Cool Worlds

Artificial gravity is a concept that is ubiquitous in our science fiction yet elusive in our space program. Why is this? And how could we develop artificial gravity soon? In a Cool Worlds special, this video essay goes in depth on the topic discussing why centrifuges are the most plausible solution and early ideas on the topic. Join us a journey from Einstein's equivalence principle, to O'Neill Cylinders and Stanford Tori; from Coriolis forces to near-term experiments. Grab a cup of a tea and enjoy. You can now support our research program and the Cool Worlds Lab at Columbia University: https://www.coolworldslab.com/support Chapters: 0:08 Introduction 5:43 The O’Neill Cylinder 8:10 The Stanford Torus 10:16 Down-Sizing 13:31 Coriolis 16:52 Vertical Coriolis 19:32 Tipping Coriolis 21:34 Canal Sickness 27:01 Stability 29:28 Near-Tear Experiments Academic articles used: ► Nesti et al. (2014), "Human sensitivity to vertical motion", Exp Brain Res., 232, 303: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898153/ ► Harris et al. (2014), "How Much Gravity Is Needed to Establish the Perceptual Upright?", PLoS One, 9, e106207: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4153541/ (0.15g) ► Cohen et al. (2000), "Effects of Prolonged Centrifugation on Orthostasis", Aerospace Medical Association 72nd Annual Scientific Meeting 2001: https://ntrs.nasa.gov/search.jsp?R=20010106394 ► Graybiel et al. (1960), "Observations on Human Subjects Living in a 'Slow Rotation Room' for Periods of Two Days", Arch Neurol., 3, 55: https://jamanetwork.com/journals/jamaneurology/fullarticle/562689 ► Theodore Hall (1993), "The Architecture of Artificial Gravity: Archetypes and Transformations of Terrestrial Design", PhD Thesis, University of Michigan: http://www.artificial-gravity.com/SSI-1993-Hall.pdf ► Theodore Hall (2002), "Architectural Considerations for a Minimum Mass, Minimum Energy, Artificial Gravity Environment", SAE Technical paper Series, http://www.artificial-g

We found two new planets using NASA's TESS mission! The paper freshly went up online today and so we thought we'd give our loyal Cool Worlders an exclusive look at the new system, how we found and confirmed it and why it is a bit special. ► Our discovery paper: https://arxiv.org/abs/1902.03900 ► Our Cool Worlds video giving some background on TESS: https://youtu.be/-2SECBi-AP8 ► Our Cool Worlds video on stellar densities by Emily Sandford: https://youtu.be/66uZPYliJz4 ► TESS ExoFop website: https://exofop.ipac.caltech.edu/tess/view_toi.php?toi=&page1=1&ipp1=500&sort=period ► Where and how to download TESS data: http://archive.stsci.edu/tess/bulk_downloads/bulk_downloads_ffi-tp-lc-dv.html ► Columbia University Department of Astronomy: http://www.astro.columbia.edu ► Cool Worlds Lab website: http://coolworlds.astro.columbia.edu ► Outro music by 8-bit Universe "Harder Better Faster Stronger [8 Bit Cover Tribute to Daft Punk]": https://8bituniverse.bandcamp.com/track/harder-better-faster-stronger-8-bit-tribute-to-daft-punk ::Playlists For Channel:: Latest Cool Worlds Videos ► http://bit.ly/NewCoolWorlds Cool Worlds Research ► http://bit.ly/CoolWorldsResearch Guest Videos ► http://bit.ly/CoolWorldsGuests Q&A Videos ► http://bit.ly/CoolWorldsQA Tabby's Star ► http://bit.ly/TabbysStar Science of TV/Film ► http://bit.ly/ScienceMovies ::Follow us:: SUBSCRIBE to the channel http://bit.ly/CoolWorldsSubscribe Cool Worlds Lab http://coolworlds.astro.columbia.edu Twitter https://twitter.com/david_kipping THANKS FOR WATCHING!!

How could we one day travel between the stars with real physics? Perhaps the greatest challenge to interstellar flight is energetics - it takes vast amounts of energy to accelerate even small ships to 20% the speed of light. But what if we could steal that energy from where? Perhaps even a black hole. Enter the "halo drive", a video by Prof David Kipping based on his new peer-reviewed research paper on the subject. This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support Further reading and resources: ► Kipping, David (2018), "The Halo Drive: Fuel Free Relativistic Propulsion of Large Mases via Recycled Boomerang Photons", JBIS, 71, 458: https://arxiv.org/abs/1903.03423 ► Dyson, Freeman (1963), "Gravitational Machines", in A.G.W. Cameron, ed., Interstellar Communication, New York Benjamin Press: https://www.ifa.hawaii.edu/~barnes/ast242_s14/Dyson_Machines.pdf ► Breakthrough Starshot homepage: https://breakthroughinitiatives.org/initiative/3 ► Our Cool Worlds video giving some background on Breakthrough Starshot: https://youtu.be/Ksb6Vh0BT_E ► Our Cool Worlds video on relativistic moving mirrors: https://youtu.be/msK9d9k6K0E ► Our Cool Worlds video on mirror distortion effects: https://youtu.be/1iNA-GTocI0 ► Columbia University Department of Astronomy: http://www.astro.columbia.edu ► Cool Worlds Lab website: http://coolworlds.astro.columbia.edu * There’s an error in the video at around 8:30, 2 trillion joules is the cumulative energy output of a typical nuclear power station after 2000 seconds, not 20 days Music is largely by Chris Zabriskie (http://chriszabriskie.com/) and is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/), in order of appearance; ► Cylinder Five (http://chriszabriskie.com/cylinders/) ► Music from Neptune Flux, "We Were Never Meant to Live He

Could advanced civilizations be using a network of black holes for interstellar travel? In our last video, the "halo drive" was discussed covering the basic physics of how this new system could potentially enable interstellar flight. Here, we go much deeper on the halo drive concept, answering many of the questions which have been raised, and going further by considering the possibilities of a galactic wide network of such systems. This video is based on research conducted at the Cool Worlds Lab at Columbia University. You can now support our research program directly here: https://www.coolworldslab.com/support Chapters: 0:08 Introduction 4:39 The Halo Drive 7:14 Non-Binary Halo Drive 13:41 Leaving the Black Hole 18:40 Deceleration 21:15 A Halo Network 26:29 Civilizations around Black Holes Academic articles used: ► Kipping, David (2018), "The Halo Drive: Fuel Free Relativistic Propulsion of Large Mases via Recycled Boomerang Photons", JBIS, In Press: https://arxiv.org/abs/1903.03423 ► Kipping, David (2017), "Relativistic Light Sails", AJ, 153, 277: https://arxiv.org/abs/1704.04310 ► Dyson, Freeman (1963), "Gravitational Machines", in A.G.W. Cameron, ed., Interstellar Communication, New York Benjamin Press: https://www.ifa.hawaii.edu/~barnes/ast242_s14/Dyson_Machines.pdf ► Breakthrough Starshot homepage: https://breakthroughinitiatives.org/initiative/3 ► Cool Worlds video giving some background on Breakthrough Starshot: https://youtu.be/Ksb6Vh0BT ► Cool Worlds video on relativistic moving mirrors: https://youtu.be/msK9d9k6K0E ► Cool Worlds video on mirror distortion effects: https://youtu.be/1iNA-GTocI0 ► Semyonov, Oleg (2006), "Radiation Hazard of Relativistic Interstellar Flight": https://arxiv.org/abs/physics/0610030 ► Hoang et al. (2017), "The interaction of relativistic spacecrafts with the interstellar medium", ApJ, 837, 16: https://arxiv.org/abs/1608.05284 ► Heger, et al. (2003), "How massive single stars end their life", ApJ, 591,

Arguably the greatest scientific discoveries are the unexpected ones. The discoveries that defy explanation and for which no theory or model predicted. Yet, looking for such signals is incredibly challenging. How can you look for something when you don't know what it looks like? This has been a problem we've thought about a lot here in the Cool Worlds Lab at Columbia University and this week we're thrilled to share the outcome of a new research project in this area. Graduate student Adam Wheeler presents the "Weird Detector" - an algorithm capable of finding the truly weird signals lurking in astronomical data! Our paper can be found at: ► Wheeler, Adam & Kipping, David (2019), "The Weird Detector: Flagging periodic, coherent signals of arbitrary shape in time series photometry", MNRAS, 485, 5498 : https://arxiv.org/abs/1903.09213 Video materials and graphics used: ► Night sky time lapse: https://www.youtube.com/watch?v=lqUgqGdkrzI ► Milky Way animation by Stefan Payne-Wardenaar: https://vimeo.com/330625918 ► Oumuamua animation: https://www.eso.org/public/videos/eso1737d/ ► Kepler video available at the NASA Kepler homepage: https://kepler.nasa.gov ► TESS video available at the NASA TESS homepage: https://tess.gsfc.nasa.gov ► Binary Stars: https://www.youtube.com/watch?v=E9GG1y_sk98 ► James Davenport starpot simulation: https://vimeo.com/155093319 ► Sunspot footage from NASA Solar Dynamics Observatory: https://sdo.gsfc.nasa.gov/gallery/main/item/43 ► Binary orbit gallery by Adrian Price-Whelan: http://adrian.pw/viz.html ► Earth-Moon tidal bulge animation by Kevin Gill: https://www.youtube.com/watch?v=7AHshzLquOU ► Flare and complex flare figures from Davenport et al. (2014): https://www.spacetelescope.org/videos/heic0310c/ ► Comet video from https://www.spacetelescope.org/videos/heic0310c/ ► TESS comet video https://svs.gsfc.nasa.gov/13030 Filmclips, in order of appearance; ► Star Trek, The Next Generation ► Music from Neptune Flux, "We W

There are trillions upon trillions of stars and worlds in our Universe. Faced with such large numbers, it's tempting to conclude that there must surely be other life out there, somewhere. But is this right? Could the probability of life beginning be a number so small that we are alone? A video essay by Professor David Kipping. You can now support our research program and the Cool Worlds Lab at Columbia University: https://www.coolworldslab.com/support Further reading and resources: ► Chen, Jingjing & Kipping, David (2018), "On the Rate of Abiogenesis from a Bayesian Informatics Perspective", Astrobiology, 18, 12: https://www.liebertpub.com/doi/10.1089/ast.2018.1836 ► Hanson, Robin (1998), "Must Early Life Be Easy? The Rhythm of Major Evolutionary Transitions": http://mason.gmu.edu/~rhanson/hardstep.pdf ► Benzene in space materials and story: http://sci.esa.int/hubble/24530-stellar-cocoon-crl-618/ ► Columbia University Department of Astronomy: http://www.astro.columbia.edu ► Cool Worlds Lab website: http://coolworlds.astro.columbia.edu Music is largely by Chris Zabriskie (http://chriszabriskie.com/) and is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/), in order of appearance; ► The Sun is Scheduled to Come Out Tomorrow (https://soundcloud.com/chriszabriskie/the-sun-is-scheduled-to-come) ► Music from Neptune Flux, "We Were Never Meant to Live Here" (http://chriszabriskie.com/neptuneflux/) ► Cylinder Five (http://chriszabriskie.com/cylinders/) ► Music from Neptune Flux, "Stories About the World That Once Was" (http://chriszabriskie.com/neptuneflux/) ► "Waking Up" by Atlas, licensed through SoundStripe.com: https://app.soundstripe.com/songs/3984 ► Cylinder Two (http://chriszabriskie.com/cylinders/) ► Piano cover of S.T.A.Y. (Hans Zimmer) byt Jordie Eskes: https://youtu.be/dbSyDsNxAHM Video materials used: ► Intro/outro video by Miguel Aragon of Johns Hopkins University with Mark Subbarao o

Could humans ever travel to other galaxies within their lifetime? The immense scale of the Universe seems to prohibit such voyages, after all the nearest galaxy is so far away that it takes light itself - the fastest thing in the Universe - 2.5 million years to complete the trip. Remarkably, there is a trick that might allow humans to accomplish this feat - join us today as we step onboard the constantly accelerating spaceship! Written and presented by Professor David Kipping. You can now support our research program and the Cool Worlds Lab at Columbia University: https://www.coolworldslab.com/support Chapters 0:00 - Prologue 2:57 - A Journey to Alpha Centauri 11:27 - Returning from Distant Shores 21:12 - Onward to the End Further reading and resources: ► Lee, J. & Cleaver, G., 2015, "The Relativistic Blackbody Spectrum in Inertial and Non-Inertial Reference Frames": https://arxiv.org/abs/1507.06663 ► Yurtsever, U. & Wilkinson, S. 2015, "Limits and Signatures of Relativistic Flight": https://arxiv.org/abs/1503.05845v3 ► Margalef-Bentabol, B., Margalef-Bentabol, J., Cepa, J., 2013, "Evolution of the Cosmological Horizons in a Concordance Universe": https://arxiv.org/abs/1302.1609 ► Columbia University Department of Astronomy: http://www.astro.columbia.edu ► Cool Worlds Lab website: http://coolworlds.astro.columbia.edu Music is largely by Chris Zabriskie (http://chriszabriskie.com/) and is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/), in order of appearance; ► Cylinder Five (http://chriszabriskie.com/cylinders/) ► Music from Neptune Flux, "The Oceans Continue to Rise http://chriszabriskie.com/neptuneflux/ ► Music from Neptune Flux, "We Were Never Meant to Live Here" http://chriszabriskie.com/neptuneflux/ ► Cylinder Two (http://chriszabriskie.com/cylinders/) ► Cylinder Four (http://chriszabriskie.com/cylinders/) ► Cylinder Eight (http://chriszabriskie.com/cylinders/) ► "It's Always

We now have around 5000 satellites in orbit of the Earth and all of them are compelled to follow orbital paths dictated by Johannes Kepler's Laws of Planetary Motion, first written down in the early 17th century. Could there be a way to hack the orbital physics and break away from Kepler's Laws? Today we'll explore a novel space technology called statites, and a twist on it we're calling quasites, that could very well do exactly this. This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support The paper I put together can be found at: ► Kipping, David (2019), "Transiting Quasites as a Possible Technosignature", submitted: http://coolworlds.astro.columbia.edu/quasites.pdf References cited: ► Robert Forward (submitted 1989, published 1993), “Statite: spacecraft that utilizes sight pressure and method of use”, US Patent 5183225A: https://patents.google.com/patent/US5183225A/en ► McInnes & Simmons (1992): “Solar Sail Halo Orbits Part I - Heliocentric Case”, Journal of Spacecraft and Rockets, 29, 466: https://arc.aiaa.org/doi/10.2514/3.25487 ► McInnes & Simmons (1992): “Solar Sail Halo Orbits Part II - Geocentric Case”, Journal of Spacecraft and Rockets, 29, 472: https://arc.aiaa.org/doi/10.2514/3.55639 ► Baig & McInnes (2010), “Light levitated geostationary cylindrical orbits are feasible”, Journal of Guidance, Control and Dynamics, 33, 782: https://strathprints.strath.ac.uk/18865/ Video materials and graphics used: ► Analemma visualization clip from spaceborne: https://youtu.be/V1omYlc27y4 ► Lightsail animations by the Planetary Society: https://youtu.be/bI_FH_2Cqr8 and https://youtu.be/-OmGvycgNCg ► IKAROS footage courtesy of JAXA and online via: https://youtu.be/wUSjggdG9KU ► Kepler-11 orbital animation by NASA JPL: https://photojournal.jpl.nasa.gov/archive/PIA13833_Kepler-11_Animation_lg.mov Music used: ► Music

The Solar System is an eight-planet system - but is that typical of other stars too? How often do other stars have 8 planets? Or is some other number more common? Put another way, what is the multiplicity distribution of exoplanets? This is a devilishly difficult problem to unlock because our telescopes provide incomplete views of distant stars, what about the missing planets? In new research here from the Cool Worlds Lab, we show how progress can be made by hypothesizing a family of various distributions, simulating the resulting planets and expected planet detections, and then comparing to reality. Although current techniques only reveal planets on periods less than 400 days, this still gives us a chance to quantify the multiplicity of the inner part of exoplanetary systems! Join us today as Emily Sandford walks us through her new paper and explains what it all means. This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support References cited: ► Sandford & Kipping (2019): "The multiplicity distribution of Kepler's exoplanets", MNRAS, submitted: https://arxiv.org/abs/1907.08148 ► Ballard & Johnson (2016): “The Kepler Dichotomy among the M Dwarfs: Half of Systems Contain Five or More Coplanar Planets”, The Astrophyical Journal, 816, 66: https://arxiv.org/abs/1410.4192 Video materials and graphics used: ► TRAPPIST-1 orbit animation by ESO/L. Calçada/spaceengine.org: https://www.eso.org/public/videos/eso1706g/ ► "Multiplicity" (1996), Columbia Pictures Keck in Motion by Andrew Cooper: https://vimeo.com/36442707 Music used: ► Outro music "Sad Game Boy" by Mikey Geiger, licensed through SoundStripe.com And also... ► Columbia University Department of Astronomy: http://www.astro.columbia.edu ► Cool Worlds Lab website: http://coolworlds.astro.columbia.edu ::Playlists For Channel:: Latest Cool Worlds Videos ► http

When it comes to telescopes, bigger is better. That's why we're investing billions of dollars into a new generation of "extremely large telescopes", such as the Thirty Meter Telescope (TMT). But is 30 meters truly extreme? Could it be possible to ever build a telescope on the scale of a planet? In a new research paper by our very own Professor David Kipping, a solution for turning the Earth into a "Terrascope" is presented. Join us on a journey though the history of telescope inventions as well David's own personal journey to devising this new radical approach to the telescope. Written and Presented by Professor David Kipping This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support The Terrascope paper can be found at: ► Kipping, David (2019), "The Terrascope: On the Possibility of Using the Earth as an Atmospheric Lens", PASP, accepted for publication: http://coolworlds.astro.columbia.edu/terrascope.pdf Chapters 0:00 - Prologue 0:43 - Telescopes through Time 7:48 - Natural Lensing 14:02 - The Green Flash 18:55 - The Terrascope 26:42 - Dreams of Our Youth Video materials and graphics used: ► JWST timelapse from NASA's Goddard Space Flight Center: http://svs.gsfc.nasa.gov/12145 ► GTC footage by Gianluca Lombardi: https://youtu.be/K7padkb0-n8 ► ELT animation by ESO & Herbert Zodet: https://www.eso.org/public/usa/videos/elttrailer-notext/ ► GMT mirror casting by University of Arizona Steward Observatory Mirror Lab: https://youtu.be/uWHkoU2EqyM ► Water lensing clips by Spa Nederland: https://youtu.be/yPhLTjjIHJc ► NASA/International Space Station footage of the Earth ► Green Flash footage by Mila Zinkova: https://youtu.be/t9hpvdHb7ZM ► Earth timelapse taken by EPIC onboard NOAA's DSCOVR satellite, video by NASA's Goddard Space Flight Center/Kayvon Sharghi: https://svs.gsfc.nasa.gov/12312 ► WFIRST animatio

Planets, like the Earth, could potentially serve as giant telescopes - as explored in our last video (https://youtu.be/jgOTZe07eHA). This happens because the atmosphere refracts light and so bends it into a focus, like a huge spherical lens. Parabolic dishes on Earth can be sued as both telescopes and antennae, and so in the same way - could planets be used as antennae? Today we explore the possibility of using the Jupiter as a giant antennae, perhaps serving as the basis for an interplanetary internet, and how Juno could very well test the idea today. Written and Presented by Professor David Kipping This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support ► The original Terrascope paper is Kipping, David (2019), "The Terrascope: On the Possibility of Using the Earth as an Atmospheric Lens", PASP, accepted for publication: https://arxiv.org/abs/1908.00490 ► The new Jovoscope research note is Kipping, David (2019), "A Possible Test of the Terrascope Concept Using Jupiter & Juno", RNAAS: http://coolworlds.astro.columbia.edu/jovoscope.pdf Chapters 0:00 - Whispers on the Wind 5:04 - Jovoscope 13:02 - Interplanetary Internet Video materials and graphics used: ► 2014's "COSMOS: A SpaceTime Odyssey", written by Ann Druyan and Steven Soter, Cosmos Studios, Inc: https://youtu.be/GO5FwsblpT8 ► Voyager 2 footage courtesy NASA/JPL: https://www.jpl.nasa.gov/video/details.php?id=1564 ► Juno arrival at Jupiter animation by NASA/JPL/SwRI: https://youtu.be/NNt9DTw7nzk ► Juno Perijove-18 Jupiter Flyby by NASA/JPL/SwRI/MSSS/SPICE/Gerald Eichstädt: https://youtu.be/HKCldl39CF0 ► "Juno's Communications" by NASA/JPL/SwRI: https://youtu.be/QA3UiDbCPGE ► "Juno Engineering: Precision Matters" by NASA/JPL/SwRI: https://youtu.be/eV5Ot2HCKXI ► Water droplet by stepvideolabs: https://youtu.be/RLn1ErhxOPo ► Diffraction by Andrew Norton

Over recent years, newspapers have been filled with headlines such as "billions of Earths in the Milky Way alone". But how many Earth-like planets are there really? Join us as we explore all of the different estimates for how many Earths there really are, how each team arrived at their answers, and why they seem to differ so wildy from each other, before finally we'll offer our own answer to this monumental question. Written & presented by Prof David Kipping This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support References: ► Youdin, A., 2011, ApJ, 742, 38: https://arxiv.org/abs/1105.1782 ► Catanzarite, J. & Shao, M., 2011, ApJ, 738, 151 https://arxiv.org/abs/1103.1443 ► Dong, S. & Zhu, Z., 2013, ApJ, 778, 11: https://arxiv.org/abs/1212.4853 ► Petigura, E., Howard, A., Marcy, G. W., 2013, PNAS, 110, 19273: https://arxiv.org/abs/1311.6806 ► Foreman-Mackey, D., Hogg., D. W. & Morton, T. D., 2014, ApJ, 795, 12: https://arxiv.org/abs/1406.3020 ► Farr, W. M., Mandel, I., Aldridge, C., Stroud, K., 2014, arXiv:1412.4849: https://arxiv.org/abs/1412.4849 ► Burke, C. J., Christiansen, J. L., Mullally F. et al., 2015, ApJ, 809, 19: https://arxiv.org/abs/1506.04175 ► Silburt, A., Gaidos, E., Wu, Y., 2015, ApJ, 799, 180: https://arxiv.org/abs/1406.6048 ► Traub, W., 2016, ApJ submitted: https://arxiv.org/abs/1605.02255 ► Belikov, R., Stark, C., Batalha, N., et al., 2017: https://exoplanets.nasa.gov/system/internal_resources/details/original/680_SAG13_closeout_8.3.17.pdf ► Garrett, D., Savransky, D., Belikov, R., 2018, PASP, 130, 114403: https://arxiv.org/abs/1810.02847 ► Mulders, G. D., Pascucci, I., Apai, D., Ciesla, F. J., 2018, AJ, 156, 24: https://arxiv.org/abs/1805.08211 ► Hsu, D. C., Ford, E. B., Ragozzine, D., Ashby, K., 2019, ApJ, 158, 20: https://arxiv.org/abs/1902.01417 ► Bryson, S., Coughlin, J., Batalha,

The 2019 Nobel Prize in Physics has just been announced, with one half going to the first discovery of an exoplanet around a Sun-like star. Here’s our brief take on why this is great news for those who love planets. Presented by Prof. David Kipping. All planetary images and videos shown are artistic representations. References: ► Mayor & Queloz, 1995, "A Jupiter-mass companion to a solar-type star", Nature, 378, 355: https://www.nature.com/articles/378355a0 ► Latham et al., 1989, "The unseen companion of HD114762: a probable brown dwarf", Nature, 339, 38: https://www.nature.com/articles/339038a0 ► Campbell, Walker & Yang, 1988, "A Search for Substellar Companions to Solar-type Stars", ApJ, 331, 902: https://ui.adsabs.harvard.edu/abs/1988ApJ...331..902C/abstract ► Hatzes &Cochran, 1993, "Long-Period Radial Velocity Variations in Three K Giants", ApJ, 413, 339: https://ui.adsabs.harvard.edu/abs/1993ApJ...413..339H/abstract ► Wolszczan & Frail, 1992, "A planetary system around the millisecond pulsar PSR1257+12", Nature, 355, 145 Video materials and graphics used: ► GJ 357 animations by NASA's Goddard Space Flight Center/Chris Smith: https://svs.gsfc.nasa.gov/13266 ► Trappist-1 animation by ESO/L. Calçada/spaceengine.org: https://www.eso.org/public/videos/eso1706h/ Music used, in chronological order: ► Music from Neptune Flux, "We Were Never Meant to Live Here" by Chris Zabriskie (http://chriszabriskie.com/neptuneflux/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) ► Cylinder Two (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) ► "Sad Game Boy" by Mikey Geiger, licensed through SoundStripe.com: https://app.soundstripe.com/songs/6347 And also... ► Columbia University Department of Astronomy: http://www.astro.columbia.edu ► Cool Worlds Lab website: http

Is it possible to go backwards through time? We travel forwards every day, but traveling back could let us change our past, visit old friends, or manipulate the timeline to our benefit... Although our knowledge of space and time remains incomplete, we can still use what we know to consider possible time machines. But what kind of paradoxes would this entail and how can we resolve them? Join us today on a special journey through time. An educational video written and presented by Professor David Kipping This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support All music used is licensed by SoundStripe.com or through Creative Commons: ► "It's Always Darkest Before the Dawn" by Hill, licensed through SoundStripe.com: https://app.soundstripe.com/songs/7441 ► "Waking Up" by Atlas, licensed through SoundStripe.com: https://app.soundstripe.com/songs/3984 ► Cylinder Four (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) ► "Always Dreaming" by Caleb Etheridge, licensed through SoundStripe.com: https://app.soundstripe.com/songs/5534 ► Cylinder Two (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) ► "Fable" by Stephen Keech, licensed through SoundStripe.com: https://app.soundstripe.com/songs/6312 ► "Selha" by Stephen Keech, licensed through SoundStripe.com: https://app.soundstripe.com/songs/7102 Further reading and resources: ► Echeverria, F., Klinkhammer, G. & Thorne, K. S. (1991), "Billiard balls in wormhole spacetimes with closed timelike curves: Classical theory", Phys. Rev. D., 44, 1077: https://ui.adsabs.harvard.edu/abs/1991PhRvD..44.1077E/abstra

In the last few decades, our astronomical techniques have developed to the point that we can now detect planets orbiting other stars. Planets which transit their star make up most of our catalogs, because they are so easy to find and can reveal so much more information about the planets. For example, in the near future we might even be able to detect life remotely on these worlds. This makes us wonder - could someone out there already be using this method on us? Here, we explore which stars are best placed to detect us using the transit method, what they might learn about us and the possibility of reciprocal transit configurations, enabling a possible means of direct communication across the stars. Written and Presented by Prof. David Kipping. All planet images/videos shown are artistic impressions and not real photographs, except for the pixelated image of TRAPPIST-1 (see below) This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support References: ► Rauscher, B. J. et al., 2016, "Detectors and cooling technology for direct spectroscopic biosignature characterization", JATIS, 2, 041212: https://www.spiedigitallibrary.org/journals/Journal-of-Astronomical-Telescopes-Instruments-and-Systems/volume-2/issue-04/041212/Detectors-and-cooling-technology-for-direct-spectroscopic-biosignature-characterization/10.1117/1.JATIS.2.4.041212.full ► Burke, C. J., Mullally, F., Huber, D., 2018, "K2 Exoplanet Ecliptic Survey - KEES": https://keplerscience.arc.nasa.gov/data/campaigns/c2/GO2072_Burke.pdf ► Kipping, D. & Teachey, A., 2016, "A Cloaking Device for Transiting Planets", MNRAS, 459, 1233 Video materials and graphics used: ► ESO animations credit to ESO and Herbert Zodet: https://www.eso.org/public/videos/eso1706a/ ► TRAPPIST-1 pixels animation by NASA Ames/G. Barentsen: https://www.nasa.gov/image-feature/ames/kepler/light-from-

Black holes are one of the most bizarre and terrifying results from general relativity - a singularity of infinite density from which even light cannot escape. Black holes fascinate us and this has led some to wonder if the could even be used as a power source. Micro black holes, that is black holes much lighter than a star, could be one of way of doing this. Today we explore the possibilities of a micro black hole and exactly how it might be possible to turn them into power banks. Written and Presented by Prof. David Kipping. All planet images/videos shown are artistic impressions and not real photographs, except for the reconstructed image of Messier 87* You can now support our research program and the Cool Worlds Lab at Columbia University: https://www.coolworldslab.com/support References: ► Hawking, Stephen (1974), "Black hole explosions?", Nature, 248, 30: https://www.nature.com/articles/248030a0 ► Carter, Brandon (1971), "Axisymmetric Black Hole Has Only Two Degrees of Freedom", Physics Review Letters, 26, 331: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.26.331 ► Newman, E. T., Couch, E., Chinnapared, K., Exton, A., Prakash, A., Torrence, R. (1965), "Metric of a Rotating, Charged Mass", Journal of Mathematical Physics, 6, 918: https://aip.scitation.org/doi/10.1063/1.1704351 ► Crane, L. & Westmoreland, S. (2009), "Are Black Hole Starships Possible", arXiv e-prints 0908.1803: https://arxiv.org/abs/0908.1803 ► Kipping, David (2018), "The Halo Drive: Fuel-free relativistic propulsion of large masses via recycled boomerang photons", Journal of the British Interplanetary Society, 71, 458: https://arxiv.org/abs/1903.03423 Video materials and graphics used: ► ESO animations credit to ESO and Herbert Zodet: https://www.eso.org/public/videos/eso1706a/ ► Sun turning into a black hole credit to ESA/Hubble/M. Kornmesser: https://youtu.be/nKCqZAPGwNE ► Black hole animation credit to CGI 3D Animated Short: "INTRA" by Thomas Vanz: https