Questions we ask ourselves - What is a soap bubble, and why is it so colorful?
It’s a question that many of us likely have asked as children - why are soap bubbles so resilient, compared to water bubbles, and why are they so colorful on their surfaces? The answer is as fascinating as the question.
What is a soap bubble?
First, a soap bubble is actually a bubble of water between two layers of soap molecules. Soap is what is chemically called a surfactant - its molecules have hydrophilic, or “water-loving,” heads, and hydrophobic, or “water-hating,” tails. These parts are -philic/-phobic based on their solubility in water (polarity). This quality thus enables a surfactant to allow oil and water to mix, which is useful in cleaning products like soap.
So in a soap bubble, the hydrophilic heads are attracted to the sandwiched water, while the tails extend away from the water (Figure 2). This creates surface tension, and the material strives to achieve the smallest area based on simple physics, thus forming a round surface (and if the bubble is in the air, a sphere).
So what’s with the colors?
The beautiful colors seen on soap bubbles are a result of what’s called interference, an effect observed from butterfly wings to crystals of calcite (Figure 1). When light reaches the bubble, some of the waves reflect off of the outer soap film, but others travel farther to reflect off of the inner film. Because there’s a distance between these two layers, there is an extra distance the second wave has to travel to catch up with the first wave. These waves are transmitted parallel to each other (Figure 3).
There are two possible outcomes of interference (overall presented in Figure 4). The first is if the waves are “out of phase.” This means that the extra distance the second wave travels is equal to half a specific wavelength. As a result, the second wave will partially “cancel out” the first wave, a process called destructive interference. This leads to a reduction in the intensity of the color.
The second outcome is constructive interference. If the extra distance is equal to a specific wavelength of light, the waves are “in phase” and will enhance each other.
Different colors thus form on the surface of a bubble based on the angles of incident light waves. At a direct, right angle, the extra distance is much shorter than if the light enters from a wider angle (think of a pencil on a lined sheet of paper - if oriented up and down, the total length of pencil one row intersects is less than if the pencil is at an angle).
By the same principle, the colors are dependent on thickness, which would, again, affect those extra distances of the second waves. A bubble becomes thinner over time due to evaporation - so as time passes, the range of colors a bubble presents should change. As a bubble changes from thick to thin, the ranges are cancelled in the order of red, yellow, green, and, last, blue, until the bubble is (visibly) colorless. Usually bubbles with thick films present blue and green colors, while thinner bubbles will be yellow to colorless.
And that’s that!
Optics lecture today condensed into a few paragraphs
The GIF above is an animation of a fractal tree, one of the simplest fractals! (simple meaning you can actually draw it without computer aid)
The basis of a fractal is a pattern repeating itself. Sometimes looking exactly the same no matter how close you zoom in on a chosen area. The most popular example of this being the Mandelbrot Fractal. (look up a video of the fractal, you can stare at it for hours — it’ll still be the same)
"Beautiful, damn hard, increasingly useful, thats fractals." - Pierre Mandelbrot
It really pains me how tumblr is so in awe of the cool side of science, the flashy demonstrations and interesting science gifs and they’re all like
IT’S SO COOL!!!!
but then two posts later I see
"Haha algebra and calculus when am I ever going to use them LOL"
have I got news for you!
Slime mold was grown on an agar gel plate shaped like America and food sources were placed where America’s large cities are.
The result? A possible look at how to best build public transportation.
I just really like the idea of slime mold on a map of the US. It’s beautiful.
Very clever, Physarum polycephalum, very clever indeed. Not bad for a simple web of single-celled organisms able to solve mazes and map the Tokyo rail system using the emergent powers of swarm biology, not bad at all.
My only criticism is that a truly great transportation network should take into account the differing sizes of American cities, terrain and economic needs, so spot those colonies in varying densities or something, add some bumps and farms and then see what happens. Also, slime molds should be taught to fly, them we will REALLY be in business. But altogether I give it a 9.8.
Photo by Malcom Burrows
To the best of our knowledge, the mechanical gear—evenly-sized teeth cut into two different rotating surfaces to lock them together as they turn—was invented sometime around 300 B.C.E. by Greek mechanics who lived in Alexandria. In the centuries since, the simple concept has become a keystone of modern technology, enabling all sorts of machinery and vehicles, including cars and bicycles.
As it turns out, though, a three-millimeter long hopping insect known as Issus coleoptratus beat us to this invention. Malcolm Burrows and Gregory Sutton, a pair of biologists from the University of Cambridge in the U.K., discovered that juveniles of the species have an intricate gearing system that locks their back legs together, allowing both appendages to rotate at the exact same instant, causing the tiny creatures jump forward.
The finding, which was published today in Science, is believed to be the first functional gearing system ever discovered in nature. Insects from the Issus genus, which are commonly called “planthoppers,” are found throughout Europe and North Africa. Burrows and Sutton used electron microscopes and high-speed video capture to discover the existence of the gearing and figure out its exact function.
Read more about the first mechanical gears ever found in nature at Smithsonian.com.
As we celebrate the 50th anniversary of the March On Washington, a good time to remember what is not remembered.
"The Butler" touches on a lot of these ideas. I highly recommend it.
One Human Mind Controlling Another … Well, Sort Of:
University of Washington scientists have achieved what they call the first noninvasive human brain-to-brain interface, doing so without surgery or brain implants. We’ve seen similar things in rats, but this is the first time it’s been reported in humans. There’s a catch, though. There’s always a catch.
What they did: Two subjects, a sender and a receiver, sat in separate rooms wearing (silly-looking) EEG caps. The sender played a simple artillery-type video game, but instead of manually “pew-pew-ing” when he wanted to, he just thought about pulling the trigger.
The recipient had his finger on a trigger. He could not see the game screen and could not hear the sender. Between the two subjects was a pair of computers and brain-interpreting software. When the sender thought about firing, the recipient received a signal … and he pressed the trigger at precisely the right moment! BOOM!! Achievement unlocked!! You can watch a video of the experiment here.
What this means: Human brains can be connected, and information from one can be used to stimulate the other. Two of the most complex computers ever created are communicating through two considerably simpler computers, which is very cool.
So what’s the catch? It comes down to the word “specific”. I mean, there’s also the fact that this is coming from a press release and not a peer-reviewed research paper. That’s a big catch, but it only means that it’s preliminary, not wrong. The biggest thing is that this is certainly not the transmission of thoughts or specific brain signals between two human beings.
These researchers used a technique called EEG, those funny looking electrode caps we’re all familiar with. EEG is very good at sensing the brain’s electrical activity (like a motor signal that says “pull the trigger”) and recording it in real time (you see a blip as soon as the brain registers electrical activity). But EEG kind of sucks when it comes to spatial resolution. There’s better techniques for this kind of thing, but they are more complex.
Our brain is crowded with nearly a hundred billion neurons, and exponentially more connections between them. In the regions that control your movement, like pressing a video game trigger, they are packed in there like cellular sardines. but two neighboring neurons could be controlling very different actions. EEG can’t tell the difference, it doesn’t have the precision to read a signal and say “You meant to press the trigger” as opposed to “You meant to give the other researcher the bird”.
My guess is that the recipient did feel something, but there is so much unconscious activity going on in our brains that I have a hard time believing the command to “PUSH THE BUTTON” just fell out of the ether and he did it. He most likely got a very generalized brain buzz, and then just pushed the button.
The researchers claim this could one day be used to help someone land a plane if the pilot goes down, or communicate beyond language. Needless to say, I’m skeptical. Don’t put me on that plane.
But it’s still cool. This is another step in decoding the elaborate circuitry of the brain, and perhaps one day we will be able to recreate that information in meaningful ways, like hat-controlled prosthetic limbs, or automatic hunger-triggered pizza-ordering systems. But today is not that day (and the pizza lovers wept).
Joe points out some of the potential weaknesses with the article I reblogged earlier. It’s still very exciting, but of course the brain works in very mysterious ways and we are nowhere near being able to understand or control it.
University of Washington researchers have performed what they believe is the first noninvasive human-to-human brain interface, with one researcher able to send a brain signal via the Internet to control the hand motions of a fellow researcher.
Using electrical brain recordings and a form of magnetic stimulation, Rajesh Rao sent a brain signal to Andrea Stocco on the other side of the UW campus, causing Stocco’s finger to move on a keyboard.
While researchers at Duke University have demonstrated brain-to-brain communication between two rats, and Harvard researchers have demonstrated it between a human and a rat, Rao and Stocco believe this is the first demonstration of human-to-human brain interfacing.
“The Internet was a way to connect computers, and now it can be a way to connect brains,” Stocco said. “We want to take the knowledge of a brain and transmit it directly from brain to brain.”
The researchers captured the full demonstration on video recorded in both labs.
Rao, a UW professor of computer science and engineering, has been working on brain-computer interfacing in his lab for more than 10 years and just published a textbook on the subject. In 2011, spurred by the rapid advances in technology, he believed he could demonstrate the concept of human brain-to-brain interfacing. So he partnered with Stocco, a UW research assistant professor in psychology at the UW’s Institute for Learning & Brain Sciences.
On Aug. 12, Rao sat in his lab wearing a cap with electrodes hooked up to an electroencephalography machine, which reads electrical activity in the brain. Stocco was in his lab across campus wearing a purple swim cap marked with the stimulation site for the transcranial magnetic stimulation coil that was placed directly over his left motor cortex, which controls hand movement.
The team had a Skype connection set up so the two labs could coordinate, though neither Rao nor Stocco could see the Skype screens.
Rao looked at a computer screen and played a simple video game with his mind. When he was supposed to fire a cannon at a target, he imagined moving his right hand (being careful not to actually move his hand), causing a cursor to hit the “fire” button. Almost instantaneously, Stocco, who wore noise-canceling earbuds and wasn’t looking at a computer screen, involuntarily moved his right index finger to push the space bar on the keyboard in front of him, as if firing the cannon. Stocco compared the feeling of his hand moving involuntarily to that of a nervous tic.
“It was both exciting and eerie to watch an imagined action from my brain get translated into actual action by another brain,” Rao said. “This was basically a one-way flow of information from my brain to his. The next step is having a more equitable two-way conversation directly between the two brains.”
The technologies used by the researchers for recording and stimulating the brain are both well-known. Electroencephalography, or EEG, is routinely used by clinicians and researchers to record brain activity noninvasively from the scalp. Transcranial magnetic stimulation is a noninvasive way of delivering stimulation to the brain to elicit a response. Its effect depends on where the coil is placed; in this case, it was placed directly over the brain region that controls a person’s right hand. By activating these neurons, the stimulation convinced the brain that it needed to move the right hand.
Computer science and engineering undergraduates Matthew Bryan, Bryan Djunaedi, Joseph Wu and Alex Dadgar, along with bioengineering graduate student Dev Sarma, wrote the computer code for the project, translating Rao’s brain signals into a command for Stocco’s brain.
“Brain-computer interface is something people have been talking about for a long, long time,” said Chantel Prat, assistant professor in psychology at the UW’s Institute for Learning & Brain Sciences, and Stocco’s wife and research partner who helped conduct the experiment. “We plugged a brain into the most complex computer anyone has ever studied, and that is another brain.”
At first blush, this breakthrough brings to mind all kinds of science fiction scenarios. Stocco jokingly referred to it as a “Vulcan mind meld.” But Rao cautioned this technology only reads certain kinds of simple brain signals, not a person’s thoughts. And it doesn’t give anyone the ability to control your actions against your will.
Both researchers were in the lab wearing highly specialized equipment and under ideal conditions. They also had to obtain and follow a stringent set of international human-subject testing rules to conduct the demonstration.
“I think some people will be unnerved by this because they will overestimate the technology,” Prat said. “There’s no possible way the technology that we have could be used on a person unknowingly or without their willing participation.”
Stocco said years from now the technology could be used, for example, by someone on the ground to help a flight attendant or passenger land an airplane if the pilot becomes incapacitated. Or a person with disabilities could communicate his or her wish, say, for food or water. The brain signals from one person to another would work even if they didn’t speak the same language.
Rao and Stocco next plan to conduct an experiment that would transmit more complex information from one brain to the other. If that works, they then will conduct the experiment on a larger pool of subjects.
What’s really happening when you have a drink of water.
I just swallowed water while watching this and could totally FEEL IT HAPPENING SO WEIRD
*Gartner Hype Cycle 2013
Of course, the curve looks slightly different for each thing, but this is an important graph for everyone who cares about the world to understand. It’s only after we realize that an innovation isn’t going to change the world that it starts changing the world.
Building Better Brain Implants: The Challenge of Longevity
Aug. 20, 2013 — On August 20, JoVE, the Journal of Visualized Experiments will publish a technique from the Capadona Lab at Case Western Reserve University to accommodate two challenges inherent in brain-implantation technology, gauging the property changes that occur during implantation and measuring on a micro-scale. These new techniques open the doors for solving a great challenge for bioengineers — crafting a device that can withstand the physiological conditions in the brain for the long-term.
"We created an instrument to measure the mechanical properties of micro-scale biomedical implants, after being explanted from living animals," explained the lab’s principal investigator, Dr. Jeffrey R. Capadona. By preserving the changing properties that occurred during implantation even after removal, the technique offers potential to create and test new materials for brain implant devices. It could result in producing longer lasting and better suited devices for the highly-tailored functions.
For implanted devices, withstanding the high-temperatures, moisture, and other in-vivo properties poses a challenge to longevity. Resulting changes in stiffness, etc, of an implanted material can trigger a greater inflammatory response. “Often, the body’s reaction to those implants causes the device to prematurely fail,” says Dr. Capadona, “In some cases, the patient requires regular brain surgery to replace or revise the implants.”
New implantation materials may help find solutions to restore motor function in individuals who have suffered from spinal cord injuries, stroke or multiple sclerosis. “Microelectrodes embedded chronically in the brain could hold promise for using neural activity to restore motor function in individuals who have, suffered from spinal cord injuries,” said Dr. Capadona.
Furthermore, Capadona and his colleagues’ method allows for measurement of mechanical properties using microsize scales. Previous methods typically require large or nano-sized samples of material, and data has to be scaled, which doesn’t always work.
When asked why Dr. Capadona and his colleagues published their methods with JoVE, he responded “We choose JoVE because of the novel format to show readers visually what we are doing. If a picture is worth [a] thousand words, a video is worth a million.”
Electromagnetic Sculptures Generated
When fractals and physics meets fine art, I get happy.
If this is your kind of thing, then you’ll enjoy this bacterial fractal art from Eshel Ben-Jacob, where microbial communication begets pure beauty.