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  • You have known for a long time that the universe is expanding.

  • If you look at distant galaxies, they are moving away from us,

  • And the more distant galaxies are moving faster.

  • So really, it’s not really an explosion of galaxies away from us;

  • All galaxies are moving away from all the other galaxies.

  • Space itself is getting bigger.

  • But you would expect that the expansion of the universe is something that will slow down.

  • These galaxies have gravity and they attract each other

  • So you would expect that the expansion of the universe will diminish with time.

  • So it was a big surprise in 1998 when we realized that the galaxies were actually speeding up.

  • If you look at one galaxy, non-only it is moving away from us,

  • But tomorrow it will be moving away from us faster.

  • This is what we call the acceleration of the universe.

  • But we are not completely shocked,

  • We have a good theoretical model handed down to us

  • by Einstein.

  • The idea that even empty space has energy, what we call vacuum energy or dark energy.

  • And this vacuum energy pushes space itself and causes distant galaxies to move away from us

  • Faster and faster. That is where the acceleration comes from.

  • So theoretical cosmologists are trying to understand what could be going on.

  • Is it really vacuum energy? Is some variation of that?

  • Or is it even a modification of Einstein’s general relativity, our theory of gravity?

  • If vacuum energy is the right answer, the universe will continue to expand,

  • The galaxies will move away from us and the universe will gradually become a lonelier, darker,

  • emptier place.

You have known for a long time that the universe is expanding.

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B2 vacuum energy energy universe vacuum dark energy moving

2011 Nobel Prize: Dark Energy feat. Sean Carroll

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    Why Why posted on 2013/03/29
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