Relativity and Quantum Weirdness
Key ideas from special and general relativity and the opening of quantum physics.
Keyboard Shortcuts
💡 Pro tip: Use keyboard shortcuts for faster studying!
Study Smart Tips for Relativity and Quantum Weirdness
Master these concepts using proven study techniques that actually work:
Active Recall
Test yourself before flipping each card to strengthen memory retention
Spaced Repetition
Review difficult cards more frequently than easy ones
Multiple Sessions
Break study time into shorter, focused sessions
Explain Aloud
Verbalize answers to reinforce understanding
Questions Covered in This Set
11 cards to master
What two experimental 'cracks' broke classical physics around 1900?
Light's speed refusing to change with observer motion (Michelson–Morley), and hot objects glowing the 'wrong' color (blackbody radiation).
What were Einstein's two postulates of special relativity (1905)?
(1) The speed of light in vacuum is the same for all observers; (2) the laws of physics are the same for all observers moving at constant velocity.
What is time dilation, and what factor governs it?
A moving clock ticks slow by the Lorentz factor γ = 1/√(1 − v²/c²) — 0.5% at 10% of c, a factor of 7 at 99% of c.
What is length contraction?
A moving ruler is shortened along its direction of travel by the same factor γ.
What does the relativity of simultaneity say?
Two events simultaneous for you are not simultaneous for someone moving past you — there is no universal 'now'.
What does E = mc² mean physically?
Mass is a form of energy; this is why the Sun converts ~4 million tonnes of itself into sunlight each second.
How do cosmic-ray muons prove relativity is real?
They live only ~2.2 microseconds (~660 m of travel) yet reach detectors kilometres down — their clocks run slow in our frame, and the atmosphere is contracted in theirs.
Why does GPS need relativistic corrections?
Satellite clocks lose ~7 µs/day to speed and gain ~45 µs/day to weaker gravity; uncorrected, positions would drift ~10 km per day.
What was Einstein's 'happiest thought' and the equivalence principle?
A person in free fall feels no weight — being in a gravitational field is locally indistinguishable from accelerating.
How does general relativity (1915) explain gravity?
Mass and energy curve four-dimensional spacetime, and objects follow the straightest paths through that curvature — Wheeler: 'spacetime tells matter how to move; matter tells spacetime how to curve.'
Name four confirmed predictions of general relativity.
Starlight bending around the Sun (1919), clocks slowing in gravity wells, Mercury's orbital precession, black holes and gravitational waves (LIGO, 2015).
