What is empirically known about the shape and size of the Universe?

  • #26
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I'm on the mobile app at the DMV right now, so I can't go into detail, but you have some misconceptions about expansion, GTrax. Mainly about the 'speed' of expansion and the idea that we have to disregard a great deal of physical laws.
Very likely - in fact I rely on postings from folk like Chronos, yourself, and several others to help me there.
So much more useful than someone pointing to a lot of suggested literature, and a degree course, when all one seeks is perhaps a qualitative understanding of something from a different area of knowledge.

Possibly my reaction is just that now, with the huge information flow, one more easily becomes aware of just how many really smart and skilled people are out there! This even among educated, (though deluded) types, and an army of articulate cranks.
I just did not want to say "never".
 
  • #27
Drakkith
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Drakkith's post was insightful, and very helpful to me. Yet even so, I felt exactly as you do. He may be right about the education system effect, and in recognising the value of modern computer-assisted teamwork, but it was a leap too far to imagine that only a limited cosmologist elite club, excluding "engineers" and "regular physicists" concentrating on "mainstream theories" can have a significant contribution. There will be examples to the contrary!
Give me an example then. And I don't mean an example of an engineer or physicist contributing via a new theory used by cosmologist, such as theories on stellar formation or the interaction of radiation with matter, but of fundamental cosmological models and overarching theories.

In another field, we have a modern fairy story dressed around a mathematical model called Quantum Standard Model. It allows reliable prediction of physical realities to phenomenal accuracy, yet it still has uncomfortable logical outcomes that are more than counter-intuitive, to the point they defy credulity! We live with it, because of how useful it is, until some genius, maybe in an unrelated discipline, has an insight.
Or it could be that current quantum theory is actually quite correct and there's nothing to resolve except our own view of reality.

For me, however good is all the knowledge about our "expanding" universe, the uncomfortable thing is that we cannot wind it back and place the whole mass in a small place. The light from such a scene would have overtaken the expanding mass. It requires us to suspend all belief about nearly every physical law, and accept a sudden expansion far exceeding the speed of light, to place all this stuff far enough apart that we may have it's light arrive here some 14 billion years later.
Expansion doesn't have a speed or velocity in the conventional sense you are used to. Space doesn't expand "at light speed" or "faster than light". Instead, it is measured as the time it takes for the distance between receding objects to increase by a certain percentage. Objects can recede from each other at any velocity, including velocities above c, but this velocity is only for those two objects. Right now there are galaxies receding from us at many times greater than c. Since recession velocity increases as the distance between two objects increases, these galaxies are very, very far away from us. Nearby galaxies, though, are barely receding.

It is another model only, and I think it may be eventually supplanted. Who knows - maybe by an "engineer", or another patent clerk!
I think it's as likely to be replaced by something significantly different as the model of the Earth being round is likely to be replaced by a model saying its a wildly different shape. Will current cosmological models change? Absolutely. The models will change as we get more accurate data about the cosmos. But expansion is here to stay. Also, remember that the "patent clerk" was a real, mainstream scientist. Einstein was working on a PHD during his time at the patent office. He wasn't just some random amateur or even an engineer looking into something on their own time.
 
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  • #28
rbelli1
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There was the insistence of the Jesuits in the de-facto ruling Catholic Church that only work from a limited set of "approved" scholars working around a "mainstream" theory was to be (almost literally), taken as gospel.
The problem with the Geocentric model is that it started with the "answer" and then wove an overly complex story around that to create a model. The "truth" was that the Earth was at the center and just ignore any contradicting observations. The model works but sweeps under the rug as to how the thing that it models works.

BoB
 
  • #29
phinds
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Maybe. @Greg Bernhardt I'll try to put more together on this if that's alright.
Good idea. As a suggestion, do it the way I did my article on the Bubble Analogy: put it up as a regular thread, or even as a web page off of PF and ask knowledgeable members here for feedback and then when you have it not only to your own satisfaction but also to that of other knowledgeable people here, then make the final result an Insights article. This is a question asked often enough and one that causes enough headaches that it warrants that kind of effort and community involvement. As for my involvement in the project, I will kibbitz, :smile:
 
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  • #30
Admired the epic reply.
If it becomes an article, consider addressing whether infinity is observable. If not, why are we talking about it??
A poster above said, "...implies infini..." but not if infinity cannot be observed.
We are talking science: complete, consistent, and correct.
 
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phinds
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Admired the epic reply.
If it becomes an article, consider addressing whether infinity is observable. If not, why are we talking about it??
A poster above said, "...implies infini..." but not if infinity cannot be observed.
We are talking science: complete, consistent, and correct.
Whether or not infinity is observable is irrelevant. The options for the extent of the universe are

o finite and bounded --- believed extraordinarily unlikely because it requires weird physics at the edge and defies the Cosmological principle
o finite but unbounded --- no center, no edge, fits the Cosmological Principle
o infinite (and therefor unbounded) --- no center, no edge, fits the Cosmological Principle

So there are really only two possibilities. Would you have us not talk about one of the two just because you don't like the fact that it is not observable?
 
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  • #32
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Our education system gives people the tools they need to perform real work in their chosen field. Contrary to your claim, it does not create "convergent thinkers who are blind to other ideas", it creates people with the skills and knowledge necessary to solve problems and develop new, useful theories. You might have been able to get away with not being trained during the early days of classical physics, but relativity, quantum physics, the theories based on them, and nearly all technological developments in the last 200 years were developed by mainstream physicists, engineers, and other scientists. I cannot begin to overstate how important mainstream science has been to the world, and your criticism is both unfounded and incredibly naive given that the methods by which we are communicating right now, the internet and modern computers, are only possible because of our mainstream educational system and scientific pursuits.
If you move between disciplines you will discover different thinking models. Yes mainstream science has made incredible progress, yes we need hard proof of theories, but when you are inside a thinking mode box you do not realise how constrained your outlook is! Convergent thinkers all think alike and are blind to alternative approaches. Methods of communication are many and varied but are of no use if the recipients are not listening.
 
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  • #33
Drakkith
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If you move between disciplines you will discover different thinking models. Yes mainstream science has made incredible progress, yes we need hard proof of theories, but when you are inside a thinking mode box you do not realise how constrained your outlook is! Convergent thinkers all think alike and are blind to alternative approaches. Methods of communication are many and varied but are of no use if the recipients are not listening.
At first glance this appears to be an informative and thoughtful post. However, a deeper look at the post and your previous posts on this topic reveals it to be shallow and lacking in my opinion. Specifically, it relies on the assumption that scientists are 'convergent thinkers' who are blind to alternative approaches. I strongly disagree with this. Scientists' ways of thinking are as varied as their personalities, which range an entire spectrum just like everyone else.

What education does is to provide scientists with proven tools and methods to help them identify new phenomena and systematically form an organized, coherent, and self-consistent explanation for these phenomena. These tools and methods encompass everything from mathematics classes to lab reports to using Excel. You might as well say that the tools in a wood working shop constrain someone's thinking about what they can make out of wood. Instead, it is how things are made that is constrained, not what. So it is in science.

Most of our greatest leaps forward in knowledge have been through the fusion of ideas outside the 'mainstream'.
No they haven't. Practically all of our 'leaps forward' have come directly from mainstream theories. Meaning that you introduce one or two postulates to a mainstream theory and see what the results would be.

Quantum Mechanics: the direct result of quantizing energy, momentum, angular momentum, and other properties from classical physics at the atomic and subatomic scale. This did not come right out of the blue. Many different experiments at the time indicated that classical physics was missing something, and it was only with Max Planck's idea of quantizing the energy of a black body that these problems began to be solved. If you look at the history of QM you'll find that each step towards the development of a working theory was the direct result of someone working on a known problem in classical physics.

Special Relativity: the direct result of Einstein solving known problems in classical electrodynamics by introducing the postulates of the invariant speed of light and the principle of relativity. Both of these were already supported by contemporary experiments, such as the Michelson-Morley experiment.

General Relativity: the direct result of Einstein recognizing that objects in free fall under the influence of gravity would measure zero acceleration and behave as if they were moving inertially. IE objects in free fall are in inertial motion and objects not in free fall (such as a book on a shelf) are not in inertial motion. Once recognized, the basics of GR follow naturally from this property. Again, this was a short but complicated insight that follows directly from classical physics.

So which of our leaps forward have been the result of the fusion of non-mainstream ideas? If you think that the above are examples of non-mainstream ideas, then everything is a non-mainstream idea until it is fully explained by science. But in that case science is already doing exactly what you say it isn't, which is routinely providing non-mainstream ideas to solve problems.

One should note that none, absolutely none of these advancements would have been made without an in-depth understanding of contemporary classical physics and the advanced mathematics given to these scientists by their own education system. Not too bad for men supposedly close-minded and blind to alternative approaches.

I'm sorry but I think your idea of science and scientists is one of a caricature. A shallow, one-dimensional idea of men in lab coats scribbling equations on a whiteboard while oblivious to the rest of the world. Of bumbling, socially-inept nerds who can't understand girls or poetry. Scientists are not inflexible robots that have a short circuit if something falls outside their limited programming. They are real people with an enormous range of backgrounds and interests, giving them, as a whole, as wide and flexible an outlook on the world as any other group of people, if not more.

Education tends to open one's mind, not close it.
 
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