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photo of the batteries for the cesium clocks in the family van by Tom Van BaakProject GREAT: General Relativity Einstein/Essen Anniversary Test is not your average home experiment but it is another great example of experiments people run at home.
By keeping the clocks at altitude for a weekend we were able to detect and measure the effects of relativistic time dilation compared to atomic clocks we left at home. The amazing thing is that the experiment worked! The predicted and measured effect was just over 20 nanoseconds.
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But the time dilation was somewhere in the 20 to 30 ns range. The number we expected was 23 ns so I’m very pleased with the result.
Related: Home Experiments: Quantum Erasing - Science Toys You Can Make With Your Kids - Home Experiment: Deriving the Gravitational Constant - Statistics for Experimenters
This image looks like Albert Einstein up close. If you back up maybe 3-5 meters it will look like Marylin Monroe. Image by Dr. Aude Oliva.Hybrid images paper by Aude Oliva, MIT; Antonio Torralba, MIT; and Philippe G. Schyns University of Glasgow.
Very cool stuff.
This is just a smaller image of the above (all I did was shrink the size). For me, this already looks like Marilyn Monroe, but also needs a shorter distance to see the image seem to change.
Related: Illusions, Optical and Other - How Our Brain Resolves Sight - Seeing Patterns Where None Exists - Magenta is a Color - posts on scientific explanations of what we experience - Computational Visual Cognition Laboratory at MIT
The situation of a bubble in water is comparable to a balloon. The balloon surface is elastic. The tension of it tries to minimize the surface: if you don’t tie a knot in the balloon after blowing it up, air escapes and the surface of the balloon is minimized to the initial unstretched situation.
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Bubbles do not turn into rings naturally. Something has to be done for that. However, they have long lives and often make it up to the surface. Hence they are stable structures.
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Dolphins create bubble rings by blowing air in a water vortex ring: by flipping a fin they create a vortex ring of water. The then blow air in the ring, which goes to the center of the vortex ring. In the water vortex ring the natural location of the air is in the center of the vortex. When air and water move in a circular path like they do in the vortex ring, air and water are separated due to the centripetal force. Since density of water is larger than air, water moves at the outside, while the air ends up in the middle.
Follow the link for much more on the physics of bubble rings.
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Image courtesy of SOHO, shows an image of the sun on July 19th 2000 and March 18th 2009.Related: Solar Eruption photo - Solar Storms - Biggest Black Hole’s Mass = 18 Billion Suns
Eels in crisis after 95% decline in last 25 years
It seems pretty obvious we have over-fished the oceans. Without effective regulation we will destroy the future of both the wildlife and our food source.
Related: Fishless Future - South Pacific to Stop Bottom-trawling - North American Fish Threatened - Chinook Salmon Vanish Without a Trace
As leaf-like larvae, they are swept by the Gulf Stream towards Europe, a journey that may take a year. When the larvae reach the continental shelf they change into “glass eels” and in the spring begin to move through estuaries and into freshwater.
The animals develop pigmentation, at which point they are known as elvers and are similar in shape to the adult eel. Elvers continue to move upstream and again change colour to become brown or yellow eels.
When the fish reach full maturity - some can live to 40 and grow to 1m long - they migrate back to the ocean. Females are reported to carry as many as 10m eggs. They return to the Sargasso Sea, spawn and die.
Antigenic shift is the process by which at least two different strains of a virus, (or different viruses), especially influenza, combine to form a new subtype having a mixture of the surface antigens of the two original strains.
Pigs can be infected with human, avian and swine influenza viruses. Because pigs are susceptible to all three they can be a breeding ground for antigenic shift (as in the recent case of H1N1 Flu - Swine Flu) allowing viruses to mix and create a new virus.
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Because the magnetic fields of the eddy currents oppose the magnetic field of the falling magnet; there is attraction between the two fields. Energy is converted into heat. This principle is used in damping the oscillation of the lever arm of mechanical balances.
Related: Home Experiments: Quantum Erasing - posts on physics - MIT Physics Lecture: Electromagnetism (Faraday’s Law & Lenz Law) - 10 Most Beautiful Physics Experiments
Deriving the Gravitational Constant by Joe Marshall
Cavendish used a pair of 350 pound lead balls to attract the ends of the balance from about 9 inches away. I put a couple of 8 pound jugs of water about an inch away. The next trick was to measure the rotation of the balance. Cavendish had a small telescope to read the Vernier scale on the balance. I used some modern technology. I borrowed a laser from Tom Knight (Thanks again!), and bounced it off a mirror that I mounted on the middle of the balance. This made a small red dot on the wall about 20 feet away. (I was hoping this would be enough to measure the displacement, but I was considering an interferometer if necessary.)
To my surprise, it all worked. After carefully putting the jugs of water in place, the dot on the wall started to visibly move. Within a few minutes, it had moved an inch or two. I carefully removed the jugs of water and sure enough, the dot on the wall drifted back to its starting position.
Very cool example of a home physics experiment.
Related: Home Experiments: Quantum Erasing - 10 Most Beautiful Physics Experiments - Science Toys You Can Make With Your Kids
By rusting, aluminum is forming a protective coating that’s chemically identical to sapphire—transparent, impervious to air and many chemicals, and able to protect the surface from further rusting: As soon as a microscopically thin layer has formed, the rusting stops. (“Anodized” aluminum has been treated with acid and electricity to force it to grow an extra-thick layer of rust, because the more you have on the surface, the stronger and more scratch-resistant it is.)
This invisible barrier forms so quickly that aluminum seems, even in molten form, to be an inert metal. But this illusion can be shattered with aluminum’s archenemy, mercury. Applied to aluminum’s surface, mercury will infiltrate the metal and disrupt its protective coating, allowing it to “rust” (in the more destructive sense) continuously by preventing a new layer of oxide from forming.
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Simple elixir called a ‘miracle liquid’
In Santa Monica, the once-skeptical Sheraton housekeeping staff has ditched skin-chapping bleach and pungent ammonia for spray bottles filled with electrolyzed water to clean toilets and sinks. “I didn’t believe in it at first because it didn’t have foam or any scent,” said housekeeper Flor Corona. “But I can tell you it works. My rooms are clean.”
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It turns out that zapping salt water with low-voltage electricity creates a couple of powerful yet nontoxic cleaning agents. Sodium ions are converted into sodium hydroxide, an alkaline liquid that cleans and degreases like detergent, but without the scrubbing bubbles. Chloride ions become hypochlorous acid, a potent disinfectant known as acid water.
“It’s 10 times more effective than bleach in killing bacteria,” said Yen-Con Hung, a professor of food science at the University of Georgia-Griffin, who has been researching electrolyzed water for more than a decade. “And it’s safe.”
There are drawbacks. Electrolyzed water loses its potency fairly quickly, so it can’t be stored long. Machines are pricey and geared mainly for industrial use. The process also needs to be monitored frequently for the right strength.
Very cool use of science: providing a green cleaning agent that is effective.
Related: Clean Clothes Without Soap - posts on chemical engineering - iRobot Gutter Cleaning Robot - Water From Air
Shedding light on why long strands tend to become knotted
Which, it turns out, it basically is. In October, two UCSD researchers published the first physical explanation of why knots seem to form magically, not just in strands of Christmas lights, but in pretty much anything stringy, from garden hoses to iPod earbud cords to DNA.
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“We’re not mathematicians,” Smith said. “We’re physicists. Physicists do experiments.”
UCSD researchers constructed a knot probability machine that involved placing a single length of string in a plastic box, sealing it, then rotating the box at a set speed for a brief period of time.
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The experiment involved placing a single length of floppy string into a plastic box, sealing it, then rotating the box at a set speed for a brief time. The researchers did this 3,415 times, sometimes changing variables such as box size and string length.
Open access research paper: Spontaneous knotting of an agitated string by Dorian M. Raymer and Douglas E. Smith.
Yet another interesting case of scientists explaining the world around us (and the value of open science).
Related: Toward a More Open Scientific Culture - Electron Filmed for the First Time - Saving Fermilab - Scientists and Engineers in Congress
A team of European scientists have learned why our hair turns gray as we age. Despite the notion that gray hair is a sign of wisdom, these researchers show that going gray is caused by a massive build up of hydrogen peroxide due to wear and tear of our hair follicles. The peroxide winds up blocking the normal synthesis of melanin, our hair’s natural pigment.
“Not only blondes change their hair color with hydrogen peroxide,” said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. “All of our hair cells make a tiny bit of hydrogen peroxide, but as we get older, this little bit becomes a lot. We bleach our hair pigment from within, and our hair turns gray and then white. This research, however, is an important first step to get at the root of the problem, so to speak.”
The researchers made this discovery by examining cell cultures of human hair follicles. They found that the build up of hydrogen peroxide was caused by a reduction of an enzyme that breaks up hydrogen peroxide into water and oxygen (catalase). They also discovered that hair follicles could not repair the damage caused by the hydrogen peroxide because of low levels of enzymes that normally serve this function (MSR A and B). Further complicating matters, the high levels of hydrogen peroxide and low levels of MSR A and B, disrupt the formation of an enzyme (tyrosinase) that leads to the production of melanin in hair follicles. Melanin is the pigment responsible for hair color, skin color, and eye color. The researchers speculate that a similar breakdown in the skin could be the root cause of vitiligo.
Weissmann added. “This study is a prime example of how basic research in biology can benefit us in ways never imagined.”
Related: The Chemistry of Hair Coloring - Students Create “Disappearing” Nail Polish - Common Ancestor 6-10,000 Years Ago For All Blue-eyed People - posts with scientific explanations for the world we live in
Electromagnetic spectrum chart from the Wikimedia CommonsYes, Virgina, there is a magenta by Chris Foresman
This is a great article that uses science to explain interesting details about our brains and how we perceive the external world.
Related: How Our Brain Resolves Sight - more posts using science to explain the world - Science Explains: Flame Color - Electromagnetic Spectrum - Illusions, Optical and Other
Scientists unravelling mysteries of Saskatchewan meteorite
Later, she studied the flashes and shadows from the various surveillance and amateur videos. She used the information to plot the fireball’s path as it fell to Earth and then tried to figure out its orbit. Milley’s tentative conclusion, which she discussed in Saskatoon Monday, was that it didn’t look like the space rock came from beyond the orbit of Mars.
“It looks like it’s a very kind of tight inner solar system orbit,” she said. “It’s not something that’s extended into the asteroid belt.” If she’s correct, it would be the first time researchers have found debris from a meteorite so close to Earth, Milley said.
In terms of the composition, Milley and her colleagues have determined it’s a relatively common type of meteorite with a high iron content. However, there is still much more to learn about it, they say. More than 100 fragments have already been recovered, but this spring, researchers will be resuming their search for more.
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Fitness Isn’t an Overnight Sensation
And genetic differences among individuals mean some people respond much better to exercise than others
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Now, said Mr. Antane, who runs with a group in Princeton on Thursday nights, “everything changed — my outlook on life, who I hung out with, how I felt about myself.”
Our bodies evolved under conditions with much more exercise than we currently get if we sit in an office all day. And we had less food. It is no surprise with more food and less exercise that we gain weight. And given that the benefit of fat was to help us survive when we had little food out bodies don’t change overnight. If they did then our ancestors would have had much more difficulty surviving - the whole point was to provide a resource to tap in bad times. If that resource dissipated quickly it would not have helped much.
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Genetic Algorithms: Cool Name and Damn Simple is a very nice explanation with python code of genetic algorithms.
We’ll also randomly select some lesser performing individuals to be parents, because we want to promote genetic diversity. Abandoning the metaphor, one of the dangers of optimization algorithms is getting stuck at a local maximum and consequently being unable to find the real maximum. By including some individuals who are not performing as well, we decrease our likelihood of getting stuck.
Related: DNA Seen Through the Eyes of a Coder - Evolutionary Design - Algorithmic Self-Assembly - The Chip That Designs Itself
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