How facts, hypotheses, theories, and laws in science differ from everyday language

Distinguishing between scientific theories and laws, and why both are on equal footing

Scientific laws describe outcomes of specific conditions, and scientific theories explain why those outcomes occur. Both are supported by observational and experimental data and can each inform one another, but neither can become the other. Instead, additional data can improve each towards more accurate descriptions and explanations of reality.

Learn why modern scientific patterns have been described as theories rather than laws

After confirming that the accuracy of some laws of physics is limited to certain domains, science became more hesitant to categorize identified mathematical relationships, such as quantum mechanics, as unchanging laws. Instead, these recent, complex frameworks are designated as theories to acknowledge that they are conditional and may be part of a larger, more complete future framework.

Why being able to disprove explanations distinguishes scientific theories from pseudoscience

Introduced by philosopher Karl Popper, falsifiability holds that a scientific theory must make predictions that could be proven inaccurate by future observations. Explanations that cannot make such predictions are not scientific theories. It is scientists' jobs to seek out data to poke holes in scientific theories, thereby potentially strengthening them if they hold up to scrutiny.

Scientific progress works toward absolute truth, but can never reach it

Through the acquisition of scientific knowledge, scientists construct explanations of the world, which are rigorously tested and verified until they narrow down to a leading theory of the natural world. However, because of how science works, these ideas will never become factual, as they must always remain open to be iteratively revision based on new data.

Science is rarely a linear progression of understanding

Particularly at the frontiers, investigations conducted based on established knowledge can provide unexpected results. This opens the door to revising existing models, inspiring new lines of research, and ultimately leading to better future comprehension. For instance, experiments on the speed of light and the expansion of the universe yielded then-confusing data that led to revolutionary insights.

A list of five scientific theories that were accepted and later disproved

Humoral theory held that everyone's personality derived from different combinations of four bodily fluids: blood, phlegm, yellow bile, and black bile. The phlogiston theory stated that all combustible materials possessed a fire element—phlogiston—that was released and absorbed by the air during burning. When the air became saturated with phlogiston, the fire would go out.

Language is evolution's great mystery

What we call language is something more specific than communication. Language is about sharing what’s in our minds: stories, opinions, questions, the past or future, imagined times or places, ideas. So what does language mean for humanity, and how did we come to have it? Watch this brief video to discover more.

The simple grandeur of atomic theory

Is the universe made up of a continuous substance, or a finite amount of tiny, indivisible atoms? The atomic hypothesis, largely vindicated in the 20th century, was forgotten for nearly 2,000 years after first being formulated by the Greek philosopher Democritus. Learn more about the theory and its implications for science and human life with this reflective essay.

Particle interactions follow rules related to specific quantum properties

Like a business whose purchased inventory matches sold inventory, physicists identified specific patterns across decades of particle accelerator data, which became new conservation laws for elementary particles. These laws help identify which particle decays are expected or forbidden.

Using scientific bets, Hawking challenged and highlighted major physics ideas

Hawking famously placed wagers on high-stakes questions in theoretical physics—such as the Higgs boson—for fun and to draw attention to science. When Hawking lost a bet about Cygnus X-1 being a black hole, he paid up with a magazine subscription.

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.

Fearology, or the study of fear, explores the difference between stress and fear

Our brains involuntarily respond to our environment and signal alarm when that isn’t always needed, triggering responses that include goose bumps. But understanding fear and how to talk our brains into calming down can improve daily life.

Critics say Nobel Prizes need updating to reflect how science and society work today

The rules still favor individuals over teams and may reflect outdated views on who does science. In 2013, the Nobel Prize in physics went to two theorists, even though over 5,000 scientists helped confirm the Higgs boson.

Fantasy is heavily influenced by myths, legends, and folk tales

In fantasy, anything is possible, mirroring the supernatural worlds of history’s earliest stories. The narrative voice of fantasy is often similar to early tales, too, with an affinity for the magisterial rather than the contemporary.

Is time travel really possible?

The laws of physics, as currently understood, don’t categorically reject the possibility of time travel. But, scientists are skeptical, especially when it comes to traveling to the past. Hopping between past, present and future would require the world to have some wacky yet-to-be-discovered physical properties like negative mass, negative energy, and infinite density. Time travel also introduces philosophical questions about free will, causality, and chronology.

Spectroscopy lets scientists analyze an object's light to determine its properties

By separating the light spectrum into its component wavelengths and comparing them to what is expected based on Earth-based experiments, we can determine an object's temperature, elemental and molecular composition, and motion through space.

Statistically speaking, aliens likely exist, but we still haven't found any evidence of them

The Fermi paradox addresses this discrepancy between the lack of evidence of alien life despite the high likelihood of its existence. Physicist Brian Cox offers various theories, like the extinguished civilizations hypothesis, for why we have never found any extraterrestrial neighbors.

Authentic storytelling and audience awareness drive effective science communication

Bill Nye suggests that making people care about science requires limits on technical jargon, ensuring content is relatable to viewers, and injecting some comedy to help make the ideas stick. Having clear learning objectives can help educators stay on track and efficiently write content.

Research studies can be conducted inside or outside of living samples

While "in vitro" experiments occur outside living organisms for cost-effectiveness, "in vivo" experiments take place inside them, providing real-life insights at a higher cost and with increased ethical concerns. Alternatively, "in silico" methods use computational simulations.

What's the difference between weather and climate?

A five-minute TedEd video exploring the differences between weather and climate – what they are, how we predict them, and what those predictions can tell us.

Paleontologists apply rules about rock layering, fossilization, and radioactivity to date geological samples

Concepts such as the understanding that older rock layers will form beneath newer ones allow scientists to compare the ages of samples from various layers. Although no geological site preserves evidence across all time, samples can be combined with fossils of known age, such as those dated by analyzing the decay of their radioactive isotopes, to reconstruct Earth's timeline.

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

Large language models are examples of foundation models

Such models are trained on massive amounts of data, which enable them to perform a variety of tasks, rather than being provided task-specific data to complete a narrow function. Such models come with high compute costs and potential trust issues due to the nature of their unorganized training data.

Find out the difference between prediction markets, sports betting, and investing

As one expert put it, "investing is a long-term strategy to build wealth over time, speculation is an attempt to predict the future, and gambling is a game of luck."

US federal law dictates that all ads must not be deceptive

It also dictates that all ads must be “not misleading, and, when appropriate, backed by scientific evidence.” However, enforcing these laws can be difficult given the massive number of ads that run all over America each day. This explainer on the subject from the FTC provides more information.

Hip-hop lyrics are often used in criminal trials, blurring the line between art and evidence

Song lyrics from other genres are rarely used by prosecutors, but it's commonplace for hip-hop and rap. Legal scholars and rap artists say that's a problem, and that it fundamentally misunderstands the music by interpreting artistic expression as absolute fact.

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

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

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

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

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

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

See how fireworks are made and learn how metals like magnesium and copper are responsible for different colors.

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.

The Brothers Grimm were lawyers before they were storytellers, but became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

Learn how to read a prospectus, the juicy document that any company must file with the SEC before going public.

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.

How the most famous Ebola book, The Hot Zone, which sold 3.5 million copies and was translated into 30 languages, got aspects of the disease so wrong.

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

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

The rivalry between Alexander Hamilton and Thomas Jefferson centered on federalism—the question of how much power the federal government should hold relative to the states.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

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.