Summary
=======
There is a fundamental difference between the Observable Universe (the
universe we see) and the Current Universe (the universe as it is now).

The maximum outer limit of the Observable Universe must be expanding
at the speed of light !


Any hypothesis that the Current Universe is expanding is a
metaphysical claim (an Unscientific assertion) since the Current
Universe cannot be observed.


The fundamental difference between the Observable Univese and the
Current Universe
================================================== ==
There seems to be a failure even by senior Cosmologists to properly
distinguish between the Current Universe (lets call it the CU) and the
Observable Universe (the OU). The CU is the universe as it is now -
not as we see it but as it actually is now. The OU on the other hand
is the universe as we see it. Because of the finite speed of light,
when we look out into space we see back through time. The further out
we look, the more 'distorted' must be our view as compared to the CU
(the universe as it is now).


We know that the size of the OU is proportionate to its age ie Age x c
= Radius (where c is the speed of light). However the size of the CU
is not so easy. The CU is not observable so how can we know its
size ?


In Ned Wright's Cosmology FAQs, he regularly extrapolates from the OU
to the CU as if there were no difference; as if looking at the past
and speculating about the (unobservable) Present are factually
equivalent. For example, if the OU is observed to be expanding,
Wright assumes that the CU is also expanding.


Why does the Observable Universe appear to be expanding ?
=============================================
If the universe had a beginning then the speed of light sets the
maximum possible size for the OU eg if the age of the universe is 14
billion years then the maximum possible distance to the outer limit of
the OU is 14 billion light years (radius). This is simply because the
light which we observe from the outer reaches of the universe cannot
have travelled further than 14 billion light years since the
beginning. Note that we are talking about the OU which is unlikely to
bear any resemblance to the CU.


Continuing the previous example, after another billion years have
elapsed, the outer limit of the OU will be 15 billion light years.
So the maximum outer limit of the OU must be expanding at the speed of
light !


Note again that this relates only to the OU and not to the CU.


Note also that the observed expansion of the OU has
nothing to do with a (supposedly explosive) initial event. The 'Big
Bang' may have happened but it has no relevance to the expansion of
the Observable Universe.


So how fast is the Current Universe expanding ?
====================================
We cannot say of the CU that it is expanding. If it were expanding
how would we know since we cannot observe it? We can make guesses
about what the CU is doing but that is all that they are - guesses.
Any hypothesis that the CU is expanding is unscientific since the CU
cannot be observed. Any hypotheses about the CU are metaphysical
hypothoses - not Scientific hypotheses.

How far back is "current"?

If you type the word "now" then "current" is already in the past. To talk about something that is "current" there has to be some accepted window of time.

Now, with that in mind. You open up the window to a period of time which may be grand on our scale, but a blip on the scale of the universe.

You make various observations with that "current" universe, and you see that it corresponds to observations of the universe in the past.

Why is that non-scientific?

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Numbers are not case sensitive. (me)

Hello Neo

By 'current' universe I am trying to refer to the 'now' moment which is ever changing. A permanent 'now' so to speak which is never in the past. Obviously it is very elusive when you try to catch hold of it (so to speak) but I think we can still talk about it.

The main point of my posting is that very quickly our view of space is 'distorted' because we are looking back in time. We are not seeing 'now'.

Even our technical instruments (more powerful and accurate 'observers' than the human eye) cannot receive readings any faster than light speed (correct me if I am wrong) so even they are getting a 'distorted' reading regarding the 'now' universe.

And yet Cosmologists seem to make regular 'claims' (hypotheses) about the 'now' universe eg 'the universe IS expanding' implying that it is expanding NOW.

To me this is an assertion (hypothesis) about the unobservable - which puts the claim into the realm of Non-Science since a fundamental requirement for a scientific hypothesis is that the hypothesis can be tested and testing must require some form of observation.

As a description of why the OU appears to be expanding, this is not consistent with observation. The expansion of the universe is not derived from observations of the edge of the universe. Rather, it is derived from the observation of the consistent motions of galaxies that are clearly visible, and a lot closer than the edge (Hubble, 1929). The OU appears to be expanding, quite simply, because we think we can actually see all of its parts expanding away from each other (that is the standard interpretation of cosmological redshifts). That is where the idea of a "big bang" event comes from.

This is a metaphysical postulate that is in fact directly contradicted by your own description of the expansion of the universe (despite the fact that your description is also incorrect in any case). In your own model, as the OU expands, because we can see farther as time goes on, previously hidden parts of the CU become part of the OU. We can see that the OU is consistent. It does not suddenly change into something bizzare & different. As we see more & more of the CU, it looks just like the old OU. So, if you hold to your own model, you must also hold that the OU & CU are not observationally distinguishable. So the CU must look just like the OU, just bigger.

This in fact is the standard cosmology. Cosmologists are well aware of the fact that the observable universe is only a subset of a bigger universe, and your description of the growth of the OU is correct, but only as a description of its growth, not of its expansion. For instance, Key, et al., 2007 (Physical Review D 75(8): 084034, April 2007) place a lower bound on the size of the universe of 24 Giga parsec (78.24 billion light years).

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

That is both correct, and very much in the mind of all cosmologists

This is a misinterpretation of what cosmologists are saying. The universe is in fact expanding now, where "now" means "as we see it in our own, local here & now". Cosmologists certainly do not claim that the universe is expanding "now" in some global sense of "now", and indeed any cosmologist is likely to tell you that "now" in the global sense is not even a viable concept.

Whan cosmologists talk about that universe, they are always talking about the observable universe, as we see it, in our own local here & now, unless they explicitly say otherwise (which they sometimes do).

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

Point of order Tim Thompson.

What is 'observed' is the redshift.

That is, photons of light have a longer wavelength on arrival than when these same photons set off.

Some people interpret this as 'motion' and thus expansion.

Motion of galaxies is not 'observed.'

Cheers,
Lyndon

Point of order lyndonashmore, but I already said that.

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

If you read between the lines in my post, you can say the same thing about any science and any observation.

"is" is instantanious and not recordable. The only difference with Cosmology is that the scales are much larger, and the precisions only seem to be larger than they are.

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Numbers are not case sensitive. (me)

The quote I gave from you was verbatim. One must never mix up 'observations' with 'interpretations.'
Cheers,
Lyndon

redshifts are 'observations'?

Didn't you write, in your post, an interpretation (of redshift), not an observation?

What is 'observed' is stuff on computer monitors, or the marks made by ink on paper charts.

One must never mix up 'observations' with 'interpretations.'

he he

Very sloppy science!
The is a recording of the observations not the observation itself. To observe is to "watch carefully" and this can be done by eyes or instruments.
We watch carefully the light from distant galaxies and observe that the wavelength is longer than expected.
We may make a record of this on paper or VDU.
We then try to interpret these observations in terms of some sort of theory.
However, there is only one observation here and several differing interpretations - hence the fascinating original post and thread.
I believe that there is a tendency on this site to quote that an expanding universe is a fact when we all know that it is only one of many interpretations.
This can be misleading to those who are not scientists.
Cheers,
Lyndon

We can see that the universe is expanding by looking at the galaxites around us. We have seen this and have measured it.

No, we do not see this and we have certainly not measured it. What we have 'seen' is that the wavelength of photons from these galaxies is longer than we expect it to be.
Some people explain this as being due to their motion. But not everyone.
There is no direct evidence that the univese is expanding and so D Bryan is perfectly correct.
Cheers,
Lyndon

Then what is it?

If the universe is not expanding then why has the universe not collasped in on itself?

If red shift (or blue) is not explain by the Doppler effect then what explains it?

I agree with DBryan as well, which is why I was questioning Redshift in my ATM thread on Dark Matter Spacetime and Antimatter. I personally think the universe is expanding but not in the way that it has been suggested. Time should be a factor in our equations. If we look back in time we are seeing events that took place millions or billions of years ago. A Redshift seen in the 19th Century could have well been a Blue one in present time due to the wavelengths decreasing over time. And thats the whole basis for the expansion theory. We have since however noticed that Galaxies seem to be moving apart which may suggest expansion? I dont want to hijack DBryans conversation so if you wish to look further my theory on that is also in my threads. The current mainstream thinking is based mainly on two events, one being the Redshift observation in the 19th century and the second being the Galaxies moving apart. Which I think the Redshift may fall into question.

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The notion that man is the center of all things is as antiquated as the belief that the world was flat. - me 2009

Have do the photons become more redshifted over time?

Has there been any experment that proves photons can become redshifted over time? If so do you have a source?

I havn't heard any other theory that explains the redshift.

I will look at your other threads.

No, we have not:
All we have noticed is that the wavelength of photons on arrival is longer than we expect them to be- and that this discrepancy seems to increase with distance. That is all.
What did someone say about repeating a lie often enough?
Cheers,
Lyndon

lyndonashmore

Has there been any experment that proves photons can become redshifted over time? If so do you have a source?

I have just re read the OP and I think that an answer could be considered as 'hijacking' - and we all know that I would never do that!
I will PM you.
Cheers,
Lyndon

You are right. I say there is a difference between what I call the Observable Universe (OU) - probably the same as yours - and the rest of it, or what I call, the Universe as a Whole (UAW) and just to say the UAW is expanding because the OU is expanding is unscientific, since there is no evidence for this.

What radius? Is this about the Big Bang? What if it never happened - what if NASA's COBE satellite's photograph of the Universe as it Started was exactly that - a photo of the Universe at birth?

This infra-red snapshot that COBE took showed a 'hot smooth soup', with no sign of any Big Bang anywhere. Maybe the Cosmos came that way - already expanded.

You seem to show a certain level of understanding... and yet you're a Big Banger..?

They all do.


Because it's falling..?
If you say so.


Quite right, and so we should be looking for other reasons. To me, this sounds like there is hope...

Or maybe it didn't. Well said.


I always thought the behaviour of the OU was the same as the behaviour of any falling body - accellerating due to gravity, into the center of mass of the UAW.

I suppose, just the fact that the Cosmos is falling - can tell you quite a bit about what it must be falling into.

Look around, in Space - we see lots of things falling. When they fall, they do certain things, things that falling bodies do in Space. There's no shortage of evidence, surely?

It is unscientific - with no evidence - I agree.

The OU can teach us much about the UAW, if we will just let it.

Why does all this sound so familiar? Probably because it's the same ideas you tried to present here:

Outward expansion versus inward expansion

In case you don't remember, that thread was locked because you repeatedly ducked questions, gave handwaving responses, and singularly failed in defending the claims you tried to make. IMHO, it's very bad manners to hijack someone else's thread in an attempt to re-introduce your own ATM ideas.

Yes, that was a former Thread of mine.

I'm not here to argue with you, or hijack someone else's Thread. Well be honest, then.

I'm simply agreeing with the Thread owner and seeing how far the agreement runs. I am certainly not trying to re-introduce my ideas. If I wanted to do that I would start my own Thread.

I was agreeing with DBryan although I worded it wrong. I dont think Redshift is correct either. If it does exist the wavelengths that we look at NOW may be a billion years old, and a billion years ago it may have been Blue? Its kind of hard to explain but TIME is the factor I was agreeing was missing in our calculations. A wavelength should decrease in distance over time I believe?

And as Lyndon said,

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The notion that man is the center of all things is as antiquated as the belief that the world was flat. - me 2009

AstroCat - please keep your ATM ideas confined to your ATM thread.

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"I have this theory that the Apollo missions were faked when NASA found out that general relativity was wrong because the Earth was expanding due to the Sun's iron core being influenced by magnetic waves from the electric universe after being perturbed by Planet X and thereby causing global warming. Where should I start a thread about this?" ~ ToSeek

"Those are the people that wonder how a thermos knows whether to keep something hot or keep something cold." ~ NeoWatcher

I'm not trying to be rude, or flippant, but these are ATM ideas, and this is the ATM part of the Forum.

But, I'll do as you say. Sorry.

I want to make clear that our intent here is that each ATM idea is intended to be defended on its own, and that the introduction of a different ATM idea clutters the discussion. So, while you may see a connection between your idea and one being discussed in another thread, bringing it up in that thread hurts the flow of the discussion.

As a made-up and extreme illustrative example, imagine that in a discussion of Arp's changing mass, someone sees a parallel to the universe being like a bowl of cherries, and inserts such a statement into the Arp discussion. Anything posted in response to the Cherries idea takes away from the original discussion.

Now, if you do see something synergistic between the two ideas and it hasn't been previously discussed, it is reasonable to lay out that idea as the start of a new thread. Maybe it will work, or maybe good arguments will be made against it that you can't defend against. Either way, you've learned something, and the new thread has not polluted the original discussion.

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Forming opinions as we speak

Read and understood. Willco.

Um, do you have a model for your Universe, even if just in general terms, so we can better understand what you're proposing?

This is incorrect. Please check the many explanations in this Q&A thread

I'm not sure why you think "senior cosmologists" are unaware of this. If you check out this page, I believe you'll realize that they understand the situation much more completely than you.

I would say the CU is likely to look much like the OU. What is your reason for thinking differently?

Again, incorrect. Look at that second link again. The little animation is especially illuminating.

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Everyone is entitled to his own opinion, but not his own facts.