Popcorn is one of the few foods that announces it’s ready with a series of tiny explosions. One minute it’s a handful of small, hard kernels; just a few minutes later, it’s white, fluffy, and delicious with butter.

You can’t just throw any corn on the cob into the microwave and expect fireworks, though. Popcorn isn’t ordinary corn —  it comes from a specific variety of flint corn, known scientifically as Zea mays everta. Two qualities make this variety especially well-suited for the movie theater. 

Here’s what makes it pop.

Pressure Cooking

A popcorn kernel is like that one uncle in your family — tough on the outside, but really a softie on the inside. Similarly, every kernel of Zea mays everta contains three important parts: a starchy center called the endosperm, a tiny embryo that could grow into a new corn plant, and a tough outer shell known as the pericarp.

That outer shell is the key to making popcorn. Unlike the shells of sweet corn or field corn, it’s strong enough to trap steam inside as the kernel heats up. Although popcorn looks dry, each kernel contains water. The ideal moisture level for a kernel to pop is about 14%. The temperature inside the kernel climbs to roughly 350 degrees Fahrenheit, turning the water into steam. Because the steam can’t escape, it continues building.

As all of this is happening, the starch inside begins to soften into a thick, almost molten paste. Scientists call this process gelatinization, and it’s similar to what happens when starch thickens a sauce. Inside the kernel, it’s happening while steam continues pressing against the shell. Essentially, each kernel has become a tiny pressure cooker.

When the pressure inside reaches about 135 pounds per square inch (psi) — roughly four times the air pressure inside a car tire — the shell gives way. It cracks open almost instantly, similar to how built-up gas explodes from a can of soda when you shake it.

As the shell bursts, the trapped steam expands in a fraction of a second. The softened starch puffs outward and rapidly cools, hardening into the airy, irregular shape we recognize as popcorn. The familiar popping sound isn’t the starch expanding — it’s the shell finally cracking open.

Not every kernel pops perfectly. If there’s too little moisture inside, it can’t produce enough steam to burst. If the shell has even a tiny crack, that steam can escape before enough pressure can build for the kernel to pop. 

That’s why you usually end up with a few stubborn kernels at the bottom of the bowl, and why throwing them back into the microwave isn’t going to “re-pop” them.

The term “fossil fuel” might have you picturing the remains of a T. rex or Brachiosaurus decomposing into the unleaded you pump into your car. But, the process doesn’t generally involve the kinds of fossils found in museums. No dinosaurs were harmed in the making of your gasoline (probably). 

In fact, most of the fuel that powers our modern civilization doesn’t come from animals at all. Fossil fuel is technically solar power, because it originates with the sun. Here’s how.

What Lies Beneath

Fossil fuels (coal, oil, and natural gas) generally aren’t made from fossils, at least not in the usual sense of preserved bones or shells or traces in rock. Instead, they’re formed primarily from the remains of ancient plants, algae, bacteria, and plankton.

These organisms had something valuable in common: They captured energy from sunlight. Through photosynthesis, they used that solar energy to turn carbon dioxide and water into carbon-rich organic matter that became the basis of modern fuels. 

Normally, when an organism dies, decomposers break down that material, returning much of its carbon to the atmosphere. But under certain conditions, some carbon-rich remains escape that fate.

Coal began forming largely from plants that died in ancient bogs and swamps. Waterlogged, oxygen-poor conditions slowed decomposition, allowing layers of partially decayed vegetation to accumulate as peat. As sediment piled on top, the peat was buried more deeply. 

Increasing heat and pressure (think of all that rock crushing the sediment from above) gradually squeezed out water and other substances, concentrating the carbon and transforming the peat into coal.

Oil and natural gas followed a different route. Much of their raw material came from tiny marine organisms such as plankton, which died and sank to the bottoms of ancient oceans. Buried beneath layers of mud and sediment, the remains were cut off from oxygen and partly broken down by microbes. Over time, chemical reactions turned this material into a waxy substance called kerogen.

Burial over the eons pushed the kerogen deeper into Earth, where rising heat and pressure continued to alter its molecules. Under the right conditions, kerogen became liquid hydrocarbons — crude oil (also called petroleum). At even higher temperatures, it produced smaller, lighter hydrocarbons, including methane, the main component of natural gas.

Carbon and hydrogen are particularly potent together, as their atoms form tight chemical bonds with one another. These bonds contain high amounts of chemical potential energy, which is why hydrocarbons make such a potent fuel source. When coal, oil, or gas burns, its hydrocarbons react with oxygen, releasing the potential energy as heat. That ancient energy, which originally came from the sun, can then warm a house, power a car, or spin turbines to generate electricity.

How Much Oil Is There?

Oil and gas don’t necessarily remain where they form. Because they are less dense than the surrounding rock and water, they can seep upward through tiny pores and cracks. When they encounter an impermeable layer of rock, however, they become trapped beneath it and accumulate in underground reservoirs. Drilling into one of these reservoirs releases material that may have been confined there for millions of years.

It’s estimated that no more than 6 trillion barrels of oil (a barrel is 42 gallons) currently reside somewhere in the ground. That supply is called the “oil in place,” but only about a quarter of that is considered to be part of the world’s “proven reserves,” which are the fossil fuels that we are at least 90% confident we can actually mine and use.

In 2024, the world used roughly 100 million barrels per day. At that rate, we’d consume the 1.7 trillion-barrel supply of proven oil reserves in less than 60 years, sometime in the early 2080s. Commercial oil drilling began in the 1850s, which means that modern civilization will have burned through Earth’s entire supply of usable fossil fuel, which took hundreds of millions of years to form, in less than 250 years.

Fortunately, we don’t have to sit around in the dark for millions of years waiting for new fossil fuel. The original source of energy that gave oil its kick in the first place — the sun — is readily available and isn’t going anywhere anytime soon.

You won’t find many products that are equally useful for making cookies, soothing bug bites, and unclogging toilets. But there’s a compound that claims all of those abilities and many more besides, like some kind of magical potion gifted to humanity. 

That compound is baking soda, and its uses extend far beyond its namesake purpose. Here’s a closer look at what makes baking soda an ideal substance for solving a surprisingly long list of everyday household problems.

What Even Is Baking Soda?

The technical name for baking soda is sodium bicarbonate, a chemical compound that’s typically in the form of an odorless, white, crystalline powder. The fact that it’s a powder may be confusing, since it’s not the same as baking powder.

Baking soda is pure sodium bicarbonate, which reacts with acid (usually not the acid that eats through metal; think more like lemon juice). Baking powder, on the other hand, comes with some form of acid mixed into sodium bicarbonate already, so it only needs water to be activated.

The reason sodium bicarbonate reacts strongly with acid is because it has a high pH. That makes it the opposite of an acid, known as a base. Because of this, baking soda is alkaline, which effectively means it’s water-soluble and can be used to neutralize acids. It’s also nontoxic and mildly abrasive. Together, these properties give baking soda its wide range of uses. Here are 10 of the most

Baking

Obviously, baking soda is useful for baking. Perhaps less obvious is why. When added to recipes, baking soda acts as a leavening agent, producing light, fluffy baked goods. This leavening process is activated when baking soda is mixed with an acidic liquid such as vinegar or lemon juice, which in turn releases carbon dioxide gas that causes dough to expand.

Dental Care

Baking soda is a natural whitening agent, since its mildly abrasive texture makes it useful for scrubbing away superficial stains on the teeth. The basic (as in properties of being a base) nature of baking soda can also be used to neutralize acids in the mouth, which increases the pH of your saliva and inhibits the ability of oral bacteria to thrive. 

Bacteria help form plaque and also lead to bad breath, so essentially, by mixing baking soda with warm water, you can use the compound just like any typical mouthwash.

Cleaning Clothes

Baking soda’s effectiveness in the laundry room is because of its alkaline nature. When dissolved in water, baking soda neutralizes acids that might be causing unpleasant odors or stains. This helps your clothing come out smelling fresh, and it also helps whiten mild discoloration.

Deodorizing

Whether you’re using it to deodorize your fridge, shoes, or even reaching for it as a replacement for your Old Spice, baking soda is a highly effective deodorizer. Many of the bad odors we’re faced with come from acidic substances. By applying some baking soda, you can neutralize those acids and keep odors at bay.

Unclogging Drains

When mixed with vinegar, baking soda produces a bubbling reaction (similar to how it works when fluffing up pancakes and cookies). If you were to pour the combination down a clogged tub or sink drain, that chemical reaction can also physically rustle the clog loose. Then all you need to do is flush the debris from your pipes with boiling water.

Treating Bug Bites

Mixing 1 tablespoon of baking soda with just enough water to create a paste can be an effective remedy for treating itchy bug bites. The alkaline baking soda neutralizes any of the acids that are being produced by the bite and causing you to itch. Just apply the paste and let it sit for 10 minutes. Wipe it away, and you should feel immediate relief.

Killing Weeds

Pulling weeds out of the ground typically isn’t enough to remove them in the long term, as they have deep roots that’ll inevitably regrow. But if you sprinkle a bit of baking soda onto the soil where the weeds are growing it creates an inhospitable (but nontoxic) environment for future growth. 

This time, baking soda’s secret power isn’t its alkalinity — it’s that the substance is also high in sodium. You’re essentially salting the earth, which prevents vegetation from being able to absorb water and grow.

Cleaning Food

When you buy fresh produce, one of the most pressing concerns is whether there are pesticides remaining on the skin of food, even after washing it under the sink. Research has shown that baking soda can help relieve those worries. 

The alkaline nature of sodium bicarbonate breaks down the chemical bonds of pesticides, loosening and dislodging toxins from the skin of an apple or other food surface. Simply soak fruits or veggies in a solution of baking soda and water for up to 15 minutes before rinsing off to help remove any residual pesticide.

Treating Heartburn

For anyone struggling with heartburn, baking soda may be a welcome solution. As you may know, heartburn is caused by stomach acids backing up in the esophagus (the tube that connects your throat to your stomach). To fix this, drink a half teaspoon of baking soda and four ounces of water. The alkaline properties of baking soda will neutralize excessive acids in your stomach or esophagus to provide relief.

Freshening Carpets

Dirty carpets can be quite hard to clean, especially without using harsh chemicals. Enter baking soda, the solution to so many housekeeping woes. 

Just sprinkle baking soda onto the carpet and let it sit for anywhere from 15 minutes to several hours if the problem is especially serious (we’re looking at you, pet owners, smokers, and parents of young children). The compound will absorb odors and mild staining caused by acidic sources. After that, simply vacuum it up and the carpet should be cleaner and refreshed.

These are just some of the many uses for baking soda, largely due to its alkaline nature. It’s not a magic potion — it’s just chemistry in motion.

If your knowledge of physics includes little more than what you’ve seen on The Big Bang Theory, we get it. Physics is a particularly difficult subject — after all, its goal is to explain how the entire universe works. Not to mention, it involves advanced math such as calculus and linear algebra, and deals with particles so small they make atoms look huge. Indeed, some concepts defy intuition so thoroughly they seem more like magic than science. Just because something looks mind-blowing doesn’t mean it’s impossible to wrap your head around, though. Here are five seemingly impossible things that, at the end of the day, are just physics at work.

Curveballs

If you’ve seen a pitcher throw a baseball that seemingly changed direction in midair before crossing home plate, you might think it’s magic (or dark magic, if the pitcher’s on the opposing team). The “magic” lies in the spin of the ball, relying on a phenomenon known as the Magnus effect.

Breaking ball pitches, such as curveballs and sliders, “break” their trajectory as they fly toward the plate. When a pitcher throws a curveball, for instance, they snap their wrist over the ball to put spin on it. This makes the ball move downward and sideways over home plate, while the batter still expects it to follow a straight line.

Here’s how it works: The spinning ball curves midair because it drags air along with it. This causes air to move faster on one side and slower on the other. The drag creates a pressure difference that pushes the ball sideways, bending the direction of its path.

Airplanes

Magicians never reveal their secrets, but we’re pretty sure they’re not really making anyone levitate on stage. But physics does make things float. It’s known as Bernoulli’s principle, and here’s a simple way to visualize it.

Imagine a fan pointed so the air is blowing upward. If you place a beach ball in just the right spot within the airflow, it will hover, as if it’s levitating. The magic is in the air pressure. The faster the air moves around the beach ball, the less pressure there is pushing on it from the sides. But if the ball moves outside of the column of blowing air, the stationary air will exert higher pressure onto the ball, and it will fall. 

Our understanding of Bernoulli’s principle is also used to design the wings of aircraft, which use the difference in air pressure to seemingly float in midair.

Bending Water

Bending a stream of falling water sounds impossible, but it’s a physics trick you can do right at your kitchen sink. No magic needed — but you do need static electricity, the kind you create when you rub a balloon on your head and your hair stands on end.

That trick generates static electricity because some of your hair’s negative charge moves to the balloon. The same idea works with a negatively charged balloon and water. A single water molecule (H2O) has one negatively charged oxygen atom, but two positively charged hydrogen atoms.

If you use a negatively charged balloon and hold it close to the water, the flow will be attracted to the negatively charged atoms on the balloon. In other words, the positive regions of the water molecules will realign toward the negatively charged balloon, essentially “bending” the water toward the balloon.

Instantly Freezing Water

We all know water turns to solid ice when it reaches 32 degrees Fahrenheit, right? Well, not always. Pure water can remain liquid even well below freezing temperatures. And you can make a bottle of water turn to ice — on command.

It’s not magic; it’s supercooling. Your average tap water won’t do it, though. Supercooling only works with water that’s completely free of impurities or minerals, such as distilled water, because ice needs these to form crystals. Water molecules crystallize when they touch and lock together. Impurities, whether calcium, bacteria, or other common microscopic things in tap water, make it easy for water molecules to bump into each other — like riding on a crowded subway train.

Distilled water, on the other hand, flows freely, so ice crystals don’t readily form even if the water is below freezing temperatures. To see supercooling in action, put an unopened bottle of distilled water in the freezer and leave it for about two and a half hours. It will reach a supercooled state. Very carefully remove it from the freezer. 

Either shake the bottle or tap it on the table and watch the water instantly form into a band of ice crystals. The supercooled water remains liquid in the freezer because the nucleation process hasn’t begun. That’s the first step in freezing when crystals form around minerals, impurities, or ice in the water.

Shaking or tapping the water bottle jumpstarts the nucleation process by forcing the water molecules to collide, locking them into ice crystals right before your eyes.

Bending Light

Ever placed a straw in a clear glass of water and noticed that the part of the straw under the surface of the water seems to be completely disjointed from the straw that’s above? 

It’s not an optical illusion, but an example of light refraction, which is when light bends as it passes from one medium to another. Another, iconic, example is the cover art for Pink Floyd’s album The Dark Side of the Moon. It features a beam of white light passing through a glass prism and splitting into a rainbow. 

Refraction occurs when light (made of particles called photons) changes speed as it enters a new material, such as from air to water. The denser the medium is with electrons that can interfere with photons, the slower the light travels, which dictates how and where the light will bend. (The “speed of light” we typically think of refers to the speed of light in a vacuum.) 

The bent rays of light reflecting off the submerged part of the straw make it look like the straw has broken apart from the segment above water.

People often use the term “mirage” to describe a false promise, but it’s a real scientific phenomenon.

Your first encounter with the concept was probably in animation, as many classic cartoons feature a recurring trope where a character wandering the desert will hallucinate a tropical pond — or occasionally some other desirable feature — only to find nothing but sand there in reality.

Yet we encounter mirages in our everyday lives any time we’re in a vehicle on a hot day, when the distant road looks slick with water despite being bone dry. This illusion and the desert oasis cliche are formed the same exact way.

Not a Drop to Drink

On sunny days, roads can get particularly hot — which you know if you’ve ever made the mistake of walking barefoot on concrete or pavement on a sweltering summer day.

The hot road heats the air just above it. Scientifically speaking, heat occurs when molecules are excitedly moving faster and farther apart from each other rather than staying tightly packed and still as they do when they’re cold. Because of this, warmer air expands and becomes less dense.

This allows light to move through it faster than cooler air (remember, there’s more space between the molecules). As light travels through the difference in temperature and density, it bends, directing light from the sky up and into your eyes. 

The reflection appears to shimmer, since the light is constantly refracting at different speeds and angles due to the turbulent nature of the excited molecules dancing above the hot road. This shimmer makes the road appear wet, but as we get closer the illusion vanishes. That’s because it’s only visible from certain angles.

The stereotypical mirage of seeing an oasis in the desert can be explained the same way. Heat above the sand bends light, which reflects the blue sky, making it look as if there’s a pool of blue water just waiting for you to come take a drink.

The wet road illusion is known as an inferior mirage, meaning an upside-down image appears below a real object. It applies not just to hot roads or sand, but to the seemingly wavy air you might see over a toaster or barbecue grill.

A superior mirage is when a distant object appears to be higher than it really is. It occurs for the opposite reason: The layer of air closer to the surface is cooler than the air above it, causing light to bend downward. It’s commonly seen across bodies of water or ice, where a ship might appear to be slightly above the water’s surface. Historian Tim Maltin suggested a superior mirage may have contributed to the sinking of the Titanic, creating a haze that prevented the ship from seeing the oncoming iceberg until it was too late.

While there may not be icebergs on the highway, it’s an important reminder to always keep your eyes on the road — even when the road isn’t exactly what it appears to be.