The tale of much of Barbara McClintock’s life is that of the scientist working long hours with a microscope seeking to solve mysteries. The mystery she spent most of her career trying to solve was how all cells in an organism can contain the same DNA, and yet divide to produce cells serving different functions; basically how cells differentiate. And for that, she got a Nobel prize all to herself, which is no small feat either.
Becoming a Scientist
McClintock was born on June 16, 1902, in Hartford, Connecticut, USA. From age three until beginning school, she lived with her aunt in Brooklyn, New York while her father strove financially to start up a medical practice. She was a solitary and independent-minded child, a trait she later called her “capacity to be alone”.
In 1919, she began her studies at Cornell’s College of Agriculture and took her first course in genetics in 1921. A year later, due to the interest she showed in genetics, she was invited to take the graduate genetics course at Cornell. It was here that she became interested in the new field of cytogenetics, specifically of maize or corn. Cytogenetics studies how the chromosomes relate to cell behavior, particularly during cell division. Chromosomes are the long strands of DNA within the nucleus of every cell and shown here in the photo at a time when they are condensed, or coiled up.
While still at Cornell she developed a number of methods for visualizing and characterizing maize which ended up in textbooks. She also became the first to describe the morphology of the ten maize chromosomes, basically their form and structural relationships, which then allowed her to discover more about the chromosomes. One of her colleagues observed that ten of the seventeen significant advances made in the field at Cornell between 1929 and 1935 were hers. This was only the first step in what would be the remarkable career of a very well respected scientist.
Maria Goeppert-Mayer was one of only two women to win the Nobel prize for physics thus far, the other being Marie Curie. And yet her name isn’t anywhere near as well known as Marie Curie’s. She also worked on the Manhattan Project and spent time during her long career with Enrico Fermi, Max Born, Edward Teller, and many other physics luminaries.
She was “other” in another way too. She followed her husband from university to university, and due to prevailing rules against hiring both husband and wife, often had to take a non-faculty position, sometimes even with no salary. Yet being the other, or plus-one, seemed to give her what every pure scientist desires, the freedom to explore. And explore she did, widely. She was always on the cutting edge, and all the time working with the leading luminaries of physics. For a scientist, her story reads like it’s too good to be true, which is what makes it so delightful to read about.
Hold out your hands in front of you, palms forward. They look quite similar, but I’m sure you’re all too aware that they’re actually mirror images of each other. Your hands are chiral objects, which means they’re asymmetric but not superimposable. This property is quite interesting when studying the physical properties of matter. A chiral molecule can have completely different properties from its mirrored counterpart. In physics, producing the mirror image of something is known as parity. And in 1927, a hypothetical law known as the conservation of parity was formulated. It stated that no matter the experiment or physical interaction between objects – parity must be conserved. In other words, the results of an experiment would remain the same if you tired it again with the experiment arranged in its mirror image. There can be no distinction between left/right or clockwise/counter-clockwise in terms of any physical interaction.
The nuclear physicist, Chien-Shiung Wu, who would eventually prove that quantum mechanics discriminates between left- and right-handedness, was a woman, and the two men who worked out the theory behind the “Wu Experiment” received a Nobel prize for their joint work. If we think it’s strange that quantum mechanics works differently for mirror-image particles, how strange is it that a physicist wouldn’t get recognized just because of (her) gender? We’re mostly here to talk about the physics, but we’ll get back to Chien-Shiung Wu soon.
The End of Parity
Conservation of parity was the product of a physicist by the name of Eugene P. Wigner, and it would play an important role in the growing maturity of quantum mechanics. It was common knowledge that macro-world objects like planets and baseballs followed Wigner’s conservation of parity. To suggest that this law extended into the quantum world was intuitive, but not more than intuition. And at that time, it was already well known that quantum objects did not play by the same rules as classical objects. Would quantum mechanics be so strange as to care about handedness? Continue reading “There Is No Parity: Chien-Shiung Wu”→
Remember in the late 90s and early 2000s when everything had blue LEDs in them? Blinding blue LEDs that lit up a dark room like a Christmas tree? Nobel prize. There’s a good /r/askscience thread on why this is so important. The TL;DR is that it’s tough to put a p-type layer on gallium nitride.
Have a Segway and you’re a member of the 501st? Here’s your Halloween costume. It’s a model of the Aratech 74-Z speeder bike, most famously seen careening into the side of trees on the forest moon of Endor.
[Wilfred] was testing a titanium 3D printer at work and was looking for something to print. The skull ‘n wrenches was a suitable candidate, and the results are fantastic. From [Wilfred]: “Just out of the printer the logo looks amazing because it isn’t oxidized yet (inside the printer is an Argon atmosphere) Then the logo moves to an oven to anneal the stress made by the laser. But then it gets brown and ugly. After sandblasting we get a lovely bluish color as you can see in the last picture.”
The folks at Lulzbot/Aleph Objects are experimenting with their yet-to-be-released printer, codenamed ‘Begonia’. They’re 2D printing, strangely enough, and for only using a standard Bic pen, the results look great.
Everyone is going crazy over the ESP8266 UART to WiFi module. There’s another module that came up on Seeed recently, the EMW3162. It’s an ARM Cortex M3 with plenty of Flash, has 802.11 b/g/n, and it’s $8.50 USD. Out of stock, of course.