Galileo’s experiment on falling objects

In the late 1500’s, everyone knew that heavy objects fall faster than lighter ones. After all, Aristotle had said so. That an ancient Greek scholar still held such sway was a sign of how far science had declined during the dark ages.

Galileo Galilei, who held a chair in mathematics at the University of Pisa, was impudent enough to question the common knowledge. The story has become part of the folklore of science: he is reputed to have dropped two different weights from the town’s Leaning Tower showing that they landed at the same time. His challenges to Aristotle may have cost Galileo his job, but he had demonstrated the importance of taking nature, not human authority, as the final arbiter in matters of science.
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Young’s double-slit experiment applied to the interference of single electrons

Though it is not simply made of particles, neither can it be described purely as a wave. In the first five years of the 20th century, Max Planck and then Albert Einstein showed, respectively, that light is emitted and absorbed in packets — called photons. But other experiments continued to verify that light is also wavelike.

It took quantum theory, developed over the next few decades, to reconcile how both ideas could be true: photons and other subatomic particles — electrons, protons, and so forth — exhibit two complementary qualities; they are, as one physicist put it, ”wavicles.”

Assuming the earth is spherical, its circumference spans 360 degrees. So if the two cities are seven degrees apart, that would constitute seven-360ths of the full circle — about one-fiftieth. Estimating from travel time that the towns were 5,000 ‘’stadia” apart, Eratosthenes concluded that the earth must be 50 times that size — 250,000 stadia in girth.

Dolphins do sleep, but not quite in the same way that people do. They sleep with one half of the brain at a time and with one eye closed. Dolphins rest this way on and off throughout the day, switching which side of the brain they shut down. During these periods, everything inside the dolphin slows down, and the mammal moves very little.

It turns out that about 8 percent of the human genome is made up of viruses that once attacked our ancestors. The viruses lost. What remains are the molecular equivalents of mounted trophies, insects preserved in genomic amber, DNA fossils.

The thousands of human endogenous retroviruses, or HERVs, sketch a history of rough times during the 550 million years of vertebrate evolution. The best-preserved one, HERV-K113, probably arrived less than 200,000 years ago, long after human beings and chimpanzees diverged from a common ancestor.

But these retroviruses are more than just curiosities. They are some of the most important enemies we ever had. They helped mold the immune system that is one of the evolutionary marvels of life on Earth.

What is your cat trying to tell you? A blinking cat is a happy cat. Blinking in cats is a signal that they recognize the presence of another cat in their vicinity but they are not going to fight it. A blink sends the message: “You are my friend. I am not angry. I am not threatened, or threatening.”

This kind of message is very important in the wild, where cats battle for territory. Run across a neighboring cat and you’d better make your intentions clear, or you may find yourself in a fight. The blink serves to say: all’s well here.
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So, why do cats blink at us, when we aren’t cats and don’t understand such feline messages? Well — do you ever speak to your cat?

Hundreds of insect species spend much of their time underwater, where food may be more plentiful. MIT mathematicians have now figured out exactly how those insects breathe underwater.

By virtue of their rough, water-repellent coat, when submerged these insects trap a thin layer of air on their bodies. These bubbles not only serve as a finite oxygen store, but also allow the insects to absorb oxygen from the surrounding water.

“Some insects have adapted to life underwater by using this bubble as an external lung,” said John Bush, associate professor of applied mathematics, a co-author of the recent study.

Thanks to those air bubbles, insects can stay below the surface indefinitely and dive as deep as about 30 meters, according to the study co-authored by Bush and Morris Flynn, former applied mathematics instructor. Some species, such as Neoplea striola, which are native to New England, hibernate underwater all winter long.

A hiccup is an unintentional contraction of your diaphragm - the muscle that separates your chest from your abdomen and plays an important role in breathing. This contraction makes your vocal cords close very briefly, which produces the sound of a hiccup.

Although there’s often no clear cause for a bout of hiccups, some factors that can trigger acute or transient hiccups include: Eating spicy food. Spicy food may cause irritation to the nerves that control normal contractions of your diaphragm.

Rajat Mittal, a professor of mechanical and aerospace engineering at the George Washington University, was studying dolphins for the U.S. Navy five years ago. “We were asked to understand how fish swim so efficiently,” Mittal says, “and it seemed like a natural extension to apply this to human swimming.”
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They decided to “essentially compare these swimmers to the dolphin, assuming that the dolphin is the ultimate swimmer,” Mittal says. “And the thing that we found is that Michael [Phelps] is able to use his body in a way that is very, very different from the other athletes, and also seems to be much closer to dolphins than we have seen for any other swimmer.”

The dolphin kick first hit Olympic swimming big-time 20 years ago, after Harvard backstroker David Berkoff figured out something fundamental. “It seemed pretty obvious to me that kicking underwater seemed to be a lot faster than swimming on the surface,” Berkoff says.

That’s because there’s turbulence and air on the surface of the water, and they create resistance. The “Berkoff Blastoff,” as it was called, was used at the start and after turns, with long stretches of that underwater undulating kick.

The debate about what counts as a living thing is fuelled today by the discovery of the first virus that is able to fall “ill” by being infected with another virus.
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the discovery of a giant virus that itself falls ill through infection by another virus seems to suggest they too are alive, highlighting how there is no watertight definition of what exactly scientists mean when they refer to something as “living”.

“There’s no doubt, this is a living organism,” the journal Nature is told by Prof Jean-Michel Claverie, director of the Mediterranean Institute of Microbiology in Marseilles, part of France’s basic-research agency CNRS. “The fact that it can get sick makes it more alive.”

scientists found that histatin, a small protein in saliva previously only believed to kill bacteria was responsible for the healing.

To come to this conclusion, the researchers used epithelial cells that line the inner cheek, and cultured in dishes until the surfaces were completely covered with cells. Then they made an artificial wound in the cell layer in each dish, by scratching a small piece of the cells away.

In one dish, cells were bathed in an isotonic fluid without any additions. In the other dish, cells were bathed in human saliva. After 16 hours the scientists noticed that the saliva treated “wound” was almost completely closed. In the dish with the untreated “wound,” a substantial part of the “wound” was still open. This proved that human saliva contains a factor which accelerates wound closure of oral cells.

Because saliva is a complex liquid with many components, the next step was to identify which component was responsible for wound healing. Using various techniques the researchers split the saliva into its individual components, tested each in their wound model, and finally determined that histatin was responsible.

A bee can generally only sting you once, while hornets and wasps can sting multiple times.
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Bees are fuzzy pollen collectors that almost always die shortly after stinging people (because the stinger becomes embedded in the skin, which prevents multiple stings). Bees don’t die each time they sting, though; the primary purpose of the stinger is to sting other bees, which doesn’t result in the loss of the stinger.

Wasps are members of the family Vespidae, which includes yellow jackets and hornets. Wasps generally have two pairs of wings and are definitely not fuzzy. Only the females have stingers, but they can sting people repeatedly.

Hornets are a small subset of wasps not native to North America (the yellow jacket is not truly a hornet). Somewhat fatter around the middle than your average wasp, the European hornet is now widespread on the East Coast of the U.S. Like other wasps, hornets can sting over and over again and can be extremely aggressive.

There was no fire, but the ground was hot enough in a Colorado Springs park to burn through an eight year old boy’s shoes and cause at least second degree burns on his feet.
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After the boy was treated and sent to the hospital firefighters took surface readings that showed hard to believe temperatures. According to Chief Matthews, “The highest temperature we got at the surface of the soil with the sun shining on it was 800 degrees, which is pretty darn significant. Radiant heat from the sun will get it up around 150, 160 degrees, but not to that level.”

Firefighters have taped off the area and are monitoring it until they can figure out what’s causing the ground to get so hot. Tests by hazmat team members show there are no dangerous gases. Crews have cut a fire-line around the area to prevent the heat from potentially starting a wildfire.

Early assessments show the problem area is coal dust. Neighbors say the area has appeared blackened as long as they can remember. What has to be determined is if it was dumped here years ago or if there’s something happening underground. Crews from the state geological are on the way to figure out an explanation.

What they found has a relatively simple solution according to Kurt Schroeder with Colorado Springs Parks, “What the state representatives indicated to us is that the coal spoil that’s been on top of the ground for years and years reacts with the sun, heat of the sun and it spontaneously combusts.”

Because it’s coal refuse likely dumped at this spot years ago, the recommendation from geologists is capping it. Crews will dump two feet of fill over the spot to keep the sun causing the coal remnants from igniting again.

discovered surprising magnetic properties in the new superconductors that suggest they may have very powerful applications — from improved MRI machines and research magnets, to a new generation of superconducting electric motors, generators and power transmission lines. The research also adds to the long list of mysteries surrounding superconductivity, providing evidence that the new materials, which scientists are calling “doped rare earth iron oxyarsenides,” develop superconductivity in quite a new way
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Early this year, Japanese scientists who had been developing iron-based superconducting compounds for several years, finally tweaked the recipe just right with a pinch of arsenic. The result: a superconductor, also featuring oxygen and the rare earth element lanthanum, performing at a promising -413 degrees F (26 K). The presence of iron in the material was another scientific stunner: Because it’s ferromagnetic, iron stays magnetized after exposure to a magnetic field, and any current generates such a field. As a rule, magnetism’s effect on superconductivity is not to enhance it, but to kill it.

The new superconductors seem like they will be able to make improved MRI machines and research magnets, a new generation of superconducting electric motors, generators and power transmission lines. Tesla is a unit of magnetic field strength; the Earth’s magnetic field is one twenty thousandth of a tesla.

Everything that we measure is within the Universe, and we see no edge or boundary or center of expansion. Thus the Universe is not expanding into anything that we can see, and this is not a profitable thing to think about. Just as Dali’s Corpus Hypercubicus is just a 2-D picture of a 3-D object that represents the surface of a 4-D cube, remember that the balloon analogy is just a 2-D picture of a 3-D situation that is supposed to help you think about a curved 3-D space, but it does not mean that there is really a 4-D space that the Universe is expanding into.

It is one the biggest mysteries in physics - where did all the antimatter go? Now a team of physicists claims to have found the first ever hint of an answer in experimental data. The findings could signal a major crack in the standard model, the theoretical edifice that describes nature’s fundamental particles and forces.

In its early days, the cosmos was a cauldron of radiation and equal amounts of matter and antimatter. As it cooled, all the antimatter annihilated in collisions with matter - but for some reason the proportions ended up lopsided, leaving some of the matter intact.

Physicists think the explanation for this lies with the weak nuclear force, which differs from the other fundamental forces in that it does not act equally on matter and antimatter. This asymmetry, called CP violation, could have allowed the matter to survive to form the elements, stars and galaxies we see today.
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“It is tantalisingly interesting at the moment,” says Val Gibson, an expert on B meson physics at the University of Cambridge. “If it is true, it is earth-shattering.” Jacobo Konigsberg, who leads the CDF collaboration, says that Tevatron researchers are “cautiously excited” about the analysis. He points out that more data needs to be analysed to rule out a statistical fluke, which has happened several times before in particle physics.

What many people do not realize is that iron is a pyrophoric material; in the presence of oxygen, iron catches on fire automatically! It just starts burning. “But how can this be?” you may ask. “I can hold a chunk of iron in my hand and it does not burn me”.

The answer lays in the fact that the portion of the iron object in contact with the air and your skin is not pure iron. Rather it has developed a thin coating of iron oxide, or rust, immediately upon contact with the oxygen in the air. This serves to seal off the iron inside from exposure to the air and reduces the rate of further rusting.

Iron, whether man-made objects or naturally occurring in rocks, will rust upon exposure to oxygen in the air. The act of rusting is actually an exothermic reaction called “oxidation”, which is a fancy way of saying when iron touches the oxygen in the air a reaction occurs; the iron rusts (turns into iron oxide) and gives off heat. In other words, it burns. The simplified chemical reaction can be expressed as:

Fe2 + O2 = Fe2O3 + heat

Or in English:

Iron + Oxygen = Rust + Heat