Science and Nature

PBS Space Time

PBS Space Time explores the outer reaches of space, the craziness of astrophysics, the possibilities of sci-fi, and anything else you can think of beyond Planet Earth. Host Matt O'Dowd breaks down both the basic and incredibly complex sides of space and time.

What If the Cosmological Constant Is Not Constant?

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.

Episodes

  • 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.

  • Can We Test Quantum Gravity?: asset-mezzanine-16x9

    Can We Test Quantum Gravity?

    S10 E20 - 16m 51s

    If we discover how to connect quantum mechanics with general relativity we’ll pretty much win physics. There are multiple theories that claim to do this, but it’s notoriously difficult to test them. Let’s talk about some ideas for quantum gravity experiments that can be done on a non-galaxy-sized lab bench, and in some cases already have been done.

  • Is Gravity RANDOM Not Quantum?: asset-mezzanine-16x9

    Is Gravity RANDOM Not Quantum?

    S10 E19 - 19m 25s

    The holy grail of theoretical physics is to find the long-sought theory of quantum gravity. But what if this theory is as mythical as the grail of legend? What if gravity isn’t weirdly quantum at all, but rather … just a bit messy? Or random? So says the postquantum gravity hypothesis of Jonathan Oppenheim.

  • Can We Create New Elements Beyond the Periodic Table: asset-mezzanine-16x9

    Can We Create New Elements Beyond the Periodic Table

    S10 E18 - 17m 2s

    Scientists have been slowly extending the periodic table one element at a time, pushing to higher and higher masses, and have discovered some incredibly useful materials along the way. But the elements at the current end of the table are so unstable that they decay almost as soon as they’re created in our particle accelerators. Astronomers have found a cosmic phenomenon that may populate table.

  • Do Black Holes Have to Be Black?: asset-mezzanine-16x9

    Do Black Holes Have to Be Black?

    S10 E17 - 15m 32s

    It turns out there is a way to make a coloured black hole—as long as by colour you mean quantum chromodynamic charge.

  • Was Penrose Right? New Evidence For Quantum Effects In The Brain: asset-mezzanine-16x9

    Was Penrose Right? New Evidence For Quantum Effects In The Brain

    S10 E16 - 18m 26s

    Nobel laureate Roger Penrose is widely held to be one of the most brilliant living physicists for his wide-ranging work from black holes to cosmology. And then there’s his idea about how consciousness is caused by quantum processes. Most scientists have dismissed this as a cute eccentricity—a guy like Roger gets to have at least one crazy theory without being demoted from the smartypants club.

  • How To Detect Faster Than Light Travel: asset-mezzanine-16x9

    How To Detect Faster Than Light Travel

    S10 E15 - 16m 28s

    Warp drives may or may not be possible, but if they are then could a distant alien civilization’s warp fields produce gravitational waves that we could see here on Earth? According to a recent study.. Actually maybe, at least eventually. And we now know just what to look for and how to look for it.

  • Can a Particle Be Neither Matter Nor Force?: asset-mezzanine-16x9

    Can a Particle Be Neither Matter Nor Force?

    S10 E14 - 20m 7s

    All particles belong to two large groups: fermions like protons and electrons make everything we consider "matter", while bosons like photons and gluons transmit the fundamental forces. And that about covers the universe: matter moving through space and time under the action of forces. But what if we could create particles in between these two possibilities. Physics says these neither matter nor f

Extras + Features

  • Black Holes from the Dawn of Time: asset-mezzanine-16x9

    Black Holes from the Dawn of Time

    S2 - 10m 16s

    Primordial black holes may be lurking throughout our universe. How large are they, how many are out there and what would happen if they moved through our solar system?

  • Quantum Entanglement (The Bohr-Einstein Debate): asset-mezzanine-16x9

    Quantum Entanglement (The Bohr-Einstein Debate)

    S2 - 11m 24s

    Albert Einstein strongly disagreed with Niels Bohr when it came to Bohr’s interpretation of quantum mechanics. Quantum entanglement settled the argument once and for all.

  • Will the Universe Expand Forever?: asset-mezzanine-16x9

    Will the Universe Expand Forever?

    S2 - 9m 51s

    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.

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