what was the SOL during inflation?

[tommac]

what was the SOL during inflation?

[Hornblower]

what was the SOL during inflation?

What is SOL?

[peter eldergill]

SOL = Speed of light (at least in Astronomy....it can also be used as a colloquialism to mean something entirely different )

Pete

PS I can't answer the question

[Hornblower]

Please bear with me and my feeble brain. I am not so good at acronyms that lead off a narrative without being spelled out first.

[Cougar]

I am not so good at acronyms that lead off a narrative without being spelled out first.

I'm with you, Hornblower. I was wondering why tommac wanted to know the statute of limitations during inflation. I figured it would be about 10^-32 seconds, so one better get that case filed in a hurry.

what was the SOL during inflation?

Oh, the speed of light? Currently considered as one of the very few absolute constants of nature, why would you, tommac, think it might be any different during inflation?

[antoniseb]

Please bear with me and my feeble brain. I am not so good at acronyms that lead off a narrative without being spelled out first.

Same here. I was sure he wasn't talking about "luck", but "Speed o'Light" didn't spring to mind either. Thanks for the clarification Peter.

[Drunk Vegan]

Oh, the speed of light? Currently considered as one of the very few absolute constants of nature, why would you, tommac, think it might be any different during inflation?

There have been postulates that treat C as a variable, not a constant.

The thinking is that the speed of light might have been slower or faster during the creation of the universe when the laws of physics were not yet firmly set.

Or alternately that as the universe has expanded the measurable speed of light has slowed or sped up because the medium through which light travels has changed.

All extremely theoretical and ATM but it is possible for C to be variable.

In answer to original poster's question though, it's impossible to know what the speed of light was during inflation (if it was different from now at all).

[cosmocrazy]

what was the SOL during inflation?

It was the speed of light!

But i see what you are trying to get at.

We don't know how fast light traveled relative to everything else in the earlier universe. Most would say about 300,000 kps as it is now. But if we consider that space-time determines the speed of light then i guess it could be variable. But "C" would still remain constant relative to anything defined within the same space-time. (the whole observable universe)

[Nereid]

Here, perhaps, is a related question that may be more directly tested: how can you tell what the SOL was, during the time of inflation, today?

Or, expressed a little differently, what experiments could you perform (today), or observations could you make (today), that would test any well-formulated hypothesis concerning the SOL in that physical regime?

[cosmocrazy]

Here, perhaps, is a related question that may be more directly tested: how can you tell what the SOL was, during the time of inflation, today?

Or, expressed a little differently, what experiments could you perform (today), or observations could you make (today), that would test any well-formulated hypothesis concerning the SOL in that physical regime?

Are you referring to observations/predictions of the most distance parts of the observable universe that seem to be inflating faster than light?

If it is true that space-time is expanding faster than light the further out we observe then could the speed of light increase relative to this inflation in those regions? And yet somehow remain constant relative to that local space-time? But this would seem to violate causality or devoid "c" as a constant?

Is it at all possible to determine if the speed of light was any different in the past relative to the present based on future observations?

[Cougar]

...the speed of light might have been slower or faster during the creation of the universe when the laws of physics were not yet firmly set.

Well put. As I think Smolin speculated in The Trouble With Physics, the laws of physics may not have been a unique, necessary setting, but rather like a pencil balanced on its tip that just happens to fall over in a certain direction as its symmetry was broken.

[Nereid]

Here, perhaps, is a related question that may be more directly tested: how can you tell what the SOL was, during the time of inflation, today?

Or, expressed a little differently, what experiments could you perform (today), or observations could you make (today), that would test any well-formulated hypothesis concerning the SOL in that physical regime?

Are you referring to observations/predictions of the most distance parts of the observable universe that seem to be inflating faster than light?

If it is true that space-time is expanding faster than light the further out we observe then could the speed of light increase relative to this inflation in those regions? And yet somehow remain constant relative to that local space-time? But this would seem to violate causality or devoid "c" as a constant?

Well, it's t's question, so I guess we should ask t, shouldn't we?

In any case, it should be fairly simple to discover the extent to which "c" has its usual (here and now) meaning in the various (theoretical) models of inflation ... simply read the relevant papers.

FWIW, I would expect that the authors of the various papers will have tried very hard to keep as much of the key parts of modern physics intact in their various models of inflation, and if "c" were varied in some important way, they'd have mentioned it. So, for example, massless particles travelled at c, gravitational waves at c, and cause-and-effect was limited to c during inflation ... except if the relevant model explicitly assumed otherwise.

Is it at all possible to determine if the speed of light was any different in the past relative to the present based on future observations?

That's an excellent question! And it's one that quite a deal of research has been done on, albeit via alpha, the fine structure constant.

Would you be interested in some details of the many different kinds of observations made on the constancy of alpha over cosmological time?

[tommac]

I'm with you, Hornblower. I was wondering why tommac wanted to know the statute of limitations during inflation. I figured it would be about 10^-32 seconds, so one better get that case filed in a hurry.



Oh, the speed of light? Currently considered as one of the very few absolute constants of nature, why would you, tommac, think it might be any different during inflation?

Well during inflation stuff was moving away from each other at faster than the current SOL right?

[tommac]

yes

Would you be interested in some details of the many different kinds of observations made on the constancy of alpha over cosmological time?

[Argos]

You could say that the speed of light was = 1 [normalized, natural unit] and be done with that...

[Nereid]

Well during inflation stuff was moving away from each other at faster than the current SOL right?

Indeed, but so what?

Are you familiar with the Davis and Lineweaver material, on common misconceptions about (LCDM) cosmology (and GR in general)? There are certainly plenty of BAUT threads presenting this, and discussing it.

It may be useful to remind ourselves of what 'c' is ...

In contemporary physics, it is the speed of massless particles (such as photons and gluons) in a vacuum, and also the speed of gravitational waves (the kind that LIGO etc are trying to detect). It is also the maximum speed at which information can travel (this comes from careful consideration of the relevant parts of quantum theory, esp concerning entangled particles).

Another interesting angle comes from definitions and measurements.

'speed' is easily enough defined (crudely, distance divided by time), so something's speed can be estimated by measuring some relevant distance and time. But then you need to have a ruler and a clock, to define the units of length (distance) and time! And what are those defined as, today?

This page is very interesting:

The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.

Cool!

Our ruler is defined in terms of c! Why?

[Nereid]

yes

Would you be interested in some details of the many different kinds of observations made on the constancy of alpha over cosmological time?

OK, start with Oklo, the ancient natural nuclear reactors here on Earth ... I'll dig up some other stuff later ...

[tommac]

Indeed, but so what?

Well what is your answer?

[speedfreek]

Well during inflation stuff was moving away from each other at faster than the current SOL right?

Yes, and so was stuff moving away from other stuff faster than the current SOL 380,000 years later at decoupling/recombination, when the CMBR was emitted. The edge of the observable universe, the surface of last scattering, was receding at over 58 times the SOL at that time.

We receive those CMBR photons 13.7 billion years later, and that surface of last scattering is still receding from us faster than the current SOL.

so.....?

[tommac]

So ?? So ??

Well if the SOL (and by the SOL I mean more the part where things can not travel faster than the SOL part of SOL) was faster than it was today ... then that would mathmatically effect a few things wouldnt it? It may also shed light on what space-time really is? The speed of light really is just a ratio right a max ratio of space / time that stuff can move away from each other.

If during a inflation stuff was moving away from each other now ... wouldnt that mean that the speed of light is dependant on the amount of energy density in a system ?

Yes, and so was stuff moving away from other stuff faster than the current SOL 380,000 years later at decoupling/recombination, when the CMBR was emitted. The edge of the observable universe, the surface of last scattering, was receding at over 58 times the SOL at that time.

We receive those CMBR photons 13.7 billion years later, and that surface of last scattering is still receding from us faster than the current SOL.

so.....?

[Nereid]

Indeed, but so what?

Well what is your answer?

The same as the rest of the post (of mine) that you are quoting:

Are you familiar with the Davis and Lineweaver material, on common misconceptions about (LCDM) cosmology (and GR in general)? There are certainly plenty of BAUT threads presenting this, and discussing it.

It may be useful to remind ourselves of what 'c' is ...

In contemporary physics, it is the speed of massless particles (such as photons and gluons) in a vacuum, and also the speed of gravitational waves (the kind that LIGO etc are trying to detect). It is also the maximum speed at which information can travel (this comes from careful consideration of the relevant parts of quantum theory, esp concerning entangled particles).

Another interesting angle comes from definitions and measurements.

'speed' is easily enough defined (crudely, distance divided by time), so something's speed can be estimated by measuring some relevant distance and time. But then you need to have a ruler and a clock, to define the units of length (distance) and time! And what are those defined as, today?

This page is very interesting:

The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.

Cool!

Our ruler is defined in terms of c! Why?

I see from a later post of yours that you seem to have not read this (latter) part of my post, and have introduced an idiosyncratic definition of SOL ("by the SOL I mean more the part where things can not travel faster than the SOL part of SOL").

Now of course you are free to define terms (such as "SOL") in any way you wish ... but if you are truly looking for answers to your questions, I recommend that you either a) stick with textbook definitions of key terms, or b) clearly explain how the words you use differ from those in standard textbooks.

So, which parts of my (earlier) post did you not understand?

ETA: I added some bold; I hope this clarifies my answer a bit (in light of your non-standard definition of SOL)

[tommac]

I see from a later post of yours that you seem to have not read this (latter) part of my post, and have introduced an idiosyncratic definition of SOL ("by the SOL I mean more the part where things can not travel faster than the SOL part of SOL").

this part:
It is also the maximum speed at which information can travel

isnt that close to:

things can not travel faster than the SOL

[Cougar]

Well if the SOL... was faster than it was today...

Whoa, there. This is a major misunderstanding. Inflation posits that the universe was expanding faster than the speed of light. Unless evidence to the contrary shows up, there is no reason to think that any light that was propagating at the time of inflation was moving at any speed different than what we measure today.

[tommac]

Whoa, there. This is a major misunderstanding. Inflation posits that the universe was expanding faster than the speed of light. Unless evidence to the contrary shows up, there is no reason to think that any light that was propagating at the time of inflation was moving at any speed different than what we measure today.

Les forget about light ... I am not saying anything about light propogating.

I am merely talking about the SPEED of light and things expanding away from each other at speeds faster than the current SOL.

[Nereid]

I see from a later post of yours that you seem to have not read this (latter) part of my post, and have introduced an idiosyncratic definition of SOL ("by the SOL I mean more the part where things can not travel faster than the SOL part of SOL").

this part:
It is also the maximum speed at which information can travel

isnt that close to:

things can not travel faster than the SOL

It might seem, on first reading, to be similar, but it is actually very different.

"things" is, to put it mildly, vague.

One thing (!) that is important in doing science is to be pedantic, and sometimes mind-bogglingly pedantic.

Especially with things (!) like the scope of a theory, hypothesis, model, etc.

Ditto with the definitions of the key terms used in such theories, hypotheses, models, etc.

'c is the maximum speed at which information can travel' is a nice, simple statement ... but it hides some mind-blowing concepts, like quantum entanglement, and a bunch of very clever experiments that pit some of Einstein's views against implications of quantum mechanics (the results are: Einstein 0, quantum theory N, where N is an integer possibly >100 by now).

Much the same sort of thing can be said with 'cause' or 'causality' replacing 'information'.

A simple illustration: imagine a gigantic pair of scissors, being closed. The point at which the scissors close could be called a "thing", and this thing could certainly move at speeds much greater than c (depends on how big the scissors are, and how quickly they are being closed).

Another: imagine a rotating beam, like a lighthouse; imagine you are a very, very long way from the source, and have a nice white sheet on which the beam falls. Depending on how fast the source is rotating and how far from it you are, the spot on your white sheet where the beam hits could move at a speed very much greater than c ... and you could certainly call this beam spot a "thing".

Now in neither illustration is any information travelling at a speed > c, nor can any cause.

And these illustrations involve ordinary things, in a plain old euclidian/newtonian universe ...

[Nereid]

Les forget about light ... I am not saying anything about light propogating.

I am merely talking about the SPEED of light and things expanding away from each other at speeds faster than the current SOL.

Huh?

What is "the SPEED of light" if not the speed at which light propagates?

"Things" expand away from each other at speeds faster than the current SOL in our current, non-inflating universe ... that's what my question about the Davis and Lineweaver articles was about ("Are you familiar with the Davis and Lineweaver material, on common misconceptions about (LCDM) cosmology (and GR in general)? There are certainly plenty of BAUT threads presenting this, and discussing it.")

So, are you familiar with the Davis and Lineweaver material, on common misconceptions about (LCDM) cosmology (and GR in general)?

If not, then someone will, I'm sure, be kind enough to point you to some of the relevant threads and/or give you URLs for the material.

If so, what part(s) of that material do you not understand?

[tommac]

It depends on your definition of things ... the definition I am using does not include infinitely large scissors or a "beam spot". my definition of things is :

"stuff" that is limited in velocity by the speed of light.

It might seem, on first reading, to be similar, but it is actually very different.

"things" is, to put it mildly, vague.

One thing (!) that is important in doing science is to be pedantic, and sometimes mind-bogglingly pedantic.

Especially with things (!) like the scope of a theory, hypothesis, model, etc.

Ditto with the definitions of the key terms used in such theories, hypotheses, models, etc.

'c is the maximum speed at which information can travel' is a nice, simple statement ... but it hides some mind-blowing concepts, like quantum entanglement, and a bunch of very clever experiments that pit some of Einstein's views against implications of quantum mechanics (the results are: Einstein 0, quantum theory N, where N is an integer possibly >100 by now).

Much the same sort of thing can be said with 'cause' or 'causality' replacing 'information'.

A simple illustration: imagine a gigantic pair of scissors, being closed. The point at which the scissors close could be called a "thing", and this thing could certainly move at speeds much greater than c (depends on how big the scissors are, and how quickly they are being closed).

Another: imagine a rotating beam, like a lighthouse; imagine you are a very, very long way from the source, and have a nice white sheet on which the beam falls. Depending on how fast the source is rotating and how far from it you are, the spot on your white sheet where the beam hits could move at a speed very much greater than c ... and you could certainly call this beam spot a "thing".

Now in neither illustration is any information travelling at a speed > c, nor can any cause.

And these illustrations involve ordinary things, in a plain old euclidian/newtonian universe ...

[Nereid]

It depends on your definition of things ... the definition I am using does not include infinitely large scissors or a "beam spot". my definition of things is :

"stuff" that is limited in velocity by the speed of light.

Then you have answered your own question ... "the SOL during inflation" is whatever the model/theory of inflation you are examining/researching/wondering about/etc says it is.

And, as a good guide, that will be the same as c in the universe of here and now unless the model/theory says otherwise.

So, do you have a particular version of inflation you are looking at?

[tommac]

lets look at a few of them ... lets start with chaotic.

Then you have answered your own question ... "the SOL during inflation" is whatever the model/theory of inflation you are examining/researching/wondering about/etc says it is.

And, as a good guide, that will be the same as c in the universe of here and now unless the model/theory says otherwise.

So, do you have a particular version of inflation you are looking at?

[Nereid]

lets look at a few of them ... lets start with chaotic.

I am unfamiliar with "chaotic inflation", can you clarify please?

A simple query on ADS ("inflation" in the title, published between 2000 and 2008) brings up >3000 entries.

Now not all of these are papers, and not all the papers are all that pertinent; further, among the >1000 papers (that's a guess) which are, perhaps only a dozen or so cover distinct models or theories.

Care to choose a couple, from among these?

Would you like some help with how to search using ADS, to find published papers on inflation?