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← How to Weigh a Star Using Gravitational Lensing

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Ukazujem Revíziu 2 vytvorenú 05/22/2020 od Ethan See Eng Kiat.

  1. Here's some exciting space news.
  2. Astronomers have used the Hubble Telescope
  3. and a technique pioneered by
  4. Albert Einstein to weigh a white
  5. dwarf star for the first time.
  6. So in 1916, Einstein said that
  7. a massive object like a star would
  8. actually warp the fabric of spacetime
  9. and what that means is that a ray of
  10. light going past the star would actually
  11. get bent and move in different paths
  12. as it was before.
  13. In 1936, a Czech engineer named Mandl
  14. came knocking on Einstein's door and asked
  15. him to do a little calculation.
  16. He said what would happen if a star passed in front
  17. of another star, and Einstein really
  18. didn't want to do it. He was kind of busy but
  19. he felt sorry for him and he did the
  20. calculation and wrote a paper for Science,
  21. very short paper saying if one star passed
  22. in front of another star, the distant star
  23. would be magnified and distorted by this
  24. gravitational lensing effect. And today,
  25. gravitational lensing is one of the most
  26. powerful tools in astronomy. People use
  27. it to measure the size of the universe and
  28. to map out dark matter and to find distant
  29. galaxies they couldn't find otherwise
  30. because they were too dim. What people in
  31. space telescope have done is watch as a
  32. distant ordinary star passed behind a
  33. white dwarf. It was distorted just as
  34. Einstein said it would. And by looking at
  35. the exact distortion, they were able to
  36. calculate how much the white dwarf was
  37. distorting spacetime and therefore,
  38. what its mass was, which turned out to be
  39. two-thirds of the mass of the Sun (more or less), which
  40. is what the theory has said. But still,
  41. it's good to know. So once more, we have
  42. Einstein to thank for yet another discovery
  43. even though he died way back in 1955.
  44. This is Mike Lemonick for Scientific American.
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