Antiperspirants work by forming a gel with the moisture in your armpits that blocks sweat glands from releasing more sweat. 

The active ingredients are usually aluminum salts.

There's something that seems icky or potentially unhealthy about blocking sweat, like magic, and that might be why some people have wondered whether they could cause cancer. 

But these worries are unfounded.

Researchers at the National Cancer Institute wrote that they "are not aware of any conclusive evidence linking the use of underarm antiperspirants or deodorants and the subsequent development of breast cancer."

They also said that the US Food and Drug Administration doesn't have any evidence supporting this fear, either.

Early research on aluminum exposure in rabbits found that it might be connected to Alzheimer's disease, but studies since then have not found this connection in animals or in humans.

We probably get more aluminum from food than antiperspirants, anyways. 

You might worry that blocking sweat from being released could be a problem, too, since sweat can flush toxins from the body. But Dr. Hooman Khorasani from the Icahn School of Medicine at Mount Sinai told The New York Times that other sweat glands throughout the body can pick up the slack. 

"There is not a significant buildup of biological waste with the use of antiperspirants," he said. You don't sweat only from your armpits, after all.

So if you want to keep your underarms dry, swipe on some antiperspirant. It shouldn't hurt.

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We've all been there.

You're in a liquor or grocery store, trying to pick out wine with a group of friends, when, inevitably, some unexpected member offers up their expert opinion. 

Truth be told, there's a whole lot of science behind wine: genetics, chemistry, microbiology, and even psychology all play a role in everything from how it's produced to which ones we buy and when.

To get a better sense of what goes into making that glass of red or white, we chatted with James Harbertson, a Washington State University professor of enology (that's the study of wine).  

NEXT: The definitive, scientific answers to 20 health questions everyone has

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Is cheap wine bad for you?

No way. Last year, rumors of a lawsuit that claimed that cheap wines had high levels of arsenic in it began circulating. One small detail the rumors left out: the lawsuit compared the levels of arsenic in wine to that of drinking water. To have any kind of negative experience as a result of this, you'd most likely have to drink about 2 liters of wine (a little more than 13 servings worth).

That's an awful lot of wine.

What's the difference between a wine that costs $50 and a wine that costs $500?

The short answer? Not a lot — so long as you're just drinking it.

The price comes from a number of different factors — the maker, the type of grape, how long it's aged, etc. But if you're just looking for a solid bottle of wine, an inexpensive bottle could taste just as good if not better than a thousand-dollar bottle.

If anything, there's a bigger psychological component at play: A study that conducted blind taste test in which people were given samples of wine found that they did not get any more enjoyment from a more expensive wine compared to a less expensive version. In another study, researchers found that untrained wine tasters actually liked the more expensive wines less than  the cheaper ones.  

If you're collecting, on the other hand, of course the price tag will make a difference.

"In the end, it's just wine," said Harbertson.

What are tannins and what are they doing in my wine?

You know that dry feeling you get in your mouth after a sip of red wine? You can thank tannins, naturally occurring chemicals that are found in wine and other beverages like black tea.

Tannins give wine its weight (what makes it more milky than watery), so they're integral to all red wines, Harbertson said. They bind to proteins like the ones in saliva, which is what makes your mouth dry out. It's not as simple an experience as tasting something that's bitter, he said. The interaction of red wine in your mouth ends up feeling more like a texture than just a taste, something known as a "mouthfeel."

Here's a tip: Salt your vegetables.

This simple trick to make veggies taste better isn't exactly groundbreaking, but the science behind why it works is interesting.

Salting makes them taste delicious by a little process called osmosis, which you may remember from science class. That's when a solvent, like water, moves through a membrane, like a vegetable cell wall, so that the solvent concentration is equal inside and out of the cell.

America's Test Kitchen chef and food science expert Dan Souza told Tech Insider how it works when you salt veggies.

"You've got all this water inside the plant cell. So by the power of osmosis, the water wants to come out and dilute that salt because you don't have equilibrium," he said.

When the water comes out of the vegetables and the salt goes in, Souza said, three things happen.

"Salt will diffuse into the plant material, so it's going to season it and it's going to taste more salty, which is usually a good thing," he said. "You're also getting rid of water so in a way you're concentrating flavor. And finally, we find that salt has the ability to mask bitterness."

This last effect is particularly useful for a bitter vegetable like eggplant, which also happens to be super watery. Souza said that if you're frying eggplant, salting it before can really help with the bitterness.

And if you are making an eggplant dish that you don't want to get too soggy — like rollatini, for example — Souza says to cut it very thin, salt it, and then microwave it on paper towels to remove the excess water.

"You can achieve a lot of things with salt," he said.

And if you want to go even further, remember to salt most vegetables — not just eggplant — early in the cooking process. That gives the salt more time to penetrate the vegetables and do its thing.

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While browsing for wines, your instinct may be to reach for the bottles that require a corkscrew rather than those with a screw cap.

But which is actually better: bottles under cork, or bottles under screw cap?

Business Insider recently spoke with James Harbertson, a Washington State University professor of enology — that's the study of wine — to ask him some of our most embarrassing questions about wine. On the topic of screw-cap wines, his answer was clear: No, they are not inferior to corked wines, and in some ways might actually keep your wine from spoiling.

While many bulk wines use screw caps — which is likely where the stigma originated — a screw cap is by no means and indicator of the quality of your wine.

In fact, any high-end wines also bear a twist-able top. For example, New Zealand has been transitioning to the twist-off style in recent years. Harbertson said that the screw-top is just as effective as cork at keeping air out.

Why wine bottles typically use cork

There are lots of reasons to use cork instead of a screw-cap. Cork is made from bark, which makes it a renewable resource. Plus, it can form to the shape of a wine bottle, making it an incredibly appealing way to seal wine.

But there's a drawback: Occasionally bad cork can get into the wine, something called "cork taint." It's not going to harm you necessarily, but it will make the wine taste or smell a little funky, like moldy cardboard. Some people are fine drinking that wine, but others — like Harbertson — can't stand it. It's why New Zealand decided to switch from cork to screw after getting fed up with bad cork that kept causing this cork taint.

And interestingly enough, a 2013 study that looked into why cork tainted wine smells so bad found that it was because a certain chemical called "2,4,6-trichloroanisole" that's known to induce cork taint actually suppresses smell rather than create the off-putting odor. 

So in the end, going for the screw-cap style wine bottle might be the safest way to go. Unless you'll terribly miss the pop of a cork coming unstopped. 

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DON'T MISS: 14 of your most embarrassing questions about wine answered with science

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NOW WATCH: There's something unsettling about these photos from NASA's Curiosity Mars rover

Adam Savage and Jamie Hyneman spent 14 seasons as cohosts of Discovery Channel's wildly popular "MythBusters." But it turns out that their on-screen chemistry was caused by a lot of off-screen friction.

The "MythBusters" series finale airs at 8 p.m. on Saturday, March 5, on Discovery, with a duct-tape special airing on Sunday, March 6, at 8 p.m. on Science Channel.

Story by Jacob Shamsian, editing by Stephen Parkhurst

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British company Surrey NanoSystems has outdone itself.

Researchers there made the blackest material ever back in 2014, called Vantablack, and now they've made a material that's even blacker.

In a YouTube video the researchers posted March 4 (and we found via ScienceAlert), they run a red laser across the solid material to show just how black it is.

You can see how the material absorbs almost all of the light, reflecting nothing detectable back to our eyes:

They make Vantablack by tightly packing carbon nanotubes — rods of carbon that are much, much thinner than any human hair — so close together that light gets trapped inside, ScienceAlert reports.

Researchers say their new material is so black that even their spectrometers (machines that record colors and light) can't measure its darkness. It's likely higher than the original Vantablack, which could absorbed 99.96% of the light that hit it.

To be clear, Vantablack isn't paint and is unlikely to be as durable, too. Even a little bit of water can mess up other ultra-black materials made of nanomaterials — though the original Vantablack seems to hold up pretty well to dunking in water as well as liquid nitrogen.

Surrey NanoSystems isn't just making blacker and blacker materials to set records. They've tested Vantablack to see if it could withstand going into space. There, it could be used to calibrate NASA's powerful cameras to take more accurate photos of our universe. (Artists are also interested in using the black material.)

Maybe the blackest material could help us see through the darkness.

Watch the company's video below:

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This new material is so black, scientists can't even measure it. In fact, it barely reflects any light at all.

This is a highly unusual property for most substances. Normally, when you shine a laser on a material, you can see the light from the laser drift across it as it reflects back at you.

This is how our eyes can see the colors that make up the world around us.

But when engineers from British company Surrey NanoSystems trace a laser over the blackest material ever, the light disappears.

Watch:

Where does the light go? Basically, it gets trapped inside the material.

Vantablack, as the material is called, is made by tightly packing carbon nanotubes — rods of carbon that are much, much thinner than any human hair — so close together that light goes in, but can't escape.

Surrey NanoSystems made the original Vantablack back in 2014, which they said absorbed 99.96% of the light that hit it.

But this new version of Vantablack (which we first heard about from ScienceAlert) is so black that their machines aren't powerful enough to measure its darkness.

Vantablack is mainly being used in research applications now, so you can't, say, buy a can of it to paint your walls with.

But that would be cool. Let us know if they ever start doing that.

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Going to any social gathering involving alcohol inevitably clues you in to who is the sommelier and who is the amateur.

And if the latter happens to fit your description, have no fear. Here's a handy guide to 14 of your slightly embarrassing and nerdy questions about wine that will increase your wine expertise. 

NEXT: 14 of your most embarrassing questions about wine answered with science

SEE ALSO: 15 simple ways to relax, according to scientists

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NOW WATCH: Watch astronaut Scott Kelly’s epic journey back to Earth in 60 seconds

It's St. Patrick's Day, which means hordes of green-clad booze hounds will be flocking to neighborhood bars and house parties to pound some cold ones.

And what beer is more quintessentially "Irish" than a Guinness?

If you're celebrating with a bottle or a can of this Irish dry stout, you may notice the clink-clank of a tiny object rattling around the inside.

That little gadget is called a "widget," and you should be thankful for it. It's making your beer taste like it was just poured fresh from the tap.

Here's how.

A widget is a hollow, spherical piece of plastic with a tiny hole in it — it looks like a little ping pong ball.

During the canning process, brewers add pressurized nitrogen to the brew, which trickles into the hole along with a little bit of beer. The entire can is then pressurized.

When you open the can, the pressure inside the can drops to equalize with the pressure in the room. Since the pressure inside the widget is still much higher than the pressure in the beer around it, the nitrogenated beer from inside the widget squirts into the beer — providing a burst of tiny bubbles of nitrogen gas that rise to the top of beer, giving it a thick, creamy head like the one you'd get straight from a tap.

Guinness brewers first patented the idea of the widget in 1969, but it wasn't until 20 years later, in 1989, when they released their first-generation widget, which was a flattened sphere that sat at the bottom of the can.

This little piece of plastic did its job well when serving the beer cold, but when served warm, the beer exploded everywhere after the can was cracked open:

So in 1997, Guinness released the floating, spherical widget you can see in cans today — which they call the "Smoothifier"— to fix this problem.

Breweries typically use carbon dioxide to give a beer its quintessential bitter fizz, but when a drink calls for a sweeter, silkier experience — such as the experience you get when drinking a Guinness — brewers infuse the ale with nitrogen rather than with carbon dioxide. Nitrogen bubbles are smaller than CO₂ bubbles, so the resulting head and taste is smoother and more delicate.

Nitrogen gas also doesn't easily dissolve in water, so when you crack open a beer, most of the gas is released into the air but the foamy bubbles in the head still remain. This — along with the smaller bubbles — gives the brew a thicker, more velvety "mouthfeel" without the acidic bite of carbonation with CO₂.

Because of the fleeting nature of nitrogen gas in liquid, it's really hard to maintain tasty levels of the gas in packaged beers once you open them.

"With nitrogen, you would require way higher (and dangerous) levels of pressure, and still loose plenty of nitrogen (and beer due to foaming) during packaging," Xavier Jirau, scientific advisor of the homebrew club The Brewminaries, previously told Tech Insider via email. "In order to deal with this issue, brewers got little creative, and there is where Guinness plastic widgets come into play."

The popularity of widgets have caught on since Guinness introduced them in the late 80s. Other beers such as Old Speckled Hen, Young's Double Chocolate Stout, Murphy's Stout, and Boddingtons Pub Ale all have widgets in their cans.

So go crack a cold one on this glorious day, and thank that little plastic sphere for delivering your delicious, velvety brew.

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NOW WATCH: Is draft beer better than bottled beer?

If you're joining in on the St. Patrick's Day celebrations today, chances are you'll be throwing back a few cold ones at a bar.

And if you're a beer snob like me, you'll probably want to be sure that you're drinking from a spotless glass.

But how can you tell if it's clean or if it's dirty?

Luckily, there's a super easy way. If the inside of your pint glass is grimy, one main thing will happen: Streams of bubbles will flow from the walls of your glass.

I know, it sounds weird because — unless your beer is flat — there are going to be bubbles dancing all over the place. But if the fizz is originating from the inside walls, your cup likely has some gunk in it.

Here's why.

The tiny layers of grime are creating rough spots on the glass that agitate the beer. These are called "nucleation points," which provide a place for the dissolved gas in your beer — usually carbon dioxide — to grab onto and promote bubble formation. This makes your beer fizzy.

The physical process is similar to what happens when you drop a Mentos tablet into a can of Diet Coke. The dissolved gas in the soda gives the drink its bubbles.

It's the same for beer. The liquid is bottled under pressure to keep the gas dissolved and, when you open the can or bottle, bubbles start to make their way out of the liquid to create the beer's distinctive fizz.

While the gas will create bubbles naturally, this process can be sped along by giving the bubbles something to latch on to. An object with rough ridges or a bumpy surface — including a grime on a glass — can catalyze bubble-making.

In the classic Mentos and Diet Coke experiment, the mint drops into the soda and forms so many bubbles that it creates intense pressure. Those bubbles have nowhere to go but up, causing an eruption.

Nucleation is generally a good thing when it comes to beers. More and more, brewers and glass manufacturers designing glasses with lasered etchings onto the bottom of the cup to agitate the beer and promote fizziness and a frothy head.

But if this fizziness is coming from a dirty glass, then you should definitely bring it back and demand a new one. There's no shame in becoming even more of a beer snob than you already are.

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NOW WATCH: We put cheap beer to a blind taste test and were surprised by the results

If you're hopping from bar to bar this St. Patrick's Day, make sure to pay extra special attention to your glass.

Commercial brewers put a ton of time and research into ensuring their canned and bottled beers taste as if they were just poured from the tap. But the design of a pint glasses has a lot to do with how good a beer tastes as well.

Carefully curved lips and double-walled glasses improve the presentation and drinking experience of beer, but some brewers and manufacturers take the design a step further by using lasers to etch marks or patterns onto the bottoms of their glasses.

This practice makes the beer bubblier, and it's becoming increasingly more common. Perhaps you've had a drink out of one of these glasses without even knowing it.

These rough etchings are called nucleation points, and their job is to disturb the beer when it touches them. This gives the dissolved gas in the liquid something to latch on to and form bubbles, producing a steady stream of bubbles as they rise from the base.

"Etchings on the bottom of glasses do not improve carbonation; they actually release some carbonation that is already dissolved as the beer hits the surfaces of the etching," Sheri Jewhurst, the “dictator” of the homebrew club The Brewminaries, told Tech Insider via email.

This is similar to what happens when you drop a Mentos tablet into a can of Diet Coke. The gas that has been dissolved in the soda or beer — usually carbon dioxide — is what gives the drink its bubbles.

The liquid is bottled under pressure to keep the bubbles in, and when you open the can or bottle, those bubbles start to make their way out of the liquid, giving you a great fizz.

While the gas will create bubbles on its own, you can speed this process along by giving the bubbles something to latch on to. Any object with rough ridges or a bumpy surface — the Mentos, for example — can catalyze bubble-making.

In the classic Mentos and Diet Coke experiment, the candy drops into the soda and forms so many bubbles that it creates intense pressure. Those bubbles have nowhere to go but up, causing an eruption.

Nucleated beer glasses don't cause eruptions, but they produce just enough bubbles to rise through the glass and "refresh" your beer, Jewhurst said. Refresh, in this case, means making it fizzier as opposed to flatter, tasting more like it was just poured from the tap.

The photo below shows a side-by-side comparison of a glass with nucleation points (left) versus one without them (right). You can see how much more fizzy the drink on the left is.

But this bubble stream effect, while neat in appearance, isn't ideal for every beer.

"With highly carbonated beers such as wit beers," Jewhurst said, "having the constant flow of bubbles coming up from the bottom can actually be kind of a nuisance since they are so prolific."

Next time you purchase a pint glass or get one from your local pub, check out the inside. If it has the lasered etchings, you know you'll be in for a fizzy ride.

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NOW WATCH: Is draft beer better than bottled beer?

This teeny-tiny lattice is smaller than a water droplet, but it's unbelievably strong.

Researchers from the Karlsruhe Institute of Technology made the honeycombs out of carbon, which they claim are the smallest human-built lattices ever constructed. They describe the work in a study published February 1 in Nature Materials.

To make them, the researchers first zapped a pattern into some carbon with lasers, hardening the rough design.

Then they baked the lattice without oxygen to lock the honeycomb structures in place:

Next came the strength tests.

The lattices shouldered more pressure than there is at the bottom of the Mariana Trench — 36,000 feet below sea level — before they crumpled.

These incredibly small, extremely strong lattices could be used in electronics as conductors, or in industry as chemical filters.

But for now, they're just an awesome (and really cool-looking) accomplishment in the lab.

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NOW WATCH: These stunning videos reveal a tiny universe human eyes can't see

If you get table salt hot enough — say, 1,474 degrees Fahrenheit — it actually becomes a liquid.

And if you pour this molten salt into water, it creates a pretty impressive explosion.

The Backyard Scientist did a series of entertaining experiments testing this phenomenon in a YouTube video he posted March 8.

Everyone get ready to see the results:

Ready now? Here we go!

Think that couldn't be more awesome? Let's watch that up-close and in slow-motion:

Scientists who've also experimented with molten salt and water concluded that the explosion isn't the result of a chemical reaction — just a mechanical one.

Basically, the molten salt is so hot that it superheats the relatively cool water, causing it to undergo a shockingly fast phase change from a liquid to a vapor.

This occurrence is called homogeneous nucleation, and scientists have found that it can create shock waves. And those shock waves, in turn, can trigger explosions.

The Backyard Scientist hypothesizes that drops of water get trapped in the molten salt as it falls through the tank. Once it turns into steam, the water rapidly expands and leads to the explosion.

He illustrates this idea with silly putty:

We caution against ever trying this experiment, especially at home. Molten materials can cause severe burns, ignite hazardous fires, and have also led to serious industrial accidents.

At a foundry in Quebec in the 1960s for instance, 100 pounds of molten steel slipped from its ladle into a trough of water. The explosion cracked the walls and floor, breaking 6,000 panes of glass, according to a report on the incident.

Though it's cool to see The Backyard Scientist play with molten salt, we wish that he would have worn protective pants and a lab coat for safety.

Watch the full video below:

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NOW WATCH: This gigantic machine melts snow off the streets of NYC — and turns it into your shower water

While the world mourns those who died in the March 2016 attacks in Brussels, police are hard at work piecing together the terrorists' plot.

One thing Brussels authorities seem to have figured out, however, is the type of explosives suicide bombers set off during the attacks.

Frederic Van Leeuw, Belgium's chief prosecutor in the case, told reporters on Wednesday that investigators found 33 pounds of homemade explosives at a house used by the two bombers who struck Brussels Airport, according to the Associated Press. Those two explosions, combined with a third in Belgium's subway, injured at least 270 people and left 34 dead.

Police also found nails — presumably to serve as shrapnel — and other raw materials for making explosive vests at the residence, according to The Chicago Tribune.

The key explosive ingredient discovered, said Van Leeuw, is a compound called triacetone triperoxide, or TATP — a crystalline powder that is a nightmare to terrorists as well as authorities.

An unstable white powder

TATP is easy to make and hard to detect, but is also incredibly unstable. In fact, all it takes is a firm tap to explode TATP with a force that's about 80% as strong as TNT. (Which is why it has gained an infamous reputation as "the Mother of Satan" among terrorists who make it, according to The Future of Things.)

The infamous "shoe bomber" used TATP in 2001, as did terrorists in London in 2005 and 2006. The chemical was also in bombs detonated at the University of Oklahoma in 2005 and Texas City in 2006, according to explosives researchers at Northeastern University.

And, most recently, it was used in the November 2015 terrorist attacks on Paris.

"TATP and other explosives of the peroxide family are used extensively by terrorist organizations around the world because they are easy to prepare and very difficult to detect," Ehud Keinan, a chemist at the Technion-Israel Institute of Technology, said in a 2005 press release about his research of the chemical.

You might recognize two chemicals in TATP's full name — triacetone triperoxide— because they're ingredients you can find in your local pharmacy's cosmetics and first aid aisles.

"TATP can be easily prepared in a basement lab using commercially available starting materials,"according to GlobalSecurity.org, which also notes "it's easy to blow yourself up when you make it."

Jimmie Oxley, an explosives researcher at the University of Rhode Island, told Tech Insider by email last year that making TATP is as easy as "baking a cake."

"We have done a lot of work trying to prevent its synthesis," wrote Oxley, who has experimented with adding trace chemicals to hydrogen peroxide in hopes of foiling TATP's homemade production. "It isn't easy to do and the ingredients are very common."

Chemistry of a nightmare

One reason TATP is difficult to detect is because it does not contain nitrogen, a key component of homemade "fertilizer" bombs that security scanners are now very good at finding.

Each molecule contains only hydrogen, oxygen, and carbon — some of the most common elements on Earth — shaped in a ring.

The explosive power of TATP has puzzled scientists since its discovery in 1895. Unlike nitrogen-based bomb materials, which store up energy as they're cooked into explosive form, TATP can be made at room temperature — no flames required.

So where does it get its explosive energy, if not by heating?

It wasn't until 2005 that Keinan figured out detonating TATP is more like a massive air blast than a fire bomb. When a crystal of the explosive is rattled hard enough, each solid molecule instantly breaks into four gas molecules.

"Although the gas is at room temperature, it has the same density as the solid, and four times as many molecules, so it has 200 times the pressure of the surrounding air," according to the release about Keinan and his colleagues' 2005 study of TATP.

"This enormous pressure — one-[and-a-half] tons per square inch — then pushes outward, creating an explosive force" that's on par with TNT, states the release.

"In a TATP explosion, the gas molecules give up their energy of motion to the surroundings, in the process creating the shock wave that does the damage."

Can we detect it?

Scientists are now working feverishly to create practical ways to find TATP before it can be used to kill innocent people.

ACRO Security Technologies, a company founded by Keinan, has created a disposable marker-size "peroxide explosives tester," or ACRO-P.E.T.

"The ACRO-P.E.T. provides an immediate answer to whether a suspicious material that has been discovered somewhere ... contains even minute quantities of a peroxide-based explosive," Keinan told The Future of Things.

Other researchers are working on ways to find TATP when it's being transported, and without the need for a direct chemical test like Keinan's device.

In 2011, for example, scientists at Hitachi in Japan created a machine that sucks in air from around a passenger and — in two seconds — can sniff out minute traces of TATP.

A German research group also announced in 2015 that large amounts of TATP can be detected in transit. Because the chemical is so touchy, they say in their study, it's usually dissolved in a special liquid before being moved around — and that fluid's unique odor is what they hope security scanners of the future could sniff out.

Warning: We have purposefully omitted key details about TATP's manufacture. Do not attempt to make it or any other explosive, for that matter.

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This insane video of a teacher using methane bubbles to light a fireball in a student's hand might just make you want to go back and sit through a high school science class again.

First, the student dips his hand into a bucket of methane-filled soap bubbles. Then, his teacher sets his soapy hand aflame using a lighter.

The experiment is harmless and the student is in no danger, but we'd recommend you don't try this unless you're under the supervision of a trained science professional.

Check it out.

Turns out this experiment, which is going viral after being picked up by the Daily Mail earlier Friday, is actually pretty common in science classrooms.

Tech Insider reporter Rebecca Harrington remembers a similar demonstration in an introductory chemistry course in college, and a quick Google search turns up plenty of similar videos.

Here's a snippet of another YouTuber demonstrating the same experiment.

So how do these great balls of fire work? Why is nobody burning off their fingers?

Methane is lighter than air, so the soap bubbles filled with the gas immediately start rising off your hands the minute you touch them. When they light on fire, the bubbles are already moving up and off your skin.

When lit, the methane bubbles burn in the presence of oxygen from the air to turn into water and carbon dioxide. Poof — no more bubbles!

It's totally safe, but still looks totally crazy. And based on the cheers the student in this video received from his classmates during the experiment, we'd say science teachers everywhere might want to add this one to their lesson plans.

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NOW WATCH: This flame-suppressing dodgeball puts out fires instantly

Sometimes you need to find a working battery in your junk drawer amongst a sea of dead ones. If you're in a rush and don't have time to find a battery meter, here's how you can quickly see which batteries are good and which ones are duds.

Produced by Darren Weaver and Rebecca Harrington.

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Have you read the ingredients list on your bottled water lately?

If not, you might be surprised to see things like sodium chloride, calcium chloride, magnesium chloride, sodium bicarbonate, potassium bicarbonate, magnesium sulfate, and other compounds.

No reason to worry, though.

Salts and minerals like these typically present in trace amounts in your water and are very safe.

"If you had pure water by itself, it doesn't have any taste," agricultural scientist Bob Mahler told Time in 2014. "So companies that sell bottled water will put in calcium, magnesium, or maybe a little bit of salt."

There's also this: Salts and minerals, like those found in water, are necessary to help you sweat and perform other vital bodily functions.

The water you drink, whether bottled or tap, is never just all water molecules made of hydrogen and oxygen — no matter how pure the label claims it is. It has impurities in it.

And water that is chemically pure isn't something you'd necessarily want to drink.

Water purified to that point — distilled water — is naturally and slightly acidic, giving it a tendency to dissolve and leech away salts, minerals, and other chemicals. So if you drink some, it will pull nutrients out of your body's cells.

If you just gulped a glass of ultra-pure water, though, don't panic: It won't hurt you as long as you don't consume it regularly.

Fervent drinking of distilled water can cause you to overhydrate and overheat, since having less salt in your body makes it much harder to sweat. Athletes and other highly active people should be especially wary of drinking a lot of distilled water; it can lead to a potentially deadly electrolyte imbalance.

The one additive you should really be watching out for in your water is sugar, which only adds calories to your otherwise totally healthy and refreshing beverage.

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NOW WATCH: Here's how the '8 glasses of water a day' myth started and why it's not scientifically true

The paint used on the Hubble telescope is one of the blackest materials in space. It's there to reduce stray light so the instrument can photograph the best possible images of our solar system and beyond.

But researchers from British company Surrey NanoSystems have made something much, much blacker.

Their material, awesomely called Vantablack, is so black that they can't even measure how dark it is.

They've posted a YouTube video comparing their creation to the Hubble paint, called Aeroglaze Z306.

Vantablack makes Aeroglaze look like it's not even black. When the researchers shine a light on the two, you can see the Hubble paint reflecting light back, but not Vantablack:

The same thing happens when they shine a red laser on the two materials:

Vantablack absorbs almost all of the light, reflecting nothing detectable back to our eyes. It's made by tightly packing carbon nanotubes — rods of carbon that are much, much thinner than any human hair — so close together that light goes in, but can't escape.

Surrey NanoSystems has tested Vantablack to see if it could withstand going into space, so maybe the material could replace Aeroglaze on the next space telescope.

They've also turned Vantablack into a spray paint that captures 99.8% of light (slightly lower than Vantablack's 99.965%). You can't find it on store shelves, though: The spray paint is currently only available through the company's processing center in the UK.

Watch the full video of the Aeroglaze vs. Vantablack comparison:

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A Stanford chemical engineering group lead by visionary scientist Zhenan Bao has developed a material that could be useful for robotic and prosthetic artificial limbs.

As detailed in the journal "Nature Chemistry," the synthetic polymer can repair itself when punctured and expand and contract when zapped with electricity. It's also remarkably stretchy — a 1-inch sample stretched over 100 inches in a laboratory test. 

The material gets its resilience through its molecular structure. As Professor Bao explained in a statement, the ions and ligands that make up the polymer can readily reconnect with each other if they're close enough together. 

This material fits in Bao's larger quest to creating artificial skin. As INSIDER reported in December, her lab has created sensors that can detect touch as light as a butterfly landing, and tell the difference between a weak and firm handshake. That technology is similar to the way your iPhone detects the touch of your finger, and will hopefully be able to restore touch in burn victims. Add the ultra-stretchy polymer, and you're that much closer to replicating the function of skin. 

The applications go beyond prosthetics. If artificial skin becomes a reality, it would be a way for artificially intelligent bots to know the world by touch.

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It sounds like a wacky fantasy, but scientists believe that it rains diamonds in the clouds of Saturn and Jupiter.

Diamonds are made from highly compressed and heated carbon. Theoretically, if you took a charcoal bricket out of your grill and heated it and pressed it hard enough for long enough, you could make a diamond. (Good luck with that.)

On Earth, diamonds form about 100 miles underground. Volcanic magma highways then bring them closer to the surface, providing us with shiny gemstones that we stick in rings and ear studs.

But in the dense atmospheres of planets like Jupiter and Saturn, whose massive size generates enormous amounts of gravity, crazy amounts of pressure and heat can squeeze carbon in mid-air — and make it rain diamonds.

Scientists have speculated for years that diamonds are abundant in the cores of the smaller, cooler gas giants, Neptune and Uranus. They believed that the larger gaseous planets, Jupiter and Saturn, didn't have suitable atmospheres to forge diamonds.

But when researchers recently analyzed the pressures and temperatures for Jupiter's and Saturn's atmospheres, then modeled how carbon would behave, they determined that diamond rain is very likely.

Diamonds seem especially likely to form in huge, storm-ravaged regions of Saturn, and in enormous quantities — Kevin Baines, a researcher at University of Madison-Wisconsin and NASA JPL,told BBC News it may rain as much as 2.2 million pounds of diamonds there every year.

The diamonds start out as methane gas. Powerful lightning storms on the two huge gas giants then zap it into carbon soot.

"As the soot falls, the pressure on it increases," Bainestold the BBC. "And after about 1,000 miles it turns to graphite - the sheet-like form of carbon you find in pencils."

And the graphite keeps falling. When it reaches the deep atmosphere of Saturn, for example — around 3,700 miles down — the immense pressure squeezes the carbon into diamonds, which float in seas of liquid methane and hydrogen.

Eventually the gems sink toward the interior of the planet (a depth of 18,600 miles), where nightmarish pressure and heat melts the diamonds into molten carbon.

"Once you get down to those extreme depths," Baines told the BBC, "the pressure and temperature is so hellish, there's no way the diamonds could remain solid."

But before you start building a Jupiter- or Saturn-bound diamond-speculating ship with De Beers, keep in mind: All that crushing pressure and searing heat would destroy any Earthly vehicle long before it got close to those clouds full of sparkling riches.

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