Science is amazing, is it not? It can tell us the size of planets light years away. It can explain the eating habits of giant dinosaurs that have been extinct for millions of years. Science can even tell us all about particles that are far too small to see with the human eye.
But there are a lot of things — many every day things, in fact — that science cannot explain.
How do magnets work? Why does watching someone yawn make you have to yawn? Why do dogs poop the way they do? These are the questions that scientists can’t quite answer…yet.
UP FIRST: Why does lightning happen?
Why Does Lightning Happen?
Some 44,000 thunderstorms rage worldwide each day, delivering as many as 100 lightning bolts to the ground every second. That’s a lot of lightning. So much, in fact, that one would be forgiven for assuming that scientists understand why lightning happens — but they don’t.
For all we know, lightning might as well come from Zeus. Counting Ben Franklin’s kite-and-key experiment as the starting point, 250 years of scientific investigation have yet to get to grips with how lightning works.
Atmospheric scientists have a basic sketch of the process. Positive electric charges build up at the tops of thunderclouds and negative charges build up at the bottoms (except for perplexing patches of positive charges often detected in the center-bottom). Electrical attraction between these opposite charges, and between the negative charges at the bottom of the cloud and positive charges that accumulate on the ground below, eventually grow strong enough to overcome the air’s resistance to electrical flow.
Like a herd of elephants wading across a river, negative charges venture down from the bottom of the cloud into the sky below and move haltingly toward the ground, forming an invisible, conductive path called a “step leader.” The charges’ path eventually connects to similar “streamers” of positive charges surging up from the ground, completing an electrical circuit and enabling negative charges to pour from the cloud to the ground along the circuit they have formed. This sudden, enormous electric discharge is the flash of lightning.
But as for how all that happens — well, it just doesn’t make much physical sense. There are three big questions needing answers, said Joe Dwyer, a leading lightning physicist based at the Florida Institute of Technology. “First, how do you actually charge up a thundercloud?” Dwyer said. A mix of water and ice is needed to provide atoms that can acquire charge, and updrafts are required to move the charged particles around. The rest of the details are hazy.
The second point of confusion is called the “lightning initiation problem.” So the question is, “How do you get a spark going inside a thunderstorm? The electric fields never seem to be big enough inside the storm to generate a spark. So how does that spark get going? This is a very active area of research,” Dwyer said.
And once the spark gets going, the final question is how it keeps going. “After you get it started, how does lightning propagate for tens of miles through clouds?” Dwyer said. “That’s an amazing thing — how do you turn air from being an insulator into a conductor?”
UP NEXT: How do magnets work?
How Do Magnets Work?
Sure, they’re run-of-the-mill household items, but that doesn’t mean magnets are easy to understand. While physicists have some understanding of how magnets function, the phenomena that underlie magnetism continue to elude scientific explanation.
Large-scale magnetism, like the kind observed in bar magnets, results from magnetic fields that naturally radiate from the electrically charged particles that make up atoms, said Jearl Walker, a physics professor at Cleveland State University and coauthor of “Fundamentals of Physics” (Wiley, 2007).The most common magnetic fields come from negatively charged particles called electrons.
Normally, in any sample of matter, the magnetic fields of electrons point in different directions, canceling each other out. But when the fields all align in the same direction, like in magnetic metals, an object generates a net magnetic field, Walker told Live Science in 2010.
Every electron generates a magnetic field, but they only generate a net magnetic field when they all line up. Otherwise, the electrons in the human body would cause everyone to stick to the refrigerator whenever they walked by, Walker said.
Currently, physics has two explanations for why magnetic fields align in the same direction: a large-scale theory from classical physics, and a small-scale theory called quantum mechanics.
According to the classical theory, magnetic fields are clouds of energy around magnetic particles that pull in or push away other magnetic objects. But in the quantum mechanics view, electrons emit undetectable, virtual particles that tell other objects to move away or come closer, Walker said.
Although these two theories help scientists understand how magnets behave in almost every circumstance, two important aspects of magnetism remain unexplained: why magnets always have a north and south pole, and why particles emit magnetic fields in the first place.
“We just observe that when you make a charged particle move, it creates a magnetic field and two poles. We don’t really know why. It’s just a feature of the universe, and the mathematical explanations are just attempts of getting through the ‘homework assignment’ of nature and getting the answers,” Walker said.
UP NEXT: Why do dogs face north or south to poop?
Why Do Dogs Face North or South to Poop?
Did you know that dogs prefer to poop while aligned with the north-south axis of the Earth’s magnetic field? Because they totally do, but scientists can’t really explain why.
Research conducted in 2014 found that dogs preferred to poop when their bodies were aligned in a north-south direction, as determined by the geomagnetic field. (True north, which is determined by the position of the poles, is slightly different from magnetic north.)
And while dogs of both sexes faced north or south while defecating, only females preferred to urinate in a north or south direction — males didn’t show much preference while urinating.
This odd finding joins a long and growing list of research showing that animals — both wild and domesticated — can sense the Earth’s geomagnetic field and coordinate their behavior with it.
A 2008 analysis of Google Earth satellite images revealed that herds of cattle worldwide tend to stand in the north-south direction of Earth’s magnetic lines when grazing, regardless of wind direction or time of day. The same behavior was seen in two different species of deer.
Birds also use magnetic fields to migrate thousands of miles, some research suggests. A 2013 report found that pigeons are equipped with microscopic balls of iron in their inner ears, which may account for the animals’ sensitivity to the geomagnetic field.
Humans, too, might possess a similar ability — a protein in the human retina may help people sense magnetic fields, though the research into this and many other related geomagnetic phenomena is preliminary and therefore remains inconclusive.
But why do animals of all shapes and sizes seem to be ruled by Earth’s geomagnetic field? The answer remains elusive, the scientists admitted.
“It is still enigmatic why the dogs do align at all, whether they do it ‘consciously’ (i.e., whether the magnetic field is sensorial[ly] perceived) … or whether its reception is controlled on the vegetative level (they ‘feel better/more comfortable or worse/less comfortable’ in a certain direction),” the study authors wrote.
The researchers also found that when the Earth’s magnetic field was in a state of flux — it changes during solar flares, geomagnetic storms and other events — the dogs’ north-south orientation was less predictable. Only when the magnetic field was calm did researchers reliably observe the north-south orientation.
Further research is needed to determine how and why dogs and other animals sense and use the planet’s magnetic field every single day.
: What causes gravity?
What Causes Gravity?
You know gravity? That invisible force holding you (and every person and object around you) to the Earth? Well, you might learn all about gravity in a science classroom, but scientists still aren’t sure what causes it.
In the deepest depths of space, gravity tugs on matter to form galaxies, stars, black holes and the like. In spite of its infinite reach, however, gravity is the wimpiest of all forces in the universe.
This weakness also makes it the most mysterious, as scientists can’t measure it in the laboratory as easily as they can detect its effects on planets and stars. The repulsion between two positively charged protons, for example, is 10^36 times stronger than gravity’s pull between them—that’s 1 followed by 36 zeros less macho.
Physicists want to squeeze little old gravity into the standard model—the crown-jewel theory of modern physics that explains three other fundamental forces in physics—but none has succeeded. Like a runt at a pool party, gravity just doesn’t fit in when using Einstein’s theory of relativity, which explains gravity only on large scales
“Gravity is completely different from the other forces described by the standard model,” said Mark Jackson, a theoretical physicist at Fermilab in Illinois. “When you do some calculations about small gravitational interactions, you get stupid answers. The math simply doesn’t work.”
The numbers may not jibe, but physicists have a hunch about gravity’s unseen gremlins: Tiny, massless particles called gravitons that emanate gravitational fields.
Each hypothetical bit tugs on every piece of matter in the universe, as fast as the speed of light permits. Yet if they are so common in the universe, why haven’t physicists found them?
“We can detect massless particles such as photons just fine, but gravitons elude us because they interact so weakly with matter,” said Michael Turner, a cosmologist at the University of Chicago. “We simply don’t know how to detect one.”
Turner, however, isn’t despondent about humanity’s quest for gravitons. He thinks we’ll eventually ensnare a few of the pesky particles hiding in the shadows of more easily detected particles.
“What it really comes down to is technology,” Turner said.
UP NEXT: Why do cats purr?
Why Do Cats Purr?
From house cats to cheetahs, most felid species produce a “purr-like” vocalization, according to University of California, Davis, veterinary professor Leslie Lyons. Domestic cats purr in a range of situations — while they nurse their kittens, when they are pet by humans, and even when they’re stressed out. Yes, you read right: Cats purr both when they’re happy and when they’re miserable. That has made figuring out the function of purring an uphill struggle for scientists.
One possibility is that it promotes bone growth, Lyons explained in Scientific American. Purring contains sound frequencies within the 25- to 150-Hertz range, and sounds in this range have been shown to improve bone density and promote healing. Because cats conserve energy by sleeping for long periods of time, purring may be a low-energy mechanism to keep muscles and bones healthy without actually using them.
Of course, cats purr even when they aren’t injured. Many domestic cats purr to indicate hunger, for example. A recent study out of the U.K. shows that some cats have even developed a special purr to ask their owners for food. This “solicitous purr” incorporates cries with similar frequencies as those of human babies. These conniving kitties have tapped into their owners’ psyches — all for more kibble.
However, this study doesn’t explain why cats purr in all of the situations they do. And scientists aren’t likely to find out more answers until cats learn to speak human…
UP NEXT: How does the brain work?
How Does the Brain Work?
With billions of neurons, each with thousands of connections, the human brain is a complex, and yes congested, mental freeway. Neurologists and cognitive scientists nowadays are probing how the mind gives rise to thoughts, actions, emotions and ultimately consciousness, but they still don’t have all the answers.
The complex machine is difficult for even the brainiest of scientists to wrap their heads around. What makes the brain such a tough nut to crack?
According to Scott Huettel of the Center for Cognitive Neuroscience at Duke University, the standard answer to this question goes something like: “The human brain is the most complex object in the known universe … complexity makes simple models impractical and accurate models impossible to comprehend.”
While that stock answer is correct, Huettel said, it’s incomplete. The real snag in brain science is one of navel gazing. Huettel and other neuroscientists can’t step outside of their own brains (and experiences) when studying the brain itself.
“A more pernicious factor is that we all think we understand the brain—at least our own—through our experiences. But our own subjective experience is a very poor guide to how the brain works,” Huettel told Live Science in 2007.
Scientists have made some progress in taking an objective, direct “look” at the human brain.
In recent years, brain-imaging techniques, such as functional magnetic resonance imaging (fMRI) have allowed scientists to observe the brain in action and determine how groups of neurons function.
They have pinpointed hubs in the brain that are responsible for certain tasks, such as fleeing a dangerous situation, processing visual information, making those sweet dreams and storing long-term memories. But understanding the mechanics of how neuronal networks collaborate to allow such tasks has remained more elusive.
The prized puzzle in brain research is arguably the idea of consciousness. When you look at a painting, for instance, you are aware of it and your mind processes its colors and shapes. At the same time, the visual impression could stir up emotions and thoughts. This subjective awareness and perception is consciousness.
Many scientists consider consciousness the delineation between humans and other animals.
So rather than cognitive processes directly leading to behaviors (unbeknownst to us), we are aware of the thinking. We even know that we know!
If this mind bender is ever solved, an equally perplexing question would arise, according to neuroscientists: Why? Why does awareness exist at all?
UP NEXT: How do bicycles work?
How Do Bicycles Work?
The brain is a super complicated organ, so it kind of makes sense that scientists haven’t yet learned all its secrets. But surely those same scientists have figured out something as simple as a bicycle, right? Wrong: The brainiacs of the world still aren’t sure how bicycles work.
Bikes can stay upright all by themselves, as long as they’re moving forward; it’s because any time a moving bike starts to lean, its steering axis (the pole attached to the handlebars) turns the other way, tilting the bike upright again. This restorative effect was long believed to result from a law of physics called the conservation of angular momentum: When the bike wobbles, the axis perpendicular to its wheels’ spinning direction threatens to change, and the bike self-corrects in order to “conserve” the direction of that axis. In other words, the bike is a gyroscope. Additionally, the “trail effect” was thought to help keep bikes stable: Because the steering axis hits the ground slightly in front of the ground contact point of the front wheel, the wheel is forced to trail the steering of the handlebars.
But recently, a group of engineers led by Andy Ruina of Cornell University upturned this theory of bicycle locomotion. Their investigation, detailed in a 2011 article in the journal Science, showed that neither gyroscopic nor trail effects were necessary for a bike to work. To prove it, the engineers built a custom bicycle, which could take advantage of neither effect. The bike was designed so that each of its wheels rotated a second wheel above it in the opposite direction. That way, the spinning of the wheels canceled out and the bike’s total angular momentum was zero, erasing the influence of gyroscopic effects on the bike’s stability. The custom bike’s ground contact point was also positioned in front of its steering axis, destroying the trail effect. And yet, the bike worked.
The engineers know why: they added masses to the bike in choice places to enable gravity to cause the bike to self-steer. But the work showed there are many effects that go into the stability of bicycles — including gyroscopic and trail effects in the case of bikes that have them — that interact in extremely complex ways.
“The complex interactions have not been worked out. My suspicion is that we will never come to grips with them, but I don’t know that for sure,” Ruina told Live Science.
UP NEXT: Why are moths drawn to light?
Why Are Moths Drawn to Light?
“Look! That moth just flew straight into that light bulb and died!” said no one ever. We see it happen so often that it’s more likely to invoke yawns than discussion. But, surprisingly, the reason for these insects’ suicidal nosedives remains a total mystery. Science’s best guesses about why they do it aren’t even very good.
Some entomologists believe moths zoom toward artificial light sources because the lights throw off their internal navigation systems. In a behavior called transverse orientation, some insects navigate by flying at a constant angle relative to a distant light source, such as the moon. But around man-made lights, such as a campfire or your porch light, the angle to the light source changes as a moth flies by. Jerry Powell, an entomologist at the University of California, Berkeley said the thinking is that moths “become dazzled by the light and are somehow attracted.”
But this theory runs into two major stumbling blocks, Powell explained: First, campfires have been around for about 400,000 years. Wouldn’t natural selection have killed off moths whose instinct tells them to go kamikaze every time they feel blinded by the light? Secondly, moths may not even use transverse navigation; more than half of the species don’t even migrate.
Alternate theories are riddled with holes, too. For example, one holds that male moths are attracted to infrared light because it contains a few of the same light frequencies given off by female moths’ pheromones, or sex hormones, which glow very faintly. In short, male moths could be drawn to candles under the false belief that the lights are females sending out sex signals. However, Powell points out that moths are more attracted to ultraviolet light than infrared light, and UV doesn’t look a bit like glowing pheromones.
Moth deaths: not as yawn-inducing as you might think.
UP NEXT: Why are there lefties (and righties)?
Why Are There Lefties (& Righties)?
One-tenth of people have better motor dexterity using their left limbs than their right. No one knows why these lefties exist. And no one knows why righties exist either, for that matter. Why do people have just one hand with top-notch motor skills, instead of a double dose of dexterity?
One theory holds that handedness results from having more intricate wiring on the side of the brain involved in speech (which also requires fine motor skills). Because the speech center usually sits in the brain’s left hemisphere — the side wired to the right side of the body — the right hand ends up dominant in most people. As for why the speech center usually (but not always) ends up in the left side of the brain, that’s still an open question.
The theory about the speech center controlling handedness gets a big blow from the fact that not all right-handed people control speech in the left hemisphere, while only half of lefties do. So, what explains those lefties whose speech centers reside in the left sides of their brains? It’s all very perplexing.
Research published in 2013 suggests that genes that play a role in the orientation of internal organs may also affect whether someone is right- or left-handed.
The study, published today (Sept. 12) in the journal PLOS Genetics, suggest those genes may also play a role in the brain, thereby affecting people’s handedness.
Still, the findings can’t yet explain the mystery of why a minority of people are left-handed because each gene only plays a tiny role in people’s handedness.
UP NEXT: Is yawning contagious?
Are Yawns Contagious?
In 2012, Austrian researchers won an Ig Nobel Prize for their discovery that yawns are not contagious among red-footed tortoises.
We know so much about tortoises, but human yawning? Still an enigma. The sight of a person’s gaping jaws, squinting eyes and deep inhalation “hijacks your body and induces you to replicate the observed behavior,” writes the University of Maryland, Baltimore County, psychologist Robert Provine in his new book, “Curious Behavior” (Belknap Press, 2012). But why?
Preliminary brain-scan data indicate that regions of the brain associated with theory of mind (the ability to attribute mental states and feelings to oneself and others) and self-processing become active when people observe other people yawning. Many autistic and schizophrenic people do not exhibit this brain activity, and they do not “catch” yawns. These clues suggest contagious yawning reflects an ability to empathize and form normal emotional ties with others, Provine explained.
But why should our social connections with one another circulate through yawning, as opposed to hiccupping or passing gas? No one knows for sure, and that’s because no one knows quite why we yawn. Embryos do it to sculpt the hinge of their jaws. Fully formed people do it when we’re sleepy and bored. But how does yawning ameliorate these complaints?
UP NEXT: What causes static electricity?
What Causes Static Electricity?
Static shocks are as mysterious as they are unpleasant. What we know is this: They occur when an excess of either positive or negative charge builds up on the surface of your body, discharging when you touch something and leaving you neutralized. Alternatively, they can occur when static electricity builds up on something else — a doorknob, say — which you then touch. In that case, you are the excess charge’s exit route.
But why all the buildup? It’s unclear. The traditional explanation says that when two objects rub together, friction knocks the electrons off the atoms in one of the objects, and these then move onto the second, leaving the first object with an excess of positively charged atoms and giving the second an excess of negative electrons. Both objects (your hair and a wool hat, say) will then be statically charged. But why do electrons flow from one object to the other, instead of moving in both directions?
This has never been satisfactorily explained, and a study by Northwestern University researcher Bartosz Grzybowski found reason to doubt the whole story. As detailed last year in the journal Science, Grzybowski found that patches of both excess positive and excess negative charge exist on statically charged objects. He also found that entire molecules seemed to migrate between objects as they are rubbed together, not just electrons. What generates this mosaic of charges and migration of material has yet to be determined, but clearly, the explanation of static is changing.