FACTS & DATA
SCIENCE DATA
The Numbers That Describe Our Universe
Physics Constants & Laws
The speed of light in a vacuum is exactly 299,792,458 meters per second (about 186,282 miles per second). It is so fundamental that the meter is now defined in terms of it — one meter is the distance light travels in 1/299,792,458 of a second.
Newton's Second Law states F = ma (Force = mass × acceleration). This single equation governs everything from a falling apple to a rocket launch. It means doubling the mass of an object requires twice the force to produce the same acceleration.
Einstein's E = mc² tells us that mass and energy are interchangeable. The 'c²' factor is enormous — about 9 × 10¹⁶ — meaning a tiny amount of mass converts to a tremendous amount of energy. One gram of matter contains as much energy as 21,000 tons of TNT.
Planck's constant (h ≈ 6.626 × 10⁻³⁴ joule-seconds) is the fundamental quantum of action. It sets the scale of the quantum world — below this scale, classical physics breaks down and quantum mechanics takes over. It appears in the uncertainty principle: ΔxΔp ≥ h/4π.
Astronomy & Space
One light-year is approximately 9.461 × 10¹⁵ meters — about 5.88 trillion miles. The nearest star to our Sun, Proxima Centauri, is 4.24 light-years away. A spacecraft traveling at 40,000 mph (the speed of Voyager 1) would take over 70,000 years to reach it.
The Sun contains 99.86% of all the mass in the solar system. Its diameter is about 1.39 million kilometers — roughly 109 Earths lined up side by side. Every second, the Sun converts about 4 million tons of mass into energy via nuclear fusion.
There are an estimated 2 trillion galaxies in the observable universe, each containing hundreds of billions of stars. The observable universe has a radius of about 46 billion light-years — larger than the 13.8 billion light-year age of the universe because space itself has been expanding.
The International Space Station orbits Earth at about 408 km altitude and 27,600 km/h. At that speed, it completes one orbit every 92 minutes — meaning astronauts aboard see about 16 sunrises and sunsets every 24 hours.
Chemistry & The Elements
Avogadro's number (6.022 × 10²³) is the number of atoms or molecules in one mole of a substance. If you had a mole of sand grains, they would cover the entire surface of Earth to a depth of several meters. This number makes atomic-scale chemistry calculable.
Water (H₂O) has a uniquely high specific heat capacity of 4,182 joules per kilogram per degree Celsius — higher than almost any other common substance. This is why oceans moderate Earth's climate: they absorb enormous amounts of heat without large temperature swings.
The periodic table currently contains 118 confirmed elements. Elements 1–94 occur naturally; elements 95–118 have only been synthesized in laboratories. The heaviest naturally occurring element is uranium (atomic number 92), first isolated in 1841.
Absolute zero — the coldest possible temperature — is −273.15°C (0 Kelvin). At this temperature, atoms would have minimum possible energy. It has never been achieved in practice, though scientists have cooled matter to within billionths of a degree above it.
Biology & The Human Body
The human body contains approximately 37 trillion cells. If you laid all your DNA end to end, it would stretch about 2 meters per cell — meaning the total DNA in your body would reach from Earth to the Sun and back roughly 300 times.
The human brain contains about 86 billion neurons, each connected to thousands of others. The total number of synaptic connections is estimated at 100 trillion — more connections than there are stars in the Milky Way galaxy.
The heart beats about 100,000 times per day, pumping roughly 7,500 liters of blood. Over an average lifetime of 79 years, that is about 2.5 billion heartbeats and 200 million liters of blood pumped — enough to fill over 80 Olympic swimming pools.
Human DNA is 99.9% identical between any two people. The 0.1% difference — about 3 million base pairs out of 3 billion — accounts for all visible human variation: height, eye color, skin tone, and susceptibility to certain diseases.