What is a calorie?

Explore the complex relationship between calories and weight

What if you found out that weight loss is actually much more complex than "calories in, calories out" and that the 2,000 calorie-a-day recommendation may not actually be accurate?

How 'vibes' factor into scientists' decisions about using certain units

Although there are absolute quantities from which units can be defined, such as the speed of light and the corresponding light year for distance, the usefulness of units comes from their ability to easily communicate values, rather than how fundamental their origins are. For example, while Kelvin measures absolute temperature, Celsius is scaled to the temperatures of boiling and freezing water, making them more practical for everyday usage.

What is metabolic rate?

Read this article to better understand the concept of metabolic rate, which is defined as the amount of energy expended by an organism over the course of a day. Basic metabolic rate (or BMR) is this metabolic rate at rest, during which the body only...

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.

Cookies were originally used as low-stakes ways to test the temperature of an oven

In 7th century Persia, bakers used small mounds of dough to test the heat in ovens before baking larger cakes. Afterward, they'd add honey, nuts, and other items to the small mounds, creating early cookies.

T. rex needed the same amount of calories as 80 people every day

Tyrannosaurus rex is the most extensively studied fossil creature ever known. Every year, new research is added to the towering list of papers that try to draw …

What is a heat dome?

The world is seeing regular heat waves with multiple causes, including so-called "heat domes," a term rising in use in recent years. A heat dome occurs when the atmosphere traps hot ocean air like a lid or cap, creating stifling conditions and resulting in extended periods of heat. See an illustration of this phenomenon and read how it works with this brief explainer.

Why is rice so popular?

From Spanish paella to West African jollof rice, rice is a staple in dishes across the world. This colorful animated video dives into the global expansion of rice, which contributes more than 20% of the calories consumed by humans each year. Learn about rice’s beginnings thousands of years ago, the environmental consequences of its popularity, and the potential for positive changes in the future.

Ketchup, 101

Ketchup is a tomato-based condiment mixed with vinegar, salt, and spices. The word likely originates from Southeast Asia, where it was used for a common fish brine sauce in the 18th century. For a brief period in the early 19th century, ketchup was viewed and marketed as a medicine. Henry John Heinz formulated a standard recipe in the late 1800s.

Infrared light is most often associated with thermal radiation and cooking food

Although extensively used in remote controls for electronics, where LED lights send signals wirelessly, infrared cameras allow for night vision and thermography—imaging of heat patterns in the body to non-invasively reveal blood flow for supplementary diagnostics. Infrared radiation also provides heat in toasters, saunas, and other technologies.

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...

The impact of greenhouse gases is assessed as a measure of Global Warming Potential

Since 1990, the Intergovernmental Panel on Climate Change has used GWP to measure how much energy 1 metric ton of a gas emits over a given period—usually 100 years—relative to 1 metric ton of carbon dioxide. By definition, carbon dioxide has a GWP of 1.

Particle accelerators detect subatomic particles using millions of sensors

Calorimeters measure the energy of particles. Tracking devices can measure momentum and charge from the trajectory of particles, which is determined by recording tiny electrical signals. Time-of-flight detectors provide particle velocities directly and particle mass indirectly, giving physicists a suite of properties to compare with those of known matter.

Biologist Richard Dawkins coined the term 'meme'

His 1976 book "The Selfish Gene" proposed that units of culture could be replicated, passed on, and evolve as they were transmitted, similar to human genes. He called this unit a "meme," to be pronounced like "cream."

Learn how your body is, scientifically, like a firework with its own slow, controlled burn

This NPR video makes clear that there are surprising similarities between how our bodies and fireworks function. Fireworks and our bodies are both packed with carbon atoms, and have controlled releases of energy that create heat—keeping the human body warm or fueling fireworks' heat, respectively. What's more, the human body even emits a tiny bit of light somewhat similar to fireworks—though it's not visible to the human eye.

Fifteen answers to 'what is the meaning of life?'

Writer James Bailey repeated philosopher Will Durant's 1932 project soliciting opinions on the meaning of life from a variety of luminaries. In this article, read the fascinating responses people gave to the all-important question, from renowned author Hilary Mantel to a seasoned palliative care supporter who had witnessed dozens of deaths.

What's your ACE score, and what does that mean for your health?

An ACE score is a way of measuring adverse childhood experiences, which can negatively impact health outcomes. Take this quiz to determine your score and what that means for your health. The Centers for Disease Control and Prevention and Kaiser...

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

The stages of fasting

What happens to the body when it goes without caloric intake? This article overviews the immediate physical effects of fasting. Within a day of going without food, the body will have used up its glucose stores and ordered the liver and muscles to convert their glycogen (glucose storage) into usable glucose. By the second day, glycogen stores will run out, forcing the body to use fat as energy. This process is known as ketosis.

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.

The history of the McDonald's Happy Meal

The McDonald's Happy Meal is the quintessential fast food kids meal, serving up child-appropriate portions and prizes all within a portable, fun container. So where did this pop culture icon begin? Watch this quirky 13-minute history of the Happy...

What exactly is dopamine?

Dopamine is a neurotransmitter—a chemical released by neurons that enables neural communication—that makes people want things with an "almost animalistic desire," compelling them to snack or check phone notifications. Often misrepresented as a "pleasure" chemical, dopamine is involved in motivation, learning, attention, habit formation, and more. Trends like dopamine fasting overinflate its role in mental health and often use it as part of "straw man" biohacking claims.

The word 'Earth' comes from the German root word for 'ground'

In English, "Earth" means the planet and the land, but many languages identify each with distinct words. Earth is often given a maternal name or one that identifies it as the land of the living.

You can find the value of a dollar dating back to 1635

The value of a dollar hasn’t been consistent throughout history. An inflation calculator lets you compare the value of dollars from any two years over the past four centuries.

401(k) is a section of the US tax code

How did 401(k) plans get their name? Check out the 401(k) section (and subsection) of the US tax code made famous by benefits consultant Ted Benna. Tap into your inner accountant and check out the now-famous portion of the dense, 10,000-section tome that is the Internal Revenue Code.

Explaining computer kernels and what makes monolithic kernels different from microkernels

A kernel is an intermediary piece of software on a device that manages the connection between software programs—the services and processes they perform to run correctly—and the available hardware resources, such as memory and computing bandwidth, including prioritizing resource allocation and managing access to specific hardware. A monolithic kernel manages all of an operating system's services, whereas a microkernel only handles essential services.

How did archaeology come to be?

Archaeology, also spelled archeology, is the scientific study of the material remains of past human life and activities. So when did it become an official body of science? Britannica answers this question and more in this article on the history of...

The term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

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.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

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.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

A century of Billboard issues documenting the evolution of popular music.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

El Niño, Spanish for 'the boy,' was named after Jesus Christ because the phenomenon resembled the weather changes observed around Christmastime.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

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.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

A pickleball's loud 'pop' sound can reach 120 decibels, which is equivalent to a hammer hitting a nail