Part A · the number scale — feel the gaps between orders of magnitude
From 1 to 1 trillion — with real anchors at every step
Each row is 1,000× the one above it. That gap never gets smaller.
1
one
1,000
one thousand
1 million
11.5 days in seconds
1 billion
31.7 years in seconds
1 trillion
31,700 years in seconds — before end of Ice Age
Thousand (10³)
~1,000 people
A village. Fits in a small theatre.
Million (10⁶)
~1M people
A medium city (e.g. Birmingham, Prague).
Billion (10⁹)
~1B people
China or India. ~⅛ of humanity.
Part B · the cosmic time scale
How old is everything? (years ago)
Compressed to a single bar. Human history is invisible at this scale.
Big Bang
13.8 billion years ago
Earth formed
4.5 billion years ago
First life on Earth
~3.8 billion years ago
Dinosaurs extinct
66M yrs
First humans (Homo sapiens)
300K yrs
First writing / cities
~5,500 yrs
If Earth's entire history = 1 year, humans appeared on December 31st at ~11:25pm. All of recorded history — Egypt, Rome, the Renaissance, everything — fits in the last ~35 seconds of that year.
The Cosmic Calendar — Earth's year as one year
Each month = ~375 million years. Each day = ~12.3 million years. Each second = ~143 years.
1M seconds = 11.5 days · 1B seconds = 31.7 years · 1T seconds = 31,700 years
A lifetime in weeks — 4,160 dots
Each dot = one week of an 80-year life. Each row = one year (52 weeks).
Lived (age slider)
Remaining
Age: 30
Your age across the solar system
Earth years
Each planet's year = the time it takes to orbit the Sun. Your biological age doesn't change — only the unit does.
Part D · interactive number sense — compare anything
Enter any number and see it in context.
Part E · global time zones — the world's clocks right now
Live clocks — major world cities
UTC offsets are fixed references. Daylight saving adjustments shown where applicable.
☀ = daytime (6am–8pm local) · ● = night
The UTC offset spectrum — West to East
The world spans UTC−12 to UTC+14, a total of 26 hours. Yes, two calendar days exist simultaneously.
Odd fact: The International Date Line means two calendar days always exist simultaneously on Earth. When it's Sunday morning in Samoa, it's still Saturday afternoon in American Samoa — two territories just 100 km apart, separated by a day.
Time zone converter
Pick two cities and a time — see both clocks side by side.
Time
From
To
Things worth knowing about time zones
History
Time zones were only standardised in 1884 at the International Meridian Conference. Before then, every town set its own "local solar time." When the US had 300+ local times, running railways was chaos.
Oddities
China uses a single time zone (UTC+8) across its entire territory — meaning sunrise in western Xinjiang can occur at 10am "local" time. India's UTC+5:30 and Nepal's UTC+5:45 are both half/quarter-hour offsets from the standard hourly grid.
DST
Daylight Saving Time is observed by about 70 countries, mostly in Europe and North America — but not by most of Africa, Asia, or equatorial regions where day length barely changes year-round. The twice-yearly shift costs an estimated ~$434M in US productivity alone.
Space
The International Space Station uses UTC year-round. Astronauts experience ~16 sunrises per day (orbiting every 90 minutes), making "time zones" completely meaningless. Mars missions will use "Mars Solar Time" — a Martian day (sol) is 24 hours, 39 minutes, 35 seconds.
Part F · the psychology of time — why time doesn't feel equal
Why your childhood felt longer than your 30s
The "proportional time" hypothesis: a year feels shorter as you age because it represents a smaller fraction of your total lived experience. To a 5-year-old, one year is 20% of everything they've ever known.
This is called the logarithmic time perception model. The emotional weight of a year shrinks as your denominator (total years lived) grows. A practical implication: if you want a year to feel long, fill it with new experiences. Novelty forces your brain to form more distinct memories, making the period feel denser in retrospect.
What makes time feel fast or slow
Faster
Flow states — deep focus on enjoyable tasks compresses perceived time dramatically. A programmer "in the zone" may lose 3 hours feeling like 30 minutes.
Faster
Routine and repetition. When each day is similar to the last, the brain stops forming distinct memories. A repetitive month is compressed into a single undifferentiated blur in memory.
Slower
Fear and danger. Adrenaline and noradrenaline increase the brain's sampling rate — more sensory detail per second is encoded. Survivors of accidents often report the event felt "like slow motion."
Slower
Boredom and waiting. Attention is focused on time itself, making each second feel longer. The paradox: a boring afternoon feels slow in the moment but short in retrospect (few memories formed).
Body temp
Higher body temperature speeds up your internal clock. During fever, time feels slower (more subjective moments per real-time second). Cold slows the internal clock — time feels faster.
Your "felt" lifetime — how long has life actually felt?
Using the logarithmic model: your felt age is proportional to log(actual age). We normalise to age 18 as the baseline of adult perception.
Part G · historical time — how recent everything is
Zooming in: the last 5,500 years
On this scale — 5,500 years total — modern history is shockingly recent. Each segment below is proportional.
History is shallower than you think — in human generations
At ~25–30 years per generation, a chain of surprisingly few people connects the present to antiquity. This makes history feel viscerally close.
To Julius Caesar (~44 BCE)
~82
generations of 25 years
To the pyramids (~2560 BCE)
~186
generations of 25 years
To first writing (~3400 BCE)
~216
generations of 25 years
To Homo sapiens (300K yrs)
~12,000
generations of 25 years
The handshake thought experiment: If every generation could shake hands with the next, you could shake hands with someone who shook hands with Caesar in about 164 people. To reach the builders of Stonehenge (~3000 BCE) takes about 200 handshakes. That's fewer people than fit in a large lecture hall.
Part H · calendars of the world — how humans have counted time
Why do so many calendars exist?
Every calendar is a civilisation's answer to the same three astronomical cycles: the solar year (~365.25 days), the lunar month (~29.53 days), and the day. Because these cycles do not divide evenly into each other, every calendar system involves a compromise -- and different cultures made different choices. Today more than 40 calendar systems are in active use worldwide.
Solar calendars
Track the Sun. Seasons are stable. Gregorian, Persian Shamsi.
Lunar calendars
Track the Moon. Months drift through all seasons over ~33 years. Islamic Hijri.
Lunisolar calendars
Track both, inserting leap months to re-sync. Hebrew, Chinese.
Five major calendars in depth
Year length comparison -- solar vs lunar drift
Over 33 years, a pure lunar calendar loses a full year relative to the solar calendar. This is why Islamic holy months cycle through all seasons.
Today's date in every major calendar
The same moment on Earth, expressed in five different counting systems. Pick any Gregorian date to see it converted.
Things worth knowing about calendars
Gregorian
The Gregorian calendar was introduced by Pope Gregory XIII in 1582 to fix a 10-day drift in the Julian calendar. Catholic countries switched immediately; Protestant Britain did not adopt it until 1752 -- by which point 11 days had to be dropped. People rioted in the streets shouting "Give us back our 11 days."
Islamic
Because the Hijri year is 11 days shorter than the solar year, Ramadan shifts through all seasons in a cycle of roughly 33 years. A Muslim born in 1990 will have experienced Ramadan in summer, autumn, winter, and spring before age 33. This is considered theologically significant: everyone must experience fasting under both easy and hard conditions.
Persian
The Persian Shamsi calendar is widely considered the most astronomically accurate calendar in regular use. Its leap year rule -- adding a leap day in specific patterns over a 2,820-year grand cycle -- keeps it within one day of the true solar year for that entire period, compared to the Gregorian calendar's periodic drift. Nowruz (New Year) always falls on or within one day of the March equinox.
Hebrew
The Hebrew calendar inserts a 13th "leap month" (Adar II) in 7 out of every 19 years -- the Metonic cycle, which nearly perfectly synchronises the solar and lunar cycles. This ensures Jewish holidays always fall in the same season: Passover is always in spring, Sukkot in autumn.
Chinese
The Chinese lunisolar calendar underlies one of the world's most famous cultural cycles: the 12-year animal zodiac (rat, ox, tiger...) combined with a 10-stem cycle producing a 60-year "sexagenary cycle." The calendar also defines 24 solar terms (jieqi), which historically guided agricultural decisions. Chinese New Year falls between January 21 and February 20 each year -- the second new moon after the winter solstice.
Part I · test yourself — time estimation game
How well-calibrated is your sense of time?
8 questions on durations, gaps, and historical distances. Choose the best answer.
Score:
0 / 0
Part J · Q&A
1. Someone says "I've been alive for about a billion seconds." How old are they?
About 31.7 years old. 1 billion seconds ÷ 31,536,000 seconds per year ≈ 31.7 years. This is a great party trick — you hit your "billion second birthday" around age 31 years and 8 months. Most people in their 30s have lived almost exactly 1 billion seconds.
2. The universe is 13.8 billion years old. Humans have existed for 300,000 years. What percentage of cosmic time have we been here?
About 0.0022%. 300,000 ÷ 13,800,000,000 = 0.0000217 = 0.00217%. Rounded: roughly 2 thousandths of a percent. All of human existence — every war, every civilization, every person who ever lived — occupies less than 1/45,000th of cosmic time. And recorded history (5,500 years) is just 1/360th of even that tiny slice.
3. A news story says a government spent "$2 trillion on infrastructure over 10 years." How does that compare to what you now know?
$200B per year. To calibrate: that's roughly twice Apple's annual profit, about 0.7% of US GDP, and enough to build ~150 Golden Gate Bridges per year. It sounds enormous — and it is — but spread over 10 years across a large country's entire infrastructure, it's actually a moderate commitment. The USA spends roughly $900B/year on its military alone for comparison.
4. Your friend says "I walked 10,000 steps today." How far is that in km, and how long did it take roughly?
About 7–8 km, taking roughly 1.5 hours. One step ≈ 0.75 m, so 10,000 steps ≈ 7.5 km. Walking speed is ~5 km/h, so 7.5 km ÷ 5 = 1.5 hours. This is a useful anchor: 10,000 steps ≈ 7.5 km ≈ 90 minutes of walking. It also burns roughly 300–400 calories — about the same as a Mars bar.
5. Final challenge: Apple has a market cap of ~$3 trillion. The world's population is 8.2 billion. If Apple's value were divided equally among all humans, how much would each person get?
About $365 each. $3,000,000,000,000 ÷ 8,200,000,000 ≈ $366. One year's worth of Apple's entire market value, spread across every human alive, gives each person roughly enough to buy a mid-range phone — ironically, perhaps an iPhone. This illustrates how concentrated wealth is: the entire value of the world's most valuable company amounts to about one modest purchase per person on Earth.
6. If you slept 8 hours a night for 80 years, how many years of your life would you spend asleep? And how does that compare to time spent eating?
About 26.7 years asleep -- exactly one third of your life. 8h / 24h = 33.3% x 80 years = 26.7 years. Eating takes roughly 1-1.5 hours per day, so ~3.3-5 years of your life. Working 8h/day, 5 days/week from age 22-65 consumes about ~11 years. This leaves roughly 27 years of "waking, non-working" time -- the time you are actually free to use as you choose over a lifetime.
7. Today's date in the Gregorian calendar is 2025. What is the approximate equivalent year in the Islamic Hijri calendar, the Hebrew calendar, and the Persian Shamsi calendar?
In the Islamic Hijri calendar, 2025 CE corresponds to approximately 1446-1447 AH. The Hijri calendar is a pure lunar calendar of 354 days per year, so it gains roughly one Gregorian year every 33 years -- the year count is currently about 579 years behind the Gregorian. In the Hebrew calendar, 2025 CE is approximately 5785-5786 AM (Anno Mundi, "year of the world"), counting from the traditional date of creation. In the Persian Shamsi calendar, 2025 CE corresponds to 1403-1404 SH. The Shamsi calendar began counting from the Hijra (622 CE) but uses solar months, which is why it and the Hijri calendar share the same epoch but have very different year numbers today -- the solar Shamsi year stays aligned to seasons, while the lunar Hijri year drifts through all seasons over a 33-year cycle.