I have a quick question about the Big Crunch. Let's say that our universe is a closed or oscillating universe, and that humans evolved when the universe was contracting. Would it be possible (if we didn't know that the universe had previously expanded) to determine that the universe had expanded? If so, how? Thanks.

Well, if the universe were contracting, we would see local galaxies, within 50 million LY say would be blue shifted at a higher contracting velocity. Galaxies 10 billion LY away would be contracting at a slower pace than the local galaxies. So astronomers would consider the possibility that the more distant galaxies are seen just after they have begun to fall back and local galaxies are seen in more recent times after they have had time to contract and pick-up speed.

Just my 2 cents.

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[Nitpick] Wouldn't it still be a cumulative effect? Contraction would show the distance between points farther and farther from each other would be comming toward us closer and closer to the speed of light (apparent only from point of view)... wouldn't it?

o------A------------X---------------B

o---A------X------B

o-A---X--B

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Feynman
>~~~~<
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.

Religion is a culture of faith; science is a culture of doubt.

Not if you can look back to the point where the galaxies are still growing apart from each other.

"You're not thinking fourth dimensionally!"

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I feel this is a really good question, Brady. Congrats.

I´ll be thinking about it, and try to post something later - if I find something interesting to add. I hope people get into the thread.

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Seems plasable
what we see now happens before it started to compress so we don't see it, good point

i think that the universe is an oscillating universe, it makes more sense that way

Why?

I don't see how it makes any more sense than any other scenario. I wouldn't be surprised if it were true, but I certainly don't think it's obvious.

Do we assume that the universe could expand only once? How do we know that it hasn't before, and that it won't again?

Edit: Just asking, not ranting :P

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i got no scientific facts to back me up on this, but only a gut feeling (laugh all you want), the universe stretching forever just doesnt sit right with me, i think that the hindus, buddhists, and mayans are correct on this one, universe goes in cycles

I guess, believing in all that reincarnation jazz, that's a given, eh? Anyway, you answered my question .. thanks

I'm mostly with you on this. My point is that it might be best to reserve final judgement for awhile, though I do have the same uneasy feeling about an infinitely expanding universe.

I agree aswell, no matter how fast anything is traveling in a near infinate time gravity will slow it down as it propegates through the whole of space, along with magnetic fields so by what i understand eventualy the universe has to contract or it's just not a universe i like

so both of you guys have the same feeling too?, i thought i was alone on this one

yo electro, is that einstein quote for real? lol

Yeah its real and i'd go for it aswell, the guy had some brains the job pays loads now!

so electro what makes you say the universe goes in cycles?

we dont

Well for the most part me trying to follow budism but apart from that it just seems too messy without, going along the BB thoery the universe had all its mass in 1 spot smaller then an atom and it basicly exploded. so if all the universes mass could hold it in the singularity (which is really what the BB came from as its a major error in any equation we currently could make. So that gravity well it came from still exists in every piece of matter and is acting on the whole of the universe, so all matter will eventually slow itself down to a stop (excluding zero-point field interaction which is a possible reason for the big bang) and then will slowly begin to pull itself together. Also the magnetic fields like jupiters and other planets and stars will effect the others and attract and polaritys can be changed by larger magnetic fields so even if one body is repelled by the magnetic fields at first once a big enough magnetic field or gravity well is formed it will attract it again. So to me everything points to the big crunch being an inevitable fact.

when do you think this "contracting" will begin? i really think for some reason that the univere really will contract, the universe just stretching for all eternity doesnt seem right, we dont even really know for sure if the universe is open or closed

Im not sure when For all we know it could be 50 trillion years away or it could have already started just we cant see it yet because of the light delay as the galaxys aren't moving faster then the speed of light. So we're litrally in the dark on what the universe is doing right now because we can see light millions and billions of years old but not what is happening today in alpha centurai.

And i completly agree the universe cant keep expanding forever it just gives me a queezy feeling in my gut and my gut feelings are never wrong.

yeah i agree and theres horizon we cant see beyond and never will be able to

I think it's just the "what goes up must come down" saying, i think it holds for most things. the universe expands so it must contract, my physics teacher and i got talking about the universe (in a free lesson) and we were talking about what shapes it could possibly take from how the big bang happened, we both believed it was a singularity like in the middle of a black hole. We both came to the conclusion that it would be like a balloon, the rubber being the universe and what we can move in with varied thickness the inner wall being denser material from the big bang which decelerated quicker (possibly from the immense gravity) and the outer part of the wall (i should say surface) being lighter matter which moved thurther.
In a still singulatiy it would be a round universe, but if it had spin the universe wouldn't form round but expand in a flatter shape (like jupiters shape) and with a high enough rotation speed the universe would ultimately form into a doughnut (the ones with the hole in the middle) shape. But all these theorys of how the universe is formed still boils down to the fact that their will be dense pockets of matter which distort space time enough to make the big crunch happen alot earlyer then if the universe formed like a water mist.

so what did your physics teacher think about the fate of the universe, did he think it will contract

I am thinking 4D UT. I was mearly stating that a blue shift would have a cumulative effect as well over distance. If the universe 'changed directions' we wouldn't know until it happened locally.
It's like if the sun went out/blew up, we wouldn't know for eight and a half minutes, give or take a few seconds...

__________________

Feynman
>~~~~<
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.

Religion is a culture of faith; science is a culture of doubt.

my teacher agreed that it will or is contracting but even if it is contracting it will take billions of years for it to do so. So no need to open a 6 pack and watch the show cause it wont be for a while.
In the mean time im waiting for the sun to go red giant and engulf the planet... anyone's welcome to join.

As long as its a 6 pack of Mt. Dew...

oops. forgot the ice... we'll need ice...

__________________

Feynman
>~~~~<
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.

Religion is a culture of faith; science is a culture of doubt.

heck if its the end of the universe coming we could have a 6 pack of everything its not like we'd need to pay or anything

wow a physics teacher (basically an expert) saying that it will contract?, thats a rare one 80% of the people think it wil expand forever

its his opinion and i personaly think its the right one because it doesn't make sense that everything will go one for ever and just burn out.

To me i cant help but think everyone who says it will expand forever where born with a lack of common sense but thats possibly because my opinion seemed so simple.