Expanding universe

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Sea_the_Stars

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I am Sikh but never had much awareness of my cultural and religious heritage until very recently when I decided to do some research. I discussed my findings with the ethnically and religiously diverse staff at work, all of whom were in agreement that they believed in god. Clearly I had made the obvious mistake of starting a contentous topic in the work place which made worse when I made my feelings known.

For the reason above I decided to find out more about the universe. The notion that once time itself did not exist has created a small problem. How can anything ever come into existence if time never existed in the first place. I have figured out that at the edge of the universe it must be that time does not exist. The universe would be infinate for that reason. The universe must be expanding at a rate faster than time itself. Another thing that bothers me is how single proton elements like hydrogen came into existence and what is their relation with dark matter and dark energy.
 
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Payloadcontroller

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The relationship with dark matter/energy is still being worked out.

However, hydrogen and in fact all the subatomic particles came about when the energy of the primordial "Big Bang" cooled sufficiently to begin condensing into basic forms.

Backing up from there, there is evidence that the universe (i.e. the Big Bang) originated as a quantum-mechanical fluctuation of spacetime, which spacetime evidently existed (multiversally) before the universe itself. This also means that the laws of physics existed before there was a universe (or at least, OUR universe) for them to govern. This in itself is equated by some as God, or evidence of God.

We may perhaps get closer to understanding as M Theory is developed - the theory of cosmic strings and membranes, which is one attempt to unify all the fundamental forces. It requires at least 11 dimensions in a multiversal "bulk," so don't limit your consideration to thinking of only OUR universe.
 
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Sea_the_Stars

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Payloadcontroller, thank you for your response.

My knowledge of science is limited as I am a law graduate. In order to understand this I need to do more research. Scientists have answered many of our questions and are a credit to us all.

Many of us consider ourselves lucky to win the euro millions. The odds on our very existence are infinate.
If the universe was created at a particular point and could not have come into existence before or after because time did not exist do you believe the universe, in particular the earth could not have existed in any other way? Destiny?

All this seems to by going off topic but I think our knowledge that the universe I expanding is one of the biggest developments. When we understand why I think things will become much clearer.

I am holding an object in my hand. I understand that it is a solid with billions of particles compacted. Now, in order for anything to exist there must be something. What were the particles (if any) which pre existed the big bang?
 
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Payloadcontroller

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Sea_the_Stars said:
If the universe was created at a particular point and could not have come into existence before or after because time did not exist do you believe the universe, in particular the earth could not have existed in any other way?
Well, my point was that spacetime WAS already in existence before the creation of the universe. And inflation caused it to expand from a singularity to its present size. Therefore there is no specific point in spacetime (space OR time) at which it came into existence.

Sea_the_Stars said:
What were the particles (if any) which pre existed the big bang?
That's the question. And it's a question to which we may never have an answer. Simply put (if such a thing can have the term applied to it), anything that existed before/outside is beyond our ability to detect. Unless and until we can complete M theory (minimum 11 dimensions) and unify all the fundamental forces of the universe, then learn how to manipulate it, we may never know what's outside the 4 dimensions we can perceive.
 
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chris1996

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Well dark matter has not been proven to do anything and we don't know much about it, hence the "dark."
We do know, though that it does take up a large quantity of the universe.
Dark energy, on the other hand, is what is expanding the universe. It is supposedly speeding us up as well.
Yet we still don't know much about it. Again "dark." :)
 
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MeteorWayne

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Actually, the expansion is driven by the big bang itself. Dark energy (if it exists) is what is speeding up the expansion, when we would otherwise expect the expansion to be slowing due to the gravitational attaction of all the mass in the Universe.
 
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Saiph

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odd...did we get a date glitch, or did chris ressurect a very old thread (original post was back in july).
 
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MeteorWayne

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Just a typical new user dredging up old threads when looking for subjects of interest. Welcome chris!
 
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chris1996

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I am a new poster but I got that off of the show on the History Channel, The Universe. :)
 
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Jeters_Boy

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Wayne, have you seen this video?

http://www.youtube.com/watch?v=7ImvlS8PLIo

I have a few problems with it, and one of them is this: the speaker says that billions of years from now, the universe will have expanded so much that people on Earth will not be able to see stars or detect them. He says they will make faulty scientific conclusions about the universe because of this.

What about right now? Are we coming to faulty scientific conclusions about the universe because of something we can't perceive? Maybe his entire lecture is based on a faulty premise, just like scientists billions of years from now.

I'd also be curious to get your view on the other points of the video, especially this idea that matter and energy can come from nothing because nothing is actually something. Quantum fluctuations out of nothingness, etc.
 
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MeteorWayne

Guest
Ow, that's an hour long video. It will take me some time to watch it with all the other projects I am working on right now, and the Leonids coming up :) I'll keep it in the background and look at a few minutes here and there when I can.

Regarding the point about the Universe expanding so much that no stars would be visible, from what I understand, that is true. Of course, it will happen long after the earth and it's life is gone, but astronomers in thousands of billions of years will see a much different Universe. I'm sure they will struggle to understand (just as we are) with what is beyond their view due to the limitation imposed by the speed of "light"
 
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MeteorWayne

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Wow, what a great lecture. I was just going to watch a few minutes, but got about 1/4 way through before I could stop.

His explanation of "Why there is no center to the expansion of the Universe" at about 10 minutes in should be required reading for all who are trying to understand it.

Thanx, and I will be sure to have this added to the Lecture list in Space Science and Astronomy; Thanx!!
 
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MeteorWayne

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That's one of the best hours I've spent in a long time.

Thanx!!!!

MW
 
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Jeters_Boy

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MeteorWayne":30y9gbyy said:
Educational AND Entertaining...what more can you ask for! :)
I certainly enoyed it, but a few parts didn't add up for me. I'd like to get your thoughts...

Around the 45 minute mark, he talks about "cosmological natural selection", ie, the universe only seems perfectly tuned for life because we are here to observe it. For this to be the case, there must be multiple universes.

However, there is no evidence that more than one universe exists.

Krauss is in such a hurry to dump the fine-tuned argument that he neglects to mention that the multiverse idea is just an invention without evidence.

What if there is only one universe? Does that mean the fine-tuned argument is valid again?
 
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MeteorWayne

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I don't think he's necessarily saying anything about the multiverse one way or the other. All he's doing is stating the fact if the constants of our Universe were different, we wouldn't be here to be asking the question.

I see nothing that says there MUST be multiple Universes...and so far we have no way to address that question so it's a moot point.
 
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avskier

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MeteorWayne":1sx5cr2t said:
I don't think he's necessarily saying anything about the multiverse one way or the other. All he's doing is stating the fact if the constants of our Universe were different, we wouldn't be here to be asking the question.

I see nothing that says there MUST be multiple Universes...and so far we have no way to address that question so it's a moot point.

Yes, the History channel's "The Universe" is well done. They're all good speakers, especially the young ladies. I've watched most of the 60+ episodes. Here's my viewpoint on the expanding universe. Do this test... Construct a one cubic foot Plexiglas cube. Extract all the air molecules out of it to form a near complete vacuum and then inject a small amount of visible gas. Notice that the gas will almost instantly spread evenly throughout the cube. Does this phenomena not apply to the much larger vacuum of the universe where all matter tries to fill the void? Since there is no limit to the void, matter will continue to travel and evenly disperse in the vacuum.

But what do I know? So I dream on.
 
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FlatEarth

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MeteorWayne":ok5ue1j4 said:
Wow, what a great lecture. I was just going to watch a few minutes, but got about 1/4 way through before I could stop.

His explanation of "Why there is no center to the expansion of the Universe" at about 10 minutes in should be required reading for all who are trying to understand it.

Thanx, and I will be sure to have this added to the Lecture list in Space Science and Astronomy; Thanx!!
Yes, he did a great job. I've seen the speaker on the History Channel, but his personality didn't come through there as it did in his lecture. I know it was for an atheist convention, but the anti-religion comments were unnecessary. I can't help but interpret that kind of rhetoric as an indication of insecurity.

Jeters_Boy":ok5ue1j4 said:
http://www.youtube.com/watch?v=7ImvlS8PLIo

I have a few problems with it, and one of them is this: the speaker says that billions of years from now, the universe will have expanded so much that people on Earth will not be able to see stars or detect them. He says they will make faulty scientific conclusions about the universe because of this.

What about right now? Are we coming to faulty scientific conclusions about the universe because of something we can't perceive? Maybe his entire lecture is based on a faulty premise, just like scientists billions of years from now.
Maybe you should provide an example. I'm having trouble picturing what evidence we may be missing. Maybe God's face in the sky? ;)

Sea_the_Stars":ok5ue1j4 said:
... The notion that once time itself did not exist has created a small problem. How can anything ever come into existence if time never existed in the first place. I have figured out that at the edge of the universe it must be that time does not exist. The universe would be infinate for that reason. The universe must be expanding at a rate faster than time itself. Another thing that bothers me is how single proton elements like hydrogen came into existence and what is their relation with dark matter and dark energy.
I think there are some interesting thoughts here, but unfortunately I doubt Sea_the_Stars will be back to comment further. I've never heard of the concept of time not existing at the fringes of the universe, so hats off to Sea_the_Stars for the creative thought.
 
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EarthlingX

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Thanks to BoJangles i found this thread, and have something to chew on:
from http://arxiv.org/
The Abnormally Weighting Energy Hypothesis: The origin of the cosmic acceleration
J.-M. Alimi, A. Fuzfa
(Submitted on 25 Feb 2010)

Abstract: We generalize tensor-scalar theories of gravitation by the introduction of an abnormally weighting type of energy. This theory of tensor-scalar anomalous gravity is based on a relaxation of the weak equivalence principle that is now restricted to ordinary visible matter only. As a consequence, the convergence mechanism toward general relativity is modified and produces naturally cosmic acceleration as an inescapable gravitational feedback induced by the mass-variation of some invisible sector. The cosmological implications of this new theoretical framework are studied. This glimpses at an enticing new symmetry between the visible and invisible sectors, namely that the scalar charges of visible and invisible matter are exactly opposite.
Could someone translate this in a little more common English ?
 
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MeteorWayne

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EarthlingX":3ihhrnem said:
Could someone translate this in a little more common English ?
I doubt it, and I won't even try!! :lol:
 
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EarthlingX

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MeteorWayne":609vlror said:
EarthlingX":609vlror said:
Could someone translate this in a little more common English ?
I doubt it, and I won't even try!! :lol:
I tried, finished in a bed with a headache .. :roll:

I think, the main idea is, that dark matter influences perceived red-shift, due to the hypothetical nature of it, please someone correct this ..

btw. this is really poetic :
Jeters_Boy":609vlror said:
[youtube]http://www.youtube.com/watch?v=7ImvlS8PLIo[/youtube]
Lawrence Krauss
Wikipedia : Lawrence M. Krauss
Personal page : Lawrence M. Krauss
 
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ramparts

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Eh, papers like this are honestly pretty common. Find some weird way(s) to modify normal gravity, and it's actually not hard to get cosmic acceleration - that is, the thing we call "dark energy". They do a couple of Weird Things here. The first is that instead of using Einstein's theory of general relativity to describe gravity, they use a speculative generalization of it called a scalar-tensor theory, where there are two gravitational fields (instead of one) which interact with each other (note that since in quantum language, forces and particles are pretty much equivalent, you can talk about this additional gravitational field as a new type of matter or energy). The second Weird Thing is that they do some funny things with these invisible dark energy particles (and I believe they throw in dark matter as well, for some reason) which result in the violation of the equivalence principle, which is essentially Galileo's observation that gravity affects everything equally, no matter how heavy they are or what they're made of. This violation causes the gravitational pull of ordinary matter to change over time, leading to cosmic acceleration. They derive some elegant results from these two assumptions, but they're weird Weird Things (especially the second one), and as far as I know have no motivation in observation or theory, except for this measurement that the universe's expansion is accelerating.

In general, the fewer Weird Things you do (and the less weird those are), the better. The more Weird Things you put into a theory, the easier it is to fit observations, but the less believable your theory is. There's a trade-off, especially when you really only have one observation (the acceleration of the expansion) to go on.

When I skim the new preprints in the morning, I'd probably skip over this one. It's neat, but there's a lot of other papers just like it, and I have classes to go to ;)
 
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EarthlingX

Guest
ramparts":2ic5qm2l said:
Eh, papers like this are honestly pretty common. Find some weird way(s) to modify normal gravity, and it's actually not hard to get cosmic acceleration - that is, the thing we call "dark energy". They do a couple of Weird Things here. The first is that instead of using Einstein's theory of general relativity to describe gravity, they use a speculative generalization of it called a scalar-tensor theory, where there are two gravitational fields (instead of one) which interact with each other (note that since in quantum language, forces and particles are pretty much equivalent, you can talk about this additional gravitational field as a new type of matter or energy). The second Weird Thing is that they do some funny things with these invisible dark energy particles (and I believe they throw in dark matter as well, for some reason) which result in the violation of the equivalence principle, which is essentially Galileo's observation that gravity affects everything equally, no matter how heavy they are or what they're made of. This violation causes the gravitational pull of ordinary matter to change over time, leading to cosmic acceleration. They derive some elegant results from these two assumptions, but they're weird Weird Things (especially the second one), and as far as I know have no motivation in observation or theory, except for this measurement that the universe's expansion is accelerating.

In general, the fewer Weird Things you do (and the less weird those are), the better. The more Weird Things you put into a theory, the easier it is to fit observations, but the less believable your theory is. There's a trade-off, especially when you really only have one observation (the acceleration of the expansion) to go on.

When I skim the new preprints in the morning, I'd probably skip over this one. It's neat, but there's a lot of other papers just like it, and I have classes to go to ;)
Yes, exactly those Weird Things, thank you very much, i can sleep better now :cool:
 
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