Einstein's Masterwork · 1905 – 1915
Four dimensions, woven together — where mass curves geometry, and geometry commands motion.
The Fabric
Before Einstein, space was the stage and time the clock. After him, they became inseparable actors in the same play.
Hermann Minkowski, Einstein's former mathematics teacher, fused the three dimensions of space with time into a single four-dimensional manifold: spacetime. An event is not merely where something happened, but also when — a single point in this unified fabric.
Massive objects don't simply sit in space — they curve it. This curvature tells matter how to move, and moving matter tells space how to curve. John Wheeler summarised it perfectly: gravity is geometry.
Four Pillars
01 / SPECIAL
No matter your speed or direction, light always travels at c = 299,792,458 m/s. This single postulate unravels time and space as we knew them.
02 / DILATION
Time passes more slowly for a moving object relative to a stationary observer. GPS satellites must correct for exactly this effect — without it, navigation errors accumulate by kilometres daily.
03 / MASS-ENERGY
Mass and energy are interchangeable. A tiny amount of mass is equivalent to an enormous quantity of energy — this equation underpins both nuclear power and stellar fusion.
04 / GENERAL
What we feel as gravity is simply objects following the straightest possible path through curved spacetime — a geodesic. The Earth curves spacetime; the Moon simply follows the curve.
Time Dilation
Send your twin on a journey at near-light speed. When they return, they will have aged less than you.
This is the Twin Paradox — not truly a paradox, but a genuine relativistic effect. The Lorentz factor γ tells us exactly how much time dilates. At 99% the speed of light, your twin ages over 7 times slower than you.
This is not science fiction. Muons created in the upper atmosphere survive their journey to Earth's surface only because their internal clocks tick slowly relative to ours.
"The distinction between past, present and future is only a stubbornly persistent illusion."— Albert Einstein
Adjust the velocity to see how time slows for the traveller.
History
1887
Attempts to detect the "luminiferous aether" fail utterly, planting the seed for a new understanding of light's constancy.
1905
Einstein's annus mirabilis. Five revolutionary papers, including the special theory of relativity and E = mc².
1915
The field equations describing how mass-energy curves spacetime, completing Einstein's geometric theory of gravity.
1919
Starlight bends around the Sun exactly as predicted. Einstein becomes a global celebrity overnight.
2015
LIGO detects ripples in spacetime from two colliding black holes — a billion light-years away, exactly as predicted a century earlier.
2019
The Event Horizon Telescope captures M87* — a shadow cast on the glowing fabric of spacetime itself.
Constants
| Symbol | Constant | Value |
|---|---|---|
| c | Speed of light | 2.998 × 10⁸ m/s |
| G | Gravitational constant | 6.674 × 10⁻¹¹ N·m²/kg² |
| h | Planck constant | 6.626 × 10⁻³⁴ J·s |
| γ | Lorentz factor | 1/√(1 − v²/c²) |
| t' | Dilated time | t / γ |
| Λ | Cosmological constant | 1.1 × 10⁻⁵² m⁻² |
Consequences
Every time you use GPS navigation, you're relying on corrections for both special and general relativistic effects — satellites move fast (special), and sit in weaker gravity (general). Without both corrections, your phone's position would drift by over 10 km per day.
Black holes, gravitational waves, the expanding universe, the precession of Mercury's orbit, gravitational lensing — all emerge naturally from Einstein's field equations. No tweaks. No patches. Just geometry.