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Old 16-12-2018, 08:22 AM
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A Gallaxy disappearing forever.

Put your thinking caps on make a cuppa and ponder upon this☺

Some background...having a chat on another forum re The Big Bang Theory and how it is clums6y attempt to incorporate the pagan cosmic egg concept into science...for a laugh☺

Anyways it occurred to me our conclusion that the universe is expanding relies upon interptetation of red shift...and there was a time where folk proposed what I will call "tired light" hypothesies where red shift was seen to be caused by some sort of resistence being encountered by light such that energy is reduced and it is those mechanics that produces red shift...those ideas are today seen as near crack pot but in fact were presented as faulsifiable at the time...and this part of the history of cosmology is , as all of it is, most interesting.

So lets assume only for the purpose of a discussion here that we are faced with two competing propositions ..tired light static universe or red shift due to cosmic expansion...how can we tell if the universe is expanding by other observations.
Well I have it.
We observe a gallaxy at the very edge of the observable universe at a point where it will cross over to that part of the universe we can only call the unobservable universe.
Would this be possible is the question.
Not in a humans life time comes to mind so what would be the velocity at the edge of the observable universe...how long would it take a gallaxy to finally disappear.
Further can we observe to the edge of the observable universe ....
Alex
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Old 16-12-2018, 08:27 AM
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And thinking about it more...should we would we or could we expect to find galaxies more tightly packed given our onservation is of a time where expansion has not moved them away from each other.
Alex
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Old 16-12-2018, 08:29 AM
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Alex....it’s Sunday morning, I had a late one last night, I’m a little hung over...........and those couple paragraphs have made my headache worse.

Please refrain fro posting such in-depth posts on a Sunday......I was just hoping to see pretty pictures this morning.
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Old 16-12-2018, 09:00 AM
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Alex is on the case - The James Webb Telescope will seek out exactly what he is looking for.
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Old 16-12-2018, 09:06 AM
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I found out something I really should have picked up on years ago...
I thought the Steady State Model went for a non expanding universe but it has in common with the Big Bang Model expansion...it seems it is the Static universe model that is without expansion.
And another unteresting aspect Hubble would not publicly say he favoured an expanding universe model which is rather funny given it was his onservations that were used to promote an expanding universe.
https://www.britannica.com/biography/Edwin-Hubble
Alex
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Old 16-12-2018, 09:10 AM
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This is from the above site ...take note of the last sentence.

Starting with Albert Einstein’s 1917 paper “Kosmologische Betrachtungen zur Allgemeinen Relativitätstheorien” (“Cosmological Considerations on the General Theory of Relativity”), a number of physicists, mathematicians, and astronomers had applied general relativity to the large-scale properties of the universe. The redshift-distance relation established by Hubble and Humason was quickly meshed by various theoreticians with the general relativity-based theory of an expanding universe. The result was that by the mid-1930s the redshift-distance relationship was generally interpreted as a velocity-distance relationship such that the spectral shifts of the galaxies were a consequence of their motions. But Hubble throughout his career resisted the definite identification of the redshifts as velocity shifts. Hubble hoped to shed light on this issue by investigating the numbers of extragalactic nebulae that lay at various distances in space. Hubble conducted these studies in part with the distinguished mathematical physicist and chemist Richard C. Tolman. Writing in the mid-1930s, however, Hubble and Tolman stressed the uncertainty of the observational data.
They declined to choose publicly and unambiguously between a static and a non-static model of the universe. (Hubble later argued that the evidence seemed to favour the concept of a stationary universe, but he did not definitely rule out an expanding universe.)

Alex
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Old 16-12-2018, 11:12 AM
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Atmos (Colin)
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What you’re talking about here Alex is the Cosmic Microwave Background (CMB). It is the edge of the observable universe that has been red shifted from the point in time when the universe was no longer a plasma until the microwave background that we detect today
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Old 16-12-2018, 11:51 AM
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What you’re talking about here Alex is the Cosmic Microwave Background (CMB). It is the edge of the observable universe that has been red shifted from the point in time when the universe was no longer a plasma until the microwave background that we detect today
Thanks for your input Colin.
It is hard to get ones head around this ...well it is for me...but the CBR...keeps coming it seems.
Will there be a time when it will stop?

Alex
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Old 16-12-2018, 12:06 PM
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Alex....it’s Sunday morning, I had a late one last night, I’m a little hung over...........and those couple paragraphs have made my headache worse.

Please refrain fro posting such in-depth posts on a Sunday......I was just hoping to see pretty pictures this morning.
Jon, I'm rolling down the street laughing!
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Old 16-12-2018, 12:27 PM
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My (admittedly half assed) understanding of such things is that objects do not dissapear, but rather, fade away as the wavelength of their emitted light is stretched to longer and longer wavelengths. I assume the particle nature of light would lead to a point where we get photons that are at such long wavelengths and arrive so irregularly that they are impossible to separate from noise.

Markus
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Old 16-12-2018, 02:48 PM
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Hi Markus
The way I understand things is the universe is expanding and at a point or place is expanding relative to us faster than the speed of light so anything past that point can give out light but the light gets further away..it can never reach us...think man on a truck with a hose pointing behind at you and he is going away...the water he directs at you although travling in your direction may hit you at first but falls shorter and shorter as he goes away.

The CBR is different in so far as its continually coming.
Alex
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Old 16-12-2018, 03:03 PM
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Hi Markus
The way I understand things is the universe is expanding and at a point or place is expanding relative to us faster than the speed of light so anything past that point can give out light but the light gets further away..it can never reach us...think man on a truck with a hose pointing behind at you and he is going away...the water he directs at you although travling in your direction may hit you at first but falls shorter and shorter as he goes away.

The CBR is different in so far as its continually coming.
Alex
Sort of, but that analogy doesn't take into account the extreme ends of red-shift. For example, could we ever detect a photon who's wavelength was the width of the observable universe?

Markus
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Old 16-12-2018, 03:31 PM
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Sort of, but that analogy doesn't take into account the extreme ends of red-shift. For example, could we ever detect a photon who's wavelength was the width of the observable universe?

Markus
Yes but not by any method known to exist.

I doubt if you could get such a wave length simply as the goal post is always on the move☺...I think when a photos energy is that diminished it could not go anywhere and would accumulate with others like it to form dark matter...and it would take a lot of them because they are massless.

Alex
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Old 16-12-2018, 04:35 PM
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Yes but not by any method known to exist.

I doubt if you could get such a wave length simply as the goal post is always on the move☺...I think when a photos energy is that diminished it could not go anywhere and would accumulate with others like it to form dark matter...and it would take a lot of them because they are massless.

Alex
<Alex quietly solves the problem of Dark Matter/Energy on IIS>

And why not? Maybe there are lots of photons that have energies that are not zero, yet with wavelengths too long to be detected.

Come to think on it, A photon with a wavelength equivalent to the size of the observable universe would have the highest probability of detection wherever where the observer happens to be, since every observer is at the centre of their own observable universe. To exist within the observable universe, yet have a wavelength of equivalent size *to the observable universe, places the probability wave at the centre of that same observable universe.

But I think I'm correct in saying that Heisenberg's conjugate variables would mean that a precise knowledge of the location of such a particle would therefore also mean that we couldn't *also know the energy of such a photon.

I suppose - and I'm thinking very up in the air now - that since it is not possible to have a photon with greater wavelength than the universe itself, that one could consider the wavelength of such a photon to be a 'base frequency' of the universe. Higher frequency photons would constructively or destructively interfere with the 'primordial' photon creating interference diffraction patterns (this would not be the case if the lower extent of wavelength was infinite and it were possible to have a photon with a wavelength longer than the observable universe). Perhaps detection of interference patterns would tell us if there is much energy at these lower wavelengths?

Interesting to ponder, but I'm probably just talking a load of old Bahtinov, as I don't have any kind of qualification in the area. Some long-suffering physics professor will probably chime in and slap me around the head for thinking such things, and fair enough too. :-)

Markus
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Old 16-12-2018, 04:48 PM
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Firstly dont listen to Heisenberg he has been discredited due to animal cruelty.
You can get aroundcthe uncertainty issue by getting ywo particles check the speed of one and the position of the other and average the result.
I think you are on the right track.I will add your name to the paper if you can get me a tux for prize night.
Alex
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Old 16-12-2018, 05:02 PM
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I think you are on the right track.I will add your name to the paper if you can get me a tux for prize night.
Alex
I've only got the one, but happy to split it with you. Do you want to wear the pants or the jacket? FWIW, I don't remeber the 'Wooden Spoon for Physics' awards having a formal dress code?
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Old 16-12-2018, 05:18 PM
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It is largely because of the time of the universe in which we live. Red shift is determined by the distance that light has to travel before reaching us. As the distance between us and the CMB increases, as more time passes it will reshoot more and more.

We currently call it the Cosmic MICROWAVE Background but over the course of millions of years from now that will stretch further and eventually become the Cosmic Radio Background and over many many many more tens to hundreds of billions of years, it will disappear entirely; red shirted out of detectable existence.
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Old 16-12-2018, 05:55 PM
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If it is only red shift and no blue shift - what does it tell you? :-)
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Old 16-12-2018, 06:20 PM
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If it is only red shift and no blue shift - what does it tell you? :-)
I think M31 is blue shifted.

Maybe there are others?

But if all we observe are red shifted galaxies I think that under the Big Bang Theory that means the Universe is expanding...under other models it could mean the discredited tired light idea is correct...I don't know what it means under say ancient Summerian cosmology.

Are you are suggesting the universe is expanding or do you have something else in mind?


I like red it is the colour of blood....mmm blood.
alex
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Old 16-12-2018, 06:44 PM
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Expanding Universe

The composition of the early universe is different...
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