ريتشارد دوكنز's Blog, page 611
December 17, 2015
How Do They Do That? A Closer Look at Quantum Magnetic Levitation
For three years as an undergraduate physics student performing at science magic shows and open houses, I convinced students (and sometimes their parents) that I was some kind of magician by levitating a small cube-shaped magnet. The magnet floated above a superconductor by only a centimeter or so, but that was ample space to wave a piece of paper between the two to prove there were literally no strings attached. Tapping one edge of the cube sent it spinning in place, and even if you pushed the magnet down it resolutely bounced back up again—if it failed to do so, it meant the superconductor needed to be colder.
A simple recipe for this scientifically grounded spell would be a splash of liquid nitrogen for cooling a ceramic superconductor resting in a Styrofoam basin and a magnet that produces a strong, permanent magnetic field made of rare earth elements.
The levitation works thanks to superconductivity, which could be understood through basic principals of conductivity. Certain elements and materials, aptly called conductors, serve as an electrical conduit, which means electrons can pass through them with relative ease. These electrons still bump into the atoms that make up the conductor and lose a bit of energy with each collision. But, when cooled to a sufficiently chilly temperature, the electrons can flow freely through the conductor without any collisions. That’s because electrons pair up at extremely low temperatures (whereas heat would break the tentative bond between them). Although their bonds are weak, there’s strength in numbers: Pairing up makes it so the collisions that would normally leech energy from the electron flow have no effect because the collisions are weaker than the electrons’ bond.
A superconductor’s critical temperature—how cold it needs to be for these pairings to be possible—depends on its material. Metallic superconductors such as pure aluminum or niobium, for example, have extremely low critical temperatures, typically only a few degrees above absolute zero. Using one of them for an at-home experiment isn’t an option, however, unless you happen to have a lot of liquid helium lying around. (Liquid helium boils at 4.2 kelvins or about –270 degrees Celsius, only a few degrees shy of absolute zero). Fortunately, there’s an alternative: high-temperature superconductors, which are ceramics made from multiple elements that allow electrons to flow freely under slightly higher than most critical temperatures.
77 K (about –196 degrees C) doesn’t seem like a day at the tropics, but in the world of superconductors it’s downright toasty. It’s also the temperature at which liquid nitrogen—much more accessible than liquid helium—boils. For most high-temperature ceramic superconductors, such as those made of yttrium barium copper oxide (YBCO) or bismuth strontium calcium copper oxide (BSCCO), liquid nitrogen can be used to cool them below their critical temperatures.
We’ve got two pieces of the puzzle at hand now: a high-temperature superconductor and enough liquid nitrogen to keep it cool. But how can we float a magnet above the cooled superconductor? (Or vice versa: in our video with Richard Garriott, he floated a cooled superconductor above a bed of rare earth magnets.)
Quantum magnetic levitation boils down to something called the Meissner effect, which only occurs when a material is cold enough to behave like a superconductor. At normal temperatures, magnetic fields can pass through the material normally. Once it is cold enough to exhibit superconductivity, however, those magnetic fields get expelled. Any magnetic fields that were passing through must instead move around it. When a magnet is placed above a superconductor at critical temperature, the superconductor pushes away its field by acting like a magnet with the same pole causing the magnet to repel, that is, “float”—no magical sleight of hand required.
It’s Kitzmas Time Again, Charlie Darwin
Since December 2005, when Judge John E. Jones III ruled that “intelligent design” is not science and cannot be forced into public school science classes, we’ve celebrated December 20 as Kitzmas. We write carols (and haikus). But we’ve never really had a Kitzmas tree before.
That all changes this year, for the tenth Kitzmas. Today, Science released a prepublication version of “The evolution of antievolution policies since Kitzmiller v. Dover” by former NCSE staffer Nick Matzke, in which he analyzed NCSE’s database of “academic freedom” legislation—the successor strategy to “intelligent design.” And by applying the fancypants evolutionary analysis he learned while getting his post-NCSE PhD, he came up with this tree.
Figure 1 from Matzke's phylomemetic analysis of creationist legislation. His caption explains: "The nodes (splitting events) represent copying events. The distance between a tip and a node is an inference about how much change occurred and how much time this took. When the node-to-tip distance is effectively zero, this indicates a high probability of direct ancestry. Tip labels indicate [which kind of bill this represents] year, state, bill number (SB, senate bill; HB, house bill), and versions (a, b, or c, for legislative revisions; t or f, teachers or faculty targeted)."
It’s hard to know exactly where to put the star on top, and the packages beneath tend to be unwelcome when opened, but, still, what a tree!
As the tree shows, the first of these bills originated before the 2005 trial sounded a death knell for “intelligent design” creationism. The Discovery Institute, the institutional home of ID creationism, started promoting model legislation of this form in 2007, but Matzke’s analysis was able to date that text based on the other bills and concluded that the DI text was actually written earlier. Maybe their staff were even sitting in the back of the courtroom in Pennsylvania making hasty revisions as they watched the legs fall off their hobbyhorse.
The analysis also shows that the ID camp couldn’t keep control of their new strategy. Shortly after publishing the model legislation (as part of the promotion for Ben Stein’s Expelled), it went through a rapid evolution. As Matzke’s tree shows, the legislation merged with a school district policy from Ouachita Parish, Louisiana, producing the first such bill to become law. That new language—and the merger—was shepherded by the Louisiana Family Forum (an affiliate of the radical religious rightwing group Focus on the Family and the hate group Family Research Council). Since then, that modified language has proven quite successful, while bills hewing closer to the DI model have withered on the vine. In Tennessee, the only other state to actually pass such a bill, the legislation was also promoted heavily by the state’s affiliate of Focus on the Family, with the DI largely watching from the sidelines.
And the bills’ focus on evolution has slipped as well. Where the original Alabama bills singled out evolution and the origin of life (or “chemical evolution” in some cases), the merger with the Ouachita Parish policy brought climate change and “human cloning” into the fold (the latter is a coded reference to stem cell research). Since that merger, more and more of the bills have either dropped all reference to specific topics, or have dropped their reference to evolution. A bill in Kansas in 2013 referred only to climate change, while one in Indiana this year only addressed human cloning. The bills are still harmful, letting denialist materials into classrooms, preventing teachers from reining in students who interrupt with denialist claims, and stopping administrators from disciplining teachers who attack the science in the classroom.
That diffusion of the bills’ focus can’t have them dancing at the Disco. ‘tute’s headquarters, but it’s even worse news for science education. Singling out evolution is problematic, of course, but so is singling out climate change, medical research, or even science classes in general. Science teachers don’t need academic freedom to be redefined, and schools don’t need different rules for different subjects. NCSE has fought these bills steadfastly, defeating almost 60 of them, and continuing to work for repeal of the two that passed. As we near the tenth Kitzmas, here’s hoping that Matzke’s tree stays as small and bedraggled as Charlie Brown’s infamous holiday decoration.
Gamma Rays Detected From Halfway Across The Galaxy
Photo credit:
An artist's impression of the powerful blazar-like galaxy PKS 1441+25. M. Weiss/CfA
Last April, after having traveled halfway across the universe, a powerful cascade of gamma rays was observed, allowing astronomers to see a major black hole eruption like never before.
Two teams of astronomers were able to use different instrumentation to piece together a huge amount of information about galaxy PKS 1441+25, which is 7.6 billion light-years away. The supermassive black hole at its center has a mass of 70 million suns, with an event horizon (the surface of no return around a black hole) with a radius of over 300 million kilometers (190 million miles).
Enormous Salamander Found In Chinese Cave
Photo credit:
Another Chinese salamander swimming through its habitat. muzina_shanghai/Flickr; CC BY-NC-ND 2.0
Exploring a huge cave system is an adventurous experience unlike any other, whether it’s the glowworm-filled Waitomo Cave system in New Zealand or the surreal underwater labyrinth of The Pit off the coast of Mexico. You would, however, probably not expect to encounter a 1.4-meter-long (4.6-foot-long) gigantic salamander in the process.
Electrons Are Practically Immortal
Photo credit:
Borexino detector. Borexino collaboration/INAF
Electrons are one of the building blocks of the universe, carrying the negative electric charge around the cosmos and allowing us to enjoy all the pleasures of modern life. The stability of the electron has never been in question, but putting a limit on its stability allows scientists to better understand the fundamentals that govern our existence.
STUPID ATHEIST QUESTIONS
1001 STUPID QUESTIONS ATHEISTS ASK CHRISTIANS… or maybe it’s more like questions an atheist would never ask a christian. If you’re interested in more vids like this let me know in the comments!
Be my patreon! http://www.patreon.com/Jaclyn
Get my awesome tshirts! http://www.jaclynglenn.com
Main channel: http://www.youtube.com/Jaclyn
Vlog channel: http://www.youtube.com/JaclynVlogs
Music channel: http://www.youtube.com/JaclynNoelMusic
Facebook: https://www.facebook.com/jaclynglenn
Twitter: http://twitter.com/#!/JaclynGlenn
Tumblr: http://jaclynglenn.tumblr.com/
Google +: https://plus.google.com/+JaclynGlenn
Vine: https://vine.co/u/1098021519956815872
Instagram: http://instagram.com/jaclynglenn
I only accept friends that I know, but this is if you want to follow my personal facebook page: https://www.facebook.com/JaclynLovesCats
BUSINESS INQUIRIES ONLY: jaclynglenn@gmail.com
*Please help support this channel!*
Be my patreon! http://www.patreon.com/Jaclyn
or
Use the email jaclynglenn@gmail.com to donate via PayPal, or go to https://www.youtube.com/user/JaclynGlenn and click the “donate” button at the top right corner. =)
Send me snail mail! PO BOX listed @ https://www.youtube.com/user/JaclynGlenn/about
Thanks for watching this video on stupid questions that christians think atheists ask. Atheist VS Christian viewpoints on how we think are obviously very different. Honestly this sounds like a list of stupid questions that doubting christians would ask other christians to figure things out. Atheists don’t care about god’s underwear or wonder about angels. Just ridiculous x’D
Antidepressants in Pregnancy Tied to Autism
By Lisa Rapaport
(Reuters Health) – Women who take antidepressants during pregnancy may be more likely to have children with autism, a Canadian study suggests.
The overall risk is low – less than 1 percent of the nearly 150,000 babies in the study were diagnosed with autism by age six or seven.
But children of women who took antidepressants during the second and third trimesters of pregnancy were 87 percent more likely to develop autism than kids born to women who didn’t take the drugs, researchers report in JAMA Pediatrics.
“Depression is a serious and debilitating condition,” said lead study author Anick Berard of the University of Montreal. “This study is not advocating untreated depression. However, it is certainly advocating treatment of depression with something other than antidepressants during pregnancy.”
Some women, particularly if their symptoms are mild, may be able to manage depression during pregnancy with exercise or psychotherapy, Berard added.
The study doesn’t prove antidepressants cause autism. It also doesn’t explore the potential harms of untreated depression or assess whether remedies other than medication might be safer or more effective for women and their babies.
Left untreated, depression during pregnancy is associated with underweight babies who are more likely to wind up in neonatal intensive care. Pregnant women with uncontrolled depression may not eat well or keep up with prenatal visits, and, in the most severe cases they may be at increased risk for suicide.
Read more by clicking on the name of the source below.
“Christmas Spirit” Network Found In The Brain
Photo credit:
This dog has clearly nailed the Christmas spirit. C_Gara/Shutterstock
Which one are you: “I hate Christmas,” or “Oh my god Christmaaaas aaaargh *flaps arms excitedly and knocks glass of mulled wine on the floor*”?
Christmas might sometimes seem like Marmite, but with so many people spreading infectious smiles and feelings of joy, why do people often come down with a case of “bah humbug” syndrome? A newly discovered “Christmas spirit” network in the brain might offer us some clues.
Difference between facial growth of Neanderthals and modern humans
source: New York University
An international research team, led by Rodrigo Lacruz, PhD, assistant professor in the Department of Basic Science and Craniofacial Biology at New York University’s College of Dentistry (NYUCD), has just published a study describing for the first time the developmental processes that differentiate Neanderthal facial skeletons from those of modern humans.
Lacruz’s research team showed that the Neanderthals, who appeared about 200,000 years ago, are quite distinct from Homo sapiens (humans) in the manner in which their faces grow, adding to an old but important debate concerning the separation of these two groups. The paper, “Ontogeny of the Maxilla in Neanderthals and their Ancestors,” appears in Nature Communications.
“This is an important piece of the puzzle of evolution,” says Lacruz, a paleoanthropologist and enamel biologist. “Some have thought that Neanderthals and humans should not be considered distinct branches of the human family tree. However, our findings, based upon facial growth patterns, indicate they are indeed sufficiently distinct from one another.
Read more by clicking on the name of the source below.
December 16, 2015
And, But, Therefore: Randy Olson and the Art of Science Storytelling, Part 2
Randy Olson, as you may know, is the scientist-turned-filmmaker whose movies include Flock of Dodos: The Evolution-Intelligent Design Circus and Sizzle: A Global Warming Comedy. Olson also wrote Don’t Be Such A Scientist, and now has a new book, Houston, We Have a Narrative: Why Science Needs Story, which argues that scientists should incorporate more storytelling and narrative into how they discuss their findings. Olson writes that scientists should recognize that the narrative techniques developed by Hollywood can be used to make their science more engaging to the public. Without sacrificing scientific quality, researchers can bring their findings to life using the elements of drama.
Many people misunderstand drama. To remind me and inspire my own writing, I have permanently mounted in my home the famous memo playwright David Mamet sent to the writers of the television series The Unit. You should read the whole memo here, but here's the part most relevant to this discussion (Mamet’s shouting all-capitals style made lowercase):
Every scene must be dramatic. That means: the main character must have a simple, straightforward, pressing need which impels him or her to show up in the scene.
This need is why they came. It is what the scene is about. Their attempt to get this need met will lead, at the end of the scene, to failure—this is how the scene is over. It, this failure, will, then, of necessity, propel us to the next scene.
…
Start, every time, with this inviolable rule: the scene must be dramatic. It must start because the hero has a problem and it must culminate with the hero finding him or herself either thwarted or educated that another way exists.”
An important point here is that in a truly dramatic narrative, the protagonist must face failure. The movie Contact, based on the novel by Carl Sagan, made even the funding of science dramatic. Jodie Foster’s scientist character faces loss of funding for her research; she argues passionately for the value of her work and to keep her project going, knowing that her career could evaporate unless she convinces a skeptical board. This scene was dramatic because we identify with a vulnerable protagonist facing the risk of failure. At the other end of the spectrum, Star Wars: The Phantom Menace was the antithesis of drama because the protagonists faced no danger: the movie consisted of boring montages of bored, lightsaber-wielding Jedi cutting through endless armies of robots, without receiving a single scratch—no risk to the protagonists, no interest to the audience.
In drama, after repeated failures, the protagonist must change something about himself or herself or create something that allows for success. Neil deGrasse Tyson’s Cosmos episode “The Clean Room” told the story of Clair Patterson’s attempt to determine the age of the Earth through uranium-lead dating, and of Patterson’s repeated failures because of ubiquitous lead contamination in the environment. Patterson essentially had to invent from scratch the concept of a clean room and the procedures for its use in order to overcome this difficulty. Neil deGrasse Tyson did a great job telling this scientific narrative as a dramatic arc—setting a goal, encountering failure, creating something to solve the problem.
These sorts of dramatic stories can make scientific discoveries engaging. But just as with the Force, there is light side and a dark side to the power of scientific storytelling…which we will explore in part 3.
ريتشارد دوكنز's Blog
- ريتشارد دوكنز's profile
- 106 followers
