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← How to weigh a star using gravitational lensing

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Ukazujem Revíziu 4 vytvorenú 12/30/2020 od Margarida Ferreira.

  1. Here is some exciting space news.
  2. Astronomers have used the Hubble Telescope
  3. and a technique pioneered
    by Albert Einstein
  4. to weigh a white dwarf star
    for the first time.
  5. So in 1916, Einstein says
    that a massive object like a star
  6. would actually warp
    the fabric of spacetime.
  7. What that means is that a ray of light
    going past the star
  8. would actually get bent
    and move in a different path

  9. as it was before.
  10. In 1936, a Czech engineer named Mandl
  11. came knock on Einstein's door
  12. and asked him to do
    a little calculation.
  13. He said, "What if a star passed
    in front of another star?"
  14. Einstein really didn't want to do it.
  15. He was kinda busy
    but he felt sorry for him
  16. and he did the calculation
  17. and wrote a paper for Science,
  18. a very short paper saying
  19. if one star passed
    in front of another star,
  20. the distant star would be
    magnified and distorted
  21. by this gravitational lensing effect.
  22. Today, gravitational lensing is one
    of the most powerful tools in astronomy.
  23. People use it to measure
    the size of the universe
  24. and to map out dark matter
    and to find distant galaxies
  25. they couldn't find otherwise
  26. because were too dim.
  27. What people in space telescope have done
  28. is watch as a distant ordinary star
    passed behind a white dwarf.
  29. It was distorted just
    as Einstein said it would.
  30. And by looking at the exact distortion,
  31. they were able to calculate
  32. how much the white dwarf
    was distorting spacetime
  33. and therefore, what it mass was
  34. which turned out to be
    2/3 of the mass of the Sun
  35. (more or less), as the theory has said.

  36. But still, it's good to know.
  37. So once more, we have Einstein to thank
  38. for yet another discovery
  39. even though he died way back in 1955.
  40. This is Mike Lemonick
    for Scientific American
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