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John Baez has been shared in 312 public circles

You can see here the 50 latest shared circles.
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AuthorFollowersDateUsers in CircleCommentsReshares+1Links
Richard Green74,896Engagers Showcase Circle, July 12, 2014If I sent you a notification, it means that you are included in my Engagers Showcase Circle. “Showcase” means that you are invited to leave a comment (on the original post) with a link to one of your own posts, which ideally should be one of your best recent posts.This circle consists of people who have engaged with one of my recent posts in the form of +1s, comments and reshares.Everyone mentioned below is also included in the circle.Thistlehttps://plus.google.com/101584889282878921052/posts/CKB7ks1VWZ3“Star Gate” by +Gary Matthews https://plus.google.com/101584889282878921052/posts/ean83YFix7sBubble (reshared from +Ann-Marie Jurek)https://plus.google.com/101584889282878921052/posts/PkybKJfXv14Gabriel's Hornhttps://plus.google.com/101584889282878921052/posts/MXNTuq8ZEBPHibiscus flowerhttps://plus.google.com/101584889282878921052/posts/Xsmw62v98CHStackable 12-sided dicehttps://plus.google.com/101584889282878921052/posts/5mLoukdZAA5Astronomical book priceshttps://plus.google.com/101584889282878921052/posts/S15LTNxJA9GPyritohedral symmetryhttps://plus.google.com/101584889282878921052/posts/XQUYMrKGiAQSt Stephen's Basilica (reshared from +Laura Orange)https://plus.google.com/101584889282878921052/posts/ApnSMBsUWFeCircular Pascal Arrays and Fibonacci numbershttps://plus.google.com/101584889282878921052/posts/NVqYKoRVnHg“Fungi tree” by +Tom Beddardhttps://plus.google.com/101584889282878921052/posts/J6S4bDc6QwQAs always, reshares of this circle are appreciated, and I look forward to seeing everyone's links. Thanks for reading my posts!2014-07-12 05:31:3647614990170CC G+
Refurio Anachro4,312June engagers circle: Say hello to almost 200 nice people who joined in to participate in math topics. If you're intelligent, curious, like well written posts and engaged discussion - these people will not dissappoint. Go on and add them now!Last month's posts:Spin story continues (part 3): Angular velocity and tilings in spin space. While i locked myself in a cycle, struggling to follow, +wendy krieger blew the bubble and lifted the party up to dimension 4! I couldn't resist but to guest post this gem. Next time i'll find a picture first, promised!:https://plus.google.com/115434895453136495635/posts/6F9sxQxiqEaClifford Algebra (part 1): Into Clifford algebra. Because with those one can easily describe spin in any dimension.https://plus.google.com/115434895453136495635/posts/1CtiDXou6RqUnicode math cheat sheet: ⁵√7+x² – ℵ₀ – ℝⁿ – x̅ ≟ x*⊕x⁎ – αβ ≺ ∇ϕhttps://plus.google.com/115434895453136495635/posts/GNoCEmBxSWSClifford Algebra (part 2): Multiplication in geometric algebra.https://plus.google.com/115434895453136495635/posts/NKqs5BwsCqqCardioid gears, a reshare of +Rob Kook's very unexpected video find:https://plus.google.com/115434895453136495635/posts/UMBXJihPgcaCan we get anything faster than light that way? While arguing below +John Baez' cool post i suddenly started hearing vikings...https://plus.google.com/115434895453136495635/posts/jjYu4KhHaCTClifford Algebra (part 3): Cayley graphs and a strange clock. My first attempt to quickly put my thoughts down for you to see. I guess i'll have to practice a bit to make it more appealing on shorter glance, so more people can benefit.https://plus.google.com/115434895453136495635/posts/bkHQAZLzpt8Last may's engagers circle:https://plus.google.com/115434895453136495635/posts/hGPebLWRcU2You're in this circle because you reshared, plussed or commented on one of my posts (possibly via +Spherical Reflections), or got into a discussion with me. Thank you!#engagers #engagerscircle #engagersshowcasecircle  #circleshare #circlesharing #circl2014-07-02 13:23:15194557CC G+
Peter Edenist30,747TESLA Super Science Circle 2014 - June Edition!!!! : A quality circle curated carefully and tended since 2011. Who is in this circle?  people who are either involved in science, love science or are active on the Science on G+ community. Community link is here http://goo.gl/46uFH and the Page is +Science on G+!Have you wondered where one can meet with like-minded people who love science and like to read about the real stuff? This is the ultimate SUL on science.... add and share to keep it alive.--------------------------------------------------------------------------------------------------Want to nominate someone? Please do so in comments. If you want to recommend something let us know. People who are notified are part of the circle.#science #tesla #scienceongplus #scienceeveryday 2014-06-19 13:39:49342705390CC G+
David Wees4,496This is a circle of 346 math educators. If you are interested in following the work of innovative mathematics educators, this circle is for you.If you are a mathematics educator, and I have not included you in this circle, let me know.2014-06-11 16:24:03346010CC G+
Dina Tika0Here is a group of Active Engagers, Circle Sharers, Awesome Plus Oners, and Cool People on Google Plus!   Circle Sharing is an awesome way to increase your followers and active engagers on your profile. Some of my favorite people that I've met here on Google + through Circle Sharing.    Want to be in the next Circle of Awesomeness? Follow the Steps Below!  ☛ Add the circle ☛ Share in the Public ☛ Plus 1 the Post. ☛ Comment. 2014-06-10 05:53:52479001CC G+
Refurio Anachro4,141May engagers circle: Meet the people who made the fabulous cheer of this week's spin party. Many curious people, all of them worth to add!Diagram 18: rotations and spinorshttps://plus.google.com/b/115434895453136495635/115434895453136495635/posts/dpPMfoH6zc5This is actually part two, but got posted earlier (see below). You just made my first +100, thank you! Stay tuned for more on spinning and spinors.https://plus.google.com/b/115434895453136495635/115434895453136495635/posts/TLkA6tCNwEeIf you want to know what an earlier stage of Diagram 18 looked like, see here. I posted 2/3rd of the final post with a question marking my progess. Also note the discussion below, thanks to everybody who helped me out!https://plus.google.com/b/115434895453136495635/115434895453136495635/posts/THePbpcPnqDYou're in this circle because you reshared, plussed or commented on one of my posts (possibly via +Spherical Reflections), or got into a discussion with me. Thank you!Last april's engagers circlehttps://plus.google.com/b/115434895453136495635/115434895453136495635/posts/RFMY2aYscJJ#engagers #engagerscircle #engagersshowcasecircle  #circleshare #circlesharing #circle #circleoftheday  #addcircle #findcircles #publicsharedcircles  #addpeople #plussers #awesomepeople #sciencecircle  #commenterscircle #mathematicians #friends 2014-06-02 11:57:02158447CC G+
John Nuntiatio37,49330k+ Circle - A circle worth adding and followingThe people from this circle have more than 30,000 followers.2014-06-02 08:54:46140497CC G+
Becky Collins10,282Mobile Circle :Circle of very #social #engagerspeople and companiesTo be included in my shares (#sharedcircle), be so kind to:1 - Do +1 t the post2 - Comment the post and specify your "category" (job or interest) Ex: Fashion, SEO, Companies, Social Media Marketing, Sailing, Photography, Bloggers/Writers, Web graphics and design, Italy, Artists, Sport, Finance/Economy ...3 - include the circle among your circles4 - share the circle (include yourself)Improve your popularity, be social be cool !Keep yourself updated, enjoy the Shared Circles Hellenic Alliance, you can share your shared circles inside the upcoming Community:https://plus.google.com/communities/112552559573595396104  #socialmedia   #media   #circles   #circleshare   #circlesharing   #circlecircle   #beckyscircle   #sharedcircles   #sharedpubliccircles   #sharedcircleoftheday  +Becky Collins ?2014-05-28 05:03:174777118CC G+
Jasmina Brozović53,426Notification CircleThis is a circle of people I don't wanna miss any new posts from!Great Circle idea by +Zvonimir FrasRead more :https://plus.google.com/u/0/+ZvonimirFras/posts/VsZjS7H7vJf#circles #circlethis #circleyoushare #sharedcircles #addcircle #sharedpubliccircles #circleshare #publicsharedcircles #circleoftheweek #circlesharing #publiccircle #sharedcircle #circleshare   #circle     #motivateme 2014-05-20 16:26:14179271133CC G+
Daniel Zawadzki7,897This #circle is #great, #amazing, #wonderful,Boost your visibility on Google+ - Share the circle!#1 - Click add people and create your circle#2 - share the circle (include yourself)#3 - add +1 to the post#circle   #circleshare   #circlesharing   #circleoftheday   #circleoftheweek   #share   #sharedcircles   #sharedpubliccircles   #sharedcircleoftheday   #engagers   #engagerscircle   #engagerspeople   2014-05-19 20:33:554709546124CC G+
Refurio Anachro4,070April engagers circle, a ball of intelligent, nice, and responsive people. Have a look!You're in this circle because you reshared, plussed or commented on one of my posts (possibly via +Spherical Reflections), or got into a discussion with me. Thank you!The following has been classic april fool's, of course. Works best on kids %-]https://plus.google.com/115434895453136495635/posts/SA2aNCZPrQkNot being a big fan of synchronous communication, i will try and challenge you in case you do want to hang out. That's a rather new ploy of my character, and it seems i still have to learn a lot on how to do this nicely...https://plus.google.com/115434895453136495635/posts/fM8DtSPKL2MI have been seen spreading rumours with +David Roberts, speculating that this year's Fields medal might go to Manjul Bhargava. Here for the fullest explanation, thanks again David:https://plus.google.com/115434895453136495635/posts/KUbagU2C7C7A raytraced landscape featuring two spherical mirrors. It's about dynamical billiards (chaos theory).https://plus.google.com/115434895453136495635/posts/BCduuGFS75LWhen i saw +Richard Green's post about Coxeter-Conway friezes i couldn't resist to divert my readers to have fun counting paths with +DrJamesTanton. Fibonacci inside:https://plus.google.com/115434895453136495635/posts/gKBcK1HNdMvEverybody should have played at least once with an interactive IFS demo! If you haven't, or want to try again - here's a nice one by +Felix Woitzel:https://plus.google.com/115434895453136495635/posts/N9HeysDgTzi #engagers   #engagerscircle   #engagersshowcasecircle   #circleshare   #circlesharing   #circle   #circleoftheday   #addcircle   2014-05-16 11:46:1281867CC G+
Ralph Roper2,950My travel attractive circle and share with new friends1 - Include me in your circles 2 - Share the circle (Publicly) 3 - Add +1 to the post 4 - Leave a comment if you've done the 3 steps above.#circle   #circleshare  #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare 2014-05-13 10:36:24477424169CC G+
James Brighton1,136A great circle shared By meTo be added to the Circle you have to do these simple steps:1 - include me in your circles2 - Click add people and create your circle3 - share the circle (include yourself)4 - add +1 to the original (not shared) post#circle     #circleshare     #circlesharing     #share2014-05-12 09:56:3831510012CC G+
Richard Green68,138Engagers Showcase Circle, May 12, 2014If you received a notification, it means that you are included in my Engagers Showcase Circle. “Showcase” means that you are invited to leave a comment (on the original post) with a link to one of your own posts, which ideally should be one of your best recent posts.This circle consists of people who have engaged with one of my recent posts in the form of +1s, comments and reshares.Everyone mentioned below is also included in the circle.Peruvian glacier (reshared from +Irina Tcherednichenko)https://plus.google.com/101584889282878921052/posts/Z6NR7zaZa5qGrape hyacinthshttps://plus.google.com/101584889282878921052/posts/GZoHH2bnRUiSymmetries of a regular octagonhttps://plus.google.com/101584889282878921052/posts/bFcGcsurF5HHappy Easter!https://plus.google.com/101584889282878921052/posts/YkWFA9WmxVAPerfect Squared Squareshttps://plus.google.com/101584889282878921052/posts/HDU4mWD3wptOur dog Rexhttps://plus.google.com/101584889282878921052/posts/5JtEcnt5MpPPerrott's Follyhttps://plus.google.com/101584889282878921052/posts/8DzXHLn6fe4The Lonely Runner Conjecturehttps://plus.google.com/101584889282878921052/posts/YHJkEdKg3jz“Owl” by Andrea Mininihttps://plus.google.com/101584889282878921052/posts/12uh9J9MjMXPenrose nanotileshttps://plus.google.com/101584889282878921052/posts/7PZPSLaFkAx“Interlaced Stars” by Magnenauthttps://plus.google.com/101584889282878921052/posts/5vNjv1yjVMqBlack Forest View (reshared from +Ralph Reichert)https://plus.google.com/101584889282878921052/posts/YKPsvCFDyUv“Hippie Bus Apartments” by +Richie Montgomeryhttps://plus.google.com/101584889282878921052/posts/iCMXCBVzjd2Not crazy enoughhttps://plus.google.com/101584889282878921052/posts/d5EeDSoHe5u“Impossible Sphere” by Alexey Ermushevhttps://plus.google.com/101584889282878921052/posts/J2yUMw6YASqBeethoven, high on 2014-05-12 05:07:06489214132230CC G+
Cindy Wilson02014-05-10 14:34:25371700CC G+
Pamela Baskett02014-05-10 13:35:433711505CC G+
DRESS3,901If you want to be added to the next Circle you have to do these simple steps:1 - Include me in your circles 2 - Share this post3 - Add +1 to the post 4 - Leave a comment if you have done the 3 steps above#circle   #circleshare  #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare #circle #circleshare 2014-05-05 12:20:413723411CC G+
Graeme McRae24,994Graeme's Circle of Active GooglePlussers! . . . This is a curated circle of active people on Google+* If you add this circle, you will see hundreds of new posts per day in your stream from this circle alone. It's a circle of people I started following a few months ago, and who have consistently posted something at least once a week during all of weeks since then. If you want an interesting stream, you should add this circle. If you're interested in how I curated this circle, and why I think it makes for a really great stream, read on. . .How did these people get in the circle?. . . They must have posted something interesting, at least once, because I don't follow people unless they post something interesting. By now, you're probably not surprised by the number of people on G+ whose pages are full of repeated posts, videos without comments, "what's up" and other uninteresting things. I don't follow those people.How did they stay in the circle since they were added?. . . After I add someone, I keep them in the circle of people I added around the same time. Then, several times a week, I go through all my circles and delete people who haven't posted (something visible to me) in the last 7 days. So the people who are left in the circle are consistent posters. That says something important about them, because consistency is a proxy for quality.Wait. What? Why is consistency is a proxy for quality?. . . I'll admit it: I don't have the science to back up that wild statement, but I'll tell you why I believe it to be true. People who post crap don't get a lot of followers, and the few followers they have don't bother to engage. After a while, the crappy-posting people start to think G+ is a ghost town, and they lose interest. On the other hand, the people who share (or re-share) interesting things get followers and engagement, slowly at first, but ever increasing, and this outpouring of love is what keeps them going. That's what I think anyway, and I'm sticking to it.People who share interesting things get lots of followers. . . This is another half-baked theory of mine, but hear me out. You might think this makes sense: Google+ offers suggestions of people to follow, especially to new users. Google+'s only source of names to suggest are other G+ers like yourself. The G+ers who have the most engagement are the ones Google+ knows will be good to follow, so these people get put out as suggestions more often, and some percentage of those suggestions are taken up. So the more engagement you have, the more Google+ will suggest you as a person to follow, and so the more followers you'll get. Completing the theory: the more interesting the stuff you share (or reshare), the more engagement you'll get, and hence the more followers you'll get.How can I get in your circle?. . . Don't bother trying to "get into" this circle. This circle isn't for you to get into. Think of it the other way around. This circle is for you to add, so you can follow a bunch of interesting and consistent people. The stream from this one circle will be chock-full of fascinating content for you to reshare. People will start to notice your reshares, and they will engage with you, and then Google+ will "notice" (it's a computer, but let's anthropomorphise, shall we?) you and suggest you to others, who will then follow you.No, really. How can I get in your circle?. . . First, unfollow me, then wait, oh, about a week. Spend that week posting a shitload of interesting things. Then follow me. Since you're so interesting, Google+ will notify me that you followed me (G+ doesn't notify me about every follower). I'll look at your posts, find one interestin2014-05-04 21:03:52371111319CC G+
nicholas syahputra821. Plus The Post2. Comment3. Add People To Circles4. Share The Circle!#circlesharing #circleshare #circles #circle #googleplustips #googleplus #indonesia #artists #artist #artistphotographeramateurorprofessional2014-04-30 07:03:1548531640CC G+
James Brighton1,070All the people in here have been active in the last few weeks, so if you want people who Re-Share and engage this is the circle for you.If you are not in this circle and want to be in this circle, please follow below.1. Add me to your circles, if you haven't done so already2. +1 this circle3. Publicly share this post to public, your circles and extended circles.4. If possible, leave a comment on this circle so I know you have done the three steps above.#topsharedcircle   #facciamolastoria   #leonardo   #deroplus   #circleoftheday   #sharedcircle   #topsharedcircle   #sharedcircleoftheday   #myseoissocial   #besocial   #socializethesocial  #trust #circles  #circleshare  #sharedcircle   #circlesharing   #followers   #social   #socialnetworking   #topsharedcircle   #circleoftheday   #googleplus  #communities   #topsocialcircle   #influencers   #influencer   #socialnetworking #Algeria #Algiers #Angola #Luanda #Benin #Cotonou 2014-04-29 06:34:12315513CC G+
Ryan Johnson3,346My new some cool, fun & interesting people CirclePlease reshare it#circles           #circlescirclescircles           #circleshare         #circleshare2014-04-25 06:14:362357921CC G+
Becky Collins8,289Engagers Showcase Circle :Circle of very #social #engagerspeople and companiesTo be included in my shares (#sharedcircle), be so kind to:1 - Do +1 t the post2 - Comment the post and specify your "category" (job or interest) Ex: Fashion, SEO, Companies, Social Media Marketing, Sailing, Photography, Bloggers/Writers, Web graphics and design, Italy, Artists, Sport, Finance/Economy ...3 - include the circle among your circles4 - share the circle (include yourself)Improve your popularity, be social be cool !Keep yourself updated, enjoy the Shared Circles Hellenic Alliance, you can share your shared circles inside the upcoming Community:https://plus.google.com/communities/112552559573595396104  #socialmedia  #media  #circles   #circleshare   #circlesharing  #circlecircle   #beckyscircle   #sharedcircles   #sharedpubliccircles  #sharedcircleoftheday  +Becky Collins ?2014-04-23 05:59:02400201526CC G+
Circlemania !!!2,173in this circle you can find people keen to publish, share, track and unr to good communities. see and discover new friends and circles that may interest you. Do not forget to follow me as: +Andres Aguilar  #circle   #circleshare   #circlemaina   #circlemeup  2014-04-19 15:48:55498262034CC G+
Richard Green64,997Engagers Showcase Circle, April 17, 2014If you received a notification, it means that you are included in my Engagers Showcase Circle. “Showcase” means that you are invited to leave a comment (on the original post) with a link to one of your own posts, which ideally should be one of your best recent posts.This circle consists of people who have engaged with one of my recent posts in the form of +1s, comments and reshares. Two of the posts below attracted too much engagement to be usable for the circle, but I am including links to them for completeness.Everyone mentioned below is also included in the circle.Adding cubeshttps://plus.google.com/101584889282878921052/posts/WqimoVTZWL3Flower and snail shell (reshared from +Ralph Reichert)https://plus.google.com/101584889282878921052/posts/5st1n4VBMh5April Fools' Dayhttps://plus.google.com/101584889282878921052/posts/Mxa1TNjYo4r“Trinity” by Jen Starkhttps://plus.google.com/101584889282878921052/posts/gfRheBovSZUHyperbolic honeycombs (reshared from +Roice Nelson)https://plus.google.com/101584889282878921052/posts/59yPx8yoFbuCoxeter—Conway friezeshttps://plus.google.com/101584889282878921052/posts/4XvYb9biaLpTriple helix staircase (reshared from +Romain Brasselet)https://plus.google.com/101584889282878921052/posts/SRJ7CqGNrtLWhich airport is closest to you?https://plus.google.com/101584889282878921052/posts/FxxdDb6orPy“Spinning Cosmos” by Paul Friedlanderhttps://plus.google.com/101584889282878921052/posts/RjnVfRhBPmZStrč prst skrz krkhttps://plus.google.com/101584889282878921052/posts/h87PZWs2MSbMersenne primes and perfect numbershttps://plus.google.com/101584889282878921052/posts/cLWBTddiSyy“Urge to fly” by Hermin Abramovitchhttps://plus.google.com/101584889282878921052/posts/j2K97AvLvAoKeeper of Time (reshared from +Michael Quinn)https://plus.google.com/101584889282878921052/posts/QnaHrgKjsUUSeven mutual2014-04-17 04:49:32487186133233CC G+
Ryan Johnson2,352sharedcircle   #publiccircleshare     #circleshare     #circleoftheday  #circleshares     #circlesharing     #circlesshare    #publicsharedcircle   #publicsharedcircles   #sharedcircleoftheday   #sharedcircleoftheweek     #sharedcircles     #sharedpubliccircle   #todayspublicsharedcircle  #todayssharedcircle     #publiccircle   #circle     #circles    #awesome   #awesomeness   #awesomepeople   #shareyourcircle     #bestengagers   #followers   #followback     #awesomecircles  #topsharedcircle   #topsharedcircle     #myseoissocial     #besocial     #socializethesocial     #trust   #circles   #sharedcircle     #followers      #social     #socialnetworking     2014-04-16 05:12:352629212CC G+
Adam Black6,732Transhumans CircleBy popular Demand,  I am sharing some of my Circles. This is +Mark Bruce  Transhumans Circle  Plus Others Ive been adding.If you are tagged,  you are in it.Web Link for Mobile https://plus.google.com/u/0/+AdamBlack/posts/6iQmLpEj1Zm #sharedcircles   #GeekCulture   #ScienceSunday #Transhumans #Transhumanism #HumanPlus  2014-04-13 06:25:0424522733CC G+
John Nuntiatio33,101#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport #health #tennis #europe   #asia   #america   #africa   #australia   #football   #golf   #basketball   #news  2014-04-09 06:25:5632961312CC G+
Catherine Tramell2,290Circle of VeniceCity in ItalyVenice is a city in northeastern Italy sited on a group of 118 small islands separated by canals and linked by bridges.Join this circle and also shareWelcome to  my latest Full Circle Edition of people who wish to be Discovered and also wish to find interesting G+ members themselves! Please follow given below1. Add me to your circles, if you haven't done so already2. +1 this circle3. Publicly share this circle to public, your circles and extended circles.4. Leave a comment on this circle so I know you have done the three steps above#circle #circles #circleshare #circleshares #circleshared #circlesharing #circleoftheday #circleoftheweek #follow #followme #followers #following #authicle #authiclecircleshare #authiclecircle #authiclevol46 #public #publiccircle #sharedcircles   #sharedcircle #morefollowers #sharingcircles #sharedpubliccircles #sharedpublicircles #sharedcircle #photography #photographer #bestphotographer #topphotographer #AddCircle #FindCircles 2014-04-09 05:24:1240115922CC G+
Refurio Anachro3,603You're in this march engagers circle because you reshared, plussed or commented on one of my posts (possibly via +Spherical Reflections), or got into a discussion with me. It's been fun being with you and i'm looking forward to more of it soon! Thank you!Mar 4, 2014 - links a couple of my favorite videos featuring John Conway on the occasion of +Numberphile posting a new one:https://plus.google.com/115434895453136495635/posts/AHpMJ79biC3Mar 12, 2014 - reshared an excellent post by +Gerald Stuhrberg about Richard Couranthttps://plus.google.com/115434895453136495635/posts/CzMomxKK2HzMar 18, 2014 - Diagram 17: Bratteli diagram about C★ algebrashttps://plus.google.com/115434895453136495635/posts/6EiftoFjkxmMar 19, 2014 - reshared a four dimensional platonic covered with gears by Greg Egan, thanks +John Baezhttps://plus.google.com/115434895453136495635/posts/NeaNS4XDBXNMar 22, 2014 - linked a blog post by keegan, an animated quiascrystal with a simple recipe to get one. Don't miss the link to Roger Penroses latest public lecture video in the commentshttps://plus.google.com/115434895453136495635/posts/8RUh6oQzMdpMar 31 - a link to +Vladimir Voevodsky's latest public lecture, and to an implementation of the addictive 2048 game in Coq!https://plus.google.com/115434895453136495635/posts/9bnhXDeH1UXIf you're looking for even more, please have a look at my trusty +Spherical Reflections's page. I reshare interesting circles there, and occasionally post mandelbrot beach pictures. #engagers   #circle , #circles   #circleshare   #circlesharing   #sharedcircles   #publiccircle   2014-04-03 11:25:3978165CC G+
John Nuntiatio32,205#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport #health2014-04-03 06:40:30128164CC G+
Jean-Marc Luna36,938My buddies (432/1)of the G+ villageI am happy to share (finally) my first big circles (432/1 and 432/2) with you. It is also a way to thank you and to inform you of my consideration.You will find in these two circles all the people I follow regularly since my first steps on Google+ and which accompany me for soon two years in this beautiful adventure, bringing every day, by their sympathy, their humor, their knowledge, their generosity and their open-mindedness, a bit extra to my everyday life.I do not know everybody, I have crossed the path with some, I communicate more with some and many people became friends, thing which I did not expect by landing here.When I began, I was lucky enough to discover new interesting people, thanks to the system of circles sharing, and I hope that these both will be for you of the same utility.If you add a “plus”, maybe it will have an impact on climate change,if you share this circle, maybe Putin is going to get married with an ukrainian women in 2014,if you include me in your circles, maybe it will solve the problem of hunger in the world,Maybe ... but in fact, nothing is sure ;)A good day to all :)With a special thought for #dirktalamasca   #sharedcircles   #circles   #circlesharing  2014-03-31 15:25:36432632958CC G+
Daniel Zawadzki6,461Very soccial Circle#specialcircle      #topengagers   #circleoftheday     #saturdaycircle #weekendcircleHi friends! This is very imoprtant circle, most of top g+ pplif you want to add this circle:1 - include all circle in your circles 3 - shared the circle (include yourself) 4 - add +1 to the post More you share more you are great.2014-03-22 09:41:38472571672CC G+
Richard Green61,119Engagers Showcase Circle, March 20, 2014If you received a notification, it means that you are included in my Engagers Showcase Circle. “Showcase” means that you are invited to leave a comment (on the original post) with a link to one of your own posts, which ideally should be one of your best recent posts.This circle consists of people who have engaged with one of my recent posts in the form of +1s, comments and reshares. I ran out of room, so my most recent posts will be included next time instead.Everyone mentioned below is also included in the circle.Michelangelo and the Jordan curve theoremhttps://plus.google.com/101584889282878921052/posts/UN8TetdX48VThe Kelpieshttps://plus.google.com/101584889282878921052/posts/M6aWXwu6zESAntoine's necklacehttps://plus.google.com/101584889282878921052/posts/4anPfBNTyjXThe Farey-Ford tessellationhttps://plus.google.com/101584889282878921052/posts/GrZP3ajnRGUAlien Garden (reshared from +Kevin Clift)https://plus.google.com/101584889282878921052/posts/j55RpNfocNABetween a rock and a hard placehttps://plus.google.com/101584889282878921052/posts/WGNdNFneW1uAlan Turing: a universal Turing machine?https://plus.google.com/101584889282878921052/posts/MUjAnVtL7hbVisual artist Aliza Razellhttps://plus.google.com/101584889282878921052/posts/hbd3e6U1fhSBeet it (reshared from +Laura Ockel)https://plus.google.com/101584889282878921052/posts/U7RjV31mM7WChess played on a sphere... and other animalshttps://plus.google.com/101584889282878921052/posts/LGXUE73Z3MoPass 'Em Onhttps://plus.google.com/101584889282878921052/posts/iFCQcXfhNdDArizona sunset (reshared from +Debashish Samaddar)https://plus.google.com/101584889282878921052/posts/CR1yJ48g8CWThe inside of my fridge, through Glasshttps://plus.google.com/101584889282878921052/posts/SQK6KoFL2rmBatmobile 1?https://plus.google.com/101584889282878921052/posts/aV43AZenAd9Mary O'Malley ceramics (reshared from 2014-03-20 19:09:36469199161231CC G+
John Nuntiatio30,154#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-18 08:53:47471025CC G+
John Nuntiatio30,154#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-18 08:53:18471001CC G+
John Nuntiatio30,154#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-18 08:52:50471125CC G+
John Nuntiatio30,154#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-18 08:52:22471002CC G+
John Nuntiatio30,154#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-18 08:51:36471313CC G+
John Nuntiatio29,767#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-14 19:46:45475126CC G+
John Nuntiatio29,767#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-14 19:46:00475125CC G+
John Nuntiatio29,767#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-14 19:45:28475014CC G+
John Nuntiatio29,767#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-14 19:44:37475126CC G+
John Nuntiatio29,767#circles #sharedcircles #circlesharing #circle #circleoftheday #bestofcircles #bestcircleshare #share #tech #business #sport2014-03-14 19:43:264755010CC G+
Prime Numbers0Science, Mathemathics, Tchnology, Engeneering CIRCLEThis circle has some really interesting people. It has scientist, engineers, researchers, mathematicians, computer scientists.If you wish to nominate yourself or someone to be included on my next circle, just follow these simple steps:1. Post about science and be active in science communities like STEM on Google+2. Make sure you have already added me into your circles3. Plus, Comment and Reshare this post publicly in your own stream. Please make sure you plus, reshare and comment on the Original Post or else I won't notice it...#Science #sharedcircles #sharedpubliccircles #publiccircles #circlesharing #circle #circleshare #circles #circleoftheday2014-03-12 20:26:291364106CC G+
John Nuntiatio29,392#circles #sharedcircles #circlesharing #circle #circleoftheday #newcircle #bestofcircles #bestcircleshare #share #tech #business #sport #health  #entertainment #news2014-03-10 06:55:19356117CC G+
John Nuntiatio29,392#circles #sharedcircles #circlesharing #circle #circleoftheday #newcircle #bestofcircles #bestcircleshare #share #tech #business #sport #health  #entertainment #news2014-03-10 06:55:003561094CC G+
John Nuntiatio29,361#circles #sharedcircles #circlesharing #circle #circleoftheday #newcircle #bestofcircles #bestcircleshare #share #tech #business #sport #health  #entertainment #news2014-03-09 11:43:13251109CC G+
Richard Green59,075Engagers Showcase Circle, March 4, 2014If you received a notification, it means that you are included in my Engagers Showcase Circle. “Showcase” means that you are invited to leave a comment (on the original post) with a link to one of your own posts, which ideally should be one of your best recent posts.This circle consists of people who have engaged with one of my recent posts in the form of +1s, comments and reshares. I ran out of room, so my eight most recent posts will be included next time instead.Everyone mentioned below is also included in the circle.Robert Wadlowhttps://plus.google.com/101584889282878921052/posts/442C6iBpXpTBlanchard Springs Park (reshared from +David D)https://plus.google.com/101584889282878921052/posts/ZJmBps8sgSNPascal's triangle and the number ehttps://plus.google.com/101584889282878921052/posts/3KfcsUy994bMy dog Luna, through Glasshttps://plus.google.com/101584889282878921052/posts/axiVS2b4jDjMy portrait by +Bearman Cartoons https://plus.google.com/101584889282878921052/posts/V34HkBjd5mDHow many ways can a tie be tied?https://plus.google.com/101584889282878921052/posts/RQrjPGQ6nwmWine glass photography (reshared from +Tiffany Lykins)https://plus.google.com/101584889282878921052/posts/bATjvaZrcL4Valentine's Dayhttps://plus.google.com/101584889282878921052/posts/1zHKQxAV4ynThe fractal music of Per Nørgårdhttps://plus.google.com/101584889282878921052/posts/RLuTaqtxc9jCalvin Seibert's sandcastleshttps://plus.google.com/101584889282878921052/posts/RuVoyCdhN4MHerkimer Diamonds (reshared from +BJ Bolender)https://plus.google.com/101584889282878921052/posts/9Z1KuS7sqd1Automorphic numbershttps://plus.google.com/101584889282878921052/posts/JUPgnCtRvhxIndra's pearlshttps://plus.google.com/101584889282878921052/posts/eaaFWPKrNTrMolecular machinery2014-03-04 22:10:56498223160265CC G+
Refurio Anachro3,311In this february engagers circle there's lot's of interesting people i really like to read.This month there's been three posts that gained more interest than the others (or should have...)Diagram 16: Brauer algebrahttps://plus.google.com/115434895453136495635/posts/9vKLdS9xKd8Elliptic curveshttps://plus.google.com/115434895453136495635/posts/Q6JdobnczHLThe post about Oswald Teichmüller had a catch: If you'd +1'd it i'd give you the name of a mathematician to write about. Well, i guess that scared many away... I'd say the game has ended but if you'd nevertheless like me to suggest a mathematician to you, just ask!https://plus.google.com/115434895453136495635/posts/PZtaY9fY1DhYou're in this circle because you reshared, plussed or commented on one of my posts (possibly via +Spherical Reflections), or got into a discussion with me. It's been fun being with you and i'm looking forward to more of it soon! Thank you!Anybody is invited to showcase a post in the comment section below. That'll sure get you in the next engagers circle, and maybe i'll reshare or post about! And please reshare this circle! #circleshare   #publicsharedcircles   #sharedcircles   #engagers   #commenters   #plussers   #sciencecircle  2014-03-03 16:19:451581549CC G+
Becky Collins3,213Baseball circle #Baseball  #circles   #circleshare   #circlesharing   #circlecircle   #beckyscircle   #sharedcircles   #sharedpubliccircles   #sharedcircleoftheday  +Becky Collins 2014-02-26 10:30:413883216CC G+

Activity

Average numbers for the latest posts (max. 50 posts, posted within the last 4 weeks)

31
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36
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Top posts in the last 50 posts

Most comments: 229

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2014-05-30 07:28:10 (229 comments, 27 reshares, 95 +1s)

This post on my blog tackles the question "has global warming slowed?":

http://tinyurl.com/warming-galkowski-1

This is both a climate physics question and a statistics question.

The graph here shows the statistics question in simplified form.  The blue bars say how much global mean surface temperature exceeds the 1950-1980 average.  The red and dashed curves use a smoothing spline to fit a smooth curve to this data.  They both use the same algorithm: they differ only in the setting of a smoothing parameter. Which is correct? What does “correct” mean here?

As for the physics: more heat goes into the ocean than the atmosphere, so global mean surface temperature can be misleading.  A lot of heat goes down into the Pacific during La Niña years, and a lot comes back up during El Niño years.  We may be heading for an ElNiño this ... more »

Most reshares: 199

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2014-07-06 02:29:38 (73 comments, 199 reshares, 567 +1s)

Warp cube

The N-Light Membrane is a cube of mirrors with fluorescent lights as edges.  3 mirrors are one-way, so you can see inside.   All you can see is reflections of the inside of the cube, extending to infinity!   

The other 3 mirrors are flexible, and the cube is connected to an air tank.  By inflating or deflating the air tank, you can make the cube convex or concave.  The reflections bend in weird ways. The effect is hypnotic.

This cube was created by an art collective called Numen/For Use, and it was displayed in St. Petersburg.   It's fun to watch videos of it shot from different angles:

http://www.numen.eu/installations/n-light/membrane/

What if you did a tetrahedron or octahedron?  There's no need to imagine; you can see them here:

http://www.numen.eu/installations/n-light/objects/
Numen/F... more »

Most plusones: 567

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2014-07-06 02:29:38 (73 comments, 199 reshares, 567 +1s)

Warp cube

The N-Light Membrane is a cube of mirrors with fluorescent lights as edges.  3 mirrors are one-way, so you can see inside.   All you can see is reflections of the inside of the cube, extending to infinity!   

The other 3 mirrors are flexible, and the cube is connected to an air tank.  By inflating or deflating the air tank, you can make the cube convex or concave.  The reflections bend in weird ways. The effect is hypnotic.

This cube was created by an art collective called Numen/For Use, and it was displayed in St. Petersburg.   It's fun to watch videos of it shot from different angles:

http://www.numen.eu/installations/n-light/membrane/

What if you did a tetrahedron or octahedron?  There's no need to imagine; you can see them here:

http://www.numen.eu/installations/n-light/objects/
Numen/F... more »

Latest 50 posts

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2014-07-13 03:17:24 (10 comments, 13 reshares, 80 +1s)

A rotaxane is a 2-part molecule where one part is a ring that can rotate around the other part... but can't slip off!  

People are starting to make molecular machines with rotaxanes.  That's really cool, but let's talk about something simpler.  How do you make  a rotaxane? 

The first one was made in 1967 by two chemists named Harrison.   They used a simple but clever trick.   Say you have a bunch of molecules that react and stick together in pairs to form a bigger dumbbell-shaped molecule.  Say you let them do this when mixed with copies of some other ring-shaped molecule.  Then a few of them will connect through the ring, forming a rotaxane!

By now there are better tricks:

1) Capping: you let a rod-shaped molecule fit through a ring, and then cap it off with balls that keep the ring from sliding off.

2)Clippi... more »

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2014-07-11 16:16:52 (41 comments, 13 reshares, 128 +1s)

Dumb Romans

Caligula was just insane, I think.  Here's something really dumb.

Compared to the Egyptians and Babylonians, the Romans were traditionally never great at calendars.  The early Roman calendar had 355 days a year...so they'd put in a whole extra month now and then, making the year 377 or 378 days long. 

At first it stayed roughly in line with the seasons.  But the people who ran the calendar were politicians, so if they wanted to make their enemies' terms of office end quicker, they'd refuse to stick in the extra month! 

Eventually things got way out of whack.  The politicians would only announce these extra months at the last minute, and it got really confusing.

So, Julius Caesar called together all his wise men to invent a better calendar.  And they invented a pretty good one, with 365 days a year, and an extraleap d... more »

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2014-07-11 04:23:18 (15 comments, 15 reshares, 63 +1s)

El Niño coming?

See how the eastern Pacific has gotten much hotter since May?  That could be the start of an El Niño. 

My friends and I at the Azimuth Code Project are starting to work on El Niño prediction.  Now you can get free software to study a method that uses 'climate networks'.  I'll give you hints on how to modify it and make new discoveries of your own.  If you do, please tell us what you find! 

Here's how to get started:

http://johncarlosbaez.wordpress.com/2014/07/08/el-nino-project-part-4/

This explains how to download climate data and programs to analyze it.   First you go to a website (or ftp site) and get ahold of the Earth's surface air temperatures since 1950.  Then you run a program to get just the temperatures in the Pacific.  Then you run another to see how much temperatures near theequator are ... more »

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2014-07-09 00:45:24 (32 comments, 12 reshares, 104 +1s)

It seems a lot of ultra-high-energy cosmic rays are coming from a patch of the sky near the Big Dipper!  

Cosmic rays are high-energy particles, mainly protons and atomic nuclei, which come from outer space and hit the Earth's atmosphere.  When one hits, it produces a big shower of other particles.  Most cosmic rays are believed to have picked up their energy by interacting with shock waves in the interstellar medium.  But the most energetic ones remain mysterious — nobody knows how they could have acquired such high energies.

The record is a 1994 event seen by a detector in Utah called the Fly's Eye - because that's what it looks like.   It saw a shower of particles produced by a cosmic ray with an energy of about 300 times 10¹⁸ electron volts.   That's an insane amount of energy.  It's about 50 joules: the energy of a one-kilogram mass movingat 10 meters/... more »

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2014-07-08 04:50:35 (5 comments, 6 reshares, 31 +1s)

Now you can apply to attend a workshop on Entropy and Information in Biological Systems.  This is going to be fun!

I'm running it with John Harte at Berkeley, who uses maximum entropy methods to study ecosystems, and +Marc Harper at UCLA, who uses information theory to study evolutionary games.  It's happening on April 8-10, 2015 at the National Institute for Mathematical and Biological Synthesis in Knoxville Tennesee.  There will be financial support for workshop attendees who need it.  We will choose among the best applicants and invite 10-15 of them. 

To apply, go here:

http://www.nimbios.org/workshops/WS_entropy

The idea

Information theory and entropy methods are becoming powerful tools in biology, from the level of individual cells, to whole ecosystems, to experimental design, model-building, and the measurement ofbiod... more »

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2014-07-07 12:15:18 (47 comments, 43 reshares, 112 +1s)

What if famous paintings were photoshopped like models today?

Lauren Wade writes: Whether it’s tucking tummies, contouring jaw lines, enlarging eyes and lips, brushing out cellulite, or full-out head swapping, I’ve seen it all as a photo editor. While the conversation about the media’s portrayal and obsession with an unrealistic and unattainable beauty standard is not a new one, I think it’s crazy how much retouching people don’t notice. Over the last five years, having done many of the quick, subtle fixes that are the industry standard myself, I know that even an image considered to look “natural” is anything but.

So, she changed a bunch of famous paintings.  This is Titian's Danaë With Eros.  You can see the rest here:

http://www.takepart.com/feature/2014/05/15/famous-paintings-photoshopped-to-look-like-fashion-models

posted image

2014-07-06 02:29:38 (73 comments, 199 reshares, 567 +1s)

Warp cube

The N-Light Membrane is a cube of mirrors with fluorescent lights as edges.  3 mirrors are one-way, so you can see inside.   All you can see is reflections of the inside of the cube, extending to infinity!   

The other 3 mirrors are flexible, and the cube is connected to an air tank.  By inflating or deflating the air tank, you can make the cube convex or concave.  The reflections bend in weird ways. The effect is hypnotic.

This cube was created by an art collective called Numen/For Use, and it was displayed in St. Petersburg.   It's fun to watch videos of it shot from different angles:

http://www.numen.eu/installations/n-light/membrane/

What if you did a tetrahedron or octahedron?  There's no need to imagine; you can see them here:

http://www.numen.eu/installations/n-light/objects/
Numen/F... more »

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2014-07-05 08:31:48 (21 comments, 26 reshares, 121 +1s)

Water world

Here is weather simulated on an aqua planet: a world like our Earth, but with only ocean!  With no land, the weather becomes simpler.  Here's what happens when you add land:

http://tinyurl.com/NICAM-with-land

The aqua planet simulation was done in 2004, in Japan.   The planet's surface was divided into an icosahedron!   Then each triangle was chopped into smaller triangles with sides 3.5 kilometers long.  These are just barely small enough to simulate clouds, but nobody had simulated the whole planet's atmosphere in such a fine-grained way before.  It required a supercomputer.

By the way, simulating weather is different than simulating climate. When people try to predict the climate 50 years from now, they don't do it by simulating each day's weather for the next 50 years.

This weather simulationproje... more »

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2014-07-04 02:56:43 (37 comments, 32 reshares, 112 +1s)

Open-access climate science

A recent paper says there's 75% chance of a major climate event called an El Niño by the end of 2014  This would be huge news!  So my friends and I decided to replicate this paper, criticize it, and improve it.

The paper uses a climate network, shown here.  See the little circles?   Every day, scientists measure air temperatures at each of these points.  The red ones are in the El Niño basin.   The paper calculates how temperatures in the El Niño basin are correlated to temperatures at the other points.  When the average correlation gets high enough, they predict an El Niño.

That's a very  rough summary of what the paper does!  I explain exactly what it does here:

http://johncarlosbaez.wordpress.com/2014/07/01/el-nino-project-part-3/

including how they got their data.
+Graha... more »

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2014-07-03 03:52:05 (46 comments, 22 reshares, 74 +1s)

Puzzle 1: Suppose you have 10 white balls and 10 black balls.  You can distribute them any way between two urns, as long as you put at least one ball in each urn.   Your friend selects an urn at random and randomly selects a ball from that urn.  How can you maximize the chance that your friend picks a white ball?  

This is from Paul Nahin's new book Will You Be Alive 10 Years From Now?   It's a great introduction to probability based on puzzles and history.   I like it because it's fun at many levels.   You need to know some probability theory to follow it.   But it should be okay for beginners - it uses some calculus near the end - and it was also fun for me.  

The use of history is key here.  Some books use 'human interest stories' as a way to placate the reader who is getting bored with the science.  For example, while talking aboutSchrödinger'... more »

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2014-07-02 02:49:44 (56 comments, 80 reshares, 178 +1s)

Chain reaction

A domino can knock over a domino that's one and a half times taller.  Here you see a tiny domino 5 millimeters tall starting a chain reaction 13 dominos long... which eventually knocks over a domino about half a meter tall. 

The amount of energy released by the fall of that last domino is 2 billion times the amount of energy it took to knock over the first one!

And if we could do a chain reaction like this 29 dominos long, the final domino would be the size of the Empire State Building!

I got this from +W Younes, who has been posting some nice images recently, but only privately.  So, you should become friends with him.

He in turn got it from here:

http://xysciences.com/post/90498855068/a-domino-can-knock-over-another-domino-1-5x-larger

I don't know where they got it from.  But it's clearly acha... more »

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2014-07-01 02:43:57 (16 comments, 36 reshares, 126 +1s)

Optimized Origami

This spectacular image by Greg Egan is the answer to a hard math problem.  He showed that this configuration of 4 interlocking dodecahedra is the one that makes the origami strips as wide as possible without intersecting! 

Without assuming the answer will be symmetrical, this requires studying a 9-dimensional space of different positions of the dodecahedra.   Egan did it with a computer search, and one portion of this search required checking

44 choose 10 = 2,481,256,778

possible solutions, to see which one is best!

However, the answer turned out to be highly symmetrical.  Start with a regular dodecahedron. It has 20 vertices, and we can partition these into 5 sets of 4, each 4 being the vertices of a tetrahedron. Choose one of these tetrahedra, and rescale it by a factor of 1/√5 while keeping its center fixed.  Takeyour do... more »

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2014-06-30 06:40:46 (46 comments, 7 reshares, 53 +1s)

Singapore G+ Dinner

On Friday July 4th, +Elias Mårtenson and I would like to meet any other friendly G+'ers who happen to be in Singapore.  If you want to join us, let me know!

I suggest that we meet at 6:30 pm.  Where should we meet?

Food is very important in Singapore, so let's go someplace good.  Where should we go?  I like a good hawker center better than a fancy restaurant, so I'd like to explore a new one.  A good place should at least have the four dishes shown here:

Fruit rojak - typically made of chopped-up cucumber, pineapple, benkoang (jicama), bean sprouts, taupok (puffy, deep-fried tofu) and youtiao (cut-up Chinese-style fritters), with a delicious sauce of belacan (shrimp paste), sugar, chili, and lime juice.

Grilled stingray - just what it sound like, grilled on a banana leaf and topped withsambal (c... more »

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2014-06-29 04:24:19 (56 comments, 11 reshares, 64 +1s)

Help!

This gif shows four stages of how you build a Sierpinksi carpet.  By tomorrow I'd really like a better version of this.  If you can make it for me, and sign a form giving me permission to put it on my Visual Insight blog, I'll do that and credit you!

If you create one, please put a link to it in your comment, so I can choose the first really good one and let people know I've chosen it.

[EDIT: +Noon Silk has done the job - see the comments.]

What counts as a good one?

1) I'd like an animated gif with a white background - not light blue like this.

2) I'd like the color to be a dark but saturated purple: something like this would be great:

http://www.color-hex.com/color/420082

3)  I'd like the Sierpinski carpet itself to be 729 × 729 pixels. That... more »

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2014-06-28 03:05:02 (19 comments, 97 reshares, 169 +1s)

A network of networks

We have a lot to learn from nature.  Biology has its own ways of processing information, and we're just starting to figure them out.   They work differently than the digital computers built by humans.  I recently heard a great talk about this by Luca Cardelli, an expert on biological computation who works at Microsoft Research in Cambridge and Oxford.

The little gizmos in his picture here are called influence networks. They're chemical reactions built from ‘gates’ where one chemical process activates or deactivates another. 

All these influence networks actually show up in living organisms! 

The simplest one is AM, in the blue circle.  This  stands for Approximate Majority.  It's a chemical reaction where starting with molecules of two kinds, those in the majority completely takeover: we ge... more »

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2014-06-27 04:26:57 (16 comments, 7 reshares, 59 +1s)

Neutrino Flux - 1987A

That's the title of this painting by David Fricks.  1987A is the name of a supernova in the Tarantula Nebula of the Large Magellanic Cloud whose light - and neutrinos! - reached us in 1987.  

Though it was over 150,000 light-years away, it was visible to the naked eye.  Two to three hours before the visible light reached us, a burst of neutrinos was observed at three separate neutrino observatories.  They only saw a total of 24 neutrinos... but this is what you'd expect from a supernova that far!   It probably put out 10^46 joules of energy, 99% in the form of neutrinos... for a whopping total of 10^58 neutrinos. 

Some went through you, and some went through this monkey.

Here's a little mystery about supernova 1987A.  It acted like a type II supernova, where a massive star runs out of fuel and its coresuddenl... more »

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2014-06-25 01:26:04 (12 comments, 88 reshares, 346 +1s)

Too cute!  Here's a mommy pangolin carrying its baby, photographed by Firdia Lisnawati at a zoo in Bali.  The baby was born at the zoo on May 31, and this photo was snapped last Thursday when it was less than 3 weeks old. 

A pangolin is a kind of scaly anteater found in tropical regions throughout Africa and Asia.  A friend of mine even saw one in a park in Singapore!  There are eight different species, from the giant pangolin to the tree pangolin.  Some are endangered because people eat them or - even worse - kill them for the completely imaginary medical properties of their scales!  In one incident in 2013, 10,000 kilograms of pangolin meat was seized from a Chinese vessel that ran aground in the Philippines.  ☹

When a pangolin is born, its scales are soft and white; then they gradually get harder and darker.  At first the mother stays with the baby in a burrow,nursing it... more »

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2014-06-24 01:46:46 (11 comments, 7 reshares, 78 +1s)

Wind blows west across the tropical Pacific, from the Americas to Asia. During La Niña years, water at the ocean’s surface moves along with the wind, warming up in the sun as it goes. So, warm water collects at the ocean’s surface off the coast of Asia. This makes more clouds and rainstorms there.

But sometimes the westward winds weaken enough for the warm water in the western Pacific sloshes back east!  Then we get an El Niño. This makes for more clouds and rain in the eastern Pacific—that’s when we get floods in Southern California.

You can actually see the warm surface water moving back and forth in this animation!  The height is greatly exaggerated, of course.  This was made by the TAO/TRITON array, about 70 devices anchored to the floor of the Pacific Ocean.  These measure winds, sea surface temperature, relative humidity, air temperature, andsubsurface te... more »

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2014-06-23 00:58:59 (9 comments, 10 reshares, 125 +1s)

Triple Helix

This is a picture taken by +Romain Brasselet, who wrote:

The only triple helix staircase in the world.

It is located in the Museo do pobo Galego (Museum of the Galician People) in Santiago de Compostela, Galicia, northwestern Spain.

It spans more than 3 floors and distribute them with a total of 14 doors. But on each floor, the doors are at unequal heights: the floors of the rooms happen to be at different levels. So there are additional stairs linking the rooms of the same "floor".

This is a masterpiece of architecture. I stayed at least 30 minutes looking at it and  trying to make pictures that would convey its exquisite beauty.

You can see other beautiful views of this staircase here:

https://plus.google.com/u/0/s/triple%20helix

Romain works on neurobiology... more »

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2014-06-22 05:19:18 (28 comments, 4 reshares, 91 +1s)

I now live on the 14th story of an apartment for faculty at the National University of Singapore.  In the lobby of each floor there's a door labelled electrical riser, where wires go up.  There's a door labelled TAS riser, where telecommunications cables go up.  And there's a door labelled ELV riser, where elves go up.

Well, that's what I imagined.  But then I looked it up.  Much to my surprise, I found that ELV actually stands for electrostatically levitating vampire.

I pondered this for days.  Finally, unable to resist, I opened up the ELV riser last evening.  I saw black shrouded figures, light as feathers, floating up a large shaft, lifted by the tiny voltage gradient.  They congregate in the rooftop garden, drinking cocktails and chatting... and then, when the moon comes up, they launch themselves into the night sky.  You cansee them... more »

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2014-06-22 01:43:40 (14 comments, 31 reshares, 93 +1s)

A Thorne–Żytkow object is a giant star that has swallowed a neutron star.  The idea of such a thing was invented by Kip Thorne and Anna Żytkow in 1976.  Now we may have found one! 

A Thorne–Żytkow object can be formed when a neutron star collides with a red giant or supergiant star. They might simply collide by accident... but there's a lot of room in space, so this is very unlikely.

More likely, the neutron star and the giant could be part of a binary star system!  A neutron star forms when a giant star runs out of fuel, collapses, and explodes as a supernova, blowing off its outer layers... while the core crushes down to a ball of neutronium.  So, you have to image one giant star in a binary system doing this, while its partner survives.

Then, they might slowly spiral down due to friction.  A red giant is usually surrounded by a lot of very thin hotgas.  Once t... more »

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2014-06-21 00:53:58 (36 comments, 27 reshares, 118 +1s)

The source of cow farts

This molecule looks like chlorophyll or heme - but where those have magnesium or iron, this has an atom of nickel at its heart!  And this molecule, called cofactor F430, is part of why cows fart.

Like all vertebrates, cows can't break down cellulose, the main ingredient in grass.  So they have 4 stomachs, and in the rumen there are trillions of tiny organisms that can break down cellulose. These organisms make sugars, which the cows can digest - but also other chemicals, including methane.  The cows fart and burp... and since methane is a powerful greenhouse gas, about 40% of all global warming due to agricultural activity comes from this process!  Not just from cows, but also sheep and goats.

The tiny organisms that make methane are called methanobacteria... but now we know they aren't really bacteria. We&#... more »

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2014-06-20 01:09:38 (15 comments, 48 reshares, 108 +1s)

El Niño Project

El Niño is the biggest unpredictable aspect of the Earth's weather system.  It causes floods here, droughts there, it happens roughly every 3 to 7 years, but it's very hard to predict more than 6 months before it happens.  The last really big one, in 1997, unleashed a blast of global warming as heat stored in the Pacific Ocean entered the atmosphere!   Now we're waiting for the next.

This February, a paper caused a stir by predicting that an El Niño will start in late 2014 with 75% probability.  It used ideas from 'network theory' - the math of systems made of many interacting parts.  It claims that before an El Niño, sea temperatures in a large patch of the Pacific become highly correlated, going up and down in synch.

It could be right, it could be wrong - but the cool part is, the ideas in this paper are prettysimple.  ... more »

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2014-06-19 00:51:07 (35 comments, 19 reshares, 68 +1s)

Espresso in Space

If manned space exploration is our destiny, then this is what the world needs: an espresso machine that works in zero gravity!

Jointly designed by the Italian coffee company Lavazza, the engineering firm Argotec, and the Italian Space Agency, the ISSpresso machine will be in the International Space Station by the time the next Italian astronaut goes up there.

To operate it, you put a capsule of coffee in the machine and plug in a plastic pouch of water. The ISSpresso pressurizes the water, heats it and pushes it through the capsule into a drinking pouch.  You then suck the stuff out of the pouch with a straw. 

It's designed to handle a pressure of 400 atmospheres - this requires replacing the usual plastic tube with a steel one.

If you've ever been to Italy, the image of businessmen in suits sucking espressof... more »

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2014-06-18 01:15:23 (23 comments, 6 reshares, 68 +1s)

Monk fruit

I'm back in Singapore!  I'll spend the summer doing research at the Centre for Quantum Technologies. When I showed up, the temperature was 32°C - that's 90°F - and the humidity was 75%.  And I thought: yes, I like this!   I was afraid a winter in Germany might make it hard to adapt to the tropics again... but no.  They're steamy,  sweaty, but full of life.

In Singapore, people love fruit juice.  One of my favorite kinds is made from the luo han guo (罗汉果/ 羅漢果), or monk fruit.  It has a hard thin skin, brown in color, covered with small hairs.  Inside there is an edible sweet pulp. 

I got some luo han guo juice in Chinatown yesterday.  It's slightly bitter, but also slightly sweet... really refreshing!  I can see why it's called 'monk fruit': when you drink this juice you feel a lot morevirtuous and enlightened ... more »

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2014-06-17 03:50:20 (55 comments, 52 reshares, 97 +1s)

Get smart

Electric power companies complain about wind power because it's intermittent: if suddenly the wind stops, they have to bring in other sources of power.  

This is no big deal if we only use a little wind.  Across the US, wind now supplies 4% of electric power; even in Germany it's just 8%.  The problem starts if we use a lot of wind.  If we're not careful, we'll need big fossil fuel powered electric plants when the wind stops.  And these need to be turned on, ready to pick up the slack at a moment's notice! 

So, a few years ago Xcel Energy, which supplies much of Colorado’s power, ran ads opposing a proposal that it use renewable sources for 10% of its power.   

But now things have changed.  Now Xcel gets about 15% of their power from wind, on average.  And sometimes this spikes to much more!

Whatmade the di... more »

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2014-06-15 23:19:47 (50 comments, 58 reshares, 185 +1s)

The black widow's bite

There are lots of black widows where I live in California.  I'll sometimes see one hanging in its web in a flower pot, sprinkling can or trash bin when I'm gardening.  If I think someone might accidentally put their hand there, I'll kill it.

They are sluggish and unaggressive, so this is easy to do, and I pity them.  But their bite — while rarely lethal - is very, very painful. So, I harden my heart and crush them with a broom.

In fact their bite seems fine-tuned to be as bad as possible without being lethal.  Maybe this, and the bright red hourglass, is how the spider teaches other animals to stay away!  A dead student can't learn.

Here's a story passed on by +Michael Nielsen, about a med school professor named Allan Blair who decided to get a black widow to bite him.  As Wikipedia calmly states,"t... more »

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2014-06-12 15:12:02 (8 comments, 6 reshares, 67 +1s)

Zinc blood

This beautiful molecule looks a lot like heme, but with zinc instead of iron at its heart!  If you get lead poisoning, your blood will start getting this instead of heme in it.

There are 2-4 grams of zinc in your body - most of it in your brain, muscle, bones, kidney, and liver.  It shows up in lots of important enzymes, not only in animals but also plants and bacteria.  In biology, it's the second most important 'transition metal' after iron.  (The transition metals are the ones in the long middle part of the periodic table.)

This molecule is called zinc protoporphyrin.  It can show up in your blood for several reasons, including

lead poisoning
iron deficiency
sickle cell anemia
vanadium poisoning

Puzzle 1: why?

I don't know!  I guess it makes sense that if you havean iro... more »

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2014-06-11 22:15:30 (50 comments, 21 reshares, 77 +1s)

I'm in Banff, enjoying spectacular views but thinking about chemistry, since I'm at at a workshop called Programming with Chemical Reaction Networks: Mathematical Foundations.

Suppose you have two numbers m and n, and you want to use chemical reactions to see if m ≥ n.  Here's one way.

Make m molecules of type A and n of type B.  Also include one molecule of type Y.   It doesn't matter what these molecules are, as long as these chemical reactions occur:

A + N → Y
B + Y → N

where N is some other sort of molecule.  

Y and N stand for "yes" and "no".   Let the reactions run, and at the end you'll be left with either a "yes" or a "no".  This is the answer to your question!

How does it work?  If there are no B's around, nothing will happen and you'll beleft with a &qu... more »

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2014-06-09 14:38:30 (48 comments, 12 reshares, 81 +1s)

Trends are tricky

The blue bars here show the average surface temperature of the Earth, year by year, with the 1950-1980 average subtracted out.  The difference is called the temperature anomaly.  You can see the anomaly is about 0.5 Celsius now, or 0.9 Fahrenheit.  

The green curve is an attempt to smooth out the data and extract meaningful trends.  This is where it gets tricky!   This particular curve was obtained using a cubic spline, built piece by piece from a bunch of cubic polynomials.  But doing this requires some choices: adjusting a smoothing parameter lets us build a curve that fits the data very closely and wiggles a lot, or a curve that's very smooth but doesn't stay so close to the data.

How do we pick the 'right' smoothing parameter?  What does 'right' even mean?  The answers depend on what you wantto know.<... more »

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2014-06-07 17:56:21 (136 comments, 44 reshares, 281 +1s)

The downward spiral

Three days ago my wife Lisa started seeing flashes like lightning in the peripheral vision of her right eye.  Then she started seeing black specks like gnats.  Years ago she nearly had a detached retina, which doctors bolted down with laser surgery.  So she has always been on the lookout for symptoms like this. 

We went to the emergency room around 8 pm, shortly after the black specks formed a 'curtain' in the middle of her field of vision.  Standing just yards from a mirror, she said: "I can't even see the color of my eyes."

In some ways we're all waiting for something like this to happen.

We're all going to die... or at least, most of us: some 'transhumanists' optimistically freeze their brains in hopes that future generations will revive them, but even if this hope comes true, most peoplecan&... more »

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2014-06-06 15:44:51 (26 comments, 32 reshares, 107 +1s)

Did you eat your cobalt today?

Look at this amazing molecule!  It looks a bit like chlorophyll or heme, but it's got an atom of cobalt  in the middle where those others have magnesium or iron. 

What's amazing is not that this molecule exists.  What's amazing is that you need to eat it - or something very like it.  It's called vitamin B12, and you need about 2 micrograms a day.  

In the middle ages, German miners called some rocks kobold ore - German for goblin ore - because they were poor in known metals and gave poisonous fumes when you heated them.  In 1739 a Swedish chemist named Georg Brandt discovered that these rocks contained a new metal.  So this metal, cobalt, is named after goblins!

It took a lot longer to realize that cobalt is essential for human life.  In 1934, three chemists won the Nobel prizefor disco... more »

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2014-06-05 16:38:56 (35 comments, 14 reshares, 78 +1s)

Orange as a carrot

Why are carrots orange?  Because they contain carotene.  

Carotene comes in different forms, but here I've shown one of the most common: beta-carotene.   I like it because it's perfectly symmetrical.   It has a long chain of carbons with alternating single and double bonds.  Electrons vibrating along this chain absorb blue light.  So the carrots have the opposite color: orange!

Humans need a chemical called retinal in order to see.  It looks roughly like half a carotene molecule - and like carotene, it's good at absorbing light.  Attached to a larger protein molecule called an opsin, retinal acts like a kind of antenna, catching particles of light. 

Humans can't produce retinal without help from the foods we eat. Any chemical we can use to produce retinal is called vitaminA.  So ... more »

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2014-06-04 18:33:21 (16 comments, 12 reshares, 58 +1s)

Snug triangles

You have a little circle inside a big circle.  You want to fit a triangle between the little circle and the big one.  There are two 'obvious' ways to try.   Namely, the most symmetrical ways.

But here's the cool part: when either way works, they both do!  

So, when one way just barely works, giving a triangle that fits snugly between the two circles, the other way gives another snug triangle!

Greg Egan noticed this yesterday, and drew this picture.  But the great thing about geometry is that people have been doing it for a long time.  So maybe Euclid noticed this too... or some Arab astronomer.   I don't know.

I hope you get what I mean by the two 'obvious' ways.  They're drawn in red and blue here.

The red triangle has an edge that's tangent to the small circle where it'sclosest t... more »

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2014-06-04 01:52:18 (16 comments, 7 reshares, 25 +1s)

Eno live!  With a beard!  Playing a really weird instrument!

Brian Eno never plays live anymore.  But on May 5th he came out with Someday World, an album with Karl Hyde... and on June 27th they're putting out another album, called High Life... so they're clearly on a roll, and I guess that's why they recently gave a live performance of this song, 'Daddy's Car', from the first album.

Can you figure out what instrument Eno is playing?  It looks like a modern version of the theremin, where you make sounds by wiggling your hand... but I can't hear it.  I can hear him singing, though.

You can hear the studio version of this song here:

https://soundcloud.com/warp-records/eno-hyde-daddys-car

It has much punchier bass.  But the rhythm flows more smoothly on the live version... and it has more joy.
I d... more »

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2014-06-03 15:12:28 (52 comments, 26 reshares, 98 +1s)

Red as blood

Why is blood red?  It contains heme, a molecule very similar to chlorophyll... but with iron instead of magnesium at its heart! 

Like chlorophyll, heme is a porphyrin.  That means it's made of four pentagons of carbon and nitrogen joined together by bridges of carbon.   In chlorophyll, almost all the carbons connected by alternating single and double bonds.   In heme, they all are. 

These alternating single and double bonds let electrons roam around in a smeared-out, quantum way... and when light hits the molecule, it's like a kid jumping on a trampoline!   It makes these smeared-out electrons vibrate back and forth.   But unlike the kid, the light gets absorbed if it's vibrating at the right frequency: it transfers all its energy to the molecule.

Chemists have a really sexy way of talking.  Listen to howthey say wh... more »

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2014-06-02 16:00:46 (20 comments, 12 reshares, 63 +1s)

When can you fit a tetrahedron between two nested spheres?

Here’s the answer. Suppose the radius of the large sphere is R and the radius of the small one is r. Suppose the distance between their centers is d. Then you can fit a tetrahedron between these spheres if and only if the Grace–Danielsson inequality holds:

d² ≤ (R+r)(R–3r)

This was independently proved by Grace in 1917 and Danielsson in 1949. But Antony Milne has found a new proof using quantum information theory!  

For more on how he did it, and how this stuff works in 2 dimensions, see my Visual Insight blog:

http://blogs.ams.org/visualinsight/2014/06/01/grace-danielsson-inequality/

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2014-05-30 07:28:10 (229 comments, 27 reshares, 95 +1s)

This post on my blog tackles the question "has global warming slowed?":

http://tinyurl.com/warming-galkowski-1

This is both a climate physics question and a statistics question.

The graph here shows the statistics question in simplified form.  The blue bars say how much global mean surface temperature exceeds the 1950-1980 average.  The red and dashed curves use a smoothing spline to fit a smooth curve to this data.  They both use the same algorithm: they differ only in the setting of a smoothing parameter. Which is correct? What does “correct” mean here?

As for the physics: more heat goes into the ocean than the atmosphere, so global mean surface temperature can be misleading.  A lot of heat goes down into the Pacific during La Niña years, and a lot comes back up during El Niño years.  We may be heading for an ElNiño this ... more »

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2014-05-29 13:12:07 (59 comments, 22 reshares, 74 +1s)

Green as grass

Grass is green because it contains chlorophyll.  But why is chlorophyll green?

Chlorophyll contains chlorin, shown here... and in the middle of the chlorin, a magnesium atom with 2 electrons missing!  There are different kinds of chlorophyll - but the most common have a long 'tail' of carbon and hydrogen atoms, called phytol.  Take a look:

http://en.wikipedia.org/wiki/File:Chlorophyll-a-3D-vdW.png 

The chlorin, with the magnesium ion in its heart, is the part that absorbs light.  It has lots of alternating single and double bonds, and this so-called conjugated system is really good at absorbing light. 

What role does the magnesium ion play, exactly?  I don't know!  A couple days ago I showed you a xanthophyll, a yellow-colored molecule that also absorbs light in the leaves of plants -not for... more »

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2014-05-28 05:43:41 (19 comments, 9 reshares, 90 +1s)

2.5 million years ago, while Homo habilis discovered stone tools, #GRBm31 exploded. Today the much advanced tools of their descendants observed it!

So said Jessie Christiansen on Twitter.   Why?   Astronomers claimed they saw something amazing - a mysterious burst of X-rays from Andromeda, briefly a million times more powerful than our Sun... at least if the burst was shining in all directions instead of beamed at us.  7 times 10^33 joules per second!

So everyone in the Andromeda galaxy was just killed a few million years ago?

My guess: no, at that intensity only those unlucky enough to be too close.  This event was actually very weak for a gamma ray burst, which may be caused when a very massive star collapses, or two neutron stars collide, forming a black hole and a beam of radiation that just happens to point atus.  ... more »

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2014-05-27 07:13:03 (62 comments, 48 reshares, 142 +1s)

Yellow as yolk

Why are egg yolks yellow?  They contain two very similar yellow chemicals called lutein and zeaxanthin.  You can see lutein here under the egg.  I like this molecule because it's almost but not quite symmetrical!  

These chemicals are synthesized only by plants.  They're called xanthophylls, from the Greek words for 'yellow' and 'leaf'.  You can get lots of xanthophylls from green leafy vegetables like spinach.   Plants use use xanthophylls to deal with problems that arise when it's too sunny.  Bright sunlight makes a lot of triplet chlorophyll, an excited form of chlorophyll, which can cause chemical reactions that damage the plant.  The xanthophyll cycle is a way of removing excess energy from triplet chlorophyll in a harmless way.

Animals get lutein and zeaxanthin fromplants.  T... more »

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2014-05-26 11:38:03 (15 comments, 17 reshares, 60 +1s)

Categorifying Quantum Physics

Here's a video of a talk I gave last week in Paris.  It's broken into pieces so you can read the slides along with it.

What happens when we stop pretending that things are equal when they're just the same in a way - that is, isomorphic?  A lot: this is one of the main trends of 21st century mathematics! 

In quantum physics, we describe the annihilation and creation of particles using things called - surprise! - the annihilation operator and the creation operator.  The idea goes back to Heisenberg. 

The interesting thing is that creating a particle of some type and then annihilating one of that type is not the same as first annihilating one and then creating one.  Instead, we have

a a† = a† a + 1

Here a is the annihilation operator and a† is the creation operator. What does th... more »

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2014-05-25 05:26:57 (25 comments, 5 reshares, 86 +1s)

Alhambra Reflections

The Alhambra is a marvelous palace in Granada, Spain.  It started as a small fortress, but it was renovated in the 11th century by a Moorish king, and converted into a royal palace in 1333 by the Sultan of Granada.   The Sultan’s Canal carries water from a nearby river, and it goes by aqueduct the Alhambra.  This was used for vegetable gardens and drinking water... but also fountains, ponds and a famous 'water stairway', which beautified and cooled the palace grounds.

The Alhambra is also famous for its gorgeous tiling patterns.  Since I like the math of these, I photographed the Alhambra tiles when I visited Granada to give a talk at their Department of Algebra.  (Yes, they have a department of algebra!)  You can see some of my photos here:

http://math.ucr.edu/home/baez/week267.html

along with a discussion of the 17"wa... more »

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2014-05-24 07:35:12 (32 comments, 9 reshares, 73 +1s)

At the moment of explosion, everything is white

In 1953, the US tested the M65 Atomic Cannon for the first and only time.  Also called 'Atomic Annie', it was a towed artillery piece capable of firing an atomic bomb.

Codenamed 'Grable', the test was carried on May 25 at 8:30 am at the Nevada Test Site.   The Chairman of the Joint Chiefs of Staff and the Secretary of Defense looked on as a 15 kiloton atomic bomb was fired a distance of 7 miles and exploded in the desert.

This was the only nuclear shell ever to be fired from a cannon.

After this test, at least 20 of these cannons were manufactured, at a cost of $800,000 each. They were deployed overseas to Europe and Korea, often continuously shifted around to avoid being detected and targeted by opposing forces.  But they were never used... and they were retired in 1963.
A... more »

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2014-05-23 08:30:15 (23 comments, 26 reshares, 127 +1s)

This is the category theorist Andrée Ehresmann in an anechoic chamber, computer in hand.  Yesterday we went into this room at IRCAM, a famous experimental music laboratory in Paris. 

An anechoic chamber is a room with walls designed to absorb all incident sounds - if you snap your fingers, it sounds strangely dead, and one of my hosts said you can lose your sense of orientation.  At IRCAM they sometimes suspend a piano inside the anechoic chamber to study its sounds without any echoes getting in the way.

IRCAM is the Institut de Recherche et Coordination Acoustique/Musique.  From the outside it looks unimpressive, because most of the rooms are underground.  Inside they've got a huge performance space where all the walls are speakers... using computers they can make sounds move around the room.  And I got a great demonstration of OMax, a program that canlisten... more »

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2014-05-22 09:14:14 (38 comments, 28 reshares, 91 +1s)


How much do universities pay for journal subscriptions?   The publisher Elsevier works hard to keep this secret... and a representative recently explained why:

"Well, indeed there are confidentiality clauses inherent in the system, in our Freedom Collections. The Freedom Collections do give a lot of choice and there is a lot of discount in there to the librarians. And the use, and the cost per use has been dropping dramatically, year on year. And so we have to ensure that, in order to have fair competition between different countries, that we have this level of confidentiality to make that work. Otherwise everybody would drive down, drive down, drive drive drive, and that would mean that … [audience laughs]."

They keep the prices secret to keep the prices high!  And the total cost of Elsevier subscriptions has been shooting up, not down.

So,it&#... more »

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2014-05-17 08:19:05 (34 comments, 51 reshares, 125 +1s)

“Today we present observational evidence that a large section of the West Antarctic Ice Sheet has gone into irreversible retreat.  It has passed the point of no return.”

That's what Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory, said at press conference last week. 

If true, this would raise worldwide sea levels 3 meters - about 10 feet.  It would probably take hundreds of years, slow at first, then speeding up.

What's actually going on?  For some preliminary answers, try my blog post on Azimuth:

http://johncarlosbaez.wordpress.com/2014/05/16/west-antarctic-ice-sheet-news/

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2014-05-15 08:05:53 (16 comments, 17 reshares, 70 +1s)

Cool picture!  James J. Walton explained it on my blog:

http://blogs.ams.org/visualinsight/2014/05/15/pattern-equivariant-homology-of-a-penrose-tiling/

Here's the basic idea...

Penrose invented a pair of tiles that can be used to create aperiodic tilings of the plane.  A tiling is aperiodic if it doesn’t repeat and it doesn’t even contain arbitrarily large periodic patches.

His tiles are called the 'kite' and 'dart' - if you wanna succeed in math, you gotta make up cool names for things!  The kite is a quadrilateral whose four interior angles are 72°, 72°, 72°, and 144°. The dart is a non-convex quadrilateral whose four interior angles are 36°, 72°, 36°, and 216°. 

We can fit the kite into the dart to form a rhombus, and tile the plane periodically with that.  But if we color the corners of thesetiles black and ... more »

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2014-05-14 11:17:03 (35 comments, 32 reshares, 177 +1s)

A periodic tiling is one that repeats endlessly in two or more directions.   If you're wandering around on a periodic tiling, like this bee, a map won't help you find where you are. 

But there are also tilings that aren't periodic, where a map still won't help.  For example, some of the famous Penrose tilings!   These aren't periodic... but any finite-sized portion of the tiling shows up infinitely often, scattered here and there. 

To the best of our knowledge, space in our universe extends infinitely in all directions.  Of course we can't know for sure, but measurements show that space is close to flat, not positively curved like a higher-dimensional sphere.  The easiest way for space to be finite in size yet flat would be for it to be 'curled up' like a torus.  But astronomers have looked at distant galaxies in different directions inthe sky,... more »

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2014-05-13 07:55:48 (12 comments, 1 reshares, 44 +1s)

Who is this guy?

Le Marais is a fashionable area of Paris, mostly famous today for its fancy shops and swarms of tourists.  Its name means 'the marsh',
and settlements there go back to 1240.   At first the big buildings were mainly religious institutions, but starting around 1600 the Marais became the favorite place for noblemen to build their huge mansions, called hôtels.  If you see a huge old stone building called a hôtel, don't try to get a room for the night!

Later in the 1600s, the nobility started to move to another part of Paris: the Faubourg Saint-Germain.  By 1700, the Marais had changed character: it was popular and active commercial area, hosting one of Paris' main Jewish communities.

At the end of the 19th century and during the first half of the 20th, parts of the Marais around the rue des Rosiers welcomed manyEaster... more »

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