What's the Fabric of space made out of?

I think there may be a misunderstanding about the purpose of analogies. Analogies are used not to prove a point, but to make clear a point. They are used to make more easily understood something that is hard to understand by likening it to something familiar.Analogies are for helping with understanding, not with persuasion. Analogies should not be used to persuade someone, only to help them understand, but it's a conumdrum when you're trying to help someone understand something that they don't accept.A common mistake is to rebut a position that has been argued using an analogy by attacking the analogy. No analogy is perfect. Space is not an expanding balloon and galaxies are not buttons, but the analogy of buttons remaining unchanged in size while the balloon expands is a very helpful mental image. Arguing that the buttons would fly off because of the glue holding them to the balloon completely misses the point of the analogy. You cannot argue that space isn't expanding because glue won't hold buttons onto an expanding balloon. It's only an analogy to create a helpful mental image of how we think about space. Understanding how we think about space doesn't mean you're conceding a point in the discussion.I think Sylas raised some good points in Message 120 that you haven't yet responded to.--Percy

I agree a lot about what you say about analogies. My point in the buttons flying off had more to do with the expansion of the balloon/space area the buttons occupied than it had to do with the nature of glue, however, which imo, addresses the point of the analogy.

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The immeasurable present is forever consuming the eternal future and extending the infinite past. buzsaw

It does not address the point of the analogy at all. It avoids it, and by this stage it looks to be deliberate. Deep down I am pretty sure you are merely switching off and refusing to learn. It's your choice.

No, Sylas, it's not a deliberate attempt to fiddle away bandwith and our time. It's that if you use a ballon anlalogy, the whole balloon stretches and I'm just not convinced that you should have areas of space which alegedly expand adjacent to other areas that don't, regardless of the forces relative to stuff occupying space.It's about our differences in the nature of space. Until you've convinced me otherwise, I continue to debate on the basis of my concept as you do with yours. Your comment about my insincerity about learning is a false premise on your part.I say ditch your balloon analogy if it's not more analitic as a model, since the whole balloon expands, including the dot and button areas. I don't get allowed this kind of leeway when debating my stuff. I'd soon have five counterparts calling me on it. In my iceage thread I can't even get my counterparts to admit that ice can be referred to as water in a general sense as we often do today. LOL!

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The immeasurable present is forever consuming the eternal future and extending the infinite past. buzsaw

Hi Buz,Maybe you and Sylas could work with this analogy. A loaf of raisin or nut bread. When you set this dough to rise it is much smaller than it will become...the dough rises(expands) yet the nuts/raisins do not get bigger.

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Asgara
"Embrace the pain, spank your inner moppet, whatever....but get over it"select * from USERS where CLUE > 0http://asgarasworld.bravepages.com
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Unless I'm missing the point Sylas was trying to make, I think you've misunderstood the analogy. The balloon is space, the buttons are galaxies. The buttons do not represent regions of space that don't expand, but rather groupings of matter that remain the same size while space expands through them.Asgara's analogy makes the same point in a 3D way. The nuts and raisons are not areas of space that don't expand. They're groupings of matter that remain the same size while space expands.Both these analogies are imperfect, for many reasons, but probably the biggest is that the balloon material doesn't run through the buttons, and the bread dough doesn't extend into the nuts and raisons, so here's another analogy, this one 1-dimensional. Imagine beads strung on an elastic string. As you stretch the string it expands within the beads, but the beads remain the same size. The string is space, the beads are groupings of matter held together gravitationally.As I said earlier, I think Sylas raised some good points in Message 120 that you haven't yet responded to.--Percy

Analogies are useful for someone who is actually interested in learning, to help them grasp some aspects of the more detailed mathematical models used in science. They also provide scope for others to make a lot of red herrings that just don't correspond to ANYBODY'S notion of the universe.You have your own beliefs, buz, and that's fine. It is clear than nothing on Earth will shake them; no problem.But as a simple matter of being sensible about the role of analogies, you should appreciate that whether you accept the findings of modern physics or not, it is a perspective that you don't really understand very well and which other people understand a bit better by virtue of having studied it.Ditching analogies because they are not "analytic" would be stupid, because then we'd be left with nothing to help people who can't manage tensor calculus. Analogies and mental pictures are vital for helping someone develop their understanding. You can use them to help get to the point where you can start to tackle the full analytic understanding; but by that point you should be using some textbooks rather than web posts. It is perfectly clear that no-one will ever convince you of the nature of space. But comprehension is different from agreement; and comprehension is required before agreement or disagreement can even be meaningful. You have not got to comprehension yet.I have explained about galaxies holding their size several times, you still have this wrong; in the sense that you continue to misrepresent what is proposed in physics. The same would be the case for anyone who has not studied the matter in detail; a novice is bound to misrepresent matters somewhat and they get better as they learn more. Your problem is that you do it with such confidence, and without any real recognition that you need to understand the model before you can meaningful describe what is wrong with it.What holds a galaxy together is not any failure of space to expand, but rather that the stars of a galaxy move to maintain the same size. I’ve pointed this out to you previously, in (for example) See, for example, Message 271, and few other posts.A galaxy is actually a collection of objects in continuous motion. (And this is another difference between dots or buttons on a balloon.)We can address this with another analogy. Imagine lots of ants walking all over the balloon as it expands. To grasp what it means for a galaxy to hold together, you can think of gravity being something a bit like a nest of ants who like to communicate by touching feelers. They are bustling around on the balloon all the time, but continually stopping to touch antennae with each other. The whole nest of ants will thus continue to occupy roughly the same area even while the balloon on which they walk is expanding.Now of course, this analogy still is not a full analytic model. One of the differences with the analytic model gets right back to the topic of the thread. A balloon is made of rubber; it has fabric. This just lets us visualize some of the geometric aspects more easily; but in physics there is no rubber, no fabric. There is just geometry, and expansion is an aspect of it. And if you are willing to let it, the balloon analogy can help you understand some aspects of the model, without having to learn tensor calculus.It is NOT a case of the space failing to expand inside a galaxy. It is a case of the stars continuing their local motions to maintain about the same separation distances while the space in which they move continues to expand.I don't care if you don't "agree" with this, and my aim is not to convince you it is true. I'd just like you to get to the point where you drop some of the misrepresentations about the content of the models you disagree with. But even if you never manage that; at the very least I will continue to point out for any onlookers where your criticisms involve actual errors in describing what the models used in physics actually propose.If you go off into yet another school of red herrings about how it is "illogical" that space expands, or that expansion of space would necessarily mean galaxies increasing in size, then you are not even comprehending the models used in the physics; which makes your "disagreement" rather pointless.Sheesh but this is aggravating, buz. I honestly don't care whether you agree or not, but your continuous ignorant misrepresentations of the implications of basic physics, and your refusal to accept that people who have studied the matter are in a position to try and describe its actual content, is ridiculous.Sylas

buzsawI know this is not in the complete context of the present direction in this thread but concerning space I was wondering if you might apply some reasoning to the following thought experiment.A train is travelling down the tracks beside a railway crossing moving at a constant speed.A man aboard the train drops a steel ball from the window of this passing train and from his vantage point on the train the ball{ignoring air resistence to understand the forces involved} appears to fall in a straight line through space to the ground moving past his train.
At the same moment a man on the side of the tracks looks up to see the misdeed.He watches the ball fall arcing to the ground as a result of the combination of the forward movement of the train and the pull of gravity set it in a parabloic curve.Which is the correct path in space,the straight line or the parabola?

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And since you know you cannot see yourself,
so well as by reflection, I, your glass,
will modestly discover to yourself,
that of yourself which you yet know not of

buzsawBump to check up on buzsaw's progress on post# 158.

I am no scientist, but common sense suggests that the parabola is the correct behavior. I don't know why....maybe because there are numerous arcs in spacial behavior of planatoid objects.

PhatboyEach path is valid in relativity.Einstein used this thought experiment to show that the proper way to judge events was not through the use of vague terms such as space but through the use of a defined coordinate system for describing an events location relative to a given fixed local reference frame.The person on board the train can consider himself and his train {moving at a constant speed} as motionless and the surrounding countryside as being in motion as far as his local reference frame is concerned.The same holds true for a man at the side of the tracks and is,of course,in common sense the "real" way the world acts.It is unfortunately not correct as far as special relativity is concerned.We could reverse the direction of the balls' origin of flight to the man on the ground and we would find that the man on the train still would observe a parabolic path while the man on the ground sees a straight line.The consequence of this thought experiment is that there is no absolute frame of reference valid for all localities in the universe.So we delve a little deeper into this and we find things we did not see before.In the first case{the man on the train}observes the ball to move in a straight line while the man on the ground sees it arc,and the same occurs when we reverse the origin of flight to the man on the ground so something is common to both situations.Let us compare the paths.One is a straight line and one is curved. Since both parties witness the same origin and destination for the ball but the path of one {the arc} traverses a greater distance than the other{straight line} by definition what does your common sense tell you is happening?What must be altered between the two reference frames?

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And since you know you cannot see yourself,
so well as by reflection, I, your glass,
will modestly discover to yourself,
that of yourself which you yet know not of

I remember seing a great video once on just this subject. It involved a man on a running horse riding along a path that has a ruled border. There is a vertical white line (or it may have been a pole attached to the far side of the horse, I can't quite remember).As the rider swept along the path he dropped a large ball. The ball fell to the ground but remained in line with the post. However, the point of impact was considerable further along the ruled border to the path.

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Aslan is not a Tame Lion

It must have something to do with the time that it takes the object to drop.

PhatboyExactly! Now how must the time change for the two paths to be able to occur simultaneously?This message has been edited by sidelined, Tue, 2005-03-22 09:07 AM

jarYes that would be the view to a person who's reference frame is the ground. To the rider the object appears to fall in a srtaight line.
So we have two paths of unequal length occuring for the same event.As Phatboy surmised time is altered,but how?