PBS Space Time

Will the Universe Expand Forever?

Throughout history, there has been much speculation about what the fate of the universe would be. Many theorized that the universe would eventually succumb to the pull of gravity, and reverse its expansion in what was being called ‘The Big Crunch.’ However, with the help of mathematical equations from Newton, Einstein, and Alexander Friedmann, we now have an answer.

Will the Universe Expand Forever?

9m 51s

  • What If the Cosmological Constant Is Not Constant?: asset-mezzanine-16x9

    What If the Cosmological Constant Is Not Constant?

    S10 E23 - 15m 14s

    We know that the universe is getting bigger. And we know that the speed that the universe is getting bigger is also getting bigger. The standard assumption is that the acceleration rate is itself constant, which will result in ultimate heat death. But a recent survey of primordial sound waves frozen into the way galaxies are sprinkled through the universe reveals that this fate is now in question.

  • What If The Universe Did Not Start With The Big Bang?: asset-mezzanine-16x9

    What If The Universe Did Not Start With The Big Bang?

    S10 E22 - 16m 8s

    Space is expanding evenly everywhere, but if you rewind that expansion you find that all of space was once compacted in an infinitesimal point of infinite density—the singularity at the beginning of time. The expansion of the universe from this point is called the Big Bang. We like to tell this story because it's the correct conclusion from the description of an expanding universe that followed

  • The New Physics of Black Hole Star Capture | Extreme Tidal Disruption Events: asset-mezzanine-16x9

    The New Physics of Black Hole Star Capture | Extreme Tidal Disruption Events

    S10 E21 - 17m 44s

    If you track the motion of individual stars in the ultra-dense star cluster at the very center of the Milky Way you’ll see that they swing in sharp orbits around some vast but invisible mass—that’s the Sagittarius A* supermassive black hole. These are perilous orbits, and sometimes a star wanders just a little too close to that lurking monster, leading to a tidal disruption event.

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