What Would Happen If You Put Your Hand in the LHC Beam?

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What Would Happen If You Put Your Hand in the LHC Beam?

By: Natalie Wolchover, Life’s Little Mysteries Staff Writer

A crown achievement of science, no doubt, but the Large Hadron Collider is a little tough for us regular folks to wrap our heads around.

At full throttle, a beam of protons will whiz through the LHC’s tunnel at 99.9999991 percent the speed of light, for example — but what do all those 9’s actually mean? Moreover, that beam will smash into another beam traveling equally fast in the opposite direction, stopping protons dead in their tracks and causing their immense kinetic energy to convert into never-before-seen, incredibly massive particles via Einstein’s famous equation E=mc^2 — but how fast are those protons really moving when they smack together?

One way to make an invisible beam markedly more tangible is to find out what it might feel like were it to run into you. What would happen if you stuck your hand in the beam? Sixty Symbols, video journalists with the University of Nottingham, have gone to Geneva, Switzerland, and asked LHC scientists this very question.




According to David Barney, a physicist who works on the CMS experiment at the LHC, the beam focuses the energy of an aircraft carrier in motion down to a width of less than a millimeter. “You really wouldn’t want to put your hand in there. It’d make a hole straight through it,” he said.

Steven Goldfarb of the ATLAS experiment preferred a ground-based vehicle analogy: “There’s a train going through there at full speed basically. That’s the amount of energy that there is,” he said, adding that the beam has instantly bored holes through pieces of metal set in its path.

But a hole-in-the-hand isn’t the worst of it. “The proton beam is accompanied by what’s called a ‘halo’ of electrons and some muons as well … some of which can be meters away,” Barney said. “So there’s an intense beam of particles coming down [the tunnel] that accompanies this extremely intense part. So your whole body would be irradiated. You’d die pretty quickly.”

The fatal event would be more of a fizzle than a bang. “I don’t think it would explode your hand,” Barney said. “I don’t see any mechanism for that.”



The Surprising Origins of 9 Common Superstitions

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The Surprising Origins of 9 Common Superstitions

By: Natalie Wolchover, Life’s Little Mysteries Staff Writer

Some superstitions are so ingrained in modern English-speaking societies that everyone, from lay people to scientists, succumb to them (or, at least, feel slightly uneasy about not doing so). But why don’t we walk under ladders? Why, after voicing optimism, do we knock on wood? Why do nonreligious people “God bless” a sneeze? And why do we avoid at all costs opening umbrellas indoors?

Find out the origins of all these familiar customs, and more

“It’s bad luck to open an umbrella indoors.”

Though some historians tentatively trace this belief back to ancient Egyptian times, the superstitions that surrounded pharaohs’ sunshades were actually quite different — and probably unrelated — to the modern-day one about raingear. Most historians think the warning against unfurling umbrellas inside originated much more recently, in Victorian England.

In “Extraordinary Origins of Everyday Things” (Harper, 1989), the scientist and author Charles Panati wrote: “In eighteenth-century London, when metal-spoked waterproof umbrellas began to become a common rainy-day sight, their stiff, clumsy spring mechanism made them veritable hazards to open indoors. A rigidly spoked umbrella, opening suddenly in a small room, could seriously injure an adult or a child, or shatter a frangible object. Even a minor accident could provoke unpleasant words or a minor quarrel, themselves strokes of bad luck in a family or among friends. Thus, the superstition arose as a deterrent to opening an umbrella indoors.”

“It’s bad luck to walk under a leaning ladder.”

This superstition really does originate 5,000 years ago in ancient Egypt. A ladder leaning against a wall forms a triangle, and Egyptians regarded this shape as sacred (as exhibited, for example, by their pyramids). To them, triangles represented the trinity of the gods, and to pass through a triangle was to desecrate them.

This belief wended its way up through the ages. “Centuries later, followers of Jesus Christ usurped the superstition, interpreting it in light of Christ’s death,” Panati explained. “Because a ladder had rested against the crucifix, it became a symbol of wickedness, betrayal, and death. Walking under a ladder courted misfortune.”

In England in the 1600s, criminals were forced to walk under a ladder on their way to the gallows.

“A broken mirror gives you seven years of bad luck.”

In ancient Greece, it was common for people to consult “mirror seers,” who told their fortunes by analyzing their reflections. As the historian Milton Goldsmith explained in his book “Signs, Omens and Superstitions” (1918), “divination was performed by means of water and a looking glass. This was called catoptromancy. The mirror was dipped into the water and a sick person was asked to look into the glass. If his image appeared distorted, he was likely to die; if clear, he would live.”

In the first century A.D., the Romans added a caveat to the superstition. At that time, it was believed that peoples’ health changed in seven year cycles . A distorted image resulting from a broken mirror therefore meant seven years of ill-health and misfortune, rather than outright death.

“When you spill salt, toss some over your left shoulder to avoid bad luck.”

Spilling salt has been considered unlucky for thousands of years. Around 3,500 B.C., the ancient Sumerians first took to nullifying the bad luck of spilled salt by throwing a pinch of it over their left shoulders. This ritual spread to the Egyptians, the Assyrians and later, the Greeks.

The superstition ultimately reflects how much people prized (and still prize) salt as a seasoning for food. The etymology of the word “salary” shows how highly we value it. According to Panati: “The Roman writer Petronius, in the Satyricon, originated ‘not worth his salt’ as opprobrium for Roman soldiers, who were given special allowances for salt rations, called salarium — ‘salt money’ — the origin of our word ‘salary.'”

“Knock on wood to prevent disappointment.”

Though historians say this may be one of the most prevalent superstitious customs in the United States, its origin is very much in doubt. “Some attribute it to the ancient religious rite of touching a crucifix when taking an oath,” Goldsmith wrote. Alternatively, “among the ignorant peasants of Europe it may have had its beginning in the habit of knocking loudly to keep out evil spirits.”

“Always ‘God bless’ a sneeze.”

In most English-speaking countries, it is polite to respond to another person’s sneeze by saying “God bless you.” Though incantations of good luck have accompanied sneezes across disparate cultures for thousands of years (all largely tied to the belief that sneezes expelled evil spirits), our particular custom began in the sixth century A.D. by explicit order of Pope Gregory the Great.

A terrible pestilence was spreading through Italy at the time. The first symptom was severe, chronic sneezing, and this was often quickly followed by death. [Is It Safe to Hold In a Sneeze? ]

Pope Gregory urged the healthy to pray for the sick, and ordered that light-hearted responses to sneezes such as “May you enjoy good health” be replaced by the more urgent “God bless you!” If a person sneezed when alone, the Pope recommended that they say a prayer for themselves in the form of “God help me!”

“Hang a horseshoe on your door open-end-up for good luck.”

The horseshoe is considered to be a good luck charm in a wide range of cultures. Belief in its magical powers traces back to the Greeks, who thought the element iron had the ability ward off evil. Not only were horseshoes wrought of iron, they also took the shape of the crescent moon — in fourth century Greecefor the Greeks, a symbol of fertility and good fortune.

The belief in the talismanic powers of horseshoes passed from the Greeks to the Romans, and from them to the Christians. In the British Isles in the Middle Ages, when fear of witchcraft was rampant, people attached horseshoes open-end-up to the sides of their houses and doors. People thought witches feared horses, and would shy away from any reminders of them.

“A black cat crossing your path is lucky/unlucky.”

Many cultures agree that black cats are powerful omens — but do they signify good or evil?

The ancient Egyptians revered all cats, black and otherwise, and it was there that the belief began that a black cat crossing your path brings good luck. Their positive reputation is recorded again much later, in the early seventeenth century in England: King Charles I kept (and treasured) a black cat as a pet. Upon its death, he is said to have lamented that his luck was gone. The supposed truth of the superstition was reinforced when he was arrested the very next day and charged with high treason.

During the Middle Ages, people in many other parts of Europe held quite the opposite belief. They thought black cats were the “familiars,” or companions, of witches, or even witches themselves in disguise, and that a black cat crossing your path was an indication of bad luck — a sign that the devil was watching you. This seems to have been the dominant belief held by the Pilgrims when they came to America, perhaps explaining the strong association between black cats and witchcraft that exists in the country to this day.

The 9 Biggest Unsolved Mysteries in Physics

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The 9 Biggest Unsolved Mysteries in Physics

By: Natalie Wolchover, Life’s Little Mysteries Staff Writer
Pandora’s box

In 1900, the British physicist Lord Kelvin is said to have pronounced: “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” Within three decades, quantum mechanics and Einstein’s theory of relativity had revolutionized the field. Today, no physicist would dare assert that our physical knowledge of the universe is near completion. To the contrary, each new discovery seems to unlock a Pandora’s box of even bigger, even deeper physics questions. These are our picks for the most profound open questions of all.

What is dark energy?

No matter how astrophysicists crunch the numbers, the universe simply doesn’t add up. Even though gravity is pulling inward on space-time — the “fabric” of the cosmos — it keeps expanding outward faster and faster. To account for this, astrophysicists have proposed an invisible agent that counteracts gravity by pushing space-time apart. They call it dark energy. In the most widely accepted model of dark energy, it is a “cosmological constant”: an inherent property of space itself, which has “negative pressure” driving space apart. As space expands, more space is created, and with it, more dark energy. Based on the observed rate of expansion, scientists know that the sum of all the dark energy must make up more than 70 percent of the total contents of the universe. But no one knows how to look for it.

What is dark matter?

Evidently, about 84 percent of the matter in the universe does not absorb or emit light. “Dark matter,” as it is called, cannot be seen directly, and it hasn’t yet been detected by indirect means, either. Instead, dark matter’s existence and properties are inferred from its gravitational effects on visible matter, radiation and the structure of the universe. This shadowy substance is thought to pervade the outskirts of galaxies, and may be composed of “weakly interacting massive particles,” or WIMPs. Worldwide, there are several detectors on the lookout for WIMPs, but so far, not one has been found. [If Not Dark Matter, then What?]

Why is there an arrow of time?

Time moves forward because a property of the universe called “entropy,” roughly defined as the level of disorder, only increases, and so there is no way to reverse a rise in entropy after it has occurred. The fact that entropy increases is a matter of logic: There are more disordered arrangements of particles than there are ordered arrangements, and so as things change, they tend to fall into disarray. But the underlying question here is, why was entropy so low in the past? Put differently, why was the universe so ordered at its beginning, when a huge amount of energy was crammed together in a small amount of space? [What’s the Total Energy in the Universe?]

Are there parallel universes?

Astrophysical data suggests space-time might be “flat,” rather than curved, and thus that it goes on forever. If so, then the region we can see (which we think of as “the universe”) is just one patch in an infinitely large “quilted multiverse.” At the same time, the laws of quantum mechanics dictate that there are only a finite number of possible particle configurations within each cosmic patch (10^10^122 distinct possibilities). So, with an infinite number of cosmic patches, the particle arrangements within them are forced to repeat — infinitely many times over.  This means there are infinitely many parallel universes: cosmic patches exactly the same as ours (containing someone exactly like you), as well as patches that differ by just one particle’s position, patches that differ by two particles’ positions, and so on down to patches that are totally different from ours.

Is there something wrong with that logic, or is its bizarre outcome true? And if it is true, how might we ever detect the presence of parallel universes?

Why is there more matter than antimatter?

The question of why there is so much more matter than its oppositely-charged and oppositely-spinning twin, antimatter, is actually a question of why anything exists at all. One assumes the universe would treat matter and antimatter symmetrically, and thus that, at the moment of the Big Bang, equal amounts of matter and antimatter should have been produced. But if that had happened, there would have been a total annihilation of both: Protons would have canceled with antiprotons, electrons with anti-electrons (positrons), neutrons with antineutrons, and so on, leaving behind a dull sea of photons in a matterless expanse. For some reason, there was excess matter that didn’t get annihilated, and here we are. For this, there is no accepted explanation.

What is the fate of the universe?

The fate of the universe strongly depends on a factor of unknown value: Ω, a measure of the density of matter and energy in the universe. If Ω is greater than 1, then space-time would be “closed” like the surface of an enormous sphere. If there is no dark energy, such a universe would eventually stop expanding and would instead start contracting, eventually collapsing in on itself in an event dubbed the “Big Crunch.” If the universe is closed but thereis dark energy, the spherical universe would expand forever.

Alternatively, if Ω is less than 1, then the geometry of space would be “open” like the surface of a saddle. In this case, its ultimate fate is the “Big Freeze” followed by the “Big Rip”: first, the universe’s outward acceleration would tear galaxies and stars apart, leaving all matter frigid and alone. Next, the acceleration would grow so strong that it would overwhelm the effects of the forces that hold atoms together, and everything would be wrenched apart.

If Ω = 1, the universe would be flat, extending like an infinite plane in all directions. If there is no dark energy, such a planar universe would expand forever but at a continually decelerating rate, approaching a standstill. If there is dark energy, the flat universe ultimately would experience runaway expansion leading to the Big Rip.

Que sera, sera.

How do measurements collapse quantum wavefunctions?

In the strange realm of electrons, photons and the other fundamental particles, quantum mechanics is law. Particles don’t behave like tiny balls, but rather like waves that are spread over a large area. Each particle is described by a “wavefunction,” or probability distribution, which tells what its location, velocity, and other properties are more likely to be, but not what those properties are. The particle actually has a range of values for all the properties, until you experimentally measure one of them — its location, for example — at which point the particle’s wavefunction “collapses” and it adopts just one location. [Newborn Babies Understand Quantum Mechanics]

But how and why does measuring a particle make its wavefunction collapse, producing the concrete reality that we perceive to exist? The issue, known as the measurement problem, may seem esoteric, but our understanding of what reality is, or if it exists at all, hinges upon the answer.

Is string theory correct?

When physicists assume all the elementary particles are actually one-dimensional loops, or “strings,” each of which vibrates at a different frequency, physics gets much easier. String theory allows physicists to reconcile the laws governing particles, called quantum mechanics, with the laws governing space-time, called general relativity, and to unify the four fundamental forces of nature into a single framework. But the problem is, string theory can only work in a universe with 10 or 11 dimensions: three large spatial ones, six or seven compacted spatial ones, and a time dimension. The compacted spatial dimensions — as well as the vibrating strings themselves — are about a billionth of a trillionth of the size of an atomic nucleus. There’s no conceivable way to detect anything that small, and so there’s no known way to experimentally validate or invalidate string theory.

Is there order in chaos?

Physicists can’t exactly solve the set of equations that describes the behavior of fluids, from water to air to all other liquids and gases. In fact, it isn’t known whether a general solution of the so-called Navier-Stokes equations even exists, or, if there is a solution, whether it describes fluids everywhere, or contains inherently unknowable points called singularities. As a consequence, the nature of chaos is not well understood. Physicists and mathematicians wonder, is the weather merely difficult to predict, or inherently unpredictable? Does turbulence transcend mathematical description, or does it all make sense when you tackle it with the right math?