Partial freezing results from trying to freeze water while preventing expansion

How freeze-drying leaves food with less than 4% of its original water content

In specialized equipment, foods are brought down to temperatures below freezing before a vacuum pump removes the air from the container, lowering the pressure around the food and the boiling temperature of water. Heaters beneath the food slowly raise its temperature above the now-reduced boiling point, causing the water to go from a frozen to a gaseous state.

Why trying to freeze helium creates a fluid that can travel through solids and climb walls

Once cooled to temperatures just above 2 Kelvin, helium-4 atoms begin to exhibit superfluidity, a quantum property in which all atoms collectively inhabit the same low-energy state and behave in perfect unison. This coordination removes the internal friction that causes liquids to cling to surfaces, allowing them to slide through microscopic pores and scale container walls.

What is freezing fog?

Freezing fog is a weather condition in which fog containing supercooled water freezes on contact with objects, forming a layer of ice and possibly dangerous driving conditions. Get the breakdown with this explainer.

Different types of ice link water molecules together in unique shapes

The ice used to cool drinks—Iₕ—is composed of H₂O molecules arranged in hexagonal structures. This structure forms as ice expands during freezing, providing additional space between molecules, lowering the overall density, and allowing it to float in water. Under sufficient pressure, this spacing can collapse in many ways, creating new forms of ice.

High freezing speed restricts the development of gritty crystal chunks in ice cream

For this reason, ice cream does not maintain its smoothness when refrozen in a traditional freezer over several hours. The smooth texture is also made possible by balancing fat, sugar, and emulsifiers.

Reduced inflammation from cold plunges lacks scientific support

The cold water triggers immediate cold shock, increasing heart rate and blood pressure, and prolonged exposure can lead to cold-water incapacitation and hypothermia. Plungers are encouraged to enter the water slowly and manage their breathing to reduce the risk of shock. Warm baths post-plunge are discouraged, and exercise is generally better for recovery.

Explaining the Leidenfrost effect, where water can hover and move against gravity

Water droplets can glide across surfaces whose temperatures are well above water's boiling point. This heat instantly vaporizes the bottom of the droplet, creating a layer of steam that the rest of the droplet rides and bounces upon. This can be seen when sprinkling water on skillets to determine if the surface is hot enough to cook on.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

How the loss of Earth's atmosphere would cause oceans to boil at freezing temperatures

Many phenomena requiring air pressure, from the flight of birds and aircraft to the act of breathing, would no longer be possible. Because sound travels through vibrating air molecules, the loss of the planet's atmosphere would also create a silent environment. Even during daytime hours, the sky would resemble a clear night sky.

Underwater data centers may provide an alternative to energy-intensive air cooling

By submerging electronic hardware into a non-conductive fluid, such as an oil with strong thermal transfer properties, significant thermal energy can be quickly drawn away from a chip and brought to the surface as warm materials rise. Thermal energy can then be removed from the fluid with a heat exchanger before it is recirculated.

An overview of extremophiles and the biochemical adaptations employed by various types

These organisms thrive in environments that would normally be inhospitable to most living things by using molecules that help counter deadly environmental factors. These include antifreeze-like proteins that prevent psychrophiles from freezing and rupturing in polar regions, and osmoprotectants that prevent some extremophiles from losing water to salty environments.

The extremophilic origins of watermelon snow and its impact on glacial melting

Also known as "blood snow," the red coloration is produced by snow algae that thrive in extremely cold conditions and take the shape of red spherical cysts in winter. To protect themselves from more intense summer solar radiation, these psychrophiles accumulate red, orange, and yellow pigments, intensifying their coloration and causing glaciers to reflect less sunlight than if they were white.

Explaining concentrate and how concentrate-derived juice differs from its source

Developed to reduce the volume of goods—thus lowering storage and shipping costs—the concentration process uses pressure and heat to remove water, pulp, and skin from fruits. Concentrates provide significant flavor, sugar, and calories to foods in small quantities, but do not retain most of the fiber, vitamins, and other nutrients from the source fruit.

Low temperatures led to the equipment failure that caused the Challenger disaster

The polymer chains that make up an O-ring give it the ability to quickly deform and fill in gaps to seal fluids, including the hot gases from the Challenger's rocket boosters. Cold weather on the day of launch stiffened the O-rings, reducing their flexibility and sealing properties.

Shrink-wrap is created through a treatment of plastic with high-speed electrons

Atoms in polyethylene are bonded in long strings called polymer chains, which can be destabilized by removing hydrogen atoms via collisions with electrons. These gaps serve as bonding sites for neighboring chains to bond and undergo cross-linking, strengthening the plastic while making it more malleable.

How chefs suspend liquid in edible pearls resembling caviar to introduce a new texture to fluids

Through spherification, drops of a solution of sodium alginate and a flavored liquid are placed in a calcium lactate solution, which forms a chemical skin around them. This is because calcium replaces the sodium in the alginate chains, forming a gel around each drop's liquid interior.

Sleep paralysis occurs when the body fails to 'unfreeze' in sync with waking

When the body falls into a deep enough phase of sleep, it paralyzes certain parts of itself so the brain can't force it to physically act out dreams. This well-known but little-understood phenomenon happens when the brain awakens early and typically results in haunting hallucinations and reports of supernatural terrors.

Tracing the history of refrigeration

Refrigeration has become critical to most of our lives. But not long ago, it wasn't available. How did we become so dependent on our fridges and freezers? This fun, informative podcast traces the history of keeping it cool with ice and...

Water acts as a coolant and a moderator of nuclear reactions in reactors

Nuclear reactions within a containment structure boil water into steam, which drives a turbine that generates electricity. This water is then recirculated via pumps back into the containment structure to repeat the process, with reaction rates lowered by the insertion of control rods that absorb neutrons, which trigger reactions.

A temperature of absolute zero is impossible to reach

Zero on the Kelvin scale—equivalent to -273.15 degrees Celsius—describes a system where all atomic motion completely stops, which is forbidden according to thermodynamics. As of 2025, the closest scientists have gotten to absolute zero is 0.00000000004 K.

Solid-state batteries substitute the fluid electrolyte layer with a solid

The non-flammable solid greatly reduces the risk of fire and explosion, as well as the release of toxic gases via leaks in the existing sulfide-based systems. These batteries use garnet-type solid electrolytes, which provide high ionic conductivity and chemical stability but require temperatures above 1,000 degrees Celsius (1,800 degrees Fahrenheit) for fabrication.

Niagara Falls stopped flowing for a full day in 1848 due to ice

In March 1848, ice jams halted the Niagara River entirely for over 24 hours, allowing people to walk on the riverbed—a rare event that drew international headlines.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Watch an animation of Arctic sea ice grow to its maximum

Each year, Arctic sea ice freezes over millions of square miles amid colder temperatures. This 1-minute animation depicts that process using data from the winter of 2022-23.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

In 2009, accidentally drilling into magma provided time capsules of volcanic glass

While drilling for geothermal energy in Iceland's Krafla Geothermal Field, magma encountered at a depth of 2,100 meters quickly formed glass upon making contact with drilling fluid. By trapping dissolved gases, volatile chemicals, and the physical characteristics of magma before cooling, the glass acts as a time capsule of ancient volcanic activity and magmatic conditions.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Why parts of the Earth are colder when the planet is closer to the Sun

The Earth orbits the Sun in an elliptical shape, and winter in the Northern Hemisphere occurs when the Earth reaches the point in its orbit closest to the Sun, known as perihelion. The lower temperatures result from the hemisphere tilting away from the Sun.

The Koch snowflake has an infinite perimeter enclosing a finite area

Counterintuitively, although it would be impossible to build a fence along the edges of the shape because it would require an infinite amount of materials, this perimeter can be contained in a larger shape with a finite perimeter and limited area. This is equivalent to enclosing an infinitely long spiral that never reaches the center within a circle.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

Explore what it's like inside a patient isolation unit, used in situations such as treating a patient or suspected patient with Ebola.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

'Silent' fireworks have gained more interest in recent years as a quieter celebratory option.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

The Beatles' US label rejected the band's first two singles, 'Please Please Me' and 'From Me to You,' with one executive calling the band 'dead in the water.'