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2022-08-17: What If Dark Energy is a New Quantum Field?

  • 01:41: ... that the anti-gravitational effect of dark energy is due to it having negative pressure. That’s counter-intuitive because negative pressure is an inward pulling ...
  • 02:31: ... dark energy is that, on top of the anti-gravitational effect of its negative pressure, it also produces regular attractive gravity due to its positive energy ...
  • 12:31: ... omega is between -⅓ and -1 then the outward-pushing negative pressure still dominates over the inward pull of regular gravity, so expansion ...

2022-04-20: Does the Universe Create Itself?

  • 15:24: ... because it’s a positive energy density, just like matter. But it’s negative pressure can allow even a closed universe to expand forever. Thanks, dark ...

2020-10-27: How The Penrose Singularity Theorem Predicts The End of Space Time

  • 05:01: ... always produce this convergence. It would take negative mass or negative pressure   to cause light rays to diverge. This focusing property of ...

2020-06-30: Dissolving an Event Horizon

  • 04:10: ... the central singularity - which point-like in this case - results in a negative pressure that again resists the inward pull of ...

2020-05-27: Does Gravity Require Extra Dimensions?

  • 11:58: This is the negative pressure due to the exclusion of quantum vacuum modes, or virtual particles, between two very closely separated plates.

2020-05-18: Mapping the Multiverse

  • 13:13: ... black holes the electromagnetic field within causes massive tension, or negative pressure that produces an antigravitational ...

2019-01-09: Are Dark Matter And Dark Energy The Same?

  • 02:53: But here’s the punchline: if empty space has a constant, positive energy density then it also has a negative pressure.
  • 03:02: For obscure reasons that we delve into those episodes, negative pressure produces an anti-gravitational effect.
  • 03:10: ... positive energy density gives it a positive gravitational effect but its negative pressure is ...
  • 07:57: And that a positive Lambda results in an antigravitational negative pressure?

2018-06-20: The Black Hole Information Paradox

  • 13:20: ... electric charge within the black hole produces a negative pressure that actually halts the cascade of space within the black hole and ...

2017-04-05: Telescopes on the Moon

  • 11:33: ... singularity is expected to produce an antigravitational effect through negative pressure, in a way that's mathematically similar to dark ...

2016-05-25: Is an Ice Age Coming?

  • 12:01: Last week, we wrapped up our conversation on dark energy, talking about anti-gravity, negative pressure, and conservation of energy.

2016-05-18: Anti-gravity and the True Nature of Dark Energy

  • 08:24: It's negative pressure.
  • 08:26: What does negative pressure even mean?
  • 08:33: So negative pressure would pull inwards.
  • 08:49: Negative pressure pulls in.
  • 09:05: The direct effect of dark energy's negative pressure doesn't do anything, because that negative pressure is the same everywhere in the universe.
  • 09:14: But even though the negative pressure has no direct effect, it has its relativistic effect.
  • 09:19: Relativistically, negative pressure has to do the opposite of positive pressure and results in anti-gravity, because math.
  • 09:29: The relativistic effective of negative pressure is actually really, really hard to describe intuitively.
  • 09:38: Part of the problem is that negative pressure doesn't come from the motion of dark energy particles, whatever they might be.
  • 10:09: That's exactly how we define negative pressure.
  • 10:12: A volume has negative pressure if it takes work to expand, just like a volume with positive pressure takes work to compress.
  • 10:22: Negative pressure means energy is gained on expansion.
  • 10:35: That looks like negative pressure, and yet this abstract-sounding negative pressure has a very real physical effect.
  • 11:01: But both agree that a constant energy density and the resulting negative pressure leads to accelerating expansion.

2015-10-28: Is The Alcubierre Warp Drive Possible?

  • 03:44: We can create something like it, a negative pressure, on quantum scales via Casimir effect.
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