What Do Satellites Have in Common with Falling Cats? Attitude Control

in Physics, Science, Technology | August 27th, 2012

Have you ever won­dered how the Hub­ble Space Tele­scope and oth­er satel­lites can be point­ed in any direc­tion at the will of sci­en­tists on the ground? Giv­en the ener­gy con­straints for satel­lites designed to stay in space for years, the tech­ni­cal chal­lenges are immense.

In this video from the “Smarter Every Day” YouTube series we learn a lit­tle about two clever meth­ods sci­en­tists use to con­trol the atti­tude, or ori­en­ta­tion, of satel­lites with very lit­tle ener­gy. The first method exploits the pow­er of the Earth­’s mag­net­ic field by using elec­tric cur­rent to selec­tive­ly acti­vate elec­tro­mag­nets and nudge the satel­lite in a desired direc­tion, rather like the nee­dle of a com­pass. The sec­ond and, in some ways, more fas­ci­nat­ing method takes its inspi­ra­tion from the amaz­ing­ly agile cat. It has long been known that cats can fall from any ini­tial ori­en­ta­tion and almost always land on their feet. They can reori­ent them­selves 180 degrees with­out vio­lat­ing the con­ser­va­tion of angu­lar momen­tum. They do it by adjust­ing their shape and thus rear­rang­ing the mass, and chang­ing the moment of iner­tia, with­in their bod­ies. Sci­en­tists employ a sim­i­lar tac­tic using mov­ing parts with­in satel­lites.

The host of the “Smarter Every Day” videos goes only by the name of “Des­tin,” and is report­ed­ly a mis­sile engi­neer at the U.S. Army’s Red­stone Arse­nal, near Huntsville Alaba­ma. Some view­ers will, like us, find the tone and sen­si­bil­i­ty of this video juve­nile and annoy­ing, with its overuse of the words “cool” and “awe­some” and with the gra­tu­itous cat-drop­ping scenes (note to future YouTube auteurs: con­sid­er using stock footage) but the sci­ence itself is, with­out a doubt, fas­ci­nat­ing.

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Watch Astronaut Don Pettit Conduct Cool Experiments Aboard the International Space Station

in Physics, Video - Science | August 8th, 2012

Astro­naut Don Pet­tit is a chem­i­cal engi­neer by train­ing, and he is a man who loves his work. The video above, pro­duced as part of a series called “Sci­ence off the Sphere,” shows an exper­i­ment con­duct­ed aboard the Inter­na­tion­al Space Sta­tion. In it, Pet­tit demon­strates the way a water bub­ble reacts to puffs of air in micro­grav­i­ty. The results are fas­ci­nat­ing to watch, made more so by Pettit’s total absorp­tion in the exper­i­ment.

Dur­ing his first six-month stay on the ISS in 2002–3, Pet­tit also exper­i­ment­ed on how flu­ids react in zero-grav­i­ty. He dubbed these ses­sions “Sat­ur­day Morn­ing Sci­ence.” Pet­tit returned to the ISS in Decem­ber of 2011 and is still there, orbit­ing over 240 miles above the earth, con­duct­ing exper­i­ments in his free time and pro­duc­ing “Sci­ence off the Sphere.” Episode 5 of the series (below) is mes­mer­iz­ing, and again, Pettit’s won­der as he nar­rates the exper­i­ment is pal­pa­ble.

Relat­ed Con­tent:

Great Cities at Night: Views from the Inter­na­tion­al Space Sta­tion

Drink­ing Cof­fee at Zero Grav­i­ty

Josh Jones is a doc­tor­al can­di­date in Eng­lish at Ford­ham Uni­ver­si­ty and a co-founder and for­mer man­ag­ing edi­tor of Guer­ni­ca / A Mag­a­zine of Arts and Pol­i­tics.

 

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Carl Sagan Presents Six Lectures on Earth, Mars & Our Solar System … For Kids (1977)

in Astronomy, Physics, Video - Science | August 7th, 2012

The Roy­al Insti­tu­tion Christ­mas Lec­tures for Chil­dren — it’s a tra­di­tion that began back in 1825 when the inven­tor Michael Fara­day orga­nized an annu­al lec­ture series for kids, hop­ing to instill in a younger gen­er­a­tion a love for sci­ence. Almost two cen­turies lat­er, the tra­di­tion con­tin­ues. Emi­nent fig­ures like Sir David Atten­bor­ough and Richard Dawkins (watch here) pre­sent­ed lec­tures to young­sters in 1973 and 1991 (respec­tive­ly). And the great astronomer Carl Sagan took his turn in 1977, offer­ing six lec­tures on our solar sys­tem. The first two talks offer a broad overview of the plan­e­tary sys­tem, set­ting the stage for three pre­sen­ta­tions (see below) ded­i­cat­ed to Mars, a top­ic that holds spe­cial inter­est this week. With NASA just hav­ing land­ed its rover Curios­i­ty on the sur­face of Mars, it’s par­tic­u­lar­ly inter­est­ing to watch Sagan talk about the knowl­edge gained from ear­ly NASA orbiters, par­tic­u­lar­ly the Mariner and Viking mis­sions. In a rather time­ly way, Sagan’s lec­tures put the Curios­i­ty mis­sion in a grander his­tor­i­cal con­text, a deep­er his­to­ry of space explo­ration.

Sagan’s talks assume no spe­cial­ized knowl­edge and run rough­ly 60 min­utes each. You can find more Christ­mas lec­tures on the RI web­site here.

The Out­er Solar Sys­tem and Life

The His­to­ry of Mars

Mars Before Viking

Mars After Viking

Plan­e­tary Sys­tems Beyond The Sun

We’ll be adding this course to the Astron­o­my sec­tion of our col­lec­tion, 1,700 Free Online Cours­es from Top Uni­ver­si­ties.

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Neil deGrasse Tyson’s StarTalk Radio Show Podcast Tackles the History of Video Games

in Physics, Podcasts, Science | July 31st, 2012

Neil deGrasse Tyson has a pod­cast. I repeat, Neil deGrasse Tyson has a pod­cast. If you’re unfa­mil­iar (and you shouldn’t be), Tyson is Astro­physi­cist-in-res­i­dence at New York’s Nat­ur­al His­to­ry Muse­um and Direc­tor of its Hay­den Plan­e­tar­i­um. He’s also the most promi­nent advo­cate for a revi­tal­ized U.S. space pro­gram. Okay, back to the pod­cast. As an avid con­sumer of every sci­ence-based pod­cast out there, I can tell you that the StarTalk Radio Show (iTunes — Feed — Web Site) has quick­ly risen to the top of my list. The very per­son­able Tyson is the big draw, but he has also made the wise deci­sion to include “come­di­an co-hosts, celebri­ties, and oth­er spe­cial guests.” In the episode right below, Tyson and come­di­an Eugene Mir­man (whom you might rec­og­nize as the voice of Gene from Bob’s Burg­ers) mix it up with video game design­er Will Wright and author Jeff Ryan.

Ryan’s Super Mario: How Nin­ten­do Con­quered Amer­i­ca—and the his­to­ry of video games more generally—is the top­ic of the show. Despite the less-than-stel­lar audio qual­i­ty, this is not to be missed. The con­ver­sa­tion is rapid-fire: Mir­man inter­jects hilar­i­ous inani­ties while Wright and Ryan speed through the fas­ci­nat­ing his­to­ry and Tyson throws knuck­le­ball ques­tions and enthus­es (at 4:30) that the “first real video game,” Space Wars, was about, what else, space. We also get the his­to­ry of the unfor­get­table Pong (at 5:59), the orig­i­nal Star Wars game (at 8:17), and, nat­u­ral­ly, Don­key Kong (at 3:19), designed by the now wild­ly famous (in Japan, at least) Shigeru Miyamo­to–who also invent­ed Mario, and who had nev­er designed a game in his life before Don­key Kong. All this and some clas­sic 8‑bit video game music to boot.

StarTalk in gen­er­al has much to rec­om­mend it. Tyson is the “nation’s fore­most expert on space,” and is prob­a­bly instant­ly rec­og­niz­able from his host­ing of NOVA sci­en­ceNow and his best­selling books. He is the pub­lic face of a sci­en­tif­ic com­mu­ni­ty often in need of good press, and he has the rare abil­i­ty to trans­late abstruse con­cepts to the gen­er­al pub­lic in a humor­ous and approach­able way. Pre­vi­ous guest­s/­co-hosts have includ­ed Janeane Garo­fa­lo (in the “most argu­men­ta­tive Startalk pod­cast ever”) and John Hodg­man (of the Dai­ly Show and the “Mac vs. PC” ads). But above all, c’mon, it’s Neil deGrasse Tyson. The man deserved­ly has his own inter­net meme, inspired by his dra­mat­ic ges­tures in this video dis­cus­sion of Isaac New­ton from Big Think.

Enough said.

Watch the full Big Think inter­view with Tyson here. And don’t for­get to sub­scribe to the StarTalk Radio Show (iTunes — Feed — Web Site).

Josh Jones is a doc­tor­al can­di­date in Eng­lish at Ford­ham Uni­ver­si­ty and a co-founder and for­mer man­ag­ing edi­tor of Guer­ni­ca / A Mag­a­zine of Arts and Pol­i­tics.

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Professor Ronald Mallett Wants to Build a Time Machine in this Century … and He’s Not Kidding

in Physics, Video - Science | July 20th, 2012

Time trav­el. Since Ein­stein for­mu­lat­ed his spe­cial the­o­ry of rel­a­tiv­i­ty, we have known that it is the­o­ret­i­cal­ly pos­si­ble, even if pop­u­lar notions of time trav­el have dete­ri­o­rat­ed slight­ly from the august H.G. Wells’ The Time Machine to… well, Hot Tub Time Machine. Which is to say that few people—lay or professional—take the con­cept very seri­ous­ly any­more. But Uni­ver­si­ty of Con­necti­cut Pro­fes­sor Dr. Ronald Mal­lett still believes, and he has sought to real­ize his dream of mak­ing time trav­el pos­si­ble in this cen­tu­ry by infil­trat­ing the sci­en­tif­ic pro­fes­sion, becom­ing a respect­ed the­o­ret­i­cal physi­cist, then brav­ing the ridicule and oppro­bri­um, or at least dis­agree­ment, of his col­leagues to begin work on a time machine.

In the video above, Dr. Mal­lett describes his expe­ri­ence of “risk­ing pro­fes­sion­al sui­cide,” and phys­i­cal pain, to work out his ideas. Since com­ing out, so to speak, as a pro­po­nent of time trav­el, Mal­lett pub­lished a mem­oir in 2006, Time Trav­el­er: A Scientist’s Per­son­al Mis­sion to Make Time Trav­el a Real­i­ty. It’s both a descrip­tion of his fifty years of sci­en­tif­ic work toward his project Space-time Twist­ing by Light (STL) and a mov­ing per­son­al nar­ra­tive of grow­ing up under seg­re­ga­tion, los­ing his father at a young age, and becom­ing one of the first African Amer­i­can the­o­ret­i­cal physi­cists.

Spike Lee has acquired the film rights to his mem­oir (though the project seems to be stalled), and Mal­lett has told his sto­ry on This Amer­i­can Life, CNN, and in speak­ing tours around the coun­try. Whether Mallett’s enthu­si­asm will trans­late into real­i­ty remains to be seen, but his pas­sion for Einstein’s pre­dic­tions is infec­tious and illu­mi­nat­ing.

The video comes from a new series from THNKR called EPIPHANY, a “dai­ly series invit­ing impas­sioned thought lead­ers across all dis­ci­plines to reveal the inno­v­a­tive, the improb­a­ble, and the unex­pect­ed of their worlds.” Each week is devot­ed to a new “thought leader.” Vis­it the EPIPHANY chan­nel to view the rest of Dr. Mallett’s “rev­e­la­tions.”

Anoth­er online source for infor­ma­tion, the Cas­siopeia Project, claims to “make sci­ence sim­ple.” In the video below, learn the basics of time trav­el and spe­cial rel­a­tiv­i­ty.

via Boing­Bo­ing

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The Mathematics of Spiderman and the Physics of Superheroes

in Animation, Math, Physics | July 19th, 2012

I have not seen the new Spi­der­man reboot, so I’ll have to reserve judg­ment on the virtues of the movie. But, in gen­er­al, super­hero movies suc­ceed or fail for me based on how plau­si­ble and con­sis­tent the physics of the alter­nate uni­verse they cre­ate are. In the above video from the “Emory [Uni­ver­si­ty] Looks at Hol­ly­wood” series, Skip Garibal­di, pro­fes­sor of math­e­mat­ics (who pre­vi­ous­ly exam­ined the math of rock climb­ing) explains that the new Spi­der­man film does, with a minor excep­tion, por­tray the feats of Spi­der­man in a math­e­mat­i­cal­ly pos­si­ble way—granted that we’re will­ing to believe in super­pow­ers. For exam­ple, Spi­der­man’s grace­ful swings through the city on long strands of web­bing don’t just serve a cin­e­mat­ic pur­pose; they also keep him from pos­si­bly dis­lo­cat­ing his shoul­ders while com­ing to a full-stop from a free-fall.

Ana­lyz­ing the sci­ence of super­heroes is a fun side­line for pop cul­ture-mind­ed sci­en­tists. In some cas­es, it can be an effec­tive teach­ing tool as well. Uni­ver­si­ty of Min­neso­ta physi­cist and com­ic book fan James Kakalios devotes an entire lec­ture to “The Uncan­ny Physics of Super­hero Com­ic Books.” Kakalios, who has writ­ten a book called the Physics of Super­heroes, worked as a sci­ence con­sul­tant on the Spi­der­man reboot and on Zack Snyder’s adap­ta­tion of Watch­men, which he dis­cuss­es below.

Many great physics cours­es (some intro­duc­to­ry, some advanced) can be found in the Physics sec­tion of our col­lec­tion of 500 Free Online Cours­es.

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Einstein’s Big Idea: E=mc²

in Physics, Television | July 17th, 2012

E=mc²: We’ve all heard of it. But what does it mean?

Ein­stein’s Big Idea, a film from the PBS Nova series, attempts to shed a lit­tle light on Albert Ein­stein’s equa­tion by break­ing it down into its com­po­nent parts and telling a sto­ry behind the devel­op­ment of each one. Nar­rat­ed by actor John Lith­gow, the film is based on David Bodanis’s 2000 best­seller E=mc²: A Biog­ra­phy of the World’s Most Famous Equa­tion. It pre­miered in 2005, the 100th anniver­sary of Ein­stein’s Annus Mirabilis–the “mirac­u­lous year” when the 26-year-old patent clerk pub­lished five papers with­in a six-month peri­od that would rev­o­lu­tion­ize 20th cen­tu­ry physics. Among those five were Ein­stein’s paper out­lin­ing what lat­er became known as the Spe­cial The­o­ry of Rel­a­tiv­i­ty, and a short fol­low-up paper deriv­ing his for­mu­la for the equiv­a­lence of mass and ener­gy, which he first stat­ed as m=E/c².

Does Ein­stein’s Big Idea actu­al­ly explain the equa­tion? Alas, no. Not even close. Appar­ent­ly, the film­mak­ers’ “big idea” was that they might be able to evoke empa­thy among young view­ers and stim­u­late inter­est in sci­ence by por­tray­ing Ein­stein as a rebel­lious young man with a healthy sex dri­ve. The movie fea­tures dra­mat­ic depic­tions of events, not only in Ein­stein’s ear­ly life, but in the lives of sev­er­al oth­er impor­tant fig­ures in the his­to­ry of sci­ence:  the 19th cen­tu­ry Eng­lish­man Michael Fara­day, whose exten­sive exper­i­ments and intu­itive the­o­ries in elec­tric­i­ty and mag­net­ism led direct­ly to James Clerk Maxwell’s for­mal dis­cov­ery that light was an elec­tro­mag­net­ic wave;  the 18th cen­tu­ry French chemist Antoine Lavoisi­er, whose dis­cov­ery of the con­ser­va­tion of mass had to be re-for­mu­lat­ed as the con­ser­va­tion of mass-ener­gy in the wake of Ein­stein’s Rel­a­tiv­i­ty The­o­ry; the 18th cen­tu­ry French trans­la­tor of Isaac New­ton, Emi­lie du Châtelet, who used the empir­i­cal find­ings of Willem Gravesande to change New­ton’s for­mu­la for ener­gy from E=mv to the one favored by Got­tfried Wil­helm Leib­niz, E=mv²; and the Aus­tri­an-born physi­cist Lise Meit­ner, whose ground­break­ing research into nuclear fis­sion in the 1930s helped con­firm the accu­ra­cy of Ein­stein’s equa­tion. Togeth­er, the scenes depict the his­to­ry of sci­ence as a roman­tic strug­gle of extra­or­di­nary indi­vid­u­als against the resis­tance of less­er minds.

To learn more about Rel­a­tiv­i­ty and E=mc², here are some free online resources:

“On the Elec­tro­dy­nam­ics of Mov­ing Bod­ies”, Ein­stein’s famous paper from the June 30, 1905 edi­tion of Annalen der Physik, out­lin­ing the Spe­cial The­o­ry of Rel­a­tiv­i­ty. Avail­able as HTML or PDF.

“Does the Iner­tia of a Body Depend on Its Ener­gy Con­tent?”, Ein­stein’s three-page fol­low-up to the paper above, deriv­ing his famous equa­tion from the prin­ci­ples laid out in the ear­li­er work. It was pub­lished in Annalen der Physik on Sep­tem­ber 27, 1905 and is avail­able online as a PDF.

Rel­a­tiv­i­ty: The Spe­cial and Gen­er­al The­o­ry, Ein­stein’s clas­sic guide for the lay read­er, writ­ten in 1916 and avail­able free in var­i­ous for­mats at Project Guten­berg.

The ABC of Rel­a­tiv­i­ty, Bertrand Rus­sel­l’s very acces­si­ble 1925 book, avail­able in an abridged audio edi­tion through links in our Feb. 18 post.

Cours­es on Ein­stein can be found in the Physics sec­tion of our col­lec­tion of 500 Free Online Cours­es. And don’t miss Ein­stein for the Mass­es, a lec­ture giv­en by Rama­mur­ti Shankar, Pro­fes­sor of Physics & Applied Physics at Yale.

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Stephen Hawking Loses $100 on the Higgs Boson Discovery

in Physics | July 7th, 2012

With the Hig­gs Boson dis­cov­ery this week, there were a lot of win­ners in the physics com­mu­ni­ty, and only one los­er — Stephen Hawk­ing’s bank account. It’s a loss the physi­cist (and author of best­selling books) can pre­sum­ably afford to take. A good week, all in all.

Fol­low us on Face­book, Twit­ter and now Google Plus.

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