[Bogie_smiles (OP)]

Reply #60

In the last post I referred to expanding bubbles as wave fronts, and related the velocity of bubble expansion to an event in the QFT Wiki called bubble collisions. Bubble collisions are supposed to produce particles and matter, and following the QFT scenario, it would seem safe to equate that to our own circumstance. That would mean that bubble collisions account for the production of particles, and set particles into motion.

Photons have to be part of the particle mix, and so it can be concluded that it would be consistent with QFT that the bubble collisions would set photons into motion in all directions through the vacuum energy density of space. That could be equated to an expanding wave of electromagnetic energy traversing the quantum field right along with the bubble expansion.

That is not intended to equate the bubble wall to the advance of photon energy, but from what I have read, I would expect the expanding bubble to be filled with light, and thus with photon energy. However, the quantum field is not just an electromagnetic field, it is all fields, and all forms of energy expand through it according to their individual fields. The electric field and the magnetic field combine to govern the speed of light. …


There is not yet a quantum field solution to gravity, so when we talk theory of the universe, we have to rely on General Relativity for now, which is a macro level force. Gravity, according to GR is caused by the presence of matter and energy, which tells space how to curve, and that curvature tells matter how to move. Eventually, the scientific community will come to a consensus on gravity, and the work effort is toward quantum gravity, as I understand it.

Since it seems right to say that the quantum field occupies all space, and photons being electromagnetic radiation, would logically be traversing the field at the speed of light, their velocity is presumably governed by the local density of the vacuum.

What ever relative velocity that is, c is always the same in a perfect vacuum. However, we know that the energy density of the vacuum in QFT can vary, and is never a perfect vacuum, and so the velocity of light will vary from one level of vacuum energy density to another, and therefore from one bubble to another. Some might take exception to that, and so it is open to discussion.

In the mean time, for now I’ll take my musings about how I interpret the QFT Wikis, and cosmology in general, to my threads On the Lighter Side.

[jeffreyH]

What if antimatter has a bias towards manifesting within a true vacuum. While matter has the opposite and tends to favour a false vacuum with a particular energy. This will allow two co-existing vacuum states. Virtual particle pairs can manifest temporarily in either domain. The true vacuum will have far more antimatter than matter. If the false vacuum collapses then all matter and antimatter will meet and annihilate. This is equivalent to nothing, except the true vacuum of course. This then leaves the connundrum of where the false vacuum came from.

[Bogie_smiles (OP)]

What if antimatter has a bias towards manifesting within a true vacuum. While matter has the opposite and tends to favour a false vacuum with a particular energy. This will allow two co-existing vacuum states. Virtual particle pairs can manifest temporarily in either domain. The true vacuum will have far more antimatter than matter. If the false vacuum collapses then all matter and antimatter will meet and annihilate. This is equivalent to nothing, except the true vacuum of course. This then leaves the connundrum of where the false vacuum came from.

I'm not sure anyone else will take a shot at it, lol, so here is a link from years back (2010) that refers to experiments from the 1990s, but touches on your topic. The quote I pulled from the article is a hint to its content, but viewers should read the article do their own research to get the perspective:
https://phys.org/news/2010-12-theoretical-physics-breakthrough-antimatter-vacuum.html

At the heart of this work is the idea that a vacuum is not exactly nothing.
"It is better to say, following theoretical physicist Paul Dirac, that a vacuum, or nothing, is the combination of matter and antimatter -- particles and antiparticles. Their density is tremendous, but we cannot perceive any of them because their observable effects entirely cancel each other out," Sokolov said.

You could be talking about how the observed matter in the universe can exist if matter and antimatter annihilate each other, and are concerned about the conundrum of first cause, if the "always existed" solution isn't invoked. If the way that the existing matter came into existence was spontaneous symmetry breaking, your proposal would be aimed at explaining why any matter exists after the annihilation accompanying the initial symmetry breaking event, right? I haven’t fully researched the concept of symmetry breaking in regard to the false or true vacuums of QFT, but I know there is a lot of material along that line that we can get into if it isn't too speculative for this sub-forum.

[yor_on]

This is the main stream definition

https://cosmosmagazine.com/physics/vacuum-decay-ultimate-catastrophe

[Bogie_smiles (OP)]

This is the main stream definition

https://cosmosmagazine.com/physics/vacuum-decay-ultimate-catastrophe

Thanks for the link. That is an enjoyable read, and right on topic, and I’m posting the text becasue I am going to quote from it in my next reply:

Vacuum decay: the ultimate catastrophe
Of all the ways the Universe might die, vacuum decay is the most efficient.

Conceptual illustration of the Higgs Field that physicists believe permeates the Universe, and that could theoretically bring about its end. – DAVID PARKER / Getty Images [image deleted]
Every once in a while, physicists come up with a new way to destroy the Universe. There’s the Big Rip (a rending of spacetime), the Heat Death (expansion to a cold and empty Universe), and the Big Crunch (the reversal of cosmic expansion). My favourite, though, has always been vacuum decay. It’s a quick, clean and efficient way of wiping out the Universe.
To understand vacuum decay, you need to consider the Higgs field that permeates our Universe. Like an electric field, the Higgs field varies in strength, based on its potential. Think of the potential as a track on which a ball is rolling. The higher it is on the track, the more energy the ball has.
The Higgs potential determines whether the Universe is in one of two states: a true vacuum, or a false vacuum. A true vacuum is the stable, lowest-energy state, like sitting still on a valley floor. A false vacuum is like being nestled in a divot in the valley wall – a little push could easily send you tumbling. A universe in a false vacuum state is called “metastable”, because it’s not actively decaying (rolling), but it’s not exactly stable either.
There are two problems with living in a metastable universe. One is that if you create a high enough energy event, you can, in theory, push a tiny region of the universe from the false vacuum into the true vacuum, creating a bubble of true vacuum that will then expand in all directions at the speed of light. Such a bubble would be lethal.
“VACUUM DECAY IS THE ULTIMATE ECOLOGICAL CATASTROPHE ... NOT ONLY IS LIFE AS WE KNOW IT IMPOSSIBLE, SO IS CHEMISTRY ...”
The other problem is that quantum mechanics says that a particle can ‘tunnel’ through a barrier between one region and another, and this also applies to the vacuum state. So a universe that is sitting quite happily in the false vacuum could, via random quantum fluctuations, suddenly find part of itself in the true vacuum, causing disaster.
The possibility of vacuum decay has come up a lot lately because measurements of the mass of the Higgs boson seem to indicate the vacuum is metastable. But there are good reasons to think some new physics will intervene and save the day.
One reason is that the hypothesised inflationary epoch in the early Universe, when the Universe expanded rapidly in the first tiny fraction of a second, probably produced energies high enough to push the vacuum over the edge into the true vacuum. The fact that we’re still here indicates one of three things. Inflation occurred at energies too low to tip us over the edge, inflation did not take place at all, or the Universe is more stable than the calculations suggest.
If the Universe is indeed metastable, then, technically, the transition could occur through quantum processes at any time. But it probably won’t – the lifetime of a metastable universe is predicted to be much longer than the current age of the Universe.
So we don’t need to worry. But what would happen if the vacuum did decay?
The walls of the true vacuum bubble would expand in all directions at the speed of light. You wouldn’t see it coming. The walls can contain a huge amount of energy, so you might be incinerated as the bubble wall ploughed through you. Different vacuum states have different constants of nature, so the basic structure of matter might also be disastrously altered. But it could be even worse: in 1980, theoretical physicists Sidney Coleman and Frank De Luccia calculated for the first time that any bubble of true vacuum would immediately suffer total gravitational collapse.
They say: “This is disheartening. The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in a new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it.
“However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some creatures capable of knowing joy. This possibility has now been eliminated.”
To know for sure what would happen inside a bubble of true vacuum, we’d need a theory that describes our larger multiverse, and we don’t have that yet. But suffice it to say, it would not be good. Luckily, we’re probably reasonably safe.
At least for now.

[Bogie_smiles (OP)]

In response to the link from yor-on, first let me say that I like the perspective from which David Parker writes the article “Vacuum decay: the ultimate catastrophe”. The perspective being, that of all the ways the Universe might die, vacuum decay is the most efficient. It makes for good and exciting reading, and it lets the mind wander if it wants, but let’s be serious. The article talks of the universe as if it was a finite entity upon which universe-wide events could befall the whole thing, and maybe even in an instant.
 

To have that perspective, you are dealing with events worthy of qualifying as “first cause” events, like the universe beginning from spontaneous symmetry breaking where matter and antimatter separate out of a seeming nothingness, sparked by some random perturbation. At the very least such a preexisting “nothingness” must have had the potential for such a random event, and therefore it wasn’t “nothing” to begin with (think always existed). Given that reasoning, such random spontaneous events, and their ultimate catastrophic (universal) “deaths” should at least be considered repetitive. That means the cataclysmic, catastrophic universal death wasn’t all that bad, because in the next trillion years or so things are back and ready for another ultimate catastrophe.

But that is not in character with the nature of QFT according the Wiki sources at which we have been looking. For example, it seems perfectly consistent with QFT that there is just one universe, and no reason to believe that it isn’t infinite and eternal; a concept that rests well with logic. How can any single event have the potential to swept the entire universe clean of the potential for life, forever? It isn’t going to happen, simply because such universe-wide events can’t occur everywhere at once due to distance and time constraints; “infinite and eternal” trumps any such coordination occurring around a single event.

Cataclysms would logically befall all of the living inhabitants and all of the particulate matter associated with every major bubble collision, and with the inflationary expansion associated with such collisions. But I am a practical sort, and I don’t see suggestions as to how even the most cataclysmic peculiarities that might befall an infinite and eternal universe could spell complete and utter doom that goes beyond an isolated event among the local nucleating bubbles.

Don’t get me wrong, events like big bangs, and collisions of nucleating bubble walls would utterly destroy life within the reach of such an event, if only long enough for things to reshape themselves. But still they would qualify as local events. They don’t spike any concern on my part for the continuation of the greater universe, and its ability to host habitable environments, where life can be generated and evolved through iterations, again and again, here and there.


 It brings out the poet in me:
Explosions then, great cataclysms, Booms, it’s an inferno.
Bubbles crash and burst around, as if they weren’t eternal.

But when the dust clouds settle in and particles iterate,
Then out come living molecules; it’s nucleated fate.

Reply to yor_on's link to be continued ...

[Bogie_smiles (OP)]

My last post, notwithstanding the poem, addresses what could be considered a myth that is often featured in theoretical cosmological models, and that is that the fate of the entire universe can turn on a single event.

One of the features I like about QFT is random bubble nucleation, and how nicely it can be equated with what we know and see in our own visible universe. It strongly hints that, in the context of QFT, we are inside of one of a potentially infinite number of nucleated bubbles.

My layman takeaway from the Wikis (open for comment and discussion), and from the @yor_on link to the Cosmos Magazine article, is that bubbles can occur randomly across potentially infinite space and time. Though the occurrence can be described as random in regard to where and when they occur, there is a continual process of new bubble nucleation. I would expect that there is more than pure mathematical randomness to the process because a nucleated bubble that actually produces a version or replica of what we observe around us would be preceded by tunneling and/or bubble collision. Though the “where and when” of collision events might not be predictable because of a lack of data, if in fact we had an overview of a large enough patch of the vacuum, and could measure density data to plot out the vacuum energy density of the surrounding bubbles, my expectation is that we could identify a set of natural preconditions to tunneling, bubble collisions, and nucleation of new bubbles like ours. 

The reference to “tunneling” is a way to acknowledge that the bubble “playing field” features close proximity and interaction between the walls of nucleating bubbles, and given some set of conditions, false vacuums can achieve true vacuum status. The low vacuum energy density of the false vacuum can be boosted to a higher vacuum energy density, up to or somewhere closer to the vacuum density of the true vacuum.

This is referred to as the collapse of the false vacuum, and is referred to as a catastrophic event. A result of the potentially extreme density of the new bubble would negate existing particles, void the effective physics and chemistry going on there, and set the stage for a new bubble to establish its own operative physics and chemistry. However, there is nothing to say that the natural set of preconditions wouldn’t lead to the reestablishment of the same laws, resulting in the same physics and chemistry in the new bubble.


If there is a repetitive process that does all of that, then the metastability of the false vacuum decay, as mentioned in the QFT Wikis and articles is of note. Does it mean that what seems to be the resulting catastrophe that false vacuum decay would represent to the occupants and contents of the affected false vacuum bubble, might, like the article hints, give us “good reasons to think some new physics will intervene and save the day”?

[jeffreyH]

An article of interest.
http://scholar.google.co.uk/scholar_url?url=https://arxiv.org/pdf/gr-qc/0503090&hl=en&sa=X&scisig=AAGBfm3pHMd7HXOHV_J1Or6sk-apZBGrWg&nossl=1&oi=scholarr

[Bogie_smiles (OP)]

An article of interest.
http://scholar.google.co.uk/scholar_url?url=https://arxiv.org/pdf/gr-qc/0503090&hl=en&sa=X&scisig=AAGBfm3pHMd7HXOHV_J1Or6sk-apZBGrWg&nossl=1&oi=scholarr

Yes, indeed.

Abstract
Our Universe may be a domain separated by physical phase boundaries from other domain-Universes with different vacuum energy density and matter content. The coexistence of different quantum vacua is perhaps regulated by the exchange of global fermionic charges or by fermion zero modes on the phase boundary. An example would be a static de-Sitter Universe embedded in an asymptotically flat spacetime.
——————
Thanks and I’ll have to work on that one a bit before I start talking about it.


However, it does contribute to the idea that QFT is a type of madness, as suggested in this very timely video:

The way that I put it all into perspective is to try to grow my learning at a faster rate than I lose my mind; net gain and all that, lol.

[Bogie_smiles (OP)]

Reply #69

I think the JeffreyH link is a topic of interest to a much more sophisticated audience than layman enthusiasts like me. The reason I struggle with it is probably just that I am not well enough informed to appreciate the rigor behind the paper’s perspective. It focuses on a connection between bubbles and bubble walls that can be separated by domain boundaries, and where emergent gravity in different vacuum domains can have a cause other than the notion of spacetime. It speculates that the boundary separation is regulated by a difference in the boundary charges referred to as fermionic charges or fermion zero modes on the phase boundary.

I do like the way it addresses coordinate singularities that can arise under those circumstances. It supports the concept that domain-Universes can/will have different vacuum densities and matter content, and while they remain separate, might be governed by different physics that yield different intensities of the local forces.

Being a layman and limited by layman level thinking, the paper is consistent with the position that there is some grand order to the greater Universe. The grand order would be displayed by a common larger set of invariant natural laws. In that case there is logic that the resulting lesser local set of laws that come into play at the low end of the density range, as separate domain bubbles expand, can disappear (work themselves out) via chaotic events like big bangs when expanding bubbles collide. Big bangs bring the higher vacuum energy densities to the nucleated bubble domains and therefore would unite the forces, making for a fresh start within the new domain.

Such massive events could naturally break down the domain boundaries when simple spatial overlaps occur due to bubble expansion. That might mean that the curvature of spacetime corresponds to the local domain-Universe that emerges after separated domain-universes collide and produce big bangs.

During the chaos of those collisions, Einstein’s solution to gravity might be put on hold until the collision sorts itself out. A sort of emergent orderliness within domains that are otherwise separated by corridors of time and space where a broader set of natural laws are in place. Those periods of chaos could create energy density environments that have more parameters; parameters that supersede the conditions that allow for an orderly space time gravity. The paper seems to invoke the emergence of stable domains with quiet internal places referred to as separate domain-Universes where Einstein’s solution of curved spacetime comes back into vogue.