Discussion in 'Astronomy, Exobiology, & Cosmology' started by Saint, Jun 17, 2009.
jmpet, i doubt it. That its the best aproximation we currently have is probably more accurate.
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It's logical, wouldn't you say? If everything is flying away from us, then at some point in the past, everything must have been where we are. Right?
The big bang is a complicated theory. It makes lots of predictions about different things.
The basics of the big bang (that there was one, etc.) have been confirmed beyond any serious doubt. Some of the details of exactly what happened in the first moments after the bang are still being worked out.
The thing to realise is that no single fact proves the big bang theory. Rather, there is an immense amount of evidence of different types that supports the theory. Chances are that knowing down one piece of evidence won't knock down the theory, contrary to what some people think.
Not according to experts in the field.
All we need to do is look at red shifts to establish that. So, we can and do know.
The big bang was not an expansion of matter in a pre-existing spacetime (c.f. black holes as the collapse of matter in a pre-existing spacetime). Therefore, the big bang was not a "time-reversed black hole" or anything like that. The big bang was an expansion of spacetime itself, which is quite a different kettle of fish.
Are there any other viable baskets around? If so, I haven't heard about them.
The balloon analogy commonly used must be understood correctly. The surface of the balloon represents the universe, not the inside and outside of the balloon. The surface of a balloon has no edge, in the same way that the surface of the Earth has no edge. If you walk around the Earth's surface, you never fall off the edge of the world.
Good opinion you have.
People who insist a theory should be falsifiable ought to feel slightly uncomfortable about that.
This is where falsifiability as the sole criterion of the scientific nature of a theory falls down. Scientific theories, especially comprehensive and long-standing ones, are seldom tossed out the moment a new piece of data is suspected not to fit. What happens much more often is that scientists first look for errors in the new data. If they can't find any, then they might consider modifications to the theory. If those aren't possible, then the whole theory might need to be chucked.
Even when theories are occasionally chucked out, it is often not a baby-with-the-bathwater matter. For example, Newton's law of gravity was technically falsified by Einstein's general relativity, but you'll still find Newtonian gravity used by professional physicists and engineers all the time. Why? Because Newtonian gravity is in many (perhaps most) instances an excellent approximation to Einstein's theory, and it's far easier to use than Einstein's theory.
Unless Einstein is just plain correct. I agree with you, but there are things that are hard facts and many theories which might simply be correct.
my question, what is above and below the surface?
That doesn't mean there isn't an above or below, James. So what's outside the universe?
name 1. What i mean is that even things which common sense would say are provable arnt are only falsifiable. Take one example, the tassie tiger, we cant currently prove it exists only that we havent found one yet and so on the surface we could say that you can only prove there existance true but lets look at a senario
A person brings in film of a tassi tiger, that can be proven NOT to be of a TT
they find a live animal, great there are TTs. Nope genetic (or something we havent invented yet) analisis proves its NOT a TT
All things can be disproven but they cant be PROVEN. Even that your responding to my post is only held as correct until evidence arises that its false (for instance that im in a mental hospital and you are all parts of a delusion im having including that computers exist)
The balloon analogy is just that: an analogy. I think one needs some minimal familiarity with the concept of non-Euclidean geometry to appreciate the analogy.
Reading a book written over a hundred years ago, Flatland: A Romance of Many Dimensions might help. The wikipedia entry points to some online versions of the book. In a nutshell, Flatlanders live on a plane. There is no such thing as above or below to the Flatlanders; the plane is their universe. Instead of a plane, suppose their universe is the surface of a balloon. Still two dimensional. There is no above or below; asking that is in a sense a nonsensical question but it is also an indicator that the balloon analogy is not a particularly good analogy.
I disagree. I know nothing of non-Euclidian geometry. If Playfair's postulate came up and slammed me in my Riemann curvature tensor I would just think I had stumbled over a pebble.
What one does need a minimum understanding of is analogies.
In the referenced analogy the universe is likened to the the surface of a balloon. (We shall ignore time and consider only the three conventional spacial dimensions.) So, the universe is three dimensional, the surface of a balloon is two dimensional. We are likening the universe to the surface of the balloon. Therefore anything beyond the surface of the balloon, internal or external, does not exist in the analogy.
Hence to ask a question like, what is inside the balloon means one has not understood how analogies work. The rule is we are likening these aspects of this thing, and only these aspects, with these aspects, and only these aspects, of another thing.
isn't that what i said?
it was? i never knew that.
yes, i know. i never stated otherwise did i?
it was based on the primordial conditions on earth if the solar system was spawned by the big bang
earth based experiments that simulated an atmosphere on a planet and space debris yielding the same results suggests the assumptions made in the earth based experiment was correct.
there were two possibilities, i named them both.
It was a polite way of saying you were talking unmitigated crap.
Your claim was that this was not just any primoridial atmosphere, but one that "would have formed from the big bang." That is simply incorrect. Completely incorrect. The basis of the atmosphere used was the consensus view of that time - since largely discarded - that the Earth had a strongly reducing atmosphere.
There is so much wrong here.
It was not based on "the primordial conditions if the solar system was spawned by the Big Bang".
Miller and Urey did not sit down and ask themselves, "if there was a Big Bang what would the composition of the early atmosphere have been?"
You claim they did. (Fine, you will have no difficulty finding the passage in their publications that deals with this.Please Register or Log in to view the hidden image!)
But let us pretend that they did base their atmosphere on what the Big Bang would have 'spawned'. In that case why are you agreeing with me (you say correct) that the atmosphere they selected did not depend on the Big Bang? Pure contradiction on your part.
But no assumptions were made in the experiment about the reality or character of the Big Bang. That is the central point you keep misunderstanding.
To repeat, the Miller-Urey experiment offers nothing in support of (or evidence against) the Big Bang. Your claim to the contrary is ill founded.
The issues I have with your interpretation of the work of Higgs and Pudritz I shall deal with elsewhere.
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i was under the impression that miller-urey duplicated the primordial conditions of an earth that was created from stellar dust cloud.
I understand the "flatlanders" concepts however we have to think of everything as a whole; yes, to the flatlanders there is no "outside" and perhaps to us there is no "outside", but technically there is something that exists within the balloon and outside, and so technically there is still something "outside" of the universe, no?
No, you do not need to embed such 'universes' as the ones described by the FRW metric into larger space-times.
Whose origin did not require, or depend upon the reality of the Big Bang.
The flat earth model was okay for small distances, but only for making a map or planning a journey. It was an impediment to understanding the motions of the sun, moon, planets and stars, something humans had been wondering about for ages, probably since before the dawn of civilization. The earliest astronomers were able to calculate the paths of the heavenly bodies using mathematics, but no one could turn that purely mathematical model into a physical model of a natural universe. It required belief in a supernatural universe, which is anathema to science.
My atlas has a very nice, accurate map of Antarctica and a similar one of the arctic region. I think perhaps what you're really referring to is the increasingly obvious distortion of the Mercator Projection as the "stretched balloon" model of the earth is expanded to include areas closer and closer to the poles.
We're happy with Mercator for the tropical and temperate latitudes because we were all raised on it. Everyone thinks Greenland is bigger than Mexico, Alaska is bigger than Brazil, Sweden is bigger than Iran, etc. It's biased to exaggerate the importance of the nations in the upper reaches of the Northern Hemisphere and that's why we all love it.
I'm not sure why you Aussies like it. Does it make Australia look bigger than China?
i dont know, will check
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i guess they look around the same size
Atlases are the name for collections of maps, both in terms of your usual notion of maps and the more technical notion of manifolds. A manifold is a space where you can, in small regions, approximate it to arbitrary accuracy, using flat space, but in different regions you need different maps. You can do a map of the US which is roughly flat and the same for Antarctica, but they are not going to be the same projections from a sphere to a sheet. The important thing is that where the maps overlap (well not for the US and Antartica but say Europe and Russia) is that you can smoothly go from one to the other.
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