Physics facts

Explore 12 curated physics facts on ScienceCards. Discover surprising, well-sourced science one card at a time.

• White light is a mix of all visible wavelengths. — White light is a mix of all visible wavelengths. Newton proved this in 1666 by splitting light into a rainbow with a prism, then recombining the colors back into white with a second prism.
• In 1971, Apollo 15’s David Scott dropped a hammer and… — In 1971, Apollo 15’s David Scott dropped a hammer and feather on the Moon. In the vacuum, both hit the surface at the same time, proving Galileo’s idea and supporting Einstein’s equivalence principle.
• Light slows down in water due to water’s polar molecules… — Light slows down in water due to water’s polar molecules and electron clouds delaying light’s energy absorption and re-emission, which increases the refractive index and reduces the speed of light.
• The glow of heated metals is due to black-body radiation… — The glow of heated metals is due to black-body radiation, where temperature determines the light’s color and intensity—a key concept in astronomy, materials science, and lighting.
• Unobserved electrons in the double slit experiment pass… — Unobserved electrons in the double slit experiment pass through both slits as waves, creating interference. Observing them makes the pattern vanish—measurement changes quantum reality.
• Entanglement: Two particles can be "entangled" so that… — Entanglement: Two particles can be "entangled" so that measuring one instantly affects the other regardless of distance. Scientists confirmed this in a 2017 Space-to-Ground experiment.
• Energy cannot be created or destroyed, only transformed… — Energy cannot be created or destroyed, only transformed from one form to another—the total energy in a closed system remains constant.
• 299,792,458 m/s (c) is the universal speed limit built into… — 299,792,458 m/s (c) is the universal speed limit built into spacetime itself. Any massless phenomenon—electromagnetic waves or spacetime ripples—travels at exactly this speed.
• Light can push a solar sail even though photons have no… — Light can push a solar sail even though photons have no rest mass. Momentum comes from energy, not mass alone. A photon's energy gives it momentum (p = E/c), enabling radiation pressure.
• Time runs slower closer to Earth's surface. — Time runs slower closer to Earth's surface. In 2010, NIST physicists confirmed time dilation using atomic clocks separated by just 33 cm—the higher clock ticked measurably faster.
• A lightning bolt is five times hotter than the Sun's… — A lightning bolt is five times hotter than the Sun's surface, reaching 30,000 Kelvin (53,540°F). It forces 20,000–200,000 amperes through a channel only 2–5 centimeters wide.
• Start a current in a superconductor and it flows forever—no… — Start a current in a superconductor and it flows forever—no power source needed. One experiment tracked unchanged current for 2.5+ years. It could theoretically continue indefinitely.