Discussion in 'Astronomy, Exobiology, & Cosmology' started by machiaventa, Aug 5, 2009.
The quality of expansion.
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Your sound bites are not really explaining anything.
Are you claiming that the universe is not expanding. Or what?
Try to explain your point in more than one sentence.
Only one sentence is necessary...there is no complexity to elaborate on.
Space is where energy and matter can exist. Before space expanded, there was a void, where nothing could exist. Happy with that?
Of course not.
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then again... maybe I am... spending your tax dollars... on my dog's pedicures... muhahahahaha.....
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Unless expansion is in four physical dimensions then it's origin can be calculated by taking all vectors into account.
How does space explode since it is literally nothing? Things in it can occupy a larger area so making it appear that space has "expanded" to the gullible.
How has it changed? Anything we know of that expands a zillion times becomes ever less in density which would give original space to your way of thinking a density that makes neutronium look like a vacuum.
Yes, a singularity is a god particle because like god it can do whatever is required of it. Evidence that such a thing can exist is....the same for god existing.
Several years or so ago, superstrings were said to have 26 dimensions and anyone who said otherwise didn't know what they were talking about, as I was told on various science forums. Evidence of physical dimensions 4-10 is....missing.
Your watch merely counts the vibrations of cesium atoms, assuming it is a normal digital watch.
Betrayer0fHope. We see a snapshot of the universe which will only change over cosmic time so can never have ultimate proof of expansion (seeing it happen).
On a good day, I have a view to the horizon several miles away. Some misty mornings I can see maybe a mile away, or even just a white wall hundred foot away. If I never left my house, was 100% self-sufficient and knew nothing about the outside world, if all I had was a snapshot view of one misty morning I could think that the world ended a hundred feet away just beyond the edge of my house.
The CMB could just be a distance haze.
And almost certainly is; it would be more strange if the universe magically ended there than if there was much more beyond the horizon.
Either you were misinformed or you've misunderstood. The critical dimension of any superstring theory that I know of (except M theory) is 10, and M theory has one more. You are talking about the bosonic string which has only bosonic degrees of freedom so certainly cannot be supersymmetric, and has critical dimension of 26.
Thats very impressive indeed - you have an atomic wristwatch?! My watch measures vibrations of a quartz crystal and expensive watches are mechanical devices. Pray tell, how much did your atomic watch cost and where can I get one for myself?
The point where the momentum of the universe cancels out.
Back to the beginning
In the beginning of this thread, Machiaventa very reasonably posed the question of where we are in the universe. If there was a " Big Bang" as they say in the beginning of our Universe. I surmised the explosion should have dispersed in all directions equally. So when we look from our perspective at space which side are we on ? &c.
James R deflected the question with the "explosion (=expansion) OF space" thought, which is fair enough, but since space exists to contain galaxies &c, the problem remains: expansions should be substantially spherical, unless there are external constraints. And spheres have centres and boundaries.
The only way to escape the above conclusion is to posit an infinite universe, which would by definition have no shape and no centre. However, if accept the BB, and if we accept that material objects cannot exceed the speed of light, it follows that the universe is finite, with a maximum diameter of 27 billion light years.
27 billion because it that is 13.5 x 2, accounting for particles shooting off in exactly opposite directions. Which is itself interesting, because a being on a planet going in one direction would be moving at nearly twice the speed of light away from a being on a planet going in the opposite direction...
Doc Richard: James R did not deflect the question. The question is erroneous in that it implicitly assumes that the big bang was an explosion in space. It wasn't. It was an explosion of space. You are making the same mistake by assuming that "expansions should be substantially spherical". You are assuming that the expansion was/is into an existing space and that space existed prior to the big bang. It is space itself that expanded.
You need to expand your knowledge of topology.
How big the universe is we do not know. We do know that it is much, much bigger than 27 billion light years across.
No one knows if the universe is infinitely large, or even if ours is the only universe that exists. And other parts of the universe, very far away, might be quite different from the universe closer to home. Future NASA missions will continue to search for clues to the ultimate size and scale of our cosmic home.
Thanks, DH. Interesting.
Is it not the case that space is the matrix for the distribution of physical objects, just as time is the matrix in which events happen?
If so, I myself cannot see much difference between an explosion in space and an explosion of space. Both involve a process of things flying rapidly outwards in all directions.
No matter without space, no space without matter. Or am I wrong again?
If not, it is impossible to conceive of the universe as an explosion in space, because outside the cosmos there is no matter, therefore no space.
Whatever, there is expansion, that much we do know.
If the cosmos is more than 27 billion light years across, that is a mortal challenge to the Big Bang theory, is it not?
That is not the case. That was the view up until 100 years or so ago. General relativity and modern cosmology changed all that.
Space itself exploded in the big bang; it did not exist prior to the big bang. There was no matrix. There is a huge difference between the expansion of space and an explosion in space. A star that goes supernova is an explosion in space. So is a galaxy with an active galactic nucleus. The star or the galaxy spew stuff out at very high speeds, but never faster than the speed of light. Unlike matter, the expansion of space is not constrained by the speed of light.
No, because the expansion of space is not constrained by the speed of light. The matter that occupies space gets to ride the surf of expanding space.
An article, somewhat dated: http://www.space.com/scienceastronomy/mystery_monday_040524.html
An analogy that is often used is baking a loaf of raisin bread. The bread represents space and the raisins represent the galaxies. As the loaf expands the raisins get further apart.
Notice that the loaf doesn't have to start off as spherical, or end up that way. The entire loaf expands, retaining whatever shape it had originally.
Loaves of bread have boundaries, of course, and that's where this particular analogy breaks down. Our universe, as far as we can tell, is spatially infinite. When you speak of 27 billion light years, that is the extent of the visible universe only. There's nothing to say that there isn't more outside the region from which light could have travelled since the big bang. In fact, it would be more accurate to say that our visible universe is only 13 billion light years across, centred on the Earth, but that says nothing about the size of the universe as a whole. (Note: in fact, the 13 billion figure is not correct either, since it ignores the accelerating expansion.)
Without defining space, the above posts are useless babbling.
Separate names with a comma.