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Post by abacus9900 on Sept 28, 2010 13:20:20 GMT 1
STA, even on those occasions on the BBC MB when I have repeated what you had previously told me you deny it's correctness. There seems to be no pleasing you and you seem to be on some crusade to demonstrate how clever you are and how stupid the rest of us are.
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Post by alanseago on Sept 28, 2010 13:31:24 GMT 1
How disappointing that interesting conversations can degenerate into personal attacks at the hands of so few. This is one of the reasons for the closure of the BBC board, I was expecting this one to be different. I am neither scientist nor professional mathematician, I came here to learn not to read these childish squabbles.
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Post by abacus9900 on Sept 28, 2010 14:00:17 GMT 1
How disappointing that interesting conversations can degenerate into personal attacks at the hands of so few. This is one of the reasons for the closure of the BBC board, I was expecting this one to be different. I am neither scientist nor professional mathematician, I came here to learn not to read these childish squabbles. What interesting conversations?
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Post by speakertoanimals on Sept 28, 2010 16:18:40 GMT 1
How disappointing that interesting conversations can degenerate into personal attacks at the hands of so few. This is one of the reasons for the closure of the BBC board, I was expecting this one to be different. I am neither scientist nor professional mathematician, I came here to learn not to read these childish squabbles. Except I have slipped in some cosmology along the way, just that some people want to keep claiming it means something when it does not, or that I said something when I did not. If you've got a question about cosmology, then ask!
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Post by principled on Sept 28, 2010 16:55:15 GMT 1
OK STA, here's a question. Now I don't want any of those pre-rehearsed student answers, I'd like a genuine one. So, how do YOU (not your maths) envision the universe? Would those bodies furthest out (from where?) see- as in our galaxy's case- other galaxies in all directions or would they not see galaxies in one or more directions? Is the universe like a flat sheet of stretchable rubber or is it more like an ever inflating balloon? Do you feel totally at ease with the concept of space expanding. Nothing expanding from nothing and with no energy required to do so? Or could it be that it does require a force - that mysterious force discovered recently which appears to be slowing some space satellites? Then again, is Voyager just passing through space that is already expanded or is it creating its own expanding piece of space as it travels ever outwards? Genuine questions and no put downs please. P
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Post by speakertoanimals on Sept 28, 2010 17:57:12 GMT 1
OK STA, here's a question. Now I don't want any of those pre-rehearsed student answers, I'd like a genuine one. So, how do YOU (not your maths) envision the universe? Would those bodies furthest out (from where?) see- as in our galaxy's case- other galaxies in all directions or would they not see galaxies in one or more directions? Is the universe like a flat sheet of stretchable rubber or is it more like an ever inflating balloon? Do you feel totally at ease with the concept of space expanding. Nothing expanding from nothing and with no energy required to do so? Or could it be that it does require a force - that mysterious force discovered recently which appears to be slowing some space satellites? Then again, is Voyager just passing through space that is already expanded or is it creating its own expanding piece of space as it travels ever outwards? Genuine questions and no put downs please. P There is no such thing as furthest out. FLat sheet and expanding balloon are both very poor analogies. How I see it is a daft question, in that the point is, we can't grasp it intuitively, we just can't -- hence maths is the only way to handle it properly. Nothing expanding from nothing?Who said from nothing, if infinite, was always infinite, hence we have instead space full of matter expanding to space with slightly less dense matter, and so on. Thinking it needs a force is just misplaced use of analogies yet again -- rubber needs a force to stretch it, but space just isn't like that! Saying it does kind of implies that space has some natural length, which just isn't the case. As regards Pioneer anomaly, or accelerating expansion, I dunno. The rest of it is frankly just the usual unease at the basic idea because there are no intuitive models for it. Once you accept that, that space is something other, then it doesn't worry you as much. Thinking that we should be able to have an intuitive feel for things such as the way the entire universe behaves is just wishful thinking. The more physics (or science) you do, the more you realise that our intuition is limited to a very small range of phenomena, and just can't deal intuitively with the universe at large, with things on the atomic ofr sub-atomic level. If all you can cope with is intuitive physics, better stick to classical mechanics (but leave out rotating objects, because most people are confused by the way a gyroscope behaves!). Pre-rehearsed student answers? What's wrong with them? Because we are talking baby-level physics here, like asking a baby to say disestablishmentarianism, rather than goo............... Rather than rehearsed, just that this stuff comes up over and over again, so of course most of us have standard answers, because it is quite rare that we come across a novel way of misunderstanding this stuff (although my missus is quite good at those!).This isn't supposed to be insulting, but the fact remains that we are at a very basic level here, and you shouldn't forget that.
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Post by Progenitor A on Sept 28, 2010 18:24:17 GMT 1
OK STA, here's a question. Now I don't want any of those pre-rehearsed student answers, I'd like a genuine one. So, how do YOU (not your maths) envision the universe? Would those bodies furthest out (from where?) see- as in our galaxy's case- other galaxies in all directions or would they not see galaxies in one or more directions? Is the universe like a flat sheet of stretchable rubber or is it more like an ever inflating balloon? Do you feel totally at ease with the concept of space expanding. Nothing expanding from nothing and with no energy required to do so? Or could it be that it does require a force - that mysterious force discovered recently which appears to be slowing some space satellites? Then again, is Voyager just passing through space that is already expanded or is it creating its own expanding piece of space as it travels ever outwards? Genuine questions and no put downs please. P There is no such thing as furthest out. FLat sheet and expanding balloon are both very poor analogies. How I see it is a daft question, in that the point is, we can't grasp it intuitively, we just can't -- hence maths is the only way to handle it properly. Nothing expanding from nothing?Who said from nothing, if infinite, was always infinite, hence we have instead space full of matter expanding to space with slightly less dense matter, and so on. Thinking it needs a force is just misplaced use of analogies yet again -- rubber needs a force to stretch it, but space just isn't like that! Saying it does kind of implies that space has some natural length, which just isn't the case. As regards Pioneer anomaly, or accelerating expansion, I dunno. The rest of it is frankly just the usual unease at the basic idea because there are no intuitive models for it. Once you accept that, that space is something other, then it doesn't worry you as much. Thinking that we should be able to have an intuitive feel for things such as the way the entire universe behaves is just wishful thinking. The more physics (or science) you do, the more you realise that our intuition is limited to a very small range of phenomena, and just can't deal intuitively with the universe at large, with things on the atomic ofr sub-atomic level. If all you can cope with is intuitive physics, better stick to classical mechanics (but leave out rotating objects, because most people are confused by the way a gyroscope behaves!). Pre-rehearsed student answers? What's wrong with them? Because we are talking baby-level physics here, like asking a baby to say disestablishmentarianism, rather than goo............... Rather than rehearsed, just that this stuff comes up over and over again, so of course most of us have standard answers, because it is quite rare that we come across a novel way of misunderstanding this stuff (although my missus is quite good at those!).This isn't supposed to be insulting, but the fact remains that we are at a very basic level here, and you shouldn't forget that. Jesus! This is a reasonable answer to a genuine enquiring question? You are a waste of time STA - not worth bothering with. Both you and Olmy are from the Charles Atlas School Of Science, looking for weeds so you can kick sand in their faces. Then you squeal like stuck pigs when the weed grab your Gonads and beat you around the head Why don't you go somewhere else, you contradictory waste of bloody time?
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Post by speakertoanimals on Sept 28, 2010 19:23:35 GMT 1
Yes, it IS a reasonable answer. How do I envisage it -- I try not to, because most mental pictures you can construct are wrong in some essential aspect. Hence I have to think of it in maths terms, and I just can't describe how I think about maths in other terms, because it is fairly hard to do, even harder to describe.
Flat elastic sheet and the expanding balloon are perhaps useful, but mainly in the ways in which they are wrong. SO space isn't like elastic, in that with anything elastic, the more you stretch it, the larger the force required, and it snaps back when you stop pulling. Space isn't like it, space itself doesn't know how big it should be, or whether it is stretched or not. It's NOT like a material, that is useful lesson number one, and ideas you get based on thinking about materials will probably be totally wrong.
Nor is it like anything else! That is the point, it just ISN'T.
So what is it then? Turns out that in maths terms, it is actually fairly simple and straightforward. But you can only start on that if you can get your head round the idea of geometry in non-flat spaces, and think of the balloon without the interior, or exterior, just the surface.
Difficult? Yes, which is why non-Euclidean geometries took so long to be accepted and developed.
If you don't like that, don't blame or insult me, that just is the way it is. That seems to be the sort of concepts required to describe the universe, because the more common everyday concepts, as intuitive as they were, just kept giving the wrong answer.
As I said before, any disquiet at these notions is probably because someone is stuck at the level of everyday analogies, which are at best misleading, at worst totally wrong. You have to junk them, there is no other way.
You are just not prepared to make the effort, or willing to admit that you have got a load of stuff wrong. Because seemingly you are not wiling to accept that to understand any of this requires a leap of abstraction, going beyond the everyday and what can be captured in analogies. In short, abstract maths. Instead, you would rather see my constant reminders that you have got it wrong as some sort of personal comment, or a slur on your intellectual ability. It mostly isn't, it's just saying -- if you can't do the maths, then you can never do it, no matter how smart you are. And not everyone can start to get the maths, because before you can do that, you have to be willing to admit that there are concepts that you can describe in maths that you can't grasp intuitively, and that even when you think you have an intuitive grasp, you're either wrong or misleading yourself.
You seem to think the problem is me being an awkward bastard -- it's not, that just is the way it is. If you can't grasp the maths, you can only have a limited understanding of the subject. That's not because you are necessarily stupid, just that you can't do the maths, and not that many people can. But you can certainly never start to learn any of it unless you are wiling to admit there is something there to be learnt beyond where you are, and you seem unable to do that. It isn't just -- I can understand in words, maths is just the fancy twiddles if you want to actually work something out in detail. No, the basic concepts aren't graspable (usually) in simple words, you need a new language and new concepts, which is what is in the maths.
It is something outside your direct experience, and until you accept that, you will never understand. Go kick the universe if this upsets you, rather than making silly statements based on your fragile ego (sorry, but statements involving gonads are usually a dead give away).
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Post by speakertoanimals on Sept 28, 2010 20:35:09 GMT 1
How do I envision it? I don't at least without maths, but that is rather abstract and hard to describe HOW I do it. What I definitely try NOT to do is have any mental pictures based on everyday analogies, as they are plain wrong.
To take an example, more like a rubber sheet, or an expanding ballon. Well, the rubber sheet is wrong because it is rubber (which has a natural length, pulls back harder the more you stretch it, and snaps if you pull too hard). So, wrong on all counts apart from the limited ability to expand, but only if pulled.
Balloon is slightly better, in that closed universe, rather than trying to imagine an infinite rubber sheet. But gives the wrong impression in that there is an outside into which it expands, gives the impression that started at a point, has the problem that becomes LESS curved as it expands, and so on.
Picture I prefer is more mathsy -- the plane, with equally spaced dots, infinite and flat, that expands, but still fills the plane, no outside, the dots aren't drawn on anything that requires stretching, its just a coordinate space (but there I go with the maths again!).
You see, you have to ditch the material analogies for stretching, else you get stuck in this idea that a force is required, or that space has a natural length that it knows about and will snap back to if you stop tugging, or that expanding space requires energy, that it is some sort of giant cosmic spring. ALL of these are wrong, and go back to the rubber of rubber sheet.
There is no furthest out, a bit like the balloon, but only if you can imagine the balloon without the inside or outside, just the surface, that gets bigger, but with no edge, and the view is the same wherever you are on that surface. But more like the infinite plane, where everywhere is the same as everywhere else, and there is no edge.Or the plane with a finite size, but a non-trivial topology (whoops, there goes the maths again!)...........
The only point about the analogies is that they just serve to say what is NOT the case, rather than what is.
Nothing expanding from nothing? The infinite plane doesn't expand from nothing, just that as you play the film backwards, tghe dots get ever closer together. The nothing is helpful in the sense that spacetime certainly isn't something in the rubber sense, there is no fabric to the fabric of spacetime! A nothingness, that just has the properties of geometry (here comes the maths again, no way to avoid it!).
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