nkMark Matthew BoskoMathewMatthew O'ConnorNicholas NewlinTimothy McCullochwilliam bryanАнтон КочковGamma Ray BurstA GAdrian HatchAlecZeroAndreas NautschAndrew MannAndrew RichmondAnthony KahngAstaurusAstronauticistBill BlairBleys GoodsonBradley JenkinsBrandon labonteBrandon LattinBrian BlanchardBruce BCameron SampsonCass CostelloChristopher BarronCraig StonahaDan WarrenDaniel JenningsDaniel LyonsDarren DuncanDarryl J LyleDavid HughesDavid JohnstonDawn M FinkDerek DavisDevon RosenthalDFaulkDrJYouEndre PechEric KieblerEric Websterfieldsa eleanoryFrederic SimonGeoffrey ClarionGeoffrey ShortGraydon GossGreg SmithIsaac SuttellIsmael MontecelJ. KingJames RamseyJeremiah JohnsonJeremy ReedJohn FunaiJohn GriffithJohn RobinsonKevin LeeKevin O'ConnellKevin WarneKyle HoferLily kawaiiLuaanLucas MorganMalte UblMark Daniel CohenMartin J LollarMartin SkansMD3Michael BartonMichael ConroyMirik GogriMr TNateNick VirtueNickolas Andrew FreemanOliver FlanaganPatrick SuttonPeter MertzPratik MukherjeeRichard DeightonRobert C SchuppRobert IlardiRobert WalterRuss CreechScott GossettShane CalimlimSimon OliphantSteven SartoreTim StephaniTonyfaceTybie FitzhughYannick WeynsYurii Konovaliuk Learn more about your ad choices. Visit megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices
Viewers like you help make PBS (Thank you 😃) . Support your local PBS Member Station here: https://to.pbs.org/DonateSPACEUploaded 21-03-18What do the first stars in the universe, dark matter, and superior siege engines have in common? You can further support us on Patreon at https://www.patreon.com/pbsspacetimeGet your own Space Time t-shirt at http://bit.ly/1QlzoBiTweet at us! @pbsspacetimeFacebook: facebook.com/pbsspacetimeEmail us! pbsspacetime [at] gmail [dot] comComment on Reddit: http://www.reddit.com/r/pbsspacetimeTrebuchet Challenge Winners:Vineet GalaValerie SinclairAlex FunicielloDavid ShearnGwyn PaskeBruce and Angela TremainHelp translate our videos!https://www.youtube.com/timedtext_cs_panel?tab=2&c=UC7_gcs09iThXybpVgjHZ_7gPrevious Episode:Hawking Radiationhttps://www.youtube.com/watch?v=qPKj0YnKANwSometimes space news sneaks by without getting much attention. Not everything wows like gravitational waves or spacefaring sportscars. That’s the case with the recent discovery of earliest stars in the universe. In a Nature paper published a few weeks ago, Judd Bowman and collaborators report a signal from the very first stars to form in our universe. The same result also hints at brand new physics that may help explain the nature of dark matter. This result flew under the radar in part because it’s a subtle and clever result that requires a bit of interpretation. Today we’re doing a Space Time Journal Club to explain this discovery. We’ll follow that with the solution to our recent trebuchet challenge question.Written and Hosted by Matt O'DowdProduced by Rusty WardGraphics by Grayson BlackmonAssistant Editing and Sound Design by Mike Petrow and Linda HuangMade by Kornhaber Brown (www.kornhaberbrown.com)Special thanks to our Patreon Big Bang, Quasar and Hypernova Supporters: Big BangCoolAsCatsDavid NicklasFaisal SaudAnton LifshitsJoey RednerQuasarTambe BarsbayMayank M. MehrotaMars YenturMark RosenthalDean FuquaRoman PinchukFrank SeciliaColeslawPurdieHypernovaEdmund FokschanerMatthew O’ConnorEugene LawsonMartha HuntJoseph SalomoneChuck ZegarJordan YoungRatfeastJohn HofmannBarry HatfieldCraig PetersonKevin CostelloThanks to our Patreon Gamma Ray Burst Supporters: James HughesFabian OlesenKris FernetJane MeyersJames FlowersGreg AllenTJMadisonDenys IvanovNick VirtueAlexey EromenkoNicholas RoseScott GossettMark VasilePatrick MurraySultan AlkhulaifiAlex SotoMichal-Peanut KarmiErik SteinDaniel LyonsKevin WarneJJ BagnellJ RejcAvi GoldfingerJohn PettitFlorian StinglmayrBenoit Pagé-GuitardNathan LenizBrandon LabonteDavid CraneGreg Weiss Learn more about your ad choices. Visit megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices