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Post by typobrane on Nov 11, 2010 17:30:35 GMT 1
At t=0 what was there started to expand and cool down in the process. At +400,000 it had cooled enough to produce the first light. The first primordial stars were formed as the infinite “ball” of plasma fragmented. In other words what we now detect as the CMBR fragmented into the first behemoth primordial stars and it is only then that we have a concept of empty space between them. If infinite the CMBR never had a radius if not infinite it was a dam sight bigger than 8 million light years across. Whether infinite or not most of the stars and galaxies “out there” are too far away for their light to reach us and because the universe is expanding their light never will. It may seem incomprehensible that we can see things moving away from us faster than the speed of light, think of this; if you are in the line of fire from high velocity bullets and shells you can hear them going through the air even though they are travelling faster than sound. You (hopefully) hear the sonic crack or boom as they pass overhead and then you hear them coming through the air. Although they were only in the air for less than a second in most cases you can hear them travelling for several seconds. You can hear the bullet travel through the air even when you know it has just lodged itself in the tree next to you. You see the hole appear in the tree and you hear the sonic crack you then hear it whistle through the air and then the bang of the gun that fired it. It may not be technically the best analogy but it is the best one that I have experience of.
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Post by speakertoanimals on Nov 11, 2010 18:46:32 GMT 1
Well, more precisely it was producing LOADS of stuff, gamma rays and upwards, just that photons kept converting to particle pairs and vice-versa. Hence not transparent.
The light we see is when it cooled enough to become transparent, the decoupling of the photons and matter. That is why the photons produced then, after being stretched by the expansion of the universe, are still around for us to see today. The earlier ones didn't hang about long enough.
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Post by Progenitor A on Nov 11, 2010 18:50:54 GMT 1
You are thinking in terms of things somehow moving outwards into formerly empty space, which is EXACTLY the wrong picture. Exactly the wrong picture it may be but that is not the terms I am thinking in at all So, the universe starts, a small box (but without sides!). Full of the CMB, and matter. Actually the CMB starts at t=0+400,000years THe CMB moves, but that doesn't mean that it leaves areas empty of the CMB behind it -- those are kept filled by the CMB moving in from other places. A nonsensical sentence I am afraid Box expands, as do the contents. The CMB gets redshifted because of the expansion (NOT because it is moving away from us). Nonsense. The red-shift occurs because it is moving away relative to our position The matter jiggles about, forms galaxies, stars light up, but the whole is continually bathed in the CMB which fills the whole universe. No - it fills the universe that exists after 400 000 years. CMBR then expands with the universe and stars are created after it has expanded for some time So, we see the CMB, which has travelled a,long way since it was created. But since it was created everywhere, and since it is all moving, the box remains filled with the CMB at all times. No it doesn't. You are using English badly once again. The box has the same quantity of CMBR but it is spread more thinly because of exapansion.To say it is 'Filled' implies that it somehow keeps topping itself up No good trying to explain things, I am afraid if, you are going to use loose English , if the audience has to think what you mean by English phrases As regards your dates -- you have then the wrong way round. What we see as furthest way are the youngest galaxies. Again you are confusing yourself with bad English. Things that were born earlier, such as the more distant stars are conventionally older than things that are born later (such as the nearer stars) Our galaxy was once that young, but we don't see it that young because we had to wait for the light from the young galaxy to get to us. You are attempting to explain something to me and you use quite disgracefully opaque English This to me indicates a muddled thought process So, what is constant for the objects WE CAN SEE NOW is age of object plus travel time. Yes, but they canot be separated; the travel time (self-evidently) depends upon the age of the object that we see The CMB has the largest travel time of all, so it is the youngest relic we see. Nonsense in a number of ways. The longer light takes to travel from an object to us, the older that object is, otherwise expansion means nothing. And the puzzle is that CMBR does not have the longest travel time of all - there would be no puzzle if it did - those galaxies that are so far away that their light never reaches us have the longest travel time of all. That is what the problem is about! Quite frankly I do not knoew if it is your poor use of English that causes such confusion or plain, simple muddled thinking This doesn't mean these are the only objects in the universe, just the only ones we can see. this has already been mentioned as a part of the puzzle by me think of it like this. We are surrounded by lightbulbs, which all flash at the same time. After they have flashed, they break, and the bits of glass tumble towards the floor. So, they all flash at once. One second after the flash, we see light from the lamps one lightsecond away. ones further away have flashed, but we can't see them yet, not enough time. After two seconds, we now still see a flash, but from the lamps two lightseconds away. But also in front of that we see the lamps whose flash we saw previously, but now we see the glass falling towards the floor. The flash is the CMB, the falling glass the galaxies etc that evolved afterwards. No matter how long we wait, we will always see the flash, in front of that lamps whose glass is falling -- and neither means that there aren't lamps beyond those whose flash we can't see at the moment. But the timed flashes that we see is the CMB expanding into its space. It expands at the same rate as the falling glass (which also expands) I am afraid this analogy explains nothing to me Adding in expansion just shifts the colours a bit, and makes the computation of travel-time a bit more complicated, but the basics of galaxies existing beyond the origin of the CMB we can see at the moment is just the lamps that exist beyond those whose flash we can see. This doesn't figure. Are you saying that when the CMB was created at t=0+40000years, some CMB expanded to a point where we can no longer see it and some was left behind? If so, then WHY?
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Post by speakertoanimals on Nov 11, 2010 19:06:30 GMT 1
no more mysterious than I am in a flowing river. The water next to me keeps moving and flows away, but is continually replaced by water flowing in from elsewhere. What bit of water I see at any one time has flowed from elsewhere, and I never see it again. But the next instant, different water arrives, just from further upstream than the water I saw previously.
Wrong. WHAT is moving away, because of course the light isn't, it is moving towards us at c else we wouldn't see it. The source of the light is dead and gone. What remains is the space that the light moves through being stretched as the light travels, THAT is what causes the cosmological red-shift, NOT the speed of the source, which is a different effect.
I meant by FULL the fact that there are no voids, not full in terms of constant density. A perfectly valid use of the word 'full', stop being silly.
The bit of space by me IS continuallt being topped up -- as CMB photons move out of it, others move in to KEEP it topped up.
You finally get something right. If a plus b is a constant, then a depends on b................
Actually, it is a constant for all the objects we can see at any instant, but a larger constant for the objects we will be able to see if we wait a second (or a year).
So, what are you saying, that there are galaxies OLDER than the CMB?
As I said before, what we see in the CMB is back to the earliest part of the universe, what we SEE is young. you have to remember what young or old refers to -- the object being imaged, or the light that we use to see it. The image of the object is a young object, but the light we see it with is OLD because it has been travelling the longest.
It's just the a plus b that you agreed to earlier -- old light equals youngest object. Do keep up and be consistent!
And the flashbulbs case answered it, it ISN'T HARD.
No! The CMb event is the simultaneous flash that happens everywhere at the SAME time. What flashes we see, where and when, depends on the travel time. Seeing the flashes is spread out, but the event when everything went flash isn't.
No, now you are confusing the travel time for the light, with the expansion that happens on top of that.
It's no more mysterious than you can't step in the same river twice -- the CMb flows past us and away, but that ISN'T the expansion, it's just light travelling.
The expansion stretches the wavelength of the photons, and thins them out, but its just normal lightspeed travel for light that takes them past us.
I think you have failed to keep the expansion of space, and the light travelling through the expanding space, as different movements. Which is why I had the nice flashbulbs example without expansion.
Or you could be a total idiot, or just pretending to misunderstand, that is about the only question that really stumps me..............
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Post by Progenitor A on Nov 11, 2010 19:12:55 GMT 1
At t=0 what was there started to expand and cool down in the process. At +400,000 it had cooled enough to produce the first light. Got that The first primordial stars were formed as the infinite “ball” of plasma fragmented. In other words what we now detect as the CMBR fragmented into the first behemoth primordial stars and it is only then that we have a concept of empty space between them. Got that too - don't like the 'infinite' bit, but we can put that aside If infinite the CMBR never had a radius if not infinite it was a dam sight bigger than 8 million light years across. You have lost me here. Do you mean that if the universe was infinite in volume that it never had a radius? If so would not the radius have to be infinite? Don't like this infinity stuff And ifthe CMBR was created at 400,000 years how do you calculate a radius bigger than 8 million light years? Whether infinite or not most of the stars and galaxies “out there” are too far away for their light to reach us and because the universe is expanding their light never will. I will acceptthis, but still have difficulty with the universe expanding faster than light It may seem incomprehensible that we can see things moving away from us faster than the speed of light, think of this; if you are in the line of fire from high velocity bullets and shells you can hear them going through the air even though they are travelling faster than sound. You (hopefully) hear the sonic crack or boom as they pass overhead and then you hear them coming through the air. Although they were only in the air for less than a second in most cases you can hear them travelling for several seconds. You can hear the bullet travel through the air even when you know it has just lodged itself in the tree next to you. You see the hole appear in the tree and you hear the sonic crack you then hear it whistle through the air and then the bang of the gun that fired it. It may not be technically the best analogy but it is the best one that I have experience of. But if stars are moving away faster than light then the wavelegth of the emitted lifht will surely fall below the spectrum of visible light, so we will never see them?
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Post by typobrane on Nov 11, 2010 22:25:12 GMT 1
Naymissus I can understand your angst about the universe being infinite as I feel the same way when it is insinuated that the universe is finite. We know the universe is flat to a very high degree of accuracy and suggests that the best fit model of the universe is infinite. It could still be finite if we except that it is so big the curvature is within the margins of error in our measurements but that makes the universe at least 70 billion light years across. I cannot comprehend all that expanding from an area only 8 million light years across in 13.7 billion years, but I suppose I cannot prove it either.
“But if stars are moving away faster than light then the wavelength of the emitted light will surely fall below the spectrum of visible light, so we will never see them?”
Yes the light will not be in the visible spectrum due to the red shift and just as well or we would be fried to a crisp as of Olber’s paradox and the CMBR would become the CTBHFLR (cosmic too bloody hot for life radiation)
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Post by speakertoanimals on Nov 11, 2010 22:31:19 GMT 1
Because if the universe is infinite, it always WAS, The Big Bang didn't happen at a point, it happened everywhere. Hence the universe started off infinite, was ALL fileed with the CMb when we got to that stage.
Its the fault of all those crappy TV shows that show an explosion outwards from a point, it wasn't like that AT ALL, even if the universe is finite, that image is still wrong and misleading.
Question: WHY don't you like space expanding at greater than lightspeed? It's fairly inncuous really, and as far as a distant galaxy is concerned, they are at rest. The recession speed is only APPARENT. Think of it this way, they aren't actually moving, it's just that the space in between us and them is expanding so fast that the light, however far it travels, always has further to go. And we say that matter can't MOVE faster than light, but who said anything about space not being able to expand that fast, it isn't material after all..................
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Post by Progenitor A on Nov 11, 2010 22:44:55 GMT 1
Because if the universe is infinite, it always WAS, The Big Bang didn't happen at a point, it happened everywhere. Sheer sophistry, unsophisticated bollocks, except as a very weird theory
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Post by abacus9900 on Nov 11, 2010 23:50:47 GMT 1
Because if the universe is infinite, it always WAS... What does this actually mean? Explain.
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Post by Progenitor A on Nov 12, 2010 9:57:08 GMT 1
Well the question was this: Why are we told that there are stars and galaxies that we can't see because they are too far away when we can see the CMBR that is further away than any star or galaxy?
Well after some well intentioned guidance from Tyobranes and some good points from STA - unfortunately mixed up with the most appalling gobbldeygook and terrible English, I have concluded this.
There are no stars or galaxies that we cannot see. We can 'see' all the radiating bodies that have been created since BB.
But yes there are stars and galaxies that are beyond our range of vision, yet we can see them
Now that sounds like one of STA's sentences, so let me explain what is meant by it.
Well what we can 'see 'of the radiant universe is determined by two things, one, the age of the universe and two, the speed of light.
The age of the universe is generally agreed to be about 14 billion years. Light can travel a distance of only 14 billion light years during that time.
Therefore what we see, (at the limit of our range of 'seeing' the Universe) is light that started on its progress to us 14 billion light years ago - that was approximately when the CMBR was created and CMBR is the limit of our 'visible' universe. As all other stars are younger (born later) than CMBR, then we can 'see' everything that radiates that has been created in the Universe.
We cannot see beyond the limit of 14 billion light years because light beyond that range has not yet reached us.
But examination of red shift shows that the CMBR is moving away from us at (very nearly) c the speed of light.
Therefore when we 'see' radiation from CMBR it has taken 14 billion years to reach us. Meanwhile the CMBR has moved away from us , and as it is moving away from us at nearly the speed of light, then by the time we 'see' the CMBR it is in fact about 28 billion light years away from us (and we are 'seeing' it where it was at 14 billion light years away). And of course stars and galaxies that were created close in time to the CMBR are also at about that distance from us.
So in fact we 'see' all of God's creation when we look at the night sky, and at the same time as we examine a distant galaxy the galaxy is beyond our range of 'seeing'
One little problem remains. The redshift of the CMBR has been measured and indicates that it is moving away from us at 0.99c (or as some put it, space is expanding between us and the CMBR at 0.99c). But if it has been moving away at that speed since its creation, then after 14 billion years it will be 14billion light years away from us, but we have just concluded above that it is 28 billion light years away from us! Is what we see from CMBR 7 billion light years away or 14 billion light years away?
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Post by abacus9900 on Nov 12, 2010 11:21:20 GMT 1
I honestly don't think they really know - they just make guesses.
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Post by typobrane on Nov 12, 2010 13:20:43 GMT 1
So you think planet Earth is in right smack bang in the middle of the universe, wow what’s the odds eh. You seem a bit confused about the age thing. When you look at a photo of yourself as a baby you would not say “that was when I was older”. What we see at great distances is not what it is like now. Think of it like a photograph, the older the light we are detecting the younger the universe was then when the light left the object. This is why we call the CMBR the baby universe. The recessional velocity of a distant galaxy when the light we detect left that galaxy is something we can calculate by the red shift, but that is a historical record of the recessional velocity of that galaxy and because the universe is expanding that galaxy, now that it is older, has a much higher recessional velocity. So from the 380,000 year old baby picture at red shift 1000 to 4.6 billion year old galaxies with a red shift of 1.4 we have a visible area of the universe that is now moving away from us faster than the speed of light. The first primordial stars and the first galaxies that we will hopefully be able to see when we get the James Webb telescope up and running had a recessional velocity faster than the speed of light when the light left them, and that is why we will see them going back in time and becoming the CMBR this is because we can only receive the light at the speed of light. If a tank five miles away fires a high velocity shell in your direction you will see the shell in the air for about one second but you will hear it travel through the air for about 24 seconds and the sound is reaching you in reverse order because it can only travel at the speed of sound. Things have been disappearing from are view like this for millions of years, they still exist but we will never see them again. Our visible horizon is expanding at the speed of light but the universe is out pacing it due to expansion how else can things appear to disappear yet still have a visible CMBR.
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Post by speakertoanimals on Nov 12, 2010 13:49:41 GMT 1
It is very, very simple. Let's take a non-expanding model, because expansion just makes things FURTHER away.
We have an infinite universe, where at t=0, we have flashbulbs going off everywhere, all at the same time.
From where we are, lets say a year after the big flash -- we see the flash, because what we SEE is the light from bulbs which are a lightyear away. But there are still bulbs further away than the ones we see at the moment. We obviously can't see yet those objects where light hasn't enough time to travel to us. Anyone who disputes this is just doubting the finite speed of light.
So, what do we see after a year. Furthest away, we see the flash from bulbs a light year away. Half a lightyear away, we see bulbs six months after the flash. As we come closer to home, we see bulbs which are a year after the flash. We have a nice progression, the further out, the younger the state of the object we see, until we get back to 0, which is the furthest distance light has been able to travel over the age of the universe so far.
A year later, we still see the flash, but now from objects two lightyears away.
So, based on this, we could eventually see ALL possible bulbs, we just have to wait long enough for the light from those bulbs to get to us.
If we know add expansion, we have distance bulbs whose light is trying to reach us, but as it travels, the space it still has to traverse keeps expanding. If the space still to be travelled increases in total length faster than it can cut down the length by travelleing at lightspeed, then light from those objects can never reach us. It isn't the recession of that object that matters, it is the stretching of space in front of the light that is trying to reach us.
That is the simplest explanation I can give, and if any posters think they can refute the flashbulbs example.................
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Post by Progenitor A on Nov 12, 2010 16:35:08 GMT 1
It is very, very simple. Let's take a non-expanding model, because expansion just makes things FURTHER away. We have an infinite universe, where at t=0, we have flashbulbs going off everywhere, all at the same time. From where we are, lets say a year after the big flash -- we see the flash, because what we SEE is the light from bulbs which are a lightyear away. But there are still bulbs further away than the ones we see at the moment. We obviously can't see yet those objects where light hasn't enough time to travel to us. Anyone who disputes this is just doubting the finite speed of light. So, what do we see after a year. Furthest away, we see the flash from bulbs a light year away. Half a lightyear away, we see bulbs six months after the flash. As we come closer to home, we see bulbs which are a year after the flash. We have a nice progression, the further out, the younger the state of the object we see, until we get back to 0, which is the furthest distance light has been able to travel over the age of the universe so far. A year later, we still see the flash, but now from objects two lightyears away. So, based on this, we could eventually see ALL possible bulbs, we just have to wait long enough for the light from those bulbs to get to us. If we know add expansion, we have distance bulbs whose light is trying to reach us, but as it travels, the space it still has to traverse keeps expanding. If the space still to be travelled increases in total length faster than it can cut down the length by travelleing at lightspeed, then light from those objects can never reach us. It isn't the recession of that object that matters, it is the stretching of space in front of the light that is trying to reach us. That is the simplest explanation I can give, and if any posters think they can refute the flashbulbs example................. This question has already been answered with far greater clarity in much better English
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Post by speakertoanimals on Nov 12, 2010 16:38:51 GMT 1
No refutations then, just the usual bites from a flea pretending to be a lion..............
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