Science
How Well Do You Really Know Gravity?
Newton's apple was just the beginning. Gravity is the weirdest force in the universe.
Newton's apple was just the beginning. Gravity is the weirdest force in the universe.
Without Einstein's general relativity corrections, GPS satellites would drift by about 10 kilometers per day — making your phone's map essentially useless. This quiz draws from a pool of 50 questions covering everything from Newton's falling apple to LIGO's detection of gravitational waves, with each attempt randomized so no two rounds are the same.
Each round presents 10 multiple-choice questions. Pick your answer, get instant feedback with a detailed explanation, and see your final score at the end. No signup or timer — just you and the force that keeps the universe together.
Questions span Newton's Universal Law of Gravitation, Einstein's revolutionary insight that gravity is curved spacetime, how LIGO detected ripples in space from colliding black holes 1.3 billion light-years away, what spaghettification does to anything falling into a black hole, and why astronauts on the ISS are not truly weightless — they are in constant freefall with 90% of Earth's gravity still acting on them.
Newton described gravity as a force of attraction between any two objects with mass, proportional to their masses and inversely proportional to the square of the distance between them. Einstein's general relativity refined this picture: massive objects curve the fabric of spacetime, and other objects follow those curves. We feel this curvature as gravity.
Newton treated gravity as an invisible force acting instantaneously between masses. Einstein replaced this with a geometric model: mass and energy curve spacetime itself, and objects move along the straightest possible paths (geodesics) through that curved spacetime. Einstein's theory explains phenomena Newton's cannot, such as the bending of light around massive objects and the precise orbit of Mercury.
Gravitational waves are ripples in the fabric of spacetime caused by the acceleration of massive objects, such as two black holes spiraling into each other. Predicted by Einstein in 1916, they were first directly detected by the LIGO observatory in September 2015. The signal came from two black holes merging 1.3 billion light-years away, and the measurement was smaller than one ten-thousandth the width of a proton.
Last updated: March 2026