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Member (Idle past 5845 days) Posts: 109 From: Bozeman, Montana, USA Joined: |
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Author | Topic: Universe Race | |||||||||||||||||||||||
cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
The "Copernican Principle" is assumed... ...Neither is there any evidence to support it Really? The CP essentially states that we are not priviledged observers, our place in the Universe is not special. This is observationally confirmed at just about every astronomical/cosmological length scale you care to imagine, not just our place in the Solar System (the origination of the name 'Copernican Principle for obvious reasons.)
Worse still, if the universe has a center, all observations are consistent with Earth being at or close to it. Earth??? Really? Or do you mean the Solar System, or the Galaxy? Or the Local Group? Or perhaps the entire Virgo Supercluster? Let's just say for sake of argument that the VS is the centre of the Universe... now do you claim that the Earth has a central special location within the VS?
Furthermore, if you assign reverse vectors to the visible matter in order to see where everything came from... well, that just makes them howl. I'm sorry, but this is complete nonsense. Where did you read this, or did you make it up?
Only the oldest versions of the big bang considered a physical explosion. The big bang has NEVER involved a physical explosion, despite all of the popular misrepresentations. I suggest being more familiar with the actual science before you start making such proclamations.
These are the versions perpetuated in schoolbooks and pop science to keep the actual current big bang safe from being laughed out of the schoolhouse by the students. As silly as those versions were/are, they ain't nothin' compared to the real deal. Strange - I have never been laughed at when teaching the cosmology of the big bang, either to my graduate students or, later, to my more advanced school students.
All that being said, your analogy is fairly accurate. Ah, you really don't understand any of this, do you?
Since Einstein's day they've been trying to come up with a fudge factor that will allow gravity to increase (or in some versions actually reverse) at long distances and hold things together, while still matching observations closely enough for them to fudge the observations to comply. Care to explain this gibberish more clearly? What fudge was anyone looking for 'since Einstein'? Are you completely misunderstanding Lambda (the Cosmological Constant) or are you alluding to dark matter? If so, you're the best part of a century out !!!
Inertia favors your analogy, and gravity can't prevent this. In order to exert more gravity, what do you need? More mass! More mass = more inertia, and by all mainstream accounts they don't have nearly enough mass to slow things down even if you throw in dark matter. I'm sorry, but your layman explanation of General Relativity here seems rather screwed. Care to explain to me what you mean?
But don't get sidetracked by dark matter. It's primary function is to hold galaxies together. There ain't enough visible mass and the velocities are just crazy Can you quantify 'crazy'? Do you simply mean 'different' to that predicted by the visible mass?
Without dark matter, galaxies fly apart in a few thousand years Do they??? I am surprised! But I guess if you think of galaxies poofing into existence by magic, complete with their observed rotation curves, AND with a complete absence of dark matter, then yes, I guess they would fly apart!!! I'll remember to stop teaching that. Thanks. By the way, can I see your calcs that show this 'flying apart' prediction, as I'm not familiar with them.
I won't tax you with what I know of the dark energy fantasy at this time. Oh, please, don't let me stop you. I would love to hear what you know...
But anyhow, to stop your analogy from being on target, they'd have to devise something that counteracts inertia and is capable of preventing the universe from flying apart. The mainstream bin's empty, so expect trash that's either 50 years out-of-date, or straight out of a sci-fi novel. Or invented ad hoc, can't forget that category. The analogy is completely incorrect - no more needs to be said. But perhaps you could explain why you think the analogy is on target?
If there had been a big bang, everything would have to have been exceeding this velocity from the very start. This applies no matter how many loopy extra imaginary dimensions are added. I'm sorry, what velocity? Peculiar velocity with respect to a particular local comoving frame? Or do you mean perceived recession velocity of one comoving frame from the perspective of some other comoving frame? In which case, which 'other' comoving frame? Or are you not sure what you mean? CTD, from your language, attitude, and arrogance expressed in your post, you seem to want to portray yourself as someone with some knowledge of cosmology. I'm afraid I have to tell you that your knowledge is at best woefully inadequate, and in the main is simply wrong. Might I suggest that next time you try to pass yourself as knowledgable in a subject, you do so in the absence of professionals of that subject? Edited by cavediver, : No reason given. Edited by cavediver, : No reason given.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Ok, in the moments after the Big Bang and for nearly about 400 million years after it It was ~400,000 years after the big bang that recombination occured, where electrons recombined with the bare nuclei to form neutral hydrogen and helium. This gave rise to the CMBR. It was much much later, when the first energetic objects started to form (quasars probably) that the gases were re-ionised. However, the Universe was sufficiently large by this time that the re-ionisation did not return the Universe to an opaque state, as it had been in prior to recombination. By the time we get to 400 million years, we're into the first star formation.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
If all mass and energy was compressed into such a small area, why didn't everything start at the same place? Because stars didn't begin to form until 100s of millions of years after the big bang.
But how do you get the volume of mass and energy that is in the universe in something so small? How do you manage to get all that mass and energy into something as small as our Universe is now?
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
The balloon don't fly because everything would be getting farther apart and it is not. Galxayes have colided and are going to colide. I don't think the balloon is a good example at all. It creates too many problems. And yet just about every cosmologist uses this analogy... so who's understanding do you think is screwed? Do you really think that you should be dismissing this analogy out of hand, becuase you have found problems with it? Do you not think that a better attitude would be to ask for clarification because you are confused about the possibility and actuality of galactic collisions? You have completely misunderstood the cone analogy - there is no interior to the cone. It is exactly the same situation as with the balloon - all that exists is the surface.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Probably naively I would think that each Planck volume (is there such a thing? - in any case, I'm trying to refer to the smallest unit of space) could only contain a single fundamental "something", whatever that might be, whether quarks or superstrings or whatever. Yes, you can have a Planck volume. There's not quite a google of them in a pea. If each volume has a string mode and that string mode has the Planck energy, then that's about 10^107 J. That pea has to contain the observable universe, which has a visible mass of about 10^52kg, so say a total mass of 10^54 to be safe, and that gives an energy of 10^71 J. Conclusion: our pea is actually rather uncramped...
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Is this where current theory breaks down? Exactly, though 'current theory' will be highly modified well away from that scale, becoming more and more exotic as T=0 is approached.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Nice one, Taz. I always forget to the add the ants. Mind you, they will be VERY slow ants, or that balloon is bloody big...
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
How much gravitational pull would be necessary to suck the universe into something the size a of pea? If there is sufficient density in the Universe (and ignoring the cosmological constant) then the Universe will collapse back to something the size of a pea and beyond. In terms of 'gravitational pull' (which is highly misleading) then as the Universe starts shrinking, the matter in the Universe will be closer together and so the gravitational attraction will grow, this will cause the Universe to shrink further, and so the 'pull' grows yet more. There will be no difficulty shrinking the Universe in this scenario, it will be a runaway effect.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
We always have to remember that the surface of the balloon represents space itself, not space and matter. Au contraire mon ami antipodian A model of reality incorporating GR and QFT has the ants as mere excitations/ripples in the balloon skin - though the skin is now multi-layer
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Yeah, and good luck trying to get the public to swallow that model Public? Piece of cake - I once tried to explain it to Buz and I was naive enough to think he'd go for it... I've learnt my lesson with ICANT and Buz. If someone is hostile to an idea, then you cannot explain the idea via analogy, as they will simply attack the analogy. When the idea is advanced cosmology, that doesn't leave much to work with. There comes a point where you have to simply shrug and admit that there is no point trying to educate the unwilling, when there is world of folk out there who are desperate to learn.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Would you like to explain how the universe was able to escape from this infinite gravitational field? The Universe is not some object that is attracted by gravity! The Universe is the entire space-time within which what you think of gravity is the perceived effect on small bodies (planets, stars, galaxies) casued by small-scale local curvature of the Universe. At this early time, there were no isolated clumps of matter - there was just an almost perfectly smooth distribution of energy across the Universe. In terms of simple gravity, there is nothing to attract and nothing to cause attraction, as there is nothing but continuous, uniform energy. We see almost perfect evidence of this situation in the cosmic microwave background radiation (CMBR). The physics of space-time (General Relativity) shows us that when we have this situation, although there is no local 'gravitation', the entire space of the Universe will be expanding or contracting with respect to time. In the early Universe, space is expanding. You cannot understand the early Universe by thinking of classical Newtonian pictures of gravity. They have little to no relevance.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Thanks Rahvin, that does help
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
If everything in the universe was in that pea sized something at T=O it had to be packed pretty tight. It wasn't "packed" at all - that is just the shape the Universe takes at that end of time.
With so much force pulling it together how could expansion begin? There is no 'force' - I have explained this - and the shape of the Universe (i.e. the expansion) is not controlled by 'forces'.
Call that force anything you want something had to squeeze everything in the universe that is seen and unseen into something the size of a pea. No, it did not - not in the sense you are thinking of. Unfortunately, you are asking questions way beyond your knowledge level, so there is little point trying to explain further. You need to correct all of your misunderstandings of more basic cosomology first. At the moment there is an exchange of words but not of understanding.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
Then for the Big Bang to happen you have to find a force strong enough to overcome the squeezing force. No, you do not. Your reasoning is based upon your application of your 'common sense' understanding of the world to some of the most advanced esoteric science ever considered, and is rather unsurprisingly flawed in the extreme. Communication is pointless until you realise this.
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cavediver Member (Idle past 3643 days) Posts: 4129 From: UK Joined: |
cavediver I ask these questions because I have an inquiring mind. ICANT, I'm not sure that you're aware, but these are not questions:
Now that math will only work if you can produce a force that is capable of squeezing the energy required to produce the universe into the space you say you can get it into. If you can produce such a force to accomplish that. Then for the Big Bang to happen you have to find a force strong enough to overcome the squeezing force. This is you blathering on long after you have been told that there is no force. This is you not listening. Why should I waste my time?
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