A universal discussion

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moonshadow
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A universal discussion

Post by moonshadow »

So I was watching a program on NetFlix last night about the universe, physics, etc and I got to thinking about this this morning on my way to work and though I'd engage some thoughtful discussion here on the cafe.....

I can accept what is considered modern science and physics. I am far from either a scientist or physicist, so I must admit to simply taking their word for it when I see them explain all their formulas on the grease boards.

Of course I think about things like the origin of the big bang, what the universe is expanding into, etc, bu there is one matter I've seen in many illustrations, documentaries, books, etc and it was mentioned in the program last night. This is the question of whether the universe is finite or goes on forever. The idea here is that if the universe is flat it could go on forever, however if the universe is round, it is finite, similar to how the total land/water area on Earth is finite. If I just started traveling west right now, eventually I'd come back to where I started, and that's the going idea with a finite "round" universe.

Now when I think of a finite, round universe, then I imagine that everything that is, is contained inside. However, naturally I would question what would one see if he reached the outer edge of the universe and looked out? What laws of physics would take over outside of the known universe? Is it just part of a bigger universe? And if so, is it also round? If we traveled to it's edge and looked out, what would we see?

The other idea is that the universe is flat. Now they say that mathematically, a flat universe is "physics friendly" because it could technically go on forever. Often times I see illustrations of worm holes and the concept of gravity depicted on a "flat" surface. This always somewhat confused me. There is something about a flat universe that I can't wrap my mind around (no pun intended), and that is that we are living in a 4 dimensional universe. Everything that exist in our universe exist in length, width, height, and duration (time). If the universe is flat, then why can we see it expand all around a round planet? If the universe has length and width, what would we see we we look up and observe height?

Is it a matter of "flatness" extending in all directions? Is it not so much about being flat or round, but perhaps odd shaped "bubbles" of space-time?

I'm not making statements, I'm just asking questions...

Discuss...
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Jim
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Re: A universal discussion

Post by Jim »

The roundness or flatness in these models are in another hypothesized dimension. Use it as an analogy only for things our imagination does not handle, as we only know three spacial dimensions. So in a (spatially 4 dimensional) spherical universe going straight in any direction would eventually bring you back to where you started, just as going straight on the surface of a sphere will bring you back to your starting point. ("Straight" being defined as a great circle on sphere, and the analogous definition on a 4 dimensional hypersphere.) There is no edge, or every place is on the edge, just as on the surface of a three dimensional sphere. The math works fine, just not our imaginations. Because we can make a mathematical model does not mean that the model represents reality.
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Re: A universal discussion

Post by skirtyscot »

You should read A Brief History of Time by Stephen Hawking. It's all about cosmology and that sort of stuff. If you get to the end, please tell me if it answered any of your questions, 'cause I gave up in Chapter 2!
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Re: A universal discussion

Post by moonshadow »

skirtyscot wrote:You should read A Brief History of Time by Stephen Hawking. It's all about cosmology and that sort of stuff. If you get to the end, please tell me if it answered any of your questions, 'cause I gave up in Chapter 2!
I did, in fact I own a copy and read through it once in a while. Now that you mention it, I purchased a dual hard copy of A Brief History of Time, and the Universe in a Nutshell.

I spend a lot of time thinking about this stuff.

I got to thinking, in regards to the flat universe, perhaps it does exist on flat planes, just planes that extend in every possible directions.

I fancy the fact that I was contemplating my own "multi-verse" theory back before it was cool. Around the time I was ten or eleven years old, I was thinking about time travel and thinking about the concept of action and reaction and literally visualized moving my hand before my face and spawning off infinite number of time lines (universes). I remember telling my folks about it. I think they just thought I was goofing around.

My latest interest has been the exploration of other dimensions. Somewhat of a cross between science, physics, and occultism, moving past what the five senses can detect and considering the limitations we are bound to. Consider that our only window to the cosmos is through our eyes, our eyes that detect light. Light can be bent, and easily manipulated. Who's to say that what we're looking at is really there at all. It could be somewhere else. When I consider the role gravity plays on light, and I take a step back and look at the universe through an imaginary eye, it seems more like traveling through a space of odd bubbles of space and time. Totally bizarre compared to what we are used to seeing.

Fascinating stuff.... the best part is it seems we may never fully know. And that's the magick of it. The imagination can run wild and free!
-Andrea
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Re: A universal discussion

Post by Sinned »

Try reading The Holographic Universe by Michael Talbot. Not saying it's all correct and it does seem a bit OTT as regards reality but it will give you more food for thought. Also if you google some of the examples he gives then you realise that all is not what he says it is. :?:

Also the ancient Jews considered that the Universe actually has five dimensions - 3 spatial, time and the dimension of good and evil.
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Re: A universal discussion

Post by Taj »

A random thought: if the universe is expanding we would never see the edge. By the time we would get there, even at the speed of light, the edge would have continued expanding further away. You can't get there from here.
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Re: A universal discussion

Post by Tor »

Interesting question Taj, though I have to add a couple more to yours: If the Universe is expanding, how fast does light 'think' it is expanding. Second, if light 'thinks' the Universe is expanding slower that it travels, what happens to that light when it reaches the edge of the Universe?

I suppose it risks derailing the thread, but I find it curious that there seem to be three basic states of knowledge: The often older knowledge which most or nearly every scientist who has access to the big journals agrees upon; the typically newer where everyone seems certain that their pet theory is correct, and yet everyone seems to agree no one is certain of; and finally the bounds past which everyone agrees no one really knows much of anything.

What I don't understand is why any questioning of the first category seems to provoke an almost religious defence of the "right" answer. All the more after I found this article, Scientific Regress, by William A. Wilson.
Scientific Regress wrote:In the idealized Popperian view of scientific progress, new theories are proposed to explain new evidence that contradicts the predictions of old theories. The heretical philosopher of science Paul Feyerabend, on the other hand, claimed that new theories frequently contradict the best available evidence—at least at first. Often, the old observations were inaccurate or irrelevant, and it was the invention of a new theory that stimulated experimentalists to go hunting for new observational techniques to test it. But the success of this “unofficial” process depends on a blithe disregard for evidence while the vulnerable young theory weathers an initial storm of skepticism. Yet if Feyerabend is correct, and an unpopular new theory can ignore or reject experimental data long enough to get its footing, how much longer can an old and creaky theory, buttressed by the reputations and influence and political power of hundreds of established practitioners, continue to hang in the air even when the results upon which it is premised are exposed as false?

...

...When cultural trends attempt to render science a sort of religion-less clericalism, scientists are apt to forget that they are made of the same crooked timber as the rest of humanity and will necessarily imperil the work that they do. The greatest friends of the Cult of Science are the worst enemies of science’s actual practice.
human@world# ask_question --recursive "By what legitimate authority?"
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Re: A universal discussion

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Tor wrote:Interesting question Taj, though I have to add a couple more to yours: If the Universe is expanding, how fast does light 'think' it is expanding. Second, if light 'thinks' the Universe is expanding slower that it travels, what happens to that light when it reaches the edge of the Universe?
Assuming that Einstein is correct, matter cannot move faster than the speed of light; this implies that given long enough a ray of light will reach the edge (if there is such a construct) of our universe. It'll just take a very, very, long time. Then there's the amount of time for it to return as a reflection to tell us anything.

There's also the issue that we cannot "see" back in time (for that is what we/'re doing with astronomy) beyond a certain point, because during the earliest stages of the initial forming of this universe the thing was opaque to radiation (read light), hence we cannot see through it. Interestingly, thanks to extremely powerful space-based telescopes, we're glimpsing that time now. A number of years ago, at one of the quarterly meetings that my last company held (a very good company, it was just the division I had the misfortune of working for that was crap) the keynote speaker was an astrophysicist who presented a talk on "Precision Cosmology" where he was using our software to model precisely where the "early boundary" would be, and this was subsequently backed up by observation. Unfortunately, I've managed to forget the times involved; I will say, though, that the scales are very long.
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Re: A universal discussion

Post by Jim »

Taj wrote:A random thought: if the universe is expanding we would never see the edge.
As I understand the expanding universe models, there is no edge. Think of the galaxy clusters as polka dots pasted on a balloon, with the balloon being inflated. As the balloon gets bigger, each cluster gets farther apart, but no nearer to an edge. The two dimensional balloon surface is being expanded into a third dimension; the models have the three dimensional universe expanding into a fourth spacial dimension. Each dot is equally on the edge; you can't get any closer.
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Re: A universal discussion

Post by Tor »

I've also read the notion that at the "Big Bang" matter /did/ expand faster than light or at least parts expanded FTL relative to other parts of the then tiny Universe. Of course that raises a host of questions about whether those parts ever slowed to less light speed, if they ever could (I've also read the claim that FTL matter isn't impossible, the problem is the speed of light presents a speed limit in both directions that can't be crossed. WRT matter I remain unconvinced, though there is the issue of finding and measuring that supposed FTL matter. Or perhaps that stuff whizzing about is the so-called dark matter. Or maybe the scientists are basing theories on old erroneous measurements, and new theories prompting new measurements are needed.)

If they (the segments of the just-starting-to-"explode"-Universe) did slow to comparatively less that lightspeed, then we should be seeing ever more of them show up. Unfortunately, I doubt we'd be able to tell until we've few million years of records to verify against. In that time, we will have so much data that it may be a fruitless exercise to attempt sorting the matter out.

Ah, the mysteries of life. :)
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Re: A universal discussion

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What is the speed of light in a medium that is opaque to light? That's a nasty poser to be sure. Recall that the speed of light is most certainly defined by the medium in which it's travelling through, else optical phenomena like rainbows [0] and refraction would not occur. So, if as postulated, the infant universe was mostly opaque, but possibly glowing slightly at its outer boundaries, any number of things may have been going on inside the early bubble.

The mind boggles at the possibilities.


[0] We had an absolutely beautiful rainbow overhead this morning at home. The sun was out when I headed off to work (late), and a gentle rain was falling. I walked out of the garage before getting into my car to go, looked up, and saw it. I'm glad I took the time.
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Re: A universal discussion

Post by Tor »

How many media are truly opaque to light? You probably see wood walls around you, but I can state with certainty from personal experience that wood is translucent, not opaque. Granted, it becomes opaque for all practical purposes in a very short distance, but that is (unless I'm way off) completely different from being opaque for purposes of this question. How small a thickness of material must be opaque in order for us to call it opaque? And to what forms of electromagnetic radiation?

Metals are at first glance a likely candidate, but there are a couple problems: first, there is no difference between an AM radio signal and a violet light beam except frequency (wavelength). The former goes through a great deal of wood no problem, even as that same thickness would have been long since been opaque to the violet light. Turn to metal, and a sheet will reflect the AM signal and diffuse, refract, or reflect the violet. Refract the AM signal into the metal, and it propagates at near the speed of light in vacuum.
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