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Post by speakertoanimals on Nov 8, 2010 17:28:54 GMT 1
You seem to be using a different definition of infinity to the rest of us. Or just being daft...............
Just being daft, as usual.
The poster I now imagine as someone sitting on the floor of a library with a large pile of books, merrily pulling them all to pieces and putting them through the shredder, whilst mumbling to themselves, 'bollocks, all bollocks..........'
You see, this is highly problematical from a philosophical perspective because the idea seems to be saying the BB and the subsequent expansion of the universe has 'created' something out of nothing, which is illogical. No it doesn't. Something expanding isn't creating more stuff, it only is if you are daft enough to think that there is a fabric to the universe, and where does all the wool come from for the new fabric........................
Same ole daft non-arguments we had at the start, just repeated over and over again with varying amounts of insults and some slight variety in phrasing. But no attempt to learn, or willingness to admit that you might be wrong.................
If there is a problem from a philosophical perspective -- who CARES, our physics is quite capable of saying our philsophy is bollocks, and quantum theory certainty said that! Events without cause, something from nothing, creation ex nihilo all turned out to be the rule, rather than an exception. Philosophy is bunk................
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Post by abacus9900 on Nov 8, 2010 18:12:46 GMT 1
What it is supposed to be creating is more volume where beforehand there was none. How can more volume be created where there is no 'room' for it? Again, you will say oh, the universe is just inflating by itself with no need of anything preexisting but, as I already noted, this is purely a self-referential approach and is no better an explanation that Genesis. It is also anti-scientific in that it denies any possibility of falsification by scientific means because it effectively says this is the way things are and that's that, do not try to question this since it is impossible to invalidate it as the universe is the only thing in reality and justifies itself because it 'is'. It also implies that, fundamentally, all science is based on magic. Do you remember Godel's Theorem? Same principle.
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Post by abacus9900 on Nov 8, 2010 18:28:14 GMT 1
We have to care about philosophy because without it disciplines like physics can very easily produce absurd and fallacious conclusions. The problem with observational science is that it is always in the position of not knowing enough so that any ideas derived from current data are only ever going to produce part of the bigger picture.
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Post by abacus9900 on Nov 8, 2010 18:32:26 GMT 1
You seem to be using a different definition of infinity to the rest of us. Or just being daft............... Naymissus was making a perfectly reasonable point. If something is infinite how can it be more than infinite? Illogical.
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Post by speakertoanimals on Nov 8, 2010 18:36:59 GMT 1
Nope, just plain wrong.
Hilbert hotel, infinite number of rooms, guests in each one. They get restless, so person in room 1 moves to room 2, person in room 2 moves to room 4, person in room n moves to room 2n.
Hence the infinite number of guests al still have rooms, but they only oocupy the even numbered rooms.
Replace 'guest' by x-coordinate of one of our little squares, and we have squares twice the size as before, but still filling the hotel/plane, and no extra plane needed.
The empty odd--numbered rooms represent the points where a square previously started, when we had unit squares, but now empty that the squares have all become twice the size.
how an infinite thing can expand, and still remain infinite, and we don;t need to build a new wing on the hilbert hotel.
Moral: don't try to apply the logic for finite numbers to infinite numbers, as Cantor knew..............
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Post by Progenitor A on Nov 8, 2010 19:05:14 GMT 1
Nope, just plain wrong. Hilbert hotel, infinite number of rooms, guests in each one. They get restless, so person in room 1 moves to room 2, person in room 2 moves to room 4, person in room n moves to room 2n. Hence the infinite number of guests al still have rooms, but they only oocupy the even numbered rooms. Replace 'guest' by x-coordinate of one of our little squares, and we have squares twice the size as before, but still filling the hotel/plane, and no extra plane needed. The empty odd--numbered rooms represent the points where a square previously started, when we had unit squares, but now empty that the squares have all become twice the size. how an infinite thing can expand, and still remain infinite, and we don;t need to build a new wing on the hilbert hotel. Moral: don't try to apply the logic for finite numbers to infinite numbers, as Cantor knew.............. You are mixing up mathematical theory wit paracticality my dear In fact there is probably no such thing as the physically infinite - it is beyond physics. and venturing into philosophy - nothing wrong with that incidentally - physics is simply a branch of natural philosophy Infinity in physics is a great embarrassment to real physicists - recently on R4 Penrose shrugged off infinity as beyond his pay scale - the fact that you bandy it around as if it has physical tangibility points to the probability that you are really a quite dim lab technician rather than a physicist. So be it. DON'T MENTION THE INFINITY
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Post by abacus9900 on Nov 8, 2010 19:14:58 GMT 1
This is all very well when playing mathematical games but physics isn't necessarily like this. The fact that maths can be used to understand physical processes is a happy coincidence but you cannot push maths too far when discussing physical sciences. The question of whether the universe is infinite or not is more of a philosophical question than a scientific one. I thought you abhorred philosophy!
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Post by speakertoanimals on Nov 8, 2010 20:20:42 GMT 1
This makes several assumptions. First, that an expandingn infinite universe needs more volume. Second it also somehow assumes that the universe needs room into which it expands (wrong again).
Wrong all round, frankly, based on same tired ole assumptions based on looking at balloons................................
Extra room not needed, because the universe isn't expanding INTO anything.
You can also look at it as not space getting bigger, just our measurements of distance changing -- works both ways, because there is no OUTSIDE to say how big our universe really is..............
And trying to ditch infinity doesn't work either -- we can still have a flat universe, finite in size, but with a non-trivial topology. And that can still expand without needing extra elbow room, because there doesn't have to be an outside........................
The questiojn as to whether then universe is infinite or not IS physical, hence let the physicists get on with it, because the philosophers, in my opinion, should have stuck to moral philsophy because given that they can't handle quantum theory, they are still just divorced from the physical world, so should keep out of physics -- they can't do it!
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Post by Progenitor A on Nov 10, 2010 19:01:03 GMT 1
Now come on, we must have someone clever and articulate out there who can explain why we have galaxies that have disappeared because thet are moving away from us faster than light (due to the incomprehensible space expansion) yet, the CMBR that was created before any galaxy is still visible
What is going on here
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Post by typobrane on Nov 11, 2010 12:53:27 GMT 1
I thought I had explained it, I will try again. Remember that everything we see is in the past, only a few nanoseconds for local things like your garden or the street where you live. Light travels through space at just over 186,000 miles per second. The moon is just under 250,000 miles from Earth, so light from the Moon's surface has to travel more than one second (about 1.3 seconds) to reach us. The Sun is about eight minutes away and so on and so forth, and so the relative velocity between celestial objects will have an effect on the way that they appear to behave. A good example of this is the time it takes the moons of Jupiter to orbit. Because we on Earth orbit the Sun in less time than Jupiter, sometimes we are catching Jupiter up and at other times we are leaving Jupiter behind, if we time how long it takes Io (that is one of Jupiter’s moons) to orbit Jupiter while we are catching Jupiter up and then time it again when we are leaving Jupiter behind we notice that it takes Io longer to orbit Jupiter while Earth and Jupiter are moving away from one and other. To an observer on Jupiter Earth’s moon will apparently speed up and slow down in the same way. What we see is not reality.
Our visual horizon has been and still is expanding at the speed of light ever since big bang. In our past we would have seen more and more as the universe unfolds before our eyes. But the universe is also expanding not because the galaxies are moving faster as in an A to B sort of way through space, they are moving away from each other due to more space coming into existence between them. This is recessional velocity and not actual speed. The most distant objects that we can still see are now moving away from us faster than the speed of light, if they were traveling faster than light we would not be able to see them. In the future we will see fewer things in our universe despite being able to see more of the volume of space. So the answer to your question; “Why we have galaxies that have disappeared because they are moving away from us faster than light (due to the incomprehensible space expansion) yet, the CMBR that was created before any galaxy is still visible” is that the most distant things visible will appear to be getting younger, going back in time to when they were part of the CMBR. Remember this is looking at things in the very distant past that appear to be going back into their past and like the slowing down and speeding up of Jupiter’s moons it is not reality.
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Post by Progenitor A on Nov 11, 2010 13:02:23 GMT 1
I thought I had explained it, I will try again. Remember that everything we see is in the past, only a few nanoseconds for local things like your garden or the street where you live. Light travels through space at just over 186,000 miles per second. The moon is just under 250,000 miles from Earth, so light from the Moon's surface has to travel more than one second (about 1.3 seconds) to reach us. The Sun is about eight minutes away and so on and so forth, and so the relative velocity between celestial objects will have an effect on the way that they appear to behave. A good example of this is the time it takes the moons of Jupiter to orbit. Because we on Earth orbit the Sun in less time than Jupiter, sometimes we are catching Jupiter up and at other times we are leaving Jupiter behind, if we time how long it takes Io (that is one of Jupiter’s moons) to orbit Jupiter while we are catching Jupiter up and then time it again when we are leaving Jupiter behind we notice that it takes Io longer to orbit Jupiter while Earth and Jupiter are moving away from one and other. To an observer on Jupiter Earth’s moon will apparently speed up and slow down in the same way. What we see is not reality. Our visual horizon has been and still is expanding at the speed of light ever since big bang. In our past we would have seen more and more as the universe unfolds before our eyes. But the universe is also expanding not because the galaxies are moving faster as in an A to B sort of way through space, they are moving away from each other due to more space coming into existence between them. This is recessional velocity and not actual speed. The most distant objects that we can still see are now moving away from us faster than the speed of light, if they were traveling faster than light we would not be able to see them. In the future we will see fewer things in our universe despite being able to see more of the volume of space. So the answer to your question; “Why we have galaxies that have disappeared because they are moving away from us faster than light (due to the incomprehensible space expansion) yet, the CMBR that was created before any galaxy is still visible” is that the most distant things visible will appear to be getting younger, going back in time to when they were part of the CMBR. Remember this is looking at things in the very distant past that appear to be going back into their past and like the slowing down and speeding up of Jupiter’s moons it is not reality. Sorry Typobrane, but call me stupid if you will (some on this board have already done so) but I do not understand your explanation and am none the wiser. If A happens in time before B and both A and B are receding from us (at say the speed of light) , then it is illogical to expect B to disappear beyond our horizon before A disappears from our horizon unless B is moving faster then A and overtakes A? Surely there is a simple answer?
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Post by speakertoanimals on Nov 11, 2010 13:42:22 GMT 1
Because I think you're stuck thinking that everything came from a point, hence before means further away, in some sense.
The point about the CMB is that space is FULL of it, and always was. SO, we have a universe full of the CMB. At some later stage, galaxies evolved within this CMB filled universe. Hence what we see when we look out is the CMB (because it is everywhere!), AND we see images of some galaxies, those where light has had enough time to get to us. The CMB still fills space, and always did, hence we will always see it, however the universe expands.
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Post by typobrane on Nov 11, 2010 14:07:02 GMT 1
Naymissus, you are not stupid it is just that I am challenging your beliefs. The CMBR is not an echo, there is no giant mirror at the edge of the universe, it is not light from our distant past, when we were part of that seething plasma we were still a long way from the part we can see today it is just that today we are even further away. The temperature of the CMBR is the same or certainly was the same everywhere because it was created at the same time in the same way but not in the same spot. Even if the universe is not infinite it must have been very big at the moment of creation and then got bigger or we would not be able to detect it at all. Distant galaxy B does not overtake CMBR A, it is B that becomes A. And I am sorry the answer is not simpler.
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Post by Progenitor A on Nov 11, 2010 15:52:50 GMT 1
In an expanding Universe, the CMBR was created at t=0+400,000 years. It then started expanding with the universe's expansion. About 4 milion years later the first stars were made. Now lets be reasonable and say that these first stars were made at a distance of 4 million light years - right in the midst of the CMBR. By that time the radius of the CMBR was 4 million light years. The stars then started expanding in space, (along with the continuing expansion of CMBR). . By the time the first stars got to our current radius of 13.7 billion light years, it follows that the CMBR must have been at least 13.7 Billion light years in radius away. (That the CMBR is moving away from us is confirmed by red shift) But we are told that because space is expanding the diameter of the universe is about 40 billion years. If that is so, it means the oldest matter is at that distance and matter that was created later (i.e. later stars) are at a lesser distance.
Yet we can see CMBR but are told that there are stars we cannot see because they are so distant their light does not reach us, even though those distant stars must be at most, the same distance away as the CMBR
Now come on, what is the explanation?
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Post by speakertoanimals on Nov 11, 2010 17:07:58 GMT 1
You are thinking in terms of things somehow moving outwards into formerly empty space, which is EXACTLY the wrong picture.
So, the universe starts, a small box (but without sides!). Full of the CMB, and matter. 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.
Box expands, as do the contents. The CMB gets redshifted because of the expansion (NOT because it is moving away from us). The matter jiggles about, forms galaxies, stars light up, but the whole is continually bathed in the CMB which fills the whole universe.
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.
As regards your dates -- you have then the wrong way round. What we see as furthest way are the youngest galaxies. 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.
So, what is constant for the objects WE CAN SEE NOW is age of object plus travel time.
The CMB has the largest travel time of all, so it is the youngest relic we see.
This doesn't mean these are the only objects in the universe, just the only ones we can see.
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.
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.
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