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Author | Topic: Expanding time? | |||||||||||||||||||||||||||
cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
So if the sphere is expanding does the longitude time line 'change' as the relative curve of the sphere decreases? As Mod says, the sphere is not expanding. It is a fixed size. What is expanding are the circles of latitude, as you move up the lines of longitude from the South Pole, or down from the North Pole depending on your analogy preference. The circles of latitude represent space, and the lines of longitude are time.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
Yes, that's right. And when we put it this way, the time lines can actually shrink and expand, like the space dimensions, depending on the overall geometry/topology. We just don't think of it that way as we're tied to travelling along the time lines, and also the geometry of our own universe is quite boring and doesn't behave that way (think of the lines of longitude around the globe)
Edited by cavediver, : No reason given.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
When space expands is there a reduction in anything? Not really - only anything that is a direct result of the expansion, such as density - e.g. the mass within a volume stays the same, so as the volume increases, the density must decrease. Why do you ask?
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I ask because it is difficult for me to imagine the universe expanding unless as it expands it is taking up more and more space. In other words I conceptualize that beyond the ever moving boundary of the universe there is true nothingness of space being more and more encroached upon. Yes, it is difficult to imagine - even V-Bird, who apparantly been considering these things for many years, has yet to grasp this concept. But the fact is (as in, what 99.999% of cosmologists accept) the Universe gets bigger but does not encroach on anything You have to let go of your instinctive ideas about distance. They work well around you, even across the Earth - actually, they work quite well even around our local galaxies. But at the end of the day, the distance between two objects is merely a number. Just like the strength of an electromagnetic field is a number and can vary at a point without anything else having to 'move out of its way', so too can the numerical distance between two points vary, without anything else having to move out of the way! The trick is to stop talking about the Universe expanding, and just think of the distances between things getting bigger. Imagine the Universe is infinite in extent (and it may well be) - how can it expand, it is already infinitely big? But you can easily double the distance between each two points within the Universe. So the distances grow, but the Universe itself is not expanding as such. Why do we believe this? It is exactly what Einstein's General Theory of Relativity shows us. And this theory is one of the two most successful theories ever discovered! It has told us many crazy things, and so far they have all turned out to be correct.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
But, I do not understand what you are saying. Don't worry, this is not easy, especially an esoteric subject like expansion of space. All of our simple analogies can be abused to bolster incorrect claims such as those of V-Bird, so I am jumping in at the deep end with you to try and avoid this. This may or may not help... here are three galaxies:
@ @ @ They are 100 megaparsecs apart ( about 326 million light years)
@ @ @ Now they are 200 megaparsecs apart.
@ @ @ Now they are 300 megaparsecs apart. Nothing has changed apart from this number we call distance. It will take longer to travel beween them, but that is all. There is no edge to this space either. If this universe is infinite, we can keep looking further and further left of these three galaxies, meeting more and more galaxies, all of which are also getting further away from each other. If this universe is not infinite, if we look left far enough, we will get back to where we started from! There is no edge which is expanding into some outer nothingness (as V-Bird believes). There is just the Universe. The distances between the galaxies is growing larger, but that is all. Edited by cavediver, : No reason given.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
In the last sentence, I have difficulty seeing the difference between the two ideas. That is because you are still visualising the Universe as some ball that is growing. That viewpoint does not exist. You have to look at the Universe from the inside, as only the inside exists.
I mean the two "things" with the biggest number discribing how far one is from the other. In an infinite universe, there is no biggest number, and in a finite universe, you will simply start overlapping yourself as you describe larger and larger distances. You could describe New York and Sydney as a million mile apart, if you're willing to go round the earth several times before actually landing!
1.) Years ago someone told me that if you travel in the universe in one direction long enough you will come back to the same place you started. If the Universe is finite this is quite possible, though you can't actullay do it because the space is expanding more quickly than you can travel. Imagine that the earth is expanding. It may expand so fast that you could never fly fast enough to get all the way around!
2.) Many things in the universe are rotating. Do you think that the whole universe may be rotating also? Good question. Probably not, given the type of cosmology we seem to inhabit. But it is possible to have rotating space-times.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
Correct me if I am wrong cavediver Oh, okay We could have a nice deep dicussion of Mach's ideas here, but I'm knackered so for now I'll simply say that in General Relativity, we can distinguish a rotating space-time from a non-rotating space time, from inside that space-time. A great example is the Kerr rotating black hole which differs significantly from the Schwarzschild non-rotating black hole. Edited by cavediver, : No reason given.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
Yep, that's the stuff. When you spin round, would your arms lift up if there were no other stars and galaxies It's sort of sad that most of this is answered by GR, but there are still some mysterious areas...
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
Remember what I said about abusing analogies...?
At the given scale, you would only see pin points for galaxies. And their size is irrelevant to the point I'm trying to make.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I do not doubt that the observations are correct, just the mind making sense of them is set wrong. Yes, again, we have the unbelievable arrogance of an uneducated armchair muser claiming that the world-body of cosmologists and astrophysicists are all wrong, and only the one true V-bird has cracked it and all without an ounce of mathematics and a ton of semantics and word salad. Astounding...
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I think particle physics is looking at almost everything wrongly despite it being the most successful branch of science known to mankind Look, a simple analogy is this. We have calculated pi to 1 trillion decimal places, but we're a little bit hazy how to go further. You come along, and say - aha, I know how to do this, but first you have to realise that it's not 3.14.... it's 3.24.... I mean, how do you communicate with someone like you? You're so obviously so unbelievably wrong, but you are also so obviously incapable of seeing just how unbelievably wrong you are. You are claiming to overturn 100 years of the most successful science ever conducted by whistling a few buzz words. You have 100 years of near perfect results to replicate with your theory, before you can even begin to talk about anything new.
cosmologists are reluctant to accept a singularity of moderate density or an FTL cosmos They are not reluctant to accept an "FTL cosmos" - there is no such thing. There is no such things as a "non-FTL" cosmos either. Just as there are no bullemic cars nor hypothermic pianos. You are plucking technical terms of which you have little knowledge and sticking them together to claim a new concept. It doesn't wash. FTL refers to a type of path through space-time. What is an FTL comsos? One where all paths are FTL, or just some of them, or none of them? And how does this differ from our Universe?
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
The idea of metric expansion says that two points in space remain at the same spots but the distance between them grows(while these two points remain at their same locations). This is sort of correct, but it implies that there is some way of defining a 'fixed spot' - there is not. There is simply the concept of pairs of points having a distance defined between them. Without the metric defining the distances, the points may as well be marbles loose in a bag (ignoring global topological considerations)
Extrapolating this back to the Big Bang we have a universe that did not change in size since the Singularity if we were able to view it from the "outside". I would say that the term 'size' is undefined in this context. Size only makes sense internally when using the metric.
My uncertainty is whether we can extrapolate this metric expansion all the way back to the singularity because if we could, the size of the universe, when viewed from the "outside"(if it were possible) would still be zero, as it is assumed to have been 13.7 billion years ago. From this 'outside' perspective, the size of the Universe is not 'zero' at the Big Bang, it is simply an invalid concept. And at our time, it remains an invalid concept. Size is only a meaningful concept inside the Universe.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I sort of expected this answer since i've never been able to have you speculate on anything. You mis-understand. If something is ill-defined, it is not a case that we do not know and it is open to speculation. We do know, it is ill-defined, and it is not open for speculation. There are many unknowns that are not necessarily ill-defined, and I am happy to speculate on these if I have the time.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
CD, yes PP is successful in what it does, it defined endlessly intricate actions and interactions, but it has failed to provide any evidence of Gravity [higgs or otherwise] Obviously, as the gravitational interactions are exceptionally weak at the scale of our accelerators you must forgive us physicists for not having 25th century engineering at our disposal. And what has the Higgs to do with gravity??? You are exposing more of the obvious: your physics knowledge is merely based on highly erroneous and misleading popular science articles. Meanwhile the rest of your post is pure pseudo-science gobbledigook and simply confirms your delusion. Your words portray you as a obfuscating court mystic, not a scientist interested in truth. It is harmless and if you gain enjoyment from it, more power to you. But when you start trying to interrupt genuine discussion, you becomes a nuisance and a barrier to others' knowledge. For that I will slam you hard...
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
No time right now but I will get back to this. The website is not the "official" wbesite fo string theory - there is no such thing. However, a quick glance shows me it is put together by the student of someone I used to know, and I expect it has good (or at least reasonable) content.
quote: No more or less than the implications I have already discusssed in reducing everything to the basic fields, including distance.
One of the biggest one is that space and time are also made of strings That is very misleading and I would disagree with that.
quote: That is a more reasonable way of putting it, and I would agree with this (within the context of string theory being "right") - though even this becomes vague as we enter M-theory.
I can see much logic to this prediction, as it solves all kinds of QM paradoxes. No, it doesn't QM remains exactly the same, with exactly the same weirdness and apparent paradoxes.
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