How does the Big Bang Theory explain the creation of matter from energy?

[John15]

How does the BB theory allow for the creation of matter. Bt this I mean the sub atomic particles that make up atoms i.e. the quarks and electrons. From what I have read it seems to assume that they already pre-existed and condensed out of the fireball to form atoms.

 

[bapowell]

The big bang model does not address the origin of matter/energy in the universe.

 

[phinds]

How does the BB theory allow for the creation of matter. Bt this I mean the sub atomic particles that make up atoms i.e. the quarks and electrons. From what I have read it seems to assume that they already pre-existed and condensed out of the fireball to form atoms.

There was no actual fireBALL.

"Big Bang" really mean two different things

(1) the singularity / t=0 / the "big bang event" --- this is the place where our theories totally break down and current science has no idea what happened here.

(2) The evolution of the universe starting one Plank Time AFTER the singularity. At this starting point, the universe was WAY more dense and hot than it is now, although that does NOT imply that it was finite. Lots of stuff happened. Over time, energy coalesced into matter. I commend to your reading "The First Three Minutes" by Weinberg.

 

[zhermes]

How does the BB theory allow for the creation of matter. Bt this I mean the sub atomic particles that make up atoms i.e. the quarks and electrons. From what I have read it seems to assume that they already pre-existed and condensed out of the fireball to form atoms.

Regardless of the `big-band model' per se, the idea is that the energy density in the early universe was high enough for spontaneous creation of particles. If you're familiar with electron-positron annihilation to produce 2 photons, then you won't be surprised that the opposite can happen---if two photons have enough energy, they will react to form an electron and positron pair. The same type of thing can happen with all particles. This topic is referred to as leptogenesis and baryogenesis (for leptons and baryons respectively), which both focus on how/why 'normal' particles dominate over anti-matter particles---still an unresolved issue.

 

[bapowell]

Regardless of the `big-band model' per se, the idea is that the energy density in the early universe was high enough for spontaneous creation of particles. If you're familiar with electron-positron annihilation to produce 2 photons, then you won't be surprised that the opposite can happen---if two photons have enough energy, they will react to form an electron and positron pair. The same type of thing can happen with all particles.

Right, but this has nothing necessarily to do with the origin of energy in the universe; after all, these are vacuum fluctuations -- virtual particles. How do you suppose they become real? Now, particle production via changing gravitational fields and expansion is a real phenomenon, and might be relevant to the origin of matter. In fact, one can invoke this kind of particle creation to (sort of) reheat the universe after inflation. But you still need to start with a gravitational field for this to work...

This topic is referred to as leptogenesis and baryogenesis (for leptons and baryons respectively), which both focus on how/why 'normal' particles dominate over anti-matter particles---still an unresolved issue.

In what way are you saying that the processes of lepto- and baryogenesis are related to vacuum fluctuations? They are the mechanisms by which particles come to dominate over antiparticles, as you say, but this usually done through out-of-equilibrium, beyond-the-standard model particle interactions.

 

[zhermes]

Right, but this has nothing necessarily to do with the origin of energy in the universe; after all, these are vacuum fluctuations -- virtual particles. How do you suppose they become real?

I agree, this has nothing to do with the origin of energy, in general, I supposed the existence of energy density, and tried to motivate how it can become equipartitioned with matter. As soon as there is energy, it's not just vacuum fluctuations and virtual particles.

In what way are you saying that the processes of lepto- and baryogenesis are related to vacuum fluctuations?

I'm not. You brought up vacuum fluctuations :)

I wasn't talking about virtual particle production (i.e. vacuum fluctuations) at all, just boring old particle physics.

 

[bapowell]

I wasn't talking about virtual particle production (i.e. vacuum fluctuations) at all, just boring old particle physics.

I see. My confusion then was over your statement regarding the spontaneous creation of particles but I see now that you were referring to real particles. My apologies for misreading your post.

 

[Mark M]

How does the BB theory allow for the creation of matter. Bt this I mean the sub atomic particles that make up atoms i.e. the quarks and electrons. From what I have read it seems to assume that they already pre-existed and condensed out of the fireball to form atoms.

Hi John,

The original big bang theory formulated by Lemaitre and Friedman did indeed assert that all of the matter had being compressed into a singularity, but today we've improved upon this.

The standard model of the origin of the universe is known as inflation. In very simple terms, inflation speculates that the universe is filled with an inflaton field. This field would have been at a very high energy at the beginning of the universe, violently fluctuating between different values. Eventually, it would fall down into a false vacuum. In order to reach a true vacuum, it would need to exert a huge force, resulting in an enormous negative pressure. In general relativity, negative pressures result in repulsive gravity, expanding the universe by a factor near 100¹⁰⁰, for about 10^-35 seconds.

Now, imagine a car trying to drive, but it is held back by an extraordinarily tense rubber band. As it continued to try to break free, it would pass it's energy to the rubber band holding it in place. Similarly, imagine a rocket trying to escape from a huge gravitational field. The gravity would build up huge amounts of energy.

During inflation, something similar happened with gravity. It built up enormous emounts of energy, and then at the end of inflation, dumped large amounts of energy into the universe. Since energy and mass are related through E=mc², we know this energy would eventually manifest as matter.

 

[Chalnoth]

How does the BB theory allow for the creation of matter.

The general picture goes as follows:

1. Our universe, at very early times, was incredibly, unbelievably hot (as in hotter than the temperatures available in the collisions at the LHC). This extremely high temperature meant that particles were continuously colliding with one another, producing new matter/anti-matter particle pairs. So the universe was this giant jumble of matter and anti-matter.
2. One or more of the heavier particles that existed at this time tended to decay just a little bit more into matter than anti-matter. This meant that at very early times, there was a teeny tiny bit more matter than anti-matter (around one part in a billion, if memory serves).
3. As our universe cooled, the matter and anti-matter annihilated, eventually leaving behind the tiny excess of normal matter that built up when our universe was much hotter.

Please understand that step (2) here is not currently known in detail. If we're lucky, the LHC will shed some light on this issue.

 

[John15]

A couple of points regarding answers.
Mark if gravity was involved at the start then at the singularity it would have been infinite re black holes so how could anything escape?.
Regarding baryogenisis 1 billion antimatter + 1 billion and 1 matter = 2 billion and 1 universes coming out of the BB (2 billion anhilated) that is a lot to come out of a singularity.
The obvious other question is is it reasonable to think that all that temperature and energy spontainiously came into being.
Has anyone ever tried to create matter out of energy, we create energy from matter in neuclear reactions but is it possible to reverse the process?

 

[bapowell]

Mark if gravity was involved at the start then at the singularity it would have been infinite re black holes so how could anything escape?.

Exactly. Trying to understand the physics of the singularity invariably leads to nonsense. For this reason singularities are not to be interpreted physically -- they instead signify the breakdown or inapplicability of the physical theory.

Regarding baryogenisis 1 billion antimatter + 1 billion and 1 matter = 2 billion and 1 universes coming out of the BB (2 billion anhilated) that is a lot to come out of a singularity.

Why are you associating single matter/antimatter particles with entire universes? There is a single universe, and early on there was a tiny asymmetry between matter and antimatter within that single universe. That's all.

The obvious other question is is it reasonable to think that all that temperature and energy spontainiously came into being.

These ideas are not addressed under the standard hot big bang model. This model considers instead the evolution of the universe from about the Planck time onwards.

 

[marcus]

...these are vacuum fluctuations -- virtual particles. How do you suppose they become real? Now, particle production via changing gravitational fields and expansion is a real phenomenon, and might be relevant to the origin of matter. In fact, one can invoke this kind of particle creation to (sort of) reheat the universe after inflation. But you still need to start with a gravitational field for this to work...
...

Brian, you bring up a very interesting point---particle realization via changing geometry to give it a sloppy paraphrase.

Did you happen to see this paper of Leonard Parker and a PhD student of his named Ivan Agullo? If so I'd really like to know what you think about it. There's an earlier more technical account in Physical Review D, but this is their essay for wider audience:

http://arxiv.org/abs/1106.4240
Stimulated creation of quanta during inflation and the observable universe
Ivan Agullo, Leonard Parker
(Submitted on 21 Jun 2011)
Inflation provides a natural mechanism to account for the origin of cosmic structures. The generation of primordial inhomogeneities during inflation can be understood via the spontaneous creation of quanta from the vacuum. We show that when the corresponding stimulated creation of quanta is considered, the characteristics of the state of the universe at the onset of inflation are not diluted by the inflationary expansion and can be imprinted in the spectrum of primordial inhomogeneities. The non-gaussianities (particularly in the so-called squeezed configuration) in the cosmic microwave background and galaxy distribution can then tell us about the state of the universe that existed at the time when quantum field theory in curved spacetime first emerged as a plausible effective theory.
Comments: Awarded with the First Prize in the Gravity Research Foundation Essay Competition 2011

We're familiar with other cases where geometric circumstances create real (not virtual) particles e.g. Hawking radiation at BH horizon and Unruh radiation caused by acceleration or felt by an accelerated observer. So it seems that expansion of geometry itself, especially inflation, can produce matter. And Leonard Parker seems to consider this significant.

Ivan Agullo is giving an invited talk about this next week at the Atlanta APS meeting. So I'm kind of excited and would be interested if you have a comment.

 

[bapowell]

Thanks Marcus. I will happily check it out. You mention that

We're familiar with other cases where geometric circumstances create real (not virtual) particles e.g. Hawking radiation at BH horizon and Unruh radiation caused by acceleration or felt by an accelerated observer. So it seems that expansion of geometry itself, especially inflation, can produce matter. And Leonard Parker seems to consider this significant.

I would also agree that it is significant, and it is the generally accepted way that primordial perturbations arise (although, history kind of confuses things here...in the early investigations of Parker, Ford, Fulling, Davies, and others, the phenomenon was termed "cosmological particle production", but in recent parlance we talk about the generation of "fluctuations" instead of particles, but the formalism and physical mechanisms at work are identical.) The evolution of quantum fluctuations, from their birth in the inflationary vacuum and their subsequent journey out to superhorizon scales where they become real life perturbations, is perhaps my favorite calculation in physics.

 

[Mark M]

A couple of points regarding answers.
Mark if gravity was involved at the start then at the singularity it would have been infinite re black holes so how could anything escape?.
Regarding baryogenisis 1 billion antimatter + 1 billion and 1 matter = 2 billion and 1 universes coming out of the BB (2 billion anhilated) that is a lot to come out of a singularity.
The obvious other question is is it reasonable to think that all that temperature and energy spontainiously came into being.
Has anyone ever tried to create matter out of energy, we create energy from matter in neuclear reactions but is it possible to reverse the process?

Singularity is a mathematical anomaly, not meant to be taken literally. The universe was very hot, and very dense, that is all we know.

 

[DaveC426913]

Why are you associating single matter/antimatter particles with entire universes? There is a single universe, and early on there was a tiny asymmetry between matter and antimatter within that single universe. That's all.

His point is that, since that tiny imbalance has resulted in the entire universe we see today, then the original amounts of both matter and antimatter before mutual annihilation must have been staggeringly large.

i.e. if the imbalance was on the order of 1/100th of a %, and that left behind a universe of 10⁶⁰ particles, then the original number of particles must have been 2x10⁶⁴.

 

[Chalnoth]

His point is that, since that tiny imbalance has resulted in the entire universe we see today, then the original amounts of both matter and antimatter before mutual annihilation must have been staggeringly large.

i.e. if the imbalance was on the order of 1/100th of a %, and that left behind a universe of 10⁶⁰ particles, then the original number of particles must have been 2x10⁶⁴.

If I recall, this can be directly calculated, in a way, through the relationship between matter energy density and radiation energy density (since the energy from all those annihilations would have been dumped into radiation). I believe the true imbalance was of the order of one part in a billion.

 

[marcus]

...
We're familiar with other cases where geometric circumstances create real (not virtual) particles e.g. Hawking radiation at BH horizon and Unruh radiation caused by acceleration or felt by an accelerated observer. So it seems that expansion of geometry itself, especially inflation, can produce matter. And Leonard Parker seems to consider this significant.

Ivan Agullo is giving an invited talk about this next week at the Atlanta APS meeting. So I'm kind of excited and would be interested if you have a comment.

...
I would also agree that it is significant, and it is the generally accepted way that primordial perturbations arise (although, history kind of confuses things here...in the early investigations of Parker, Ford, Fulling, Davies, and others, the phenomenon was termed "cosmological particle production", but in recent parlance we talk about the generation of "fluctuations" instead of particles, but the formalism and physical mechanisms at work are identical.) The evolution of quantum fluctuations, from their birth in the inflationary vacuum and their subsequent journey out to superhorizon scales where they become real life perturbations, is perhaps my favorite calculation in physics.

Thanks for commenting! As you point out this topic goes back a ways (Parker's thesis Harvard 1966) But there could also be something new! I'll fetch the abstract of Agullo's talk:
http://meetings.aps.org/Meeting/APR12/Event/170160
Beyond the standard inflationary paradigm
The inflationary paradigm provides a compelling argument to account for the origin of the cosmic inhomogeneities that we observe in the CMB and galaxy distribution. In this talk we introduce a completion of the inflationary paradigm from a (loop) quantum gravity point of view, by addressing gravitational issues that have been open both for the background geometry and perturbations. These include a quantum gravity treatment of the Planck regime from which inflation arises, and a clarification of what the trans-Planckian problems are and what they are not. In addition, this approach provides examples of effects that may have observational implications, that may provide a window to test the basic quantum gravity principles employed here.
=========
This abstract leaves me puzzled. But the same research is the subject of a recorded online talk by William Nelson. It's about a paper by Ashtekar, Agullo, Nelson that has not come out yet. It uses the Parker and Agullo results about *stimulated* fluctuations. I get the impression their idea is that inflation does not wipe the slate clean. Somehow earlier inhomogeneities might come through. So I'm puzzled, but also excited by what I'm hearing about.:

 

[bapowell]

Very cool. I have yet to see the trans-Planckian problem addressed within the context of loop quantum gravity, although I can't say I've necessarily been looking. And yes Marcus, there could most definitely be something new; for example, the stimulated creation of particles by the changing geometry in the Parker/Agullo paper looks novel and interesting. I plan to read it through over the weekend!

 

[marcus]

The most informative thing I've found so far is this talk by William Nelson

slide pdf: http://relativity.phys.lsu.edu/ilqgs/nelson101811.pdf
audio: http://relativity.phys.lsu.edu/ilqgs/nelson101811.wav

for lower resolution audio, replace .wav by .aif

In the audio he says when to scroll on to the next slide.

This talk is good and covers the research by Ashtekar, Agullo, and Nelson that is the subject of Agullo's APS presentation

Here is his slide #8:
==quote==
TAKE HOME POINT
Observations are (potentially) sensitive to the state at the onset of slow-roll.
The pre-inflationary dynamics will (typically) result in a state that contains particles (relative to |0⟩) and hence we have a window on to the pre-inflationary era.
Note: Non-gaussianities will provide the really strong test/restriction on the form of this initial state.
==endquote==

 

[Naty1]

How does the BB theory allow for the creation of matter.

short answer: by creating a universe for it to 'exist'...!
then it seems to get complicated as evidenced by the above posts...

From post # 12, Marcus
http://arxiv.org/abs/1106.4240
Stimulated creation of quanta during inflation and the observable universe
Ivan Agullo, Leonard Parker

...characteristics of the state of the universe at the onset of inflation are not diluted by the inflationary expansion and can be imprinted in the spectrum of primordial inhomogeneities...

That is a neat way to capture a concern I posted in another related discussion here
https://www.physicsforums.com/showthread.php?p=3836906&posted=1#post3836906

The concern was essentially that if a black hole horizon emits so little radiation as we think, undetectable levels, how could a Hubble spehere, even if a real horizon, with it's vast size emit much of anything? [sincetemperature and horizon area are presumably in an inverse relation ship.] [Chalnoth I think confirms what I have read, but don't understand, that the Hubble sphere is not actually a valid 'horizon'.

regarding the Hubble Sphere as an [accelerating] 'particle creation horizon'...a possible additional example, I believe, to the ones Marcus listed here.

I would note for the discussion here three things:
Not just matter but everything we observe in our universe seems to have been unified at the moment of the big bang and somehow the inflationary beginning converted whatever it was, let's just say energy, into space, time,gravity, strong and weak force,etc,etc and matter...EVERYTHING...even the resulting vacuum of outer space...[so we not only got 'something' we got 'nothing' [vacuum]]

Second, what we think we know, albeit with missing components, is summarized in the Standard Model of particle physics. That doesn't include gravity for instance, nor an ability to predict charge strength, masses of fundamental particles, and so forth from first principles...the big bang is 'smarter' than we so far.

Third, An alternative theory [which does not seem to be that popular in these forums] may provide an alternative beginning scenario: some form of a cyclic universe...an endless cycle of expansion and contraction, Steinhardt and Turok's model is one.

 

[Naty1]

Brian a question: regarding your post here:

The evolution of quantum fluctuations, from their birth in the inflationary vacuum and their subsequent journey out to superhorizon scales where they become real life perturbations, is perhaps my favorite calculation in physics.

In another thread, you provided some accompanying math:

https://www.physicsforums.com/showthread.php?t=590798&page=2
post #17,

In that discussion Chalnoth seemed to take issue with the author, not you, about another 'cosmological horizon', the Hubble sphere :

...The issue is that whether or not you get Hawking Radiation depends upon whether or not you have a cosmological horizon. And whether or not you have a cosmological horizon depends upon the contents of the universe: it isn't a function of the instantaneous expansion rate at any given time, but on the entire expansion history...

and later, more specifically:

OP:
Provided the Universe always has a non-negative acceleration the radius of this horizon is equal to the Hubble radius at the present cosmological time.
Chalnoth:
No, this isn't true. It reduces to this only in a universe that has nothing but cosmological constant. We also have matter. Since our universe is currently about 70% cosmological constant (assuming it is a cosmological constant...), this isn't too bad of an approximation at the moment. But it would have been a horrible approximation billions of years ago.

My question is how or if Chalnoth's comments apply to your calculation. Does your calculation have a 'valid cosmological horizon'...does it need one?

[If I recall, your calculations used De Sitter spacetime...and I already have a related question posted regarding Rindler spacetime:

Does Born rigidity describe particle creation?

https://www.physicsforums.com/showthread.php?p=3843198#post3843198

If your work relates, any comments are appreciated...

 

[Naty1]

John: In the unlikely case our posts haven't confused you enough, check out this discussion...

https://www.physicsforums.com/showthread.php?t=572299

[don't take that to mean I think I understand all this...I'm not very smart but smart enough to realize I don't understand much.]

it doesn't at first appear epecially related to your question but skim thru and you'll find some interesting
insights ...like:

...There are ...interaction effects which change the effective masses of both electrons and holes moving in a material because they change the surrounding field which must be carried around with the moving charges relative to what they would be in a vacuum. [any application during the incredible density of a bang?? holes have mass?? How 'dressed were the first electrons to emerge from the bang?? ]

... a propagating fermion [matter] interacts with its surrounding in such a way that the net effect of the interactions is to make the fermion behave as a "dressed" fermion, altering its effective mass and other dynamical properties. These "dressed" fermions are what we think of as "quasiparticles".

...electrons are quasiparticles, the same way the holes are quasiparticles, via Landau's Fermi Liquid theory...[so there are particle [matter] theories in fields, semiconductors, niow liquids, how about the 'plasma' of a bang??]

There are strong arguments that ALL elementary particles are essentially "emergent", meaning that they came out of vacuum many-body interactions.

So a natural question might be "Did a particular 'fundamental' particle emerge from the bang first, say a gluon, photon or graviton, or maybe even a 'hole' or a Higgs particle?? When did the necessary conditions for 'particle emergence' begin, before inflation or during inflation or after inflation?

 

[Chalnoth]

So a natural question might be "Did a particular 'fundamental' particle emerge from the bang first, say a gluon, photon or graviton, or maybe even a 'hole' or a Higgs particle?? When did the necessary conditions for 'particle emergence' begin, before inflation or during inflation or after inflation?

If there were any particles around during inflation, inflation spread them so far and wide that we'd be lucky to have a single pre-inflation particle in our entire observable universe. The particles that are around today are a result of the end of inflation.

As inflation ended, the field that drove inflation, the inflaton field, decayed. As it decayed, it produced an obscenely hot thermal bath of particles of all sorts. Only the stable particles survived after that thermal bath cooled.

 

[bapowell]

My question is how or if Chalnoth's comments apply to your calculation. Does your calculation have a 'valid cosmological horizon'...does it need one?

I think the problem here is lazy terminology. There is a "cosmological horizon" which is nonspecific and care should be taken to define fully what is meant. In my calculation, and I think rather commonly also, it defines the boundary of a causal region of the universe; it is equal to the particlel horizon. This distance, $\sim H^{-1}$, is what is important in my calculation, because when Fourier modes have wavelengths larger than this they cease to evolve because they are stretched across acausal distances. All spacetimes have a particle horizon, on account of the finite speed of light.

Chalnoth is referring to the cosmological event horizon, which only exists in accelerating spacetimes. For de Sitter expansion, the event horizon coincides with the particle horizon; this I believe is what he is referring to.

It's important to point out as well that neither of these horizons is accelerating -- it is the background spacetime that is doing that. In fact, during de Sitter expansion, the event horizon is constant in time!

 

[John15]

Dave in post 15 you are correct in what I am saying about the implication that far more came out of the BB than exists now.
Regarding the creation of matter do we know what quarks are made of? do they have mass or are they just energy? From what I understand singly they decay rapidly yet in groups of 3 they basicaly make up the protons and neutrons and protons seem to be virtually eternal, I have found it strange that they should decay rapidly when single yet be stable in 3's. Presumably they were all created in the early stages.
It is strange that certain things like electrons are stable and others not, is there a reason why certain configurations are stable and others not?
Is mass perhaps just energy that we think is solid for want of a better word.
By cosmological event horizon can I take it it refers to the edge of our universe? if so then should it not be expanding at the speed of light as light goes outwards from the universe? This of course gives the question what is it expanding into? and unless energy/matter is being created then the density of the universe will be going down as the volume increases.
We also have the conservation of energy which at some point must not have been valid as all the energy in the universe must have been created at some point unless the universe is not an isolated system.
Can I take it that creation of matter has either not been tried or that it failed.

 

[bapowell]

By cosmological event horizon can I take it it refers to the edge of our universe? if so then should it not be expanding at the speed of light as light goes outwards from the universe? This of course gives the question what is it expanding into?

It's the boundary of the observable universe. There's likely more universe beyond the cosmological horizon.

 

[phinds]

It's the boundary of the observable universe. There's likely more universe beyond the cosmological horizon.

And John15, just to add to what bapowell said, the edge of the observable universe (as it exists "now", although "now" is a bit of a tough subject) is receeding from us at about 3.5 times the speed of light, not "at the speed of light".

 

[phinds]

We also have the conservation of energy which at some point must not have been valid as all the energy in the universe must have been created at some point unless the universe is not an isolated system.

It has been concluded that conservation of energy does not apply on cosmological scales.

 

[Chalnoth]

I think the problem here is lazy terminology. There is a "cosmological horizon" which is nonspecific and care should be taken to define fully what is meant. In my calculation, and I think rather commonly also, it defines the boundary of a causal region of the universe; it is equal to the particlel horizon. This distance, $\sim H^{-1}$, is what is important in my calculation, because when Fourier modes have wavelengths larger than this they cease to evolve because they are stretched across acausal distances. All spacetimes have a particle horizon, on account of the finite speed of light.

Chalnoth is referring to the cosmological event horizon, which only exists in accelerating spacetimes. For de Sitter expansion, the event horizon coincides with the particle horizon; this I believe is what he is referring to.

It's important to point out as well that neither of these horizons is accelerating -- it is the background spacetime that is doing that. In fact, during de Sitter expansion, the event horizon is constant in time!

Right. And just to be clear, if we're talking about particle creation, we're talking about an event horizon specifically.

 

[Naty1]

Chalnoth:

If there were any particles around during inflation, inflation spread them so far and wide that we'd be lucky to have a single pre-inflation particle in our entire observable universe.

I am not so sure: if appropriate conditions [ such as the cosmological energy density during the period of expansion, that roughly 10^-35 seconds] remained constant...

and I was also alluding back to Marcus post #12...

...characteristics of the state of the universe at the onset of inflation are not diluted by the inflationary expansion and can be imprinted in the spectrum of primordial inhomogeneities...

If the negative gravitational pressure of inflation 'got stuck' briefly on an energy plateau, why not other factors conducive to particle production..like,maybe, virtual particles of the vacuum??...antimatter?? were NOT diluted...

...As inflation ended, the field that drove inflation, the inflaton field, decayed. As it decayed, it produced an obscenely hot thermal bath of particles of all sorts. Only the stable particles survived after that thermal bath cooled.

Yes, thanks... I do understand that and its all fine standard science for now.

My hypothetical question to john15 concerned "what an incredible coincidence that the inflation field, and its predecessor, carries all the 'constitutents', all the 'information' necessary to create the universe we observe." And I attempted to draw a crude analogy to quasiparticles, semiconductor and fermi liquid states,etc, where we already know 'particles' have different manifestations from those we normally observe in unusual circumstancs. And inflation was far, far more unusual. That the negative pressure of gravity carries ALL the constitutents of the universe is amazing!

And how does all the above relate to the following regarding particle pair production:

////
bapowell:

In my calculation... it is equal to the particlel horizon. ... when Fourier modes have wavelengths larger than this they cease to evolve because they are stretched across acausal distances. All spacetimes have a particle horizon, on account of the finite speed of light.

Chalnoth is referring to the cosmological event horizon, which only exists in accelerating spacetimes. For de Sitter expansion, the event horizon coincides with the particle horizon; this I believe is what he is referring to.

THAT is more than I understood... all makes sense...I like the 'mode/particle horizon' description...had not thought nor read that previously...

It's important to point out as well that neither of these horizons is accelerating -- it is the background spacetime that is doing that. In fact, during de Sitter expansion, the event horizon is constant in time!

Glad you mentioned that; I am unsure of the implications and have been rather unsuccessful so far in distinguishing between different 'horizons' and different spacetimes effects on particle production... Unruh, de Sitter, Rindler,etc, have me confused because of apparently different 'accelerations'...

I forget if I mentioned it in this thread, but reading about Born rigidity recently made me post elsewhere about how that desription [in a Rindler frame] might also describe a type of 'accelerating particle pair production'...all seem related as Marcus implied ...

 

[John15]

Any thoughts on my comments about particle stability and decay?
Why has it been concluded that the conservation of energy does not apply on cosmological scales?

 

[zhermes]

It has been concluded that conservation of energy does not apply on cosmological scales.

Can you site sources on that?

 

[Chalnoth]

Any thoughts on my comments about particle stability and decay?
Why has it been concluded that the conservation of energy does not apply on cosmological scales?

No idea what you mean by the first question, but the answer to the second is that this fact falls straight out of General Relativity. In General Relativity, there is no absolute way to define global energy. You can define a local energy density, but not a global energy. And you can't conserve what you can't define.

 

[Naty1]

john15:

..This of course gives the question what is it expanding into? and unless energy/matter is being created then the density of the universe will be going down as the volume increases.
We also have the conservation of energy which at some point must not have been valid as all the energy in the universe must have been created at some point unless the universe is not an isolated system.
Can I take it that creation of matter has either not been tried or that it failed.

'Expansion', as explained, refers to how much we can observe... but beyond that, AFAIK, the major portion of the universe, 'unobservable' to us so far, is likely behaving similarly...within our universe, expansion is into existing spacetime...pushing it outward all around us...

matter density IS going down as new space emerges with vacuum energy..the same energy density as existing 'old' space...we are proceeding from a matter dominated to an energy dominated universe...hence accelerated expansion...

In theory, the universe was born with equal and opposite amounts of 'mass' energy and gravitational energy; the former positive, the latter negative; it's the 'ultimate free lunch' if accurate. Total energy in the universe supposedly remains 'zero'. More here:
http://en.wikipedia.org/wiki/Zero-energy_universe

matter has been created...depending on just what you mean...fusion is an example...even radioactive decay ...More limited, formal explanation here:

more here: http://en.wikipedia.org/wiki/Matter_creation

 

[Mark M]

Any thoughts on my comments about particle stability and decay?
Why has it been concluded that the conservation of energy does not apply on cosmological scales?

Because on cosmological scales, general relativity and gravity dominate. In classical physics, energy is conserved because of time-translation invariance. Essentially, the background on which energy exists does not change. However, general relativity explains that the background, spacetime, does indeed change, and hence energy is not conserved. On top of this, general relativity is very vague about energy and mass in the first place. It allows a from of energy from gravitational waves known as gravitational energy. So how could it really 'conserve' what it does not even define? Also, read this:

http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html