Card 1 of 9: Entropy and the Second Law of Thermodynamics
Clausius gave disorder a name and a law in 1865: entropy only goes up. It's the reason ice melts but never un-melts — the only physical law that points in a single direction, forward.
A 26-year-old patent clerk rewrote physics in 1905 without a lab or a university post — showing space and time bend depending on your speed relative to what you're observing.
In 1929, using the 100-inch telescope at Mount Wilson, Hubble measured something nobody had confirmed before: the farther away a galaxy is, the faster it's flying away from us. Run that expansion backward, and everything converges.
Two Bell Labs engineers trying to eliminate radio noise from a satellite antenna in 1965 couldn't get rid of a faint hiss no matter what they cleaned. It turned out to be leftover heat from the birth of the universe.
A decade after special relativity, Einstein extended the theory to acceleration and gravity, replacing Newton's invisible pulling force with something stranger: mass literally bends the shape of space and time around it.
The Big Bang wasn't Hubble's idea. In 1927, a Catholic priest who also held a physics doctorate proposed the universe expanded from an initial dense state — before most physicists, including Einstein at first, took it seriously.
Heisenberg showed in 1927 that some pairs of properties in nature — like a particle's exact location and exact speed — can never both be known precisely at once. Not because measurement is imperfect, but because reality itself doesn't have both values pinned down simultaneously.
A meteorologist rerunning a weather simulation in 1961 rounded one input from six decimal places to three, expecting a negligible difference. The forecast came out completely different — and chaos theory was born.
In a three-page follow-up to special relativity, Einstein asked a small question — does a body's energy content affect its mass — and derived the most famous equation in physics: E=mc².