Subscribe to Veritasium - it s FREE! http://bit.ly/YSWpWm Check out other unanswered science questions: http://youtu.be/UFydagCS9fg The universe is huge. That means two things: 1. there is probably life elsewhere, 2. It is likely too far away to have reached us. Fast, Furious & Funny - http://www.youtube.com/fastfuriousand... (http://www.youtube.com/watch?v=YWxub2...) The Brain Scoop - http://www.youtube.com/thebrainscoop (http://youtu.be/mNuu0y6ZmAs) ASAPScience - http://www.youtube.com/AsapSCIENCE (http://www.youtube.com/watch?v=wgxJhp...) The Royal Institute of Great Britain - http://www.youtube.com/TheRoyalInstit... (http://www.youtube.com/watch?v=gm02Oi...) PBS Idea Channel - http://www.youtube.com/pbsideachannel (http://www.youtube.com/watch?v=TbNymw...) The Spangler Effect - http://www.youtube.com/TheSpanglerEffect (http://www.youtube.com/watch?v=4fQ4uB...) Minute Physics - http://www.youtube.com/minutephysics (http://www.youtube.com/watch?v=2yHDeK...) Head Squeeze - http://www.youtube.com/HeadsqueezeTV (http://www.youtube.com/watch?v=UPBJX1...) Vsauce - http://www.youtube.com/Vsauce (http://www.youtube.com/watch?v=L45Q1_...) Space is big. You just won t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it s a long way down the road to the chemist s, but that s just peanuts to space. ~Douglas Adams Thanks to Dr. Simon O Toole for talking exoplanets with me! We also discussed the Drake equation but there wasn t really room for it. Camera by Charles Clement Music by Kevin McLeod (incompetech.com) Mirage, Scissors

Another awesome thing the Mantis Shrimp does... The BEST Sonoluminescence reference: http://doc.utwente.nl/42577/1/single-bubble_sonoluminescence.pdf Links to other "Unknown Science Questions" videos Veritasium - http://www.youtube.com/1veritasium (http://www.youtube.com/watch?v=5JGSqG8OLjE) Fast, Furious & Funny - http://www.youtube.com/fastfuriousandfunny (http://www.youtube.com/watch?v=YWxub2XhmXM) The Brain Scoop - http://www.youtube.com/thebrainscoop (http://youtu.be/mNuu0y6ZmAs) ASAPScience - http://www.youtube.com/AsapSCIENCE (http://www.youtube.com/watch?v=wgxJhpLoFFU) The Royal Institute of Great Britain - http://www.youtube.com/TheRoyalInstitution (http://www.youtube.com/watch?v=gm02Oid8sbs) PBS Idea Channel - http://www.youtube.com/pbsideachannel (http://www.youtube.com/watch?v=TbNymweHW4E) The Spangler Effect - http://www.youtube.com/TheSpanglerEffect (http://www.youtube.com/watch?v=4fQ4uB-At-c) Minute Physics - http://www.youtube.com/minutephysics (http://www.youtube.com/watch?v=2yHDeKFW8j8) Head Squeeze - http://www.youtube.com/HeadsqueezeTV (http://www.youtube.com/watch?v=UPBJX1SW7AA) Vsauce - http://www.youtube.com/Vsauce (http://www.youtube.com/watch?v=L45Q1_psDqk) MinutePhysics is on Google+ - http://bit.ly/qzEwc6 And facebook - http://facebook.com/minutephysics And twitter - @minutephysics Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Music by Nathaniel Schroeder http://www.soundcloud.com/drschroeder Thanks to Nima Doroud for contributions. Created by Henry Reich

PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateOKAY ↓ More info and sources below ↓ Wind. Always there. Where does it come from? Click here to SUBSCRIBE, it s FREE! -- http://bit.ly/iotbs_sub Wind is everywhere. The air is constantly moving, sometimes gently, sometimes violently. Why? Pressure, temperature and rotation come together to make wind in some *cool* and unexpected ways. Written and hosted by Joe Hanson Produced by Painted On Productions (http://www.paintedon.com/) ----------- Join us on Patreon! https://patreon.com/itsokaytobesmart Twitter http://www.twitter.com/DrJoeHanson http://www.twitter.com/okaytobesmart Instagram http://www.instagram.com/DrJoeHanson http://www.instagram.com/okaytobesmart Merch https://store.dftba.com/collections/its-okay-to-be-smart Facebook https://www.facebook.com/itsokaytobesmartpbs/

View full lesson: http://ed.ted.com/lessons/a-new-way-to-diagnose-autism-ami-klin Early diagnosis of autism spectrum disorder can improve the lives of everyone affected, but the complex network of causes make it incredibly difficult to predict. At TEDxPeachtree, Ami Klin describes a new early detection method that uses eye-tracking technologies to gauge babies social engagement skills and reliably measure their risk of developing autism. (Filmed at TEDxPeachTree.) Talk by Ami Klin.

Create a colorful fishtail braid that s sure to make a splash! All you need are some extensions and...bubbles! For more fun, subscribe to our channel here: http://bit.ly/1HXmip0 & click below for more of my videos! Check out more of my videos! DIY Artist Paint Floral Nail Art: http://www.youtube.com/watch?v=OcAT9D97gU4&list=PLxrcW2MAluZID7kTTGK00HzpUOzRAgyTw DIY Traveling Vanity and Make-up Case: http://www.youtube.com/watch?v=cVT9j11xFcc&list=PLxrcW2MAluZJlmqqVn3o93A3vvvxRZkhw DIY Easy & Fun Projects Video Playlist: http://bit.ly/DIYProjectPlaylistVideos DIY Beauty & Hair Video Playlist: http://bit.ly/DIYBeautyAndHair

Click to Tweet this craziness: http://bit.ly/15nCkHW Click to Post to Facebook: http://on.fb.me/11hKH79 ⇊ Click to Expand! ⇊ While in the Rainforest we discovered a "Caterpillar Turbo Mode" How much faster can a group of caterpillars travel than an individual caterpillar on the same course? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GET SMARTER SECTION: Here is the raw video of the encounter!: http://www.youtube.com/watch?v=YehR0wSUioY I was on a tour run by Rainforest Expeditions (http://www.perunature.com) Thanks to Rainforest Expeditions for inviting me down, if you d like to go down to the Amazon Rainforest and see all of this for yourself check them out at http://www.perunature.com Phil Torres is the Conservation Biologist in the video who was wise enough to bring his books to the middle of the jungle! You can tweet Phil (http://www.twitter.com/phil_torres) Here is Phil s version of this video: http://www.youtube.com/watch?v=0l9pACNGoZY The music is an original work by Gordon McGladdery of A Shell in the Pit, who went to Peru with me. Gordon had to pay for his flight down to Peru and hasn t made his money back yet. Please donate something in exchange for his awesome work! http://ashellinthepit.bandcamp.com/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GET STUFF SECTION: (If I did this right these should be working Amazon affiliate links to purchase the stuff I like to use. When people purchase from these links it will support Smarter Every Day.) ❓Mystery Item (just for fun): https://amzn.to/3aTJ6vi Things I use and like: 📷Camera I use : https://amzn.to/2VSiruw Favorite Lens: https://amzn.to/2KPDQ1a Wide-angle: https://amzn.to/2SlPchR On-camera Mic: https://amzn.to/3aVVbjz Lav Mic: https://amzn.to/3aRek6r Hot shoe mount for Lav Receiver: https://amzn.to/35m6uAo My Tripod: https://amzn.to/2Yl6RtJ My Multi-tool: https://amzn.to/2zGm5Pz Favorite SD Card: https://amzn.to/2KQ3Edz 💾How I get footage off my phone: https://amzn.to/2KMem4K Travel Tripod: https://amzn.to/2zEa9Oi My Backpack: https://amzn.to/35jveJL My Headlamp: https://amzn.to/3deYmVt Favorite Bidet: https://amzn.to/2xnMG3b World Map: https://amzn.to/3aTFCZT Favorite Shoes: https://amzn.to/3f5trfV Everyone needs a snatchblock: https://amzn.to/2DMR4s8 🥽Goggle Up! : https://amzn.to/2zG754g Also, if you’re interested in a Smarter Every Day shirt etc. they’re really soft and you can get there here: https://www.smartereveryday.com/store ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tweet ideas to me @SmarterEveryDay Instead of saving for my kids college, I make videos using the money I would have saved. The thought is it will help educate the world as a whole, and one day generate enough revenue to pay for their education. Until then if you appreciate what you ve learned in this video and the effort that went in to it, please SHARE THE VIDEO! If you REALLY liked it, feel free to pitch a few dollars towards their college fund by clicking here: http://bit.ly/KidsCollege Warm Regards, Destin

View full lesson: http://ed.ted.com/lessons/gyotaku-the-ancient-japanese-art-of-printing-fish-k-erica-dodge How did fishermen record their trophy catches before the invention of photography? In 19th century Japan, fishing boats were equipped with rice paper, sumi-e ink, and brushes in order to create gyoktaku: elaborate rubbings of freshly caught fish. K. Erica Dodge recounts the story of this competitive fishing culture, plus some tips on how to make your very own etchings. Lesson by K. Erica Dodge, animation by Franco Barroeta.

Veritasium!! http://youtube.com/veritasium Veritasium video on temperature: http://www.youtube.com/watch?v=vqDbMEdLiCs MinutePhysics is on Google+ - http://bit.ly/qzEwc6 And facebook - http://facebook.com/minutephysics And twitter - @minutephysics Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Music by Nathaniel Schroeder http://www.soundcloud.com/drschroeder Created by Henry Reich

This week we continue to spend quality time with gases, more deeply investigating some principles regarding pressure - including John Dalton s Law of Partial Pressures, vapor pressure - and demonstrating the method for collecting gas over water. Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App! Download it here for Apple Devices: https://apple.co/3d4eyZo Download it here for Android Devices: https://bit.ly/2SrDulJ Table of Contents Theory of the Atom 1:48 Adding up the Pressures 2:34 Mixing Vinegar & Baking Soda 7:15 Collecting Gas Over Water 8:54 Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Instagram - https://www.instagram.com/thecrashcourse/ CC Kids: http://www.youtube.com/crashcoursekids

I actually have many, many more questions and answers so if you want to see them, like this video and let me know in the comments and I will edit them. Thank you for your support! I wouldn t have gotten this far without you.

Tweet this!: http://bit.ly/AntSigns How we knew this: http://bit.ly/Z8Iryh Post to FB: http://bit.ly/FBAnts Filmed on location in the Rainforests of Eastern Peru. Click here to read about how we knew this: Please Share with your friends if you enjoyed it. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GET SMARTER SECTION: I was on a tour run by Rainforest Expeditions (http://www.perunature.com) Thanks to Rainforest Expeditions for inviting me down, if you d like to go down to the Amazon Rainforest and see all of this for yourself check them out at http://www.perunature.com Phil Torres is the Conservation Biologist in the video who was wise enough to bring his books to the middle of the jungle! You can tweet Phil (http://www.twitter.com/phil_torres) Here is Phil s version of this video: http://www.youtube.com/watch?v=0l9pACNGoZY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GET STUFF SECTION: (If I did this right these should be working Amazon affiliate links to purchase the stuff I like to use. When people purchase from these links it will support Smarter Every Day.) ❓Mystery Item (just for fun): https://amzn.to/2YFX5lW Things I use and like: 📷Camera I use : https://amzn.to/2VSiruw Favorite Lens: https://amzn.to/2KPDQ1a Wide-angle: https://amzn.to/2SlPchR On-camera Mic: https://amzn.to/3aVVbjz Lav Mic: https://amzn.to/3aRek6r Hot shoe mount for Lav Receiver: https://amzn.to/35m6uAo My Tripod: https://amzn.to/2Yl6RtJ My Multi-tool: https://amzn.to/2zGm5Pz Favorite SD Card: https://amzn.to/2KQ3Edz 💾How I get footage off my phone: https://amzn.to/2KMem4K Travel Tripod: https://amzn.to/2zEa9Oi My Backpack: https://amzn.to/35jveJL My Headlamp: https://amzn.to/3deYmVt Favorite Bidet: https://amzn.to/2xnMG3b World Map: https://amzn.to/3aTFCZT Favorite Shoes: https://amzn.to/3f5trfV Everyone needs a snatchblock: https://amzn.to/2DMR4s8 🥽Goggle Up! : https://amzn.to/2zG754g Also, if you’re interested in a Smarter Every Day shirt etc. they’re really soft and you can get there here: https://www.smartereveryday.com/store ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The music is an original work by Gordon McGladdery of A Shell in the Pit, who went to Peru with me. Gordon had to pay for his flight down to Peru and hasn t made his money back yet. Please donate something in exchange for his awesome work! http://ashellinthepit.bandcamp.com/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tweet ideas to me @SmarterYouTube Instead of saving for my kids college, I make videos using the money I would have saved. The thought is it will help educate the world as a whole, and one day generate enough revenue to pay for their education. Until then if you appreciate what you ve learned in this video and the effort that went in to it, please SHARE THE VIDEO! If you REALLY liked it, feel free to pitch a few dollars towards their college fund by clicking here: http://bit.ly/KidsCollege Warm Regards, Destin

Bonjour! Get hand-painted floral nails using artist acrylic paint with this easy technique! For more fun, subscribe to our channel here: http://bit.ly/1HXmip0 & click below to see more videos! Treat your nails like tiny canvases! The artist paint and paint brush gives an impressionist look to your flowers that might just be museum worthy. For more photos and step by step see this blog post on the Mr. Kate blog: http://www.mrkate.com/?p=37421 The Mr. Kate Blog and Shop: http://www.mrkate.com Follow Mr. Kate on Twitter: http://www.twitter.com/mrkate Follow Mr. Kate on Instagram: http://www.instagram.com/mrkate Like the Mr. Kate Facebook page: http://www.facebook.com/mrkatedotcom Jewelry in the video by Mr. Kate - shop the collection http://www.mrkate.com/shop Check out more of my videos! DIY "Time Flies" Butterfly Clock: http://www.youtube.com/watch?v=lFvV6qzzUQA&list=PLxrcW2MAluZJlmqqVn3o93A3vvvxRZkhw DIY Traveling Vanity and Make-up Case: http://www.youtube.com/watch?v=cVT9j11xFcc&list=PLxrcW2MAluZJlmqqVn3o93A3vvvxRZkhw DIY Easy & Fun Projects Video Playlist: http://bit.ly/DIYProjectPlaylistVideos DIY Beauty & Hair Video Playlist: http://bit.ly/DIYBeautyAndHairVideoPlaylist Music: royalty free tracks Video shot and edited by Brad Etter

In which John Green finally gets around to talking about some women s history. In the 19th Century, the United States was changing rapidly, as we noted in the recent Market Revolution and Reform Movements episodes. Things were also in a state of flux for women. The reform movements, which were in large part driven by women, gave these self-same women the idea that they could work on their own behalf, and radically improve the state of their own lives. So, while these women were working on prison reform, education reform, and abolition, they also started talking about equal rights, universal suffrage, temperance, and fair pay. Women like Susan B. Anthony, Carry Nation, Elizabeth Cady Stanton, the Grimkés, and Lucretia Mott strove tirelessly to improve the lot of American women, and it worked, eventually. John will teach you about the Christian Temperance Union, the Seneca Falls Convention, the Declaration of Sentiments, and a whole bunch of other stuff that made life better for women. Hey teachers and students - Check out CommonLit s free collection of reading passages and curriculum resources to learn more about the events of this episode. Few women were as vocal for women s rights during the 19th century as Susan B. Anthony: https://www.commonlit.org/texts/the-life-s-work-of-susan-b-anthony Anthony worked for women s right to vote alongside great women like Sojourner Truth, who stressed the importance of intersectional feminism in her influential “Ain t I a Woman?” Speech: https://www.commonlit.org/texts/ain-t-i-a-woman Chapters: Introduction: How Women Transformed Pre-Civil War America 00:00 Women s Experience During Colonial America 0:59 Women s Participation in the Political Process 1:35 Women s Participation in the Market Revolution 2:49 Mystery Document 3:46 Women s Opportunities for Work 4:52 Women s Participation in Reform Movements 5:40 Women s Suffrage 7:24 Women in the Abolitionist Movement 8:04 Opposition to Women s Rights 8:56 The Suffragettes 9:36 The Patriarchy 11:20 Women s Participation in Reform Movements 12:03 Credits 12:38 Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Instagram - https://www.instagram.com/thecrashcourse/ CC Kids: http://www.youtube.com/crashcoursekids

View full lesson: http://ed.ted.com/lessons/what-is-fat-george-zaidan As the narrative goes, fat is bad. Well, it s actually more nuanced than that. The type of fat you eat is more impactful on your health than the quantity. George Zaidan examines triglycerides, the varied molecules that make up fat, and how to identify which types of fat you are consuming. Lesson by George Zaidan, animation by Igor Coric.

Filmed on location in the Rainforests of Eastern Peru. I was on a tour run by Rainforest Expeditions (http://www.perunature.com) Please Share with your friends if you enjoyed it. The camera we used is the Phantom Miro 320S http://www.visionresearch.com/Products/High-Speed-Cameras/Phantom-Miro-M320S/ The footage we obtained was incredible. I ll demonstrate that in upcoming videos. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GET SMARTER SECTION: Thanks to Rainforest Expeditions for inviting me down, if you d like to go down to the Amazon Rainforest and see all of this for yourself check them out at http://www.perunature.com Phil Torres is the Conservation Biologist in the video who was wise enough to bring his books to the middle of the jungle! You can tweet Phil (http://www.twitter.com/phil_torres) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GET STUFF SECTION: (If I did this right these should be working Amazon affiliate links to purchase the stuff I like to use. When people purchase from these links it will support Smarter Every Day.) ❓Mystery Item (just for fun): https://amzn.to/3f9ZUl5 Things I use and like: 📷Camera I use : https://amzn.to/2VSiruw Favorite Lens: https://amzn.to/2KPDQ1a Wide-angle: https://amzn.to/2SlPchR On-camera Mic: https://amzn.to/3aVVbjz Lav Mic: https://amzn.to/3aRek6r Hot shoe mount for Lav Receiver: https://amzn.to/35m6uAo My Tripod: https://amzn.to/2Yl6RtJ My Multi-tool: https://amzn.to/2zGm5Pz Favorite SD Card: https://amzn.to/2KQ3Edz 💾How I get footage off my phone: https://amzn.to/2KMem4K Travel Tripod: https://amzn.to/2zEa9Oi My Backpack: https://amzn.to/35jveJL My Headlamp: https://amzn.to/3deYmVt Favorite Bidet: https://amzn.to/2xnMG3b World Map: https://amzn.to/3aTFCZT Favorite Shoes: https://amzn.to/3f5trfV Everyone needs a snatchblock: https://amzn.to/2DMR4s8 🥽Goggle Up! : https://amzn.to/2zG754g Also, if you’re interested in a Smarter Every Day shirt etc. they’re really soft and you can get there here: https://www.smartereveryday.com/store ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The music is an original work by Gordon McGladdery of A Shell in the Pit, who went to Peru with me. Gordon had to pay for his flight down to Peru and hasn t made his money back yet. Please donate something in exchange for his awesome work! http://ashellinthepit.bandcamp.com/ Jeremiah Warren helped me with wing the animation (moving wing and thorax): http://www.youtube.com/user/jeremiahjw Alexander Spenny was kind enough to my request via twitter and created the Wasp and Dragonfly face. I think they re great. Licensed Photo of the PteroStigma by: Patrick Coin Creative Commons Photos by: Gil Wizen Oli Bac Samantha Williams LadyDragonFlyCC Gil Wizen Ryan Films Josh Beasley Ramona Edwards Jonathan Marino Alex Gilbert Sami Paju ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ERRORS: Yes, I misspelled ODONATA on the title screen. Yes it bothers me. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tweet ideas to me @SmarterYouTube Instead of saving for my kids college, I make videos using the money I would have saved. The thought is it will help educate the world as a whole, and one day generate enough revenue to pay for their education. Until then if you appreciate what you ve learned in this video and the effort that went in to it, please SHARE THE VIDEO! If you REALLY liked it, feel free to pitch a few dollars towards their college fund by clicking here: http://bit.ly/KidsCollege Warm Regards, Destin

View full lesson: http://ed.ted.com/lessons/your-brain-can-solve-algorithms-david-j-malan An algorithm is a mathematical method of solving problems both big and small. Though computers run algorithms constantly, humans can also solve problems with algorithms. David J. Malan explains how algorithms can be used in seemingly simple situations and also complex ones. Lesson by David J. Malan, animation by enjoyanimation.

Make your own mirrored vanity out of an old suitcase! For more fun, subscribe to our channel here: http://bit.ly/1HXmip0 & click below to see more videos! Organize and have a place to put on your make-up all in one while traveling. For more photos, steps and supplies check out the Mr. Kate blog: http://www.mrkate.com The Mr. Kate Blog and Shop: http://www.mrkate.com Follow Mr. Kate on Twitter: http://www.twitter.com/mrkate Follow Mr. Kate on Instagram: http://www.instagram.com/mrkate Like the Mr. Kate Facebook page: http://www.facebook.com/mrkatedotcom Jewelry in the video by Mr. Kate - shop the collection http://www.mrkate.com/shop Check out more of my videos! Mr. Kate Draw My Life! http://www.youtube.com/watch?v=MhgQEt5SuJ0&list=PLxrcW2MAluZIDlo9CEZWQcALK77eEi2Zc DIY Braided Sock Bun: http://www.youtube.com/watch?v=S8yD_4hu9SY&list=PLxrcW2MAluZID7kTTGK00HzpUOzRAgyTw DIY Easy & Fun Projects Video Playlist: http://bit.ly/DIYProjectPlaylistVideos DIY Beauty & Hair Video Playlist: http://bit.ly/DIYBeautyAndHair Music: royalty free tracks Video shot and edited by Brad Etter

Morally Wrong, that is... MinutePhysics is on Google+ - http://bit.ly/qzEwc6 And facebook - http://facebook.com/minutephysics And twitter - @minutephysics Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Music by Nathaniel Schroeder http://www.soundcloud.com/drschroeder Thanks to Nima Doroud for contributions. Created by Henry Reich

MinutePhysics is on Google+ - http://bit.ly/qzEwc6 And facebook - http://facebook.com/minutephysics And twitter - @minutephysics Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Music by Nathaniel Schroeder http://www.soundcloud.com/drschroeder Thanks to Nima Doroud for contributions. Created by Henry Reich

Subscribe - it s FREE! - http://goo.gl/EpIDGd And please support us on Patreon - https://goo.gl/ZVgLQZ Also, say hello on: Facebook: http://goo.gl/FpAvo6 Twitter: http://goo.gl/Y1aWVC MinuteEarth provides an energetic and entertaining view of trends in earth s environment -- in just a few minutes! Created by Henry Reich, with Alex Reich, Peter Reich, Rose Eveleth, Emily Elert, and John Guittar. Music by Nathaniel Schroeder: http://www.soundcloud.com/drschroeder References: Atmospheric escape on Earth: http://faculty.washington.edu/dcatling/Catling2009_SciAm.pdf