PDA

View Full Version : what was the SOL during inflation?



tommac
2008-Sep-09, 01:33 AM
what was the SOL during inflation?

Hornblower
2008-Sep-09, 01:40 AM
what was the SOL during inflation?What is SOL?

peter eldergill
2008-Sep-09, 02:09 AM
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
2008-Sep-09, 01:49 PM
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
2008-Sep-09, 02:51 PM
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
2008-Sep-09, 02:51 PM
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
2008-Sep-09, 06:41 PM
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
2008-Sep-09, 10:30 PM
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
2008-Sep-09, 10:44 PM
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
2008-Sep-09, 11:15 PM
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
2008-Sep-09, 11:31 PM
...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
2008-Sep-10, 02:49 AM
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
2008-Sep-10, 04:03 AM
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
2008-Sep-10, 04:08 AM
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
2008-Sep-10, 12:26 PM
You could say that the speed of light was = 1 [normalized, natural unit] and be done with that...

Nereid
2008-Sep-10, 01:31 PM
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 (http://physics.nist.gov/cuu/Units/current.html) 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
2008-Sep-10, 01:40 PM
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 (http://antwrp.gsfc.nasa.gov/apod/ap050220.html), the ancient natural nuclear reactors here on Earth ... I'll dig up some other stuff later ...

tommac
2008-Sep-10, 08:15 PM
Indeed, but so what?

Well what is your answer?

speedfreek
2008-Sep-10, 11:08 PM
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
2008-Sep-10, 11:47 PM
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
2008-Sep-11, 01:10 AM
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
2008-Sep-11, 01:56 PM
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
2008-Sep-11, 02:44 PM
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
2008-Sep-11, 03:24 PM
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
2008-Sep-11, 03:44 PM
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
2008-Sep-11, 03:49 PM
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
2008-Sep-11, 03:50 PM
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
2008-Sep-11, 03:56 PM
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
2008-Sep-11, 04:02 PM
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
2008-Sep-11, 05:57 PM
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?

speedfreek
2008-Sep-11, 05:59 PM
A few links to papers that may be relevant here.

Inflation and the Cosmic Microwave Background (http://arxiv.org/abs/astro-ph/0305179) - Charles H. Lineweaver, 2003

Abstract:

I present a pedagogical review of inflation and the cosmic microwave background. I describe how a short period of accelerated expansion can replace the special initial conditions of the standard big bang model. I also describe the development of CMBology: the study of the cosmic microwave background. This cool (3 K) new cosmological tool is an increasingly precise rival and complement to many other methods in the race to determine the parameters of the Universe: its age, size, composition and detailed evolution.


Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe
(http://arxiv.org/abs/astro-ph/0310808) - Tamara M. Davis, Charles H. Lineweaver, 2003

Abstract:

We use standard general relativity to illustrate and clarify several common misconceptions about the expansion of the Universe. To show the abundance of these misconceptions we cite numerous misleading, or easily misinterpreted, statements in the literature. In the context of the new standard Lambda-CDM cosmology we point out confusions regarding the particle horizon, the event horizon, the ``observable universe'' and the Hubble sphere (distance at which recession velocity = c). We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light. We explain why this does not violate special relativity and we link these concepts to observational tests. Attempts to restrict recession velocities to less than the speed of light require a special relativistic interpretation of cosmological redshifts. We analyze apparent magnitudes of supernovae and observationally rule out the special relativistic Doppler interpretation of cosmological redshifts at a confidence level of 23 sigma.

tommac
2008-Sep-11, 07:47 PM
Yawn ...


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?

Neverfly
2008-Sep-11, 08:26 PM
Yawn ...

Nice response to someone having offered to help you, Tommac. :neutral:

tommac
2008-Sep-11, 08:46 PM
Could the speed of light and the expansion of the universe work in tandem to keep the topography of the universe flat?

tommac
2008-Sep-11, 08:48 PM
Nice response to someone having offered to help you, Tommac. :neutral:

I must apologize if it came off rude.

tommac
2008-Sep-11, 09:00 PM
Who says it has always been constant? We dont even know why it is what it is but we are sure it has always been that way?

Is it just a ratio of energy to mass? sr(e/m) maybe that ratio changes in extreme energy states ( like when energy is compressed into a near infinite density ) ... Does this also hold true on the atomic level?

Maybe the SOL is just natures way of keeping space-time relatively flat? When it is too compressed ... the speed of light gets faster to allow a release of energy? How about if the entire universe was compacted inside 1 cubic plank length


Is the consensus answer to my question is that the SOL has always been exactly what it is today?



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?

speedfreek
2008-Sep-11, 10:01 PM
Who says it has always been constant? We dont even know why it is what it is but we are sure it has always been that way?

Is the consensus answer to my question is that the SOL has always been exactly what it is today?

From Curious About Astronomy?

Did the speed of light change over the history of the universe? (http://curious.astro.cornell.edu/question.php?number=606)

How will a change in the speed of light affect the evolution of the Universe? (http://curious.astro.cornell.edu/question.php?number=496)

Neverfly
2008-Sep-11, 10:40 PM
I must apologize if it came off rude.

It did. You reacted in similar manner when you started a thread in About BAUT;)

Just food for thought- Now back to regularly scheduled programming...

Nereid
2008-Sep-11, 10:42 PM
Who says it has always been constant? We dont even know why it is what it is but we are sure it has always been that way?

Is it just a ratio of energy to mass? sr(e/m) maybe that ratio changes in extreme energy states ( like when energy is compressed into a near infinite density ) ... Does this also hold true on the atomic level?

Maybe the SOL is just natures way of keeping space-time relatively flat? When it is too compressed ... the speed of light gets faster to allow a release of energy? How about if the entire universe was compacted inside 1 cubic plank length


Is the consensus answer to my question is that the SOL has always been exactly what it is today?
tommac, do you have trouble reading?

I ask this in all seriousness, because this post of yours, that I am quoting, contains several statements that seem to reflect either a complete non-comprehension of others' posts, earlier in this thread, or (perhaps) a deliberate avoidance of them (I hope not).

Could I suggest that you take the trouble to read the posts in this thread, slowly and carefully, and where you don't understand the answers, ask further - simple, direct - questions to clarify your lack of understanding?

tommac
2008-Sep-12, 02:08 PM
Let me reword my OP?

Why is the speed of light constant?
Could the inflation period be explained with a varying speed of light?
Can the SOL vary based on a resistance in the ether?

Drunk Vegan
2008-Sep-12, 04:09 PM
Careful how much you work out guys.

There's a theory that if the universe were properly understood, it would immediately be replaced by something more complicated and infinitely more bizarre.

There is another theory that states that this has already happened.

Nereid
2008-Sep-12, 05:21 PM
Let me reword my OP?
OK


Why is the speed of light constant?

I do hope that Ken G stops by soon, and gives a version of his excellent "what physics is and what its relationship to the universe is"!

The best, simple, answer I can give to this question has two parts:

a) because General Relativity (GR) seems to explain all the relevant observations and experimental results (within its domain of applicability)

AND

b) the "speed of light" is constant within GR (caveat: check the definition carefully)



Could the inflation period be explained with a varying speed of light?

Are you asking about the specific theories/models of inflation, published in the relevant, peer-reviewed journals to date, either as a class of theory/model or something else? If so, then my guess is almost certainly not ... because no such theory or model has been published.

There is at least one cosmologically-relevant theory in which there is a variable (or double) speed of light, but IIRC it couldn't really be said to overlap with inflation ... but I could be wrong (I'll check).

OTOH, if you asking about the possibility that some model or theory, which could be labelled "inflation", could incorporate a varying speed of light, then the only possible answer is "yes".



Can the SOL vary based on a resistance in the ether?
What "ether" are you referring to here?

Per GR, light (more generally, massless particles) does not need a medium in order to propagate ...

Nereid
2008-Sep-13, 07:24 PM
This Wikipedia page (http://en.wikipedia.org/wiki/Variable_speed_of_light) is as good a place to start as any (usual caveats apply, of course), esp wrt the references.

An extract:

The varying speed of light cosmology has been proposed independently by Jean-Pierre Petit from 1988[17][18][19][20] and then John Moffat in 1992[21] and the two-man team of Andreas Albrecht and Joćo Magueijo in 1998[22][23][24][25][26][27] to explain the horizon problem of cosmology and propose an alternative to cosmic inflation.
Magueijo's VSL ideas are perhaps the best known.

I have not been following this closely enough to have an opinion on how well any of these VSL ideas can account for, say, the WMAP5 observations.

Nereid
2008-Sep-14, 01:07 PM
Here (http://www.bautforum.com/1317468-post28.html)'s a recent post by Tim Thompson that might help you, tommac, understand the purpose and scope of science, especially cosmology:

We look at the universe in extraordinary detail, and then we make up a story that explains why the universe looks the way it does. We require our story to be entirely self consistent and entirely consistent with everything we know about physics, to the best of our ability to do so. We are not 100% successful, witness the failure of general relativistic cosmology to conserve energy globally. That may be revealing of a deep truth about the universe, or it may be revealing of our own ignorance. We do know that if there was inflation, then it would explain what we see. We do know that if there was a bang, then it would explain what we see. So we don't know why either happened, nor do we know that either actually happened at all. We do not know that either is existentially true, we know only that both make our cosmological models work better, so we include them in our story of the universe.

Lepton
2008-Sep-14, 08:31 PM
Can the SOL vary based on a resistance in the ether?

Is this the 19th century?

tommac
2008-Sep-15, 07:47 PM
What "ether" are you referring to here?

Per GR, light (more generally, massless particles) does not need a medium in order to propagate ...

By ether I mean the fabric of space-time.