The size of this universe

And you know this how? There are many mathematical treatments of this that show recessional velocity, not 'space expansion', to give the red-shift. This is likewise true for the analysis of the CMB. It is the spectrum of both a high-recessional-velocity 'plasma' at white-hot temperature, which exactly mimics a stationary much-colder 'black-body' of some 2.7K presently.

Your descriptions were loose, though I suspect you understand the basics. At that great distance of the CMB emitter we see that plasma as it was (very hot), not as it is now (cooled and expanded, then contracted into galaxy clusters) due to the finite speed of light. Because of the great recession, its white-hot spectrum is red-shifted into the microwave frequencies. We see it 'as it was', not as we believe it is now (cooled and expanded into galaxy clusters). But that matter is not the same matter as the nearer galaxies than we see now, whether at high red-shift or low red-shift. It is separate and distinct matter (not the matter that makes up the rest of the universe that we see as galaxies, etc.) that we see as a hot high-recessional plasma (whether that recession is actual recessional velocity, or 'expansion of space').

And yes, over time, we will see even more matter that we can't see now, as it in turn releases its last-scattered CMB radiation, but of higher recessional velocity than what we see now.
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Walter L. Wagner

It is not matter, it is radiation released at a certain point in time from the plasma cloud that existed up until that moment throughout the Universe. We see that time at a certain distance because of lightspeed limits and we see it one year further away for every year that passes because it is an optical illusion, not matter travelling away from us, and thus not limited by Relativity. The Whole Visible Universe is an optical illusion(meaning what we see is no longer in that configuration)except at very close distances, none of it exists as we see it today. Each event is more or less in our distant past, distance in time. The matter that released it is no longer generating that radiation, like us it is 13.7 billion years in their past(it is 13.7 billion years in the past for every point in spacetime), but they can look back at us and see that radiation being released 13.7 billion years ago here. The CMB is an radiation remnant of a past event that no longer exists, there is nothing there, just the light it emitted finally reaching us from the distance light had to travel to get here and as far in the past as that distance is in lys. That's why every particle sees itself to be in the center, every particle IS at the center of a sphere of time/distance to the beginning, which is seen as the "outside", while the now is seen as the center.

No, there is no more matter to be illuminated and the CMB will maintain the exact same configuration except at longer and longer wavelengths. The CMB is not a process that is ongoing, it it the echo of a flash that happened everywhere at once. It is the lightspeed limit that allows us to see it receding as the same "photo" is shown by points in space that are further and further away/back in time. The CMB is an image of an event frozen in time, it is not a thing, it is not matter, it is not a process, it does not change over time other than to get steadily further away in time/distance and longer in wavelength.

And over time we see less and less of the Universe. When it was young we could see it all(yes, except for our immediate neighborhood, we see that closer to us).

Grumpy

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This is so far off base that I don't know where to start.

"The Cosmic Background Radiation (CBR) released during this era of decoupling has a mean free path long enough to travel almost unperturbed until the present day, where we observe it peaked in the microwave region of the spectrum as the Cosmic Microwave Background (CMB). We see this radiation today coming from the surface of last scattering (which is really a spherical shell of finite thickness) at a distance of nearly 15 billion light years. This Cosmic Background Radiation was predicted by the Hot Big Bang theory and discovered at an antenna temperature of 3K in 1964 by Penzias & Wilson (1965). The number density of photons in the universe at a redshift z is given by (Peebles, 1993)" http://ned.ipac.caltech.edu/level5/Sept05/Gawiser2/Gawiser1.html

It has travelled UNPERTURBED since it was released from that "spherical shell of finite thickness", which is what we term a 'white-hot plasma'. It cannot be from the rest of our visible universe, as it is unperturbed since it was released. That spherical shell is NOT the matter that makes up the rest of our visible universe. It is very SIMILAR in appearance to what our region of the Universe once looked like (or other regions of the Universe looked like); a region of hot, expanding, cooling plasma that, once sufficiently expanded and cooled, became nearly clear/invisible H2 gas through which light travels unperturbed. It is referred to as 'relic' radiation because it is a relic from that era of our universe when it was that hot, expanding, cooling plasma. But it is not from the rest of the visible universe, but rather a distinct shell of matter much further away (much higher z). If we hopped in our spaceship and travelled at 0.999999+c towards any point in that spherical shell, we could eventually reach that region of the Universe and find it had cooled, expanded and become galaxies.

The amount of matter we see in the visible universe is finite (but HUGE). The amount of matter we currently see that is represented by the CMB is also HUGE, and separate and distinct matter from the rest of the visible universe. But over time the slight dimpling of the CMB will change its pattern, because over time we will continue to see other shells of finite matter not currently visible, which will have other slight variations in pattern.

If we were to stay trained on any one particular region of the CMB emitting shell, we would over time 'see' it cool, continue to expand, then regions would gravitationally contract and form galaxies. They would be galaxies that cannot now be seen because they are too far away from us (13.7 billion light-years or thereabouts), and we can only see that region of the universe as it once existed (as a hot plasma). The nearer galaxies we can see (and at lesser red-shift), because regions of what once was a cooled plasma have contracted under gravity and once again begun emitting light (star-light).

Consequently, over time, we can see more of the universe, but at an ever dimmer view.

 

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Walter L. Wagner

No, that is just wrong, as I have explained. The CMB does not change, though it can be distorted by mass through gravity lensing it will never change. We will see no other matter associated with the CMB as there is no matter to see. THE CMB IS NOT MATTER, it is radiation from an event that happened 13.7 billion years ago. You obviously know nothing about the subject you haven't googled, you certainly don't understand what the CMB is.

Bullshit! We see more of the Universe the further away it is, we see nothing of the Universe as it is today and very little within the distance light covers in the average lifetime of humans(70 lys), not even our own sun is seen in real time. EVERYTHING IN THE UNIVERSE IS AT SOME DISTANCE FROM US IN TIME, specifically we see them as they were in the past. The CMB is a radius in the distance of time, it is not matter, matter emitting radiation or a physical thing at all(other than light), it is a point in time in the history of everything and we see those points releasing that radiation at that distance because that's how long ago the event occurred, if we ever get to see into the first 300,000 years all we will see is a near perfectly uniform sea of hot plasma, with a great flux of various radiation bouncing back and forth(actually photons being absorbed and new ones emitted)very similar to the atmosphere of a star but Universe wide. There is no ongoing process 13.7 billion years ago, there was one stupendous event where all that captured radiation was suddenly released as atoms formed throughout the Universe and it became transparent. Black Body Radiation that has been set in the light it released, there's no way to go back in time and make changes, no natural process of change going on at the time(other than the single event of the release). The event was Universe wide and over in an instant(relatively)and the CMB is a flash photo of that event apparently receding away from us at lightspeed. It's an illusion of movement, it is actually just the increase of the distance that event is from us in time, it is forever fixed at that time(+300,000 years), we move forward in time at the rate of one year per year(currently +13.7 billion years), so the time distance of the radius of the CMB between us increases exactly one light year per year. Without a single physical thing moving through spacetime. It really has nothing to do with the expansion of the Universe, other than redshifting that light the Expansion is not involved with the CMB, it is strictly a baby picture of the Universe at +300,000 years as the plasma condensed into atoms, releasing that radiation and that distance in time getting longer, thus appearing to recede into the distance. It is not the CMB that is moving in time(it is fixed relative to the beginning), it is us moving in time toward the future that is increasing that distance in time, but then it's all Relative.

Grumpy

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Trying to visualize your posits;
Can we compare it to a supernova event, where an entire star ceases to exist and all we can ever see is the event itself? The star's position became fixed forever at the coordinate it went nova, and we can fix this coordinate by looking at the red shift (moving away) and blue shift (coming towards us) of the radiation generated during the nova event?

 

Write4U

Not quite, but you're on the right track. What we see of the Universe is relic light, light that left some event sometime in our past. Even in the close Universe we do not see the present configuration of the mass we see, we see it as it was in the past. Past a certain distance it is safe to say we no longer are looking at things that still exist(your star going supernova, for example), the Visible Universe becomes an illusion re the actual present day position and configuration of the mass you are seeing. This is really what is meant by those who call it a holographic Universe, what we see is a photo of the rest of the Universe as it existed at various distances in the past, it does not directly represent anything in the present day Universe, only parts of the past. If it is 1000 lys away, we won't see the event until 1000 years after it occurred, even though the matter that it consisted of is no longer in a star form and hasn't been for 1000 years.

The same principle applies to the CMB, but where a relatively nearby supernova's wave of radiation passes us in spacetime because it is a point source embedded in that spacetime(and that is true for all events from every point in space) affecting only an expanding sphere of time from that point source. The event at the beginning of time occurred at every point in the Universe at the same time, and light from new areas where it occurred(in time and space)are constantly appearing on our time horizon(IE at 13.7 billion years in our past/distance away from us). It's like a whole string of supernovas going off all at the same time in a line away from us, if they are one light year apart we would see them going off one year apart, even though they all detonated at exactly the same time. The areas we see releasing the CMB today are 13.7 billion years in our past and increasing by one ly distance per year. Along a radial vector we see those areas that are that far away in time releasing the radiation, in a year we will see the light from areas one light year further away. Light from a point source like a nova acts the same way, but only that one point had an event, so it's wave passes us and can no longer be seen here, but you will see it in a year if you are a light year further away in time than we are. The event that caused the CMB happened at all points(not just one), there will always be some area along that vector that we can see releasing that radiation at the distance in time between that event and the present until the radiation is undetectable. And spacetime expansion will cause that once hot ultraviolet radiation to cool toward absolute zero(it stretches the wavelength).

Red shift and blue shift for moving mass has nothing to do with the CMB other than the stretching of it's frequency due to the expansion of spacetime. That event had nothing to do with the motion of objects, only their temperature and the change from a dark, opaque Universe to a Universe where light travels freely. That change was an event at every point in the Universe at the same time, we just don't see it all at once but only as the light reaches us from those increasing distances in time. It is redshifted not because of motion, but because the spacetime got lots bigger since time+300,000, (by the way, that is true about(most of)the redshift of galaxies as well, it is not proper motion through spacetime but is relative apparent motion caused by spacetime around us getting bigger).

Grumpy

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Yes, now you are starting to write about it properly. "we just don't see it all at once." correct; next year we will see a slightly different CMB radiation.

notwithstanding your all-caps post above, I've never said the CMB is matter. The CMB is emitted by matter. We can't see that matter all at once. We can only see a small finite portion. Next year we will see a different small finite portion. That's what I posted before.

We can presume that all of that matter had been in close-contact in its reference frame, exchanging photons, equilibrating the energy, such that the matter that we now see by way of the CMB is of exceptionally uniform temperature in its reference frame, leading to the current WMAP survey showing only very slight temperature differences throughout that region.

One billion years from now, we will see a different CMB than that which we presently see. The matter of the current CMB will be presumed to have continued to cool and exand, forming galaxies some 13.7 billion light years from here, whereas the source of the then CMB will be some 14.7 billion light years from here.

Glad to see you're getting it. Now quit being so grumpy.

 

That's complete nonsense.

The CMBR is a result of last scattering which happened everywhere in the universe at the same cosmological time. It's still everywhere in the universe. A billion years from now it will still be everywhere in the universe. The total energy and the number of CMBR photons is constant. Forever. As the universe expands the energy density of the CMBR decreases. The temperature decreases. A billion years from now the total energy of the CMBR will be what it was at last scattering and is today. The frequency of the CMBR photons decrease as the universe expands. The wave length increases. We're looking at the remnant photons as they are today, not as they were 13 billion cosmological years ago.

 

that's so informative. nice to have you in the 'discussion'.

 

You're not in a discussion because your discussion gun isn't loaded. Grumpy trying to educate you but you're only interested in spewing nonsense. Read what I wrote again.

 

On that point.......
In a few billion years time, or thereabouts, when galaxies are expanded beyond our observable horizon, and the CMBR is undetectable, will we have any evidence for cosmological redshift and expansion of space/time?

 

I did. It doesn't really explain much, but it doesn't contradict what I wrote. Apparently you've not been reading what I wrote, and instead reply with your ad hominems, primarily.

I wrote that we can interpret the CMB as a highly red-shifted recessional plasma, with a z of about 1071 (some sources have it higher - it depends upon what the temperature of the 'last-scattering' of the plasma is, but it is 'white hot'). As Grumpy wrote, we can't see it all at once. We can only see that portion that is, in our reference frame, at a distance of about 13.7 billion light-years. Lots of good citations on this, many of which I posted. You don't disagree with those authoritative citations I posted, do you? So yes, in a billion years, we will also see a CMB, but it will be 'last-scattered' at a distance of 14.7 billion light-years from here. Likewise, 1 billion years ago, those last scattered photons of our then CMB was at a distance of 12.7 billion light years. We no longer see those photons. Where is the 'plasma' that emitted those photons at that distance? What happened to it? It is still there, but it has substantially cooled and is mostly clear, invisible H2 gas, though we are working to try to see if we can see earliest galaxy formation in that region with better telescopes, which better telescopes I've posted about in other threads.

As to Paddleboy's query, it is a good one. But that is so far in the distant future I'm not concerned. Eventually, hundreds of billions of years from now, the nearest galaxies that are receding from us will be too dim to see. But they will also likely have exhausted all of their star-formation and star-exhaustion possibilites, and likewise be filled with cold, dim, dead stars.

 

More like will WE still exist as natural phenomena. I think the CMBR would still be detectable. The author of the link

http://ned.ipac.caltech.edu/level5/Glossary/Essay_lss.html

Makes a rough prediction that the CMBR would be 1 K when the universe is 3 times larger. Our gravitationally bound group should always be in our observable universe. Otherwise I don't know. LOL.

 

Clearly it wouldn't explain much for you. Question for you. Are you the Walter Wagner that sued to stop the LHC from coming on line because he thought they might create a black hole which would consume the earth? ?

 

Still going on with the ad hominems.

 

You didn't learn anything by your participation in trying to monkey wrench the LHC start up? Your plasma theory is nonsense. Nonsense evolving to further nonsense. Grumpy knows what he's talking about and you don't. That's the bottom line. Grumpy has done his homework on these subjects and you haven't.

 

Thanks brucep....
OK, I did once see a time line of the Universe....including proton and BH decay............
This wasn't it but is all I can find.....

http://en.wikipedia.org/wiki/Timeline_of_the_far_future

 

More ad hominems. What you're saying is that all of the citations I give to reputable sources are "nonsense". Not exactly elucidating, now, is that.

 

This radiation (CMB) appears to come from a spherical surface around the observer such that the radius of the shell is the distance each photon has travelled since it was last scattered at the epoch of recombination. This surface is what is called the last scattering surface. We see our CMB from that particular surface at about 13.7 billion light-years. It (that surface of last scattering) is not the same matter as the nearer galaxies. Got it. http://ned.ipac.caltech.edu/level5/Glossary/Essay_lss.html

 

paddoboy

The CMB, in theory, will always be visible coming from the edge of our time sphere. In practice the temperature is already below 2.7 degrees K, it is going to get colder and there are physical limits to our ability to separate such a small signal from among all the closer and "louder" ones. That is different from the apparent velocity that the expansion caused. Because it is an illusion of movement it will just continue to "recede" at apparent lightspeed and will possibly be detectable even after the other galaxies are gone.

Most galaxies in our Universe are already over our light horizon, we will never see the light they release today, as time goes by that will be true for more and more of the galaxies we now see far away from us. As I tried to tell Walter, we see most if not all of the Universe as it was when it was young and small, we see none of what the present day Universe looks like(except very close to ourselves and even that is not real time), and in the far future we will only be able to see those galaxies that are gravity bound to our own, all others being beyond our light horizon.

I do not know if we will be able to deduce expansion without the evidence of galaxy recession if we must start from scratch in that era, it would be an interesting thing to investigate, to see how else it could be done. It's a good question and good questions often lead to good science. The questions lead us to more understanding than easy answers do.

Walter L. Wagner

It is NOT still there, it has aged 13.7 billion years and been incorporated into the structures that exist now. If we ever see past the surface of last scattering we will be seeing light that the hot plasma generated, but the hot plasma ceased to exist in that form billions of years ago. It's all still an illusion that there is something still there because that's what that old light shows us.

I haven't changed a thing, maybe your hard head is finally softening.

Yes, and you are still wrong. You can "interpret" it that way to make your calculations easier, but it is not the reality, what we see is light from STATIONARY plasma throughout spacetime, it is the surface of last scattering that has the apparent velocity and it is simply an artifact of time and lightspeed, there is no surface to the surface of last scattering.

Grumpy

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