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2024-02-15, 01:58 PM (ISO 8601)
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Why would a vacuum collapse event propagate
One thing I don't understand about false vacuum collapse scenarios is the assumption that the true vacuum would necessarily expand.
Wouldn't that be dependent on the difference between the false vacuum and the ground state being larger than the difference between the false vacuum and the activation energy? Because otherwise it would bot release enough energy to continue the reaction.
That seems unlikely to me as 1.) the activation energy is apparently stupendously large, and 2.) my understanding is that the difference between a true and false vacuum is likely to be small
I suppose we could assume that the reaction is self-catalyzing but even so would it necessarily be sufficiently self-catalyzing?"If you want to understand biology don't think about vibrant throbbing gels and oozes, think about information technology" -Richard Dawkins
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2024-02-15, 05:52 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Activation energy gets refunded when you fall down the other side. It's more whether the released energy can propagate away faster than it gets released.
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2024-02-15, 07:12 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
The version of this scenario I hear most often has it initially quantum tunneling into tge true vacuum, so wouldn't that mean there's no initial activation energy to refund?
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2024-02-15, 09:01 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Er, sure in that case. But I'd say to the extent that vacuum collapse is a 'likely' thing, it'd be some bubble that has been expanding elsewhere and basically snipes us from outside of our light-cone.
Furthermore once you have an extended region of some phase, it tends to massively lower activation energy for forming more of itself, because whatever order it has can be copied from the interface rather than having to happen spontaneously. That's why e.g. you can do the experiment with supercooling water and having the entire thing freeze at once.
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2024-02-16, 02:49 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Think of it like stimulated emission (the "se" in laser) - you start off with the particles in an energetic but metastable state, and when one of them goes, then it brings all the rest down with it.
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2024-02-18, 08:41 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
If the "true vacuum" is at a lower energy state than the originating state then there is a release of energy, even if the the state change happens by tunneling. Whether or not that produces enough energy to start a chain reaction depends on how large the energy difference between the original state and the final state is and how tall the barrier that needed to be tunneled through.
One interesting thing is that the size of the black hole at the center of galaxies seems to be proportional to the size of the galaxy. Active galaxies might represent a vacuum collapse in progress.
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2024-02-19, 01:04 AM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Last edited by halfeye; 2024-02-19 at 01:06 AM.
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2024-02-19, 08:22 AM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
And I'm not sure what that would have to do with vacuum collapse, anyway.
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2024-02-19, 03:56 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
I also think it's worth saying that, IIRC, we don't know that a vacuum collapse would propagate. The whole vacuum collapse hypothesis is a bit vague; people don't know exactly what the true vacuum looks like or how it would be different than the current vacuum or what the activation energy for the switch is, and therefore they can hardly say exactly what would happen if a small area did do a vacuum collapse.
As far as I know, it's never even been proven that our current reality is a false vacuum. It's just speculation that it's possible that the physical laws got frozen in a non-lowest-energy state and that some amount of energy could unfreeze them and let them refreeze in a (much) lower energy state and release energy. It's possible but not AFAIK proven.
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2024-02-20, 07:02 AM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
If a small area did a collapse, and didn't propagate, what would you have? A small area of collapsed vacuum traveling at some arbitrary velocity? "Motionless" isn't a meaningful concept under Special Relativity. At least all inertial reference frames could agree on "propagating in all directions at the speed of light".
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2024-02-20, 11:40 AM (ISO 8601)
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2024-02-20, 12:35 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Another thing to consider is that even if the energy difference per volume is low, however once the size of the bubble gets big enough the energy per area of the surface of the bubble gets arbitrarily large.
A very small event where the true vacuum emerges wouldn't be able to force the surrounding area over the hill.The thing is the Azurites don't use a single color; they use a single hue. The use light blue, dark blue, black, white, glossy blue, off-white with a bluish tint. They sky's the limit, as long as it's blue.
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2024-02-20, 09:03 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
The volume in a shell surrounding a sphere grows as r^2 while the volume inside a sphere grows as r^3. If anything, there is a minimum volume of collapse that would be able to propagate. Albeit, if the activation-to-refund ratio is the right size it will propagate no matter what.
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2024-02-21, 11:13 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
It's only the outer shell that's releasing energy though, right? The interior has already released its energy
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2024-02-22, 12:19 AM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Yes, but the amount of energy available to push the shell over the hump is the total energy released less energy that gets dumped into putting things into higher energy states (e.g. radiated off as light or absorbed by particles as kinetic energy).
This boils down to a trick I remember from a physics class: If you want to know how fast a kid is going at the bottom of a frictionless slide you can either do the (incredibly messy) integral of normal forces and gravity over the path or you can figure out how much kinetic energy said kid would develop by dropping straight down and do the (fairly simply) math to turn kinetic energy into speed.
While we have no real basis for determining that energy is conserved across a collapse to "true vacuum", or that the energy so released would be useable to transition more space into the "true vacuum" state, there really isn't any other way for things to work that would make sense. Then again, this is all high conjecture meanderings in physics for which we have no experimental evidence to connect the math to reality.
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2024-02-22, 02:59 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
Last edited by Bohandas; 2024-02-22 at 03:00 PM.
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2024-02-25, 02:12 PM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
I think that depends on the specifics, but I think the idea is that the energy released is exactly of the type that best drives the change, and that the change happens almost instantly.
If the change took a non-trivial amount of time, and released the energy over a period, that would dilute the energy in proportion to the length of the window. Still, a big enough bubble would enough power per surface area to drive the change.The thing is the Azurites don't use a single color; they use a single hue. The use light blue, dark blue, black, white, glossy blue, off-white with a bluish tint. They sky's the limit, as long as it's blue.
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2024-02-29, 08:39 AM (ISO 8601)
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Re: Why would a vacuum collapse event propagate
As with any phase transition, the activation energy is more or less equivalent to the one needed to create a domain wall between the old and new phases. Once the domain wall is there, expanding the new phase does not take any significant energy. If the new phase is energetically preferable, the domain wall will be pushed outside enlarging the new domain.
I have no clue about vacuum states, but this is how it works for any other phase transition (formation of bubbles in a liquid, magnetization reversal, etc.)In a war it doesn't matter who's right, only who's left.