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课程 11 · 年级 7–10
Black holes and dark matter
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A black hole is a region where gravity is so strong that not even light escapes. They are born when giant stars die. At the Milky Way\u2019s center sits Sagittarius A* — 4 million solar masses. In 2019, a telescope network photographed a black hole\u2019s shadow — the first "photo of the invisible".
- ●Visible matter: only ~5% of the universe
- ●~27% dark matter (invisible, holds galaxies together)
- ●~68% dark energy (speeds up expansion)
⏳ Near a black hole\u2019s horizon time slows down — an hour there could be years outside.