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	2022-08-17: What If Dark Energy is a New Quantum Field? 00:36: ... intense over time rather than having a constant density expected of a vacuum energy. That would cause the universe to eventually tear itself apart on a ... 05:18: ... fluctuations. For example, it’s actually very difficult to get the vacuum energy to be very close to zero but not quite equal to ... 05:50: ... each other out. A perfectly symmetric canceling could get you down to a vacuum energy of zero, but it’s really really hard to cancel such a large number down ... 10:55: ... fields, it could potentially cancel out their predicted extremely high vacuum energy in a natural way, so that dark energy becomes the tiny residual from ...
	2022-05-25: The Evolution of the Modern Milky Way Galaxy 18:10: ... There would indeed be an additional effect  due to the tiny vacuum energy inside   the galaxy. However the effect is minuscule, ...
	2022-02-23: Are Cosmic Strings Cracks in the Universe? 04:51: ... the same part of the Higgs minimum.   A bubble of this lower vacuum energy was  nucleated, and it expanded at the speed   of light. ... 07:33: ... the defect tighten as much  as they can. The filament of high vacuum energy is   squeezed it down to one-ten-trillionth the width  of ... 04:51: ... the same part of the Higgs minimum.   A bubble of this lower vacuum energy was  nucleated, and it expanded at the speed   of light. Many ...
	2022-02-10: The Nature of Space and Time AMA 00:03: ... new space in a sense um in this that that new space has the same vacuum energy density the old one has the same kind of behavior of virtual particles ...
	2020-11-18: The Arrow of Time and How to Reverse It 10:34: ... to be yes, at least to some degree. The Higgs field sits at a non-zero vacuum energy so could potentially decay to zero, or even to a lower non-zero state ...
	2020-06-08: Can Viruses Travel Between Planets? 15:22: ... the Casimir effect is thought to be due to an alteration in the vacuum energy between a pair of conducting surfaces, which leads to those surfaces ... 15:49: ... agrees with so-called lifshitz theory, which is based on this altered vacuum energy ...
	2020-02-03: Are there Infinite Versions of You? 08:17: But universes with large vacuum energies will exponentially expand, until that vacuum energy decays to lower values in smaller regions within.
	2019-11-11: Does Life Need a Multiverse to Exist? 09:29: ... problem is, when we try to calculate the strength of this vacuum energy from our theory we get an enormous number - 10^60 to 10^120 larger than ... 09:49: If fact, that’s true if the strength of vacuum energy were only a little larger than is observed. 10:25: ... there are other theoretical ways to get the vacuum energy to take on different values in different regions of the universe - or in ... 11:24: ... suggests that the values of the fundamental constants, including the vacuum energy, are set by the particular configuration of the extra coiled dimensions ... 12:04: ... and in each bubble the constants of nature - and especially the vacuum energy - taking on different ...
	2019-08-19: What Happened Before the Big Bang? 01:47: It had a nonzero vacuum energy.
	2019-08-06: What Caused the Big Bang? 03:42: The speed of that exponential expansion depends on the strength of the vacuum energy density. 04:32: So, the vacuum energy would need to drop from a very high value to basically zero. 07:06: We would call this a false vacuum and it gives us exactly the constant vacuum energy density needed for inflation. 07:13: There are other ways for a field to end up with a positive vacuum energy density and I'll come back to these. 03:42: The speed of that exponential expansion depends on the strength of the vacuum energy density. 07:06: We would call this a false vacuum and it gives us exactly the constant vacuum energy density needed for inflation. 07:13: There are other ways for a field to end up with a positive vacuum energy density and I'll come back to these.
	2019-03-20: Is Dark Energy Getting Stronger? 02:13: Mathematically we represent a constant vacuum energy with Einstein’s cosmological constant – or Lambda.
	2018-09-20: Quantum Gravity and the Hardest Problem in Physics 15:27: No real quantum states means no information except, perhaps, whatever information you need to track the bulk properties, like vacuum energy.
	2017-11-29: Citizen Science + Zero-Point Challenge Answer 06:57: ... a simplistic theoretical estimate of the vacuum energy density comes from assuming that there are no virtual photons above a ... 07:06: ... frequency corresponding to a photon with the Planck energy, you get a vacuum energy density of a ridiculously high 10 to the power of 112 ergs per ... 07:18: In this theoretical estimate, vacuum energy density is proportional to the fourth power of cutoff frequency. 07:59: And if vacuum energy is proportional to the fourth power of cutoff frequency, then this equation gives the relationship we need. 08:07: There are a bunch of constants in the cutoff frequency vacuum energy relation, but they cancel out. 08:32: ... the right maximum virtual photon frequency definitely can't give us the vacuum energy that we see as dark ... 06:57: ... a simplistic theoretical estimate of the vacuum energy density comes from assuming that there are no virtual photons above a certain ... 07:06: ... frequency corresponding to a photon with the Planck energy, you get a vacuum energy density of a ridiculously high 10 to the power of 112 ergs per centimeter ... 07:18: In this theoretical estimate, vacuum energy density is proportional to the fourth power of cutoff frequency. 08:07: There are a bunch of constants in the cutoff frequency vacuum energy relation, but they cancel out.
	2017-11-22: Suicide Space Robots 12:46: Hawking radiation is related to this whole vacuum energy virtual particle thing.
	2017-11-08: Zero-Point Energy Demystified 00:14: Let's talk about what vacuum energy really can and really can't do. 00:53: ... our observations of the accelerating expansion of the universe suggest a vacuum energy density of only 10 to the power of minus 8 ergs per centimeter ... 01:05: ... this mismatch between the measured and theoretical values of vacuum energy is one of the greatest unsolved problems in ... 01:35: ... source to manipulating it to generate warp fields or pushing against the vacuum energy in propulsionalist space ship ... 04:02: In order to access vacuum energy, we need to introduce a disequilibrium. 04:08: In fact, we need to reduce the vacuum energy in one region of space. 04:31: By cutting off certain frequency modes between the plates, you lower the vacuum energy in that region. 05:18: Well, if we define the average vacuum energy as 0, then the Casimir Effect produces negative energy. 05:26: Unfortunately, the vacuum energy between Casimir plates is very much positive in an absolute sense. 05:36: That means the vacuum energy between Casimir plates still produces positive spatial curvature, not the negative curvature required for warp drives. 06:59: Vacuum energy is real, and it's part of the fundamental clockwork of the universe. 07:56: Geckos literally manipulate quantum vacuum energy to climb walls. 08:35: ... as we saw last week, the theoretical density of the vacuum energy due to the electromagnetic field is estimated by integrating the energy ... 08:48: You get that the vacuum energy density is proportional to the fourth power of that cutoff frequency. 08:55: Based on the vacuum energy density, as we've already talked about, answer me this. 00:53: ... our observations of the accelerating expansion of the universe suggest a vacuum energy density of only 10 to the power of minus 8 ergs per centimeter ... 08:48: You get that the vacuum energy density is proportional to the fourth power of that cutoff frequency. 08:55: Based on the vacuum energy density, as we've already talked about, answer me this.
	2017-11-02: The Vacuum Catastrophe 01:26: Let's talk about vacuum energy from a theoretical standpoint. 02:42: We'll get back to whether the idea of an infinite vacuum energy is actually possible. 03:31: ... if we add up the vacuum energy, including virtual photons, all the way up to the Planck energy, we get a ... 03:49: ... enough energy to boil all of the oceans on the planet, yet even if vacuum energy did have a value this high-- in fact, even if it were infinite-- we may ... 04:23: As long as the vacuum energy is the same everywhere, then it's inaccessible to us as an energy source. 04:39: Long story short-- a crazily high, even infinite, vacuum energy doesn't affect the predictions of quantum field theory. 05:07: Vacuum energy should produce a gravitational effect, and a huge vacuum energy should produce a huge gravitational effect. 05:37: ... down that rabbit hole if you haven't already, but the upshot is that, if vacuum energy really did have the enormous value predicted by theory, then our gently ... 06:25: It gives particles a supersymmetric counterpart that may precisely cancel out their vacuum energy. 06:32: ... down to the so-called electroweak energy, which brings the predicted vacuum energy down to a mere 10 to the 47 ergs per centimeter ... 06:52: For a while, theorists assumed that something like this must be happening, meaning the vacuum energy was really 0. 07:09: ... is, in fact, accelerating in exactly the way we'd expect from a non-zero vacuum energy. ... 07:20: ... of accelerating expansion allows us to measure the absolute density of vacuum energy. ... 07:31: Assuming vacuum energy is to blame, dark energy weighs in at 10 to the power of negative 8 ergs per centimeter cubed. 07:59: ... can give us an extremely high vacuum energy or a vacuum energy of exactly 0 if we assume symmetry of positive and ... 11:05: Vacuum energy can't be used as a power source. 04:39: Long story short-- a crazily high, even infinite, vacuum energy doesn't affect the predictions of quantum field theory. 03:31: ... if we add up the vacuum energy, including virtual photons, all the way up to the Planck energy, we get a finite ...
	2017-10-25: The Missing Mass Mystery 11:21: A non-zero vacuum energy would have a gravitational effect. 11:34: So enough vacuum energy could result in a closed, rather than infinite, universe. 11:39: And rather differently to regular matter, vacuum energy doesn't dilute in an expanding universe.
	2017-10-19: The Nature of Nothing 07:40: ... physicist Hans Bethe successfully explained it in terms of a fluctuating vacuum energy. ... 08:34: It should have vacuum energy. 08:51: ... any non-resonant virtual photon would be excluded, reducing the vacuum energy between the ... 09:11: The higher vacuum energy outside, compared to the inside of the plates, should result in a pressure differential that pushes the plates together. 09:42: Now while there are potentially other explanations for the observed force, this has been taken as strong evidence that vacuum energy is real. 09:51: Neither the Casimir effect nor the Lamb shift allow measurement of the absolute strength of vacuum energy. 10:05: So how much vacuum energy is there? 10:18: Dark energy itself may be vacuum energy. 10:22: ... so, then the amount of vacuum energy needed to produce the observed acceleration is tiny, around one one ... 10:33: And the theoretical calculation of the strength of the vacuum energy is a little higher than that. 10:53: ... in all of science, and yet it's prediction of the strength of the vacuum energy seems to be wildly ... 10:22: ... so, then the amount of vacuum energy needed to produce the observed acceleration is tiny, around one one hundred ...
	2017-10-11: Absolute Cold 06:21: For example, the quantum fields that fill our universe also fluctuate due to the Uncertainty Principle resulting in what we know as vacuum energy.
	2017-06-28: The First Quantum Field Theory 09:40: ... fields in the so-called hyperfine splitting or spins interacting with vacuum energy fluctuations in the lamb ...
	2017-06-21: Anti-Matter and Quantum Relativity 14:02: ... vacuum field can have one or more local minima, where the vacuum energy can come to a rest in an eternally inflating spacetime, halting ... 14:14: The vacuum energy may come to a rest at different minima in different bubbles or it can be a false vacuum in one and the true vacuum in the other. 14:38: ... the high energy bubble, it's much worse because that change in the vacuum energy state would propagate at the speed of light to fill that universe, ...
	2017-06-07: Supervoids vs Colliding Universes! 09:13: In particular, its vacuum energy takes on a stable value.
	2016-05-18: Anti-gravity and the True Nature of Dark Energy 02:03: A constant cosmological constant represents a nonzero energy of empty space, a vacuum energy. 02:18: OK, the big, weird fact about a constant vacuum energy density is that leads to exponential expansion.
	2016-04-27: What Does Dark Energy Really Do? 07:36: This lets us interpret the cosmological constant as representing a sort of vacuum energy, a property of space itself. 07:48: But why should a constant vacuum energy cause the universe to accelerate?
	2016-04-20: Why the Universe Needs Dark Energy 08:04: ... density of regular matter will, at some point, drop below that of this vacuum energy, as described by the cosmological-constant ...
	2015-10-28: Is The Alcubierre Warp Drive Possible? 06:02: Quantum scale manipulation of the vacuum energy a la the Casimir effect may be enough.

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