The universe isn’t finite, it’s infinite. The ‘Big Bang’ is often misconstrued as being a finite singluarity.

New theories are gaining support that there may not have been a singularity, but a ‘brane-collision’ that created an infinite universe.

http://stevevinsac.blogspot.com/2007/10/big-bang-is-big-baloney.html

I think they may be poorly named however… and ‘dark matter’ may not end up being matter at all.

Perhaps we’ll end up seeing it as a side-effect of gravity.
E.g. String theory describes our universe made up a fabric of strings. Gravity displaces space-time, creating a gradient attracting matter together. Perhaps this gradient of dense space-time exhibits a friction upon the adjacent fabric of space.

Think of it like this…
You put a golf ball inside of a spongy material. The squeezed spongy material around the golf ball has a tension energy of it’s own.

http://stevevinsac.blogspot.com/2008/06/star-stryder-blog-archive-dark-energy.html

http://www.dailygalaxy.com/my_weblog/2008/01/scientist-says.html

“Professor Jose Senovilla, and his colleagues at the University of the Basque Country in Bilbao, Spain, have proposed a mind-bending alternative. They propose that there is no such thing as dark energy at all, and we’re looking at things backwards. Senovilla proposes that we have been fooled into thinking the expansion of the universe is accelerating, when in reality, time itself is slowing down.”

The crust cake analogy is something that is asymmetric. You are also assuming that there exists a border to the universe. Of course, I don’t know if this is true (and how do scientists think of it), but I find this less than ideal. For the time being, the universe is more likely to expand forever, due to the acceleration in expansion (one of Pamela’s posts has it).

Also, a shell of matter have no influence in terms of gravity on anything inside it. If you do the calculations right, any spherical shell has no gravitational influence on the interior matter because gravity on opposite sides cancel out.

It’s also hard to imagine cyclic universes. During a universe’s lifetime, entropy increases, and I don’t know of any mechanism that can decrease it and hence set the ground for the next universe (other than by an implausible chance).

But I do find the dark energy to be a little disturbing. I don’t see why we should have a “aether”-like field permeating everywhere, or have a cosmological constant that was later discarded and then re-added in a new form. It feels a little awkward. It also reminds me of a field called inflaton and Higgs field, for some reason…

But let’s say this is a different balloon analogy… Maybe we can use the more pleasant “crusty cake” analogy: The universe starts off as a microscopic (or not) point of “all matter” and suddenly expands creating our 3+ dimensions inside of itself. As it expands, the bulk of the matter is around the surface/crust of this spherical(+/-) cake and some of it perpetually pulls away toward the center a little at a time creating galaxies and non-luminous substances to fill the void (i.e. “cake”). After all, we believe the universe is still expanding (and hasn’t reached it’s maximum expansion yet), so is it too far fetched to hypothesize that the bulk of matter is beyond the reach of our telescopes, but is still having a gravitational effect none the less? Granted this is assuming the the universe is finite and that there is only just so-much matter in it. But there could still be other universes beyond ours which also experience the same cyclic boom behavior. So, there may still be an infinite aspect to it all.

Since we’re having a hard time explaining the repulsion effect (anti-gravity? I think not), it might be more easily explained by the gravity of the still-expanding-away-from-us shell of matter form the formation of our universe. At the risk of sounding even more ignorant, I’ll stop now.

Or am I just totally in the “dark”??

ps: my statists exam was a disaster!

I crack me up!
On the dark matter front, I make sure to mention Vera Rubin when I talk to Girl Scouts and tell them that some of the -BEST- astronomers are women. It never fails to make ‘em smile!
Rich

At the risk of making you embarrassed that you ever were one of my teachers – and this is a dead serious question on my part – how does this result (or any other recent result) invalidate other theories, specifically MOND?

Now I’m coming at this simplistically, I know, which is why I value your opinion. I KNOW there is an effect out there that is not explainable by our current mathematics. I’ve seen the galaxy rotational data and understand it enough to know this (in terms of Dark Matter…which this post is not about). But I get weirded out when we’re told to accept something that we can taste, touch, feel, detect, or measure. You say we know that Dark Energy exists because we can see its effects, and I agree we do see something being effected, but I don’t put it in the same bucket as that of a Black Hole, somehow.

Black Holes are “easy” to detect once you know what you’re looking for. Gravitational lensing and videos of the rotational speeds of stars in the Galactic Core are damn convincing. SOMETHING has this amount of mass in this amount of volume. It COULD BE all the universe’s missing socks, yes, but if its in that small of a volume, I’ll agree to call it a Black Hole.

Dark Energy and Dark Matter (sorry, I’m slightly more familiar with Dark Matter) is something different in my mind. Isn’t it possible that what we are seeing is the effect, for some reason, that due to distance, etc. our mathematical understanding just isn’t quite working out? I am NOT saying that Einstein is wrong, you know me better than that. But just as we discovered that Newton needed a “bit of tweaking,” via Relativity, to work at great speeds, might we be seeing something that needs a bit of tweaking to work at great distances with such large amounts of matter and scale?

Along these lines I’ve always liked the MOND theory. I get the impression that you don’t. Why?

Because your “Why” makes a difference.