A 2,000-year history of alarm clocks

Early timekeeping tools included sundials, water clocks, and astrolabes

Astrolabes also provided a person's latitude based on the height of the stars in the sky, thus aiding in navigation. Incense and candle clocks relied on the constant burning rate of fire to track the passage of time based on premarked locations with equal-interval spacing.

Chronobiologists study the effect of time on biological cycles

Circadian rhythms were first observed in the 1700s, when French astronomer Jean-Jacques D'Ortous de Mairan put a plant in a dark room and watched it still respond to day and night cycles, setting off further studies about specific light-dark biological cycles, an area of inquiry that continues today with the human "clock proteins" at the molecular level.

A history of raising the alarm, from rattles to 911

Because fires spread so quickly, communities around the world have deployed many tactics to raise the alarm to get help. This history from the Museum of Natural History dives into the use of rattles, bells, and brigades to gather help to fight fires, showing just how far we've come since 911 was introduced in 1968.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The origins of our fascination with time travel

Humans have been captivated by the prospect of leaping forward and backward in time for thousands of years. Georgia Institute of Technology Science Fiction Studies Professor Lisa Yaszek recounts how the concept has been utilized by storytellers from 400 BCE to modern-day to explore our relationship with the supernatural, technology, and the past. In a way, this historical recounting is a journey through time.

The extreme precision of atomic clocks highlights gravitational time dilation

Scientists at the National Institute of Standards and Technology have constructed clocks made out of stacked strontium atoms, which show differences in the passage of time across just a millimeter of height consistent with predictions from general relativity, where atoms closer to Earth's center tick off time more slowly.

The world's different calendars, explained

The calendar we use to mark the days, months, and year can feel set in stone, but the history of calendars shows these organization systems can and do change. Parse the fascinating, complex details of the Gregorian, Julian, Chinese, Hebrew, and many more calendars in this comprehensive, well-executed explainer video.

Mechanical watches measure the passage of time via the vibration of a quartz crystal

When electricity from a battery passes through the crystal inside a watch, the crystal vibrates, creating an electrical signal with a precise frequency of one vibration per second. This signal moves the hand of the watch so that it ticks once per second, allowing it to track the passage of time.

At the age of seven, Grace Hopper dismantled alarm clocks

Foreshadowing a career in computers, Hopper exhibited a curiosity for gadgets at a young age and took apart seven clocks, determined to understand how they worked. Despite having a dollhouse, Hopper built an elevator for it and showed a greater interest in building toy furniture than playing with dolls.

Charting 4,000 years of human history

Care to hang all of human history on your wall? This data visualization charts 4,000 years of humanity. This "histomap" was originally published in 1931 and sold for $1 per copy of the 5-foot-long chart. It was said to detail the course of...

From bartering to banking, temples to electronic transactions, here’s banking has evolved significantly since ancient times

A few historical facts about banking (like that one day, not long ago, certificates of deposit were physical pieces of paper) may not surprise you. But did you know that the church was the original lender? And that Julius Caesar himself invented foreclosure?

The Middle Ages produced inventions that still our lives today

Far from a “Dark Age,” the medieval era brought about significant innovations—from the printing press and mechanical clocks to navigational tools and early computing devices. This curated list of inventions demonstrates how profoundly medieval creativity has shaped the modern world.

The first printed Advent calendars were from Germany in the early 1900s

Printed Advent calendars originated in early-20th-century Germany, where printer Gerhard Lang created the first commercially produced versions. Inspired by his mother’s homemade countdowns, Lang added small doors in the 1920s, establishing the format that spread worldwide.

See a timeline of commercial radio history

Radio, as we know it, began in the 1910s. This FCC timeline traces the evolution of the medium over the century that followed, highlighting groundbreaking broadcasts, speeches, and technological breakthroughs.

Read an oral history of the Y2K panic

This oral history brings together programmers, engineers, and officials who first identified the date flaw and then spent years alerting the public to the danger and racing to repair millions of lines of code.

The history of metallurgy: an interactive timeline

Humans have long been shaping metals into useful tools and aesthetic accessories. By 8,700 BCE, humans already had mastered four types of casting copper. Within a few thousand years, people were combining metals to make the alloy bronze and had...

For most of recorded history dreams were considered divine in origin

The first venture into modern dream interpretation may have been when ancient Greek philosopher Heracleitus proposed dreams were created within the mind. In the late 1800s, the rise of psychoanalysis theorized that dreams content revealed truths about one's psyche, while the invention of the electroencephalogram linked dreams to brain functions.

Get lost in these historical libraries

The internet has changed a lot about how we learn, explore new ideas, and conduct research, particularly when it comes to the spaces we learn in. While few of us would trade our smartphones for a walk in a historical library, a walk through some of the beautifully designed cathedrals of learning could remind us to put them down sometimes. Explore 10 of the world's magnificent libraries with this quick video survey.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

Sleep is often viewed individually, when its impact and meaning may be more communal

At any given point, roughly 2 billion people may be asleep on Earth. The typical scientific description of sleep focuses on its individual impact, but the phenomenon shapes whole cultures and eons. This essay prompts a fresh rethinking of the importance of sleep for humanity.

Some colonies were centuries-old before they broke from Britain

The revolution did not happen overnight, but was a culmination of centuries of settlement, policies, and war in North America. This timeline provides key, fascinating events from the 1600s through the Revolution in a smooth, easy-to-read interface.

Watch a video about how cellphones conquered the world

A fight with a telecom giant. A stunt call on a New York sidewalk. A forgotten memo that rewired the world. Host Sony Kassam sits down with Marty Cooper, the father of the cellphone, and Arlene Harris, the first lady of wireless, to explore the innovation, politics, and high-stakes battles that pried connectivity out of corporate control, unlocked the airwaves, and built the always-on world we live in today, for better or for worse.

Why human brains were bigger 3,000 years ago

Our modern civilisation may be the most advanced to ever exist on Earth, but around 100 generations ago, our ancestors had brains that were larger than our own.

The history of China: a timeline

How long has China existed, and how and when did it evolve into its form? Explore the journey of China from empire to republic (to a republic, again) in this timeline. Archaeological evidence suggests the earliest Chinese dynasty formed at about...

A brief history of Christmas tree design

A celebration of the Christmas tree in all its festive glory. Get a glimpse into its intriguing background and the lore that accompanies it.

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.

What Stonehenge sounded like

Researchers built the first scale model of the world's best-known prehistoric stone circle, Stonehenge, to study its acoustic properties. Built approximately 5,000 years ago, the landmark in southern England has puzzled historians for centuries, but...

The Wall Street Journal: a timeline

The Wall Street Journal got its start as a financial news bulletin for people trading stocks. Since then, it has evolved beyond just financial news. It now ranks among the preeminent global business news sources.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

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

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

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.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

20,000 letters to the advice columnist 'Dear Abby' provide insight into prevailing sex, religion, and LGBTQ fears, anxieties, and concerns from the 1950s onward.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

After the Boston Tea Party, colonists switched to coffee, which became the main morning drink for revolutionaries.

The first horror movie is believed to be George Méliès' 1986 short 'The Haunted Castle,' which pioneered the use of special effects

See these 16 pieces of art evoking phobias of snakes, flying, spiders, and more. 

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

Stanford built a Google Maps for the Roman Empire, revealing how much it cost to travel in the ancient world

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

Explore a list of the 100 best novels of all time, compiled by some of the world's best living writers, including Salman Rushdie, Stephen King, and Jennifer Egan.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

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

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

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Exploring the Larry Bird punch that almost changed March Madness