the.com/event horizon
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means The boundary around a black hole beyond which gravity is so strong that nothing, not even light, can escape or ever return.
from Coined in the mid-20th century from plain English words pressed into technical service by physicists working out the math of general relativity — 'event' meaning a point in spacetime, 'horizon' borrowed from the everyday sense of the farthest line you can see, beyond which things simply vanish from view. There's no ancient root to chase; it's a modern scientific metaphor that happened to be perfect on the first try.
- not a surface
- no wall, no edge, just a point of no return
- local view
- crossing it, you would notice nothing unusual at all
- size scales
- bigger mass means bigger horizon, oddly less tidal violence
- time trick
- outside observers see you freeze there, forever, never quite falling