Electronics is really an applied branch of physics, so it isn’t surprising that if you are serious about your electronics, you probably know a little physics, too. If you’ve ever heard the term “fine structure constant” and weren’t entirely sure what it means, [Parth G] wants to explain it to you in about a minute. His video explanation appears below.
You may know that the constant, often represented by α, is approximately 1/137, but what does that mean? The answer relates to the orbit of electrons. You might remember from school that electrons orbit in shells around the nucleus. That is, an atom might have some electrons in the innermost shell, and more electrons in an outer shell.
Let’s face it — for the average person, math and formulas are not the most attractive side of physics. The fun is in the hands-on learning, the lab work, the live action demonstrations of Mother Nature’s power and prowess. And while it’s true that the student must be willing to learn, having a good teacher helps immensely.
Professor Julius Sumner Miller was energetic and enthusiastic about physics to the point of contagiousness. In pictures, his stern face commands respect. But in action, he becomes lovable. His demonstrations are dramatic, delightful, and about as far away from boring old math as possible. Imagine if Cosmo Kramer were a physics professor, or if that doesn’t give you an idea, just picture Doc Brown from Back to the Future (1985) with a thick New England accent and slightly darker eyebrows. Professor Miller’s was a shouting, leaping, arm-waving, whole-bodied approach to physics demonstrations. He was completely fascinated by physics, and deeply desired to understand it as best he could so that he could share the magic with people of all ages.
Professor Miller reached thousands of students in the course of his nearly 40-year teaching career, and inspired millions more throughout North America and Australia via television programs like TheMickey Mouse Club and Miller’s own show entitled Why Is It So? His love for science is indeed infectious, as you can see in this segment about the shock value of capacitors.
The story begins back in 1665, when [Christiaan Huygens] discovered that two pendulum clocks hanging from the same wooden beam would spontaneously synchronise over a period of time. The same principle is then demonstrated with metronomes – an experiment readily recreated in the home. Other systems that show this same eerie coordiation are then explored – from tidally locked moons orbiting around planets (like ours!), to chemical oscillators discovered by Soviet scientists during the cold war. There’s also a great explanation of the problems faced by the London Millennium Bridge, which swayed wildly under heavy foot traffic as it induced pedestrians to walk in sync.
Of all the things that were around to terrify our ancestors, lightning must have been right up there on the list. Sure, the savannahs were teeming with things that wanted to make lunch out of you, but to see a streak of searing blue-white light emerge from a cloud to smite a tree out of existence must have been a source of dread to everyone. Even now, knowing much more about how lightning happens and how to protect ourselves from it, it’s still pretty scary stuff to be around.
But for as much as we know about lightning, there are plenty of unanswered questions about its nature. To get to the bottom of this, Greg Leyh wants to build a lightning machine of gargantuan proportions: a pair of 120 foot (36 m) tall Tesla towers. Each 10-story tower will generate 8.8 million volts and recreate the conditions inside storm clouds. It’s an ambitious goal, but Greg and his team at Lightning on Demand have already built and demonstrated a 1/3-scale prototype Tesla tower, which is impressively powerful in its own right.
As you can imagine, there are a ton of engineering details that have to be addressed to make a Tesla tower work, not to mention the fascinating physics going on inside a machine like this. Greg will stop by the Hack Chat to answer our questions about the physics of lightning, as well as the engineering needed to harness these forces and call the lightning down from the sky.
Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about. Continue reading “Physics Of Lightning Hack Chat”→
Gravity is one of the more obvious forces in the universe, generally regarded as easily noticeable by the way apples fall from trees. However, the underlying mechanisms behind gravity are inordinately complex, and the subject of much study to this day.
A major component of this study is around the concept of gravitational waves. First posited by Henri Poincaré in 1905, and later a major component of Einstein’s general theory of relativity, they’re a phenomena hunted for by generations of physicists ever since. For the team at the Laser Interferometer Gravitational-wave Observatory, or LIGO, finding direct evidence of gravitational waves is all in a day’s work.
We’ve all seen recreations of the famous double-slit experiment, which showed that light can behave both as a wave and as a particle. Or rather, it’s likely that what we’ve seen is the results of the double-slit experiment, that barcode-looking pattern of light and dark stripes, accompanied by some handwaving about classical versus quantum mechanics. But if you’ve got 20 minutes to invest, this video of the whole double-slit experiment cuts through the handwaving and opens your eyes to the quantum world.
For anyone unfamiliar with the double-slit experiment, [Huygens Optics] actually doesn’t spend that much time explaining the background. Our explainer does a great job on the topic, but suffice it to say that when coherent light passes through two closely spaced, extremely fine openings, a characteristic pattern of alternating light and dark bands can be observed. On the one hand, this demonstrates the wave nature of light, just as waves on the ocean or sound waves interfere constructively and destructively. On the other hand, the varying intensity across the interference pattern suggests a particle nature to light.
To resolve this conundrum, [Huygens] jumps right into the experiment, which he claims can be done with simple, easily sourced equipment. This is belied a little by the fact that he used photolithography to create his slits, but it should still be possible to reproduce with slits made in more traditional ways. The most fascinating bit of this for us was the demonstration of single-photon self-interference using nothing but neutral density filters and a CCD camera. The explanation that follows of how it can be that a single photon can pass through both slits at the same time is one of the most approachable expositions on quantum mechanics we’ve ever heard.
Decades ago, Einstein predicted the existence of something he didn’t believe in — black holes. Ever since then, people have been trying to get a glimpse of these collapsed stars that represent the limits of our understanding of physics.
For the last 25 years, Andrea Ghez has had her sights set on the black hole at the center of our galaxy known as Sagittarius A*, trying to conclusively prove it exists. In the early days, her proposal was dismissed entirely. Then she started getting lauded for it. Andrea earned a MacArthur Fellowship in 2008. In 2012, she was the first woman to receive the Crafoord Prize from the Royal Swedish Academy of Sciences.
Now Andrea has become the fourth woman ever to receive a Nobel Prize in Physics for her discovery. She shares the prize with Roger Penrose and Reinhard Genzel for discoveries relating to black holes. UCLA posted her gracious reaction to becoming a Nobel Laureate.
A Star is Born
Andrea Mia Ghez was born June 16th, 1965 in New York City, but grew up in the Hyde Park area of Chicago. Her love of astronomy was launched right along with Apollo program. Once she saw the moon landing, she told her parents that she wanted to be the first female astronaut. They bought her a telescope, and she’s had her eye on the stars ever since. Now Andrea visits the Keck telescopes — the world’s largest — six times a year.
Andrea was always interested in math and science growing up, and could usually be found asking big questions about the universe. She earned a BS from MIT in 1987 and a PhD from Caltech in 1992. While she was still in graduate school, she made a major discovery concerning star formation — that most stars are born with companion star. After graduating from Caltech, Andrea became a professor of physics and astronomy at UCLA so she could get access to the Keck telescope in Mauna Kea, Hawaii.
The Keck telescopes and the Milky Way. Image via Flickr
The Center of the Galaxy
Since 1995, Andrea has pointed the Keck telescopes toward the center of our galaxy, some 25,000 light years away. There’s a lot of gas and dust clouding the view, so she and her team had to get creative with something called adaptive optics. This method works by deforming the telescope’s mirror in real time in order to overcome fluctuations in the atmosphere.
Thanks to adaptive optics, Andrea and her team were able to capture images that were 10-30 times clearer than what was previously possible. By studying the orbits of stars that hang out near the center, she was able to determine that a supermassive black hole with four millions times the mass of the sun must lie there. Thanks to this telescope hack, Andrea and other scientists will be able to study the effects of black holes on gravity and galaxies right here at home. You can watch her explain her work briefly in the video after the break. Congratulations, Dr. Ghez, and here’s to another 25 years of fruitful research.
