Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Blueprint on 17/04/2008 01:09:10
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This is how I understand our Universe, and its my 2nd post, so pls correct me on points.
Right now, we're on a curve of expansion that looks like it could either tail off or cause our universe to big crunch. At one point in the far distant future, the universal boundary could begin contracting, and maybe time will run backwards.
Galaxies will merge with other galaxies, black holes will join forces with other blackholes. All matter will coalesce into one super duper massive blackhole then boom, the universe will start all over again.
What I don't understand is what caused the initial release of all the matter in the Big Bang, why wasn't it content with eating up all the matter like a greedy pig. Did it hit some mass limit?
I've read about string theory and how the universe could be just 1 brane in a multiverse which explains why gravity is so weak, but a continual expansion of the universe into a dark, dark, place just sounds so boring I hope its not the reality.
Maybe the laws of science breaking down in black holes is really the laws of science outside the brane?
Will the universe continue expanding or begin to contract? Where did all the matter come from in the first place? :)
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What I have heard is that some scientists are even suggesting that they have measured that the universe is still accelerating in its expansion.
http://en.wikipedia.org/wiki/Accelerating_universe
It seems to me that if this is the case, then the notion of a big bang must come into doubt (i.e. it would appear that we do not need to think in terms of a massive injection of kinetic energy in the first instance, and then a continual deceleration caused by gravity, but you could start with very little initial kinetic energy, since there would appear to be something that continues to inject kinetic energy into the universe even today).
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Thats interesting. I thought the expansion was just all the stars and galaxies moving apart from each other, but its the spacetime in-between them thats expanding, or stretching right?
I've heard of the balloon analogy, but if u keep blowing up a balloon, it pops! How about picturing the universe like the outer surface of a balloon, or a shockwave. I read somewhere else u could picture it like a doughnut.
Maybe some unknown force providing the kinetic energy? Hmmmm :P
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Firstly - welcome, Blueprint. I hope you like TNS forum.
I have been puzzling over this expansion mallarkey. If spacetime is expanding, does that mean that time is also expanding along with space? Maybe I could use that as an excuse next time I'm late for a meeting! [:D]
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Will the universe continue expanding or begin to contract? Where did all the matter come from in the first place? :)
According to the most accepted theories, the universe is not only expanding but speeding up. The estimation is that he Universe is 13.7 billion years old. It's believed that the universe will continue to expand until it rips everything into non-existence.
This might help understand...
http://en.wikipedia.org/wiki/Age_of_the_universe
Because the light from the furthest visible galaxies is redshifted, it's assumed they're moving away faster than galaxies that are closer, so it is assumed that the universe is accelerating.
I believe the theory of relativity, states as long as there is motion, time will continue to move forward. Traveling faster than the speed of light, is the only means to go backward in time, but that's impossible due to physical limitations of acceleration.
Einstein assumed the universe must be either expanding or contracting, unless he could add a constant to his equations. He considered this constant to be his biggest mistake.
The way I see it, it doesn't matter to us, we're not going to be around to see it. Andromida will to collide with the Milky Way galaxy before that's an issue for us, which might be the end... If that' doesn't cause a problem for our solar system, then the sun will run out of hydrogen gas, and that will cause a problem for Mercury, Venus, Earth and probably Mars as well.
None of which, will we get to see... For our lives are too short.
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Where did all the matter come from in the first place? :)
An interesting question, the more so because the question not asked is "what is matter"? OK, we do have rules by which matter behaves, and we can define that which behaves by those rules as matter - but despite the ancient notion that matter is that which is tangible, we cannot actually touch matter. All we are able to sense are the forces by which matter interacts, and in our own experience, that is exclusively the coulomb force, whether it is through the chemical reactions caused by atoms swapping electrons, or whether by the transmission of kinetic energy transmitted between atoms as the electric fields of their electrons repel each other, or whether it is the relativistic effects that cause an electric field to become an electromagnetic wave. In all cases, the only thing we notice are the effects of electric fields; so the question as to what is matter boils down to what causes electric fields to behave as they do. Ofcourse, indirectly, through the medium of these electric fields, we can also see the effects of other forces (in particular, the gravitational force, although the colour and weak forces can be inferred on a smaller scale.
Ofcourse, we then get to what is being speculated upon as 'dark matter' - which is matter that seems to have a gravitational influence on visible (electric) matter, but does not seem to posses an electric field itself, so cannot be detected directly. Because we know so little about the non-electric universe, I am not even sure if we can say whether the non-electric universe is expanding with the electric universe, or is the non-electric universe filling in the gaps left as the electric universe expands?