Understanding the scientific discoveries that fundamentally changed humanity’s understanding of nature, physics, biology, and the universe.
Flashcards combined with spaced repetition improve active recall. You review at the right time, retain knowledge longer, and track progress card by card.
Card 1
Mass product and inverse-square distance.
Explanation
Newton’s law says every pair of masses attracts with a force proportional to both masses and inversely proportional to the square of the distance.
Common mistake
Thinking gravity depends only on one mass or only on distance, not both.
Card 2
It stays at rest or moves uniformly.
Explanation
Newton’s first law (inertia) states that without a net force, motion does not change.
Common mistake
Believing a force is required to keep an object moving at constant speed.
Card 3
Light is an electromagnetic wave.
Explanation
Maxwell’s equations predicted waves of electric and magnetic fields traveling at the speed of light, identifying light as electromagnetic.
Common mistake
Thinking Maxwell only described electric charges without relating them to light.
Card 4
The speed of light in vacuum.
Explanation
Einstein postulated that the speed of light is constant for all inertial observers, leading to time dilation and length contraction.
Common mistake
Assuming the speed of light should add to the observer’s speed like ordinary velocities.
Card 5
Spacetime curvature caused by mass and energy.
Explanation
Einstein described gravity as matter telling spacetime how to curve, and spacetime telling matter how to move.
Common mistake
Thinking general relativity simply adds a new force instead of redefining gravity as geometry.
Card 6
Energy comes in discrete quanta.
Explanation
Planck’s idea that energy comes in quanta launched quantum theory and fixed the ultraviolet catastrophe problem.
Common mistake
Assuming Planck still treated energy as perfectly continuous at all scales.
Card 7
Atoms contain tiny negatively charged particles that can be separated from them.
Explanation
Thomson’s cathode ray experiments showed that atoms have internal structure, overturning the idea of indivisible atoms.
Common mistake
Thinking the discovery of the electron immediately gave the full modern atomic model.
Card 8
Their light is redshifted in proportion to their distance from us.
Explanation
Hubble’s redshift–distance relation showed that space itself is expanding, leading to the modern Big Bang picture.
Common mistake
Believing galaxies move through fixed space instead of space itself expanding.
Card 9
Those with advantageous heritable traits.
Explanation
Darwin and Wallace proposed that advantageous inherited variations spread because their bearers reproduce more successfully.
Common mistake
Thinking evolution is driven by organisms trying to adapt rather than by differential survival of variants.
Card 10
It is hidden in appearance but can reappear in later generations.
Explanation
Mendel’s work showed that traits are carried by discrete factors, with recessive alleles masked but not destroyed in hybrids.
Common mistake
Believing recessive traits vanish instead of being carried silently in hybrids.
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