Quote:
Originally Posted by CPMosh
Where do we stand so far?
Would our coiled-up Megaparsec-long nanotube contract at 73.5 km/sec? Imagine the coil flipping around, in the back of Frasier's car on the way to Pamela's house, as the nanotube gets shorter.
Or... What if the coiled nanotube didn't contract? Pamela and Frasier straighten the tube and do find, however, the expanding space drifts by each (now distant) end at 36.75 km/sec (relative to the center of the nanotube).
Are there a boatload of observations that the shrinking matter (and decelerating light) model fails to explain? Would the alternate model rescue us from the need for a Dark Energy concept?
Forgive me for flogging this horse. I am grateful to everyone for taking the time to help explain this.
|
Ok. I'll have another crack at this... fortune favours the bold!
As long as the nanotube is in Fraser's truck - or anywhere in the Milky Way (or any other galaxy) - it ain't gonna shrink. Space does not expand within gravitationally or electro-magnetically bound systems like trucks or galaxies. I'm not shrinking. You're not shrinking.
Space is thought to be expanding on the largest scales due to observations of
distant galaxies.
The current theories relating to the 'expansion of space' and the 'Big Bang' are well accepted by the scientific community. Even Hoyle (who hated the Big Bang 'til his dyin' days) was able to deduce the nucleo-synthesis of atoms heavier than hydrogen and helium
because he also observed the expansion of the universe. (Hoyle's 'mistake' was only that he thought matter was generated somewhere in space in a 'Steady State' universe - it was later discovered the heavier atoms were generated inside stars.)
Somewhere (I don't know where the 'boundary' would be) this expansion effect (dark energy?) overwhelms gravity and the galaxies are observed to recede. I think astronomers caluclate for expansion even when they observe Andromeda, which has a net velocity
towards us.
As far as I know, these observations are all
really real.
But we don't know
how space expands. Max Tegmark (I think) described Dark Energy as simply a name for our ignorance. It's even possible Dark Energy is nothing more than a slight misunderstanding of Gravity. But I don't think scientists anticipate any major problems with our concept that the universe is expanding... people like Brian Greene are on the cutting edge of stuff like String Theory and I've never heard them even suggest a problem with expansion.
I've never heard an 'expert' talk about light slowing down or matter shrinking either - but hey, I'm just a science fan, not a scientist.
Just my $0.02 - and I love to debate this stuff...
Going back to our rope, in the void...
We can imagine Fraser is in a bubble of space which *pop* becomes bigger--and at the same time Pamela's bubble of space *pops* too.
I don't imagine that any debris (or any particles) that share Fraser's bubble are suddenly rushing past - why would they?
But... what has happened to the rope?
I imagine the distance between Fraser and Pamela is larger. Light travelling between them is red-shifted. No problem.
Ok. I imagine that, because every 'bubble' of space along the megaparsec of rope has also *popped*, the net effect has overcome the electromagnetism of all the atoms that make up the rope, and the rope has stretched. There are a heap of atoms along that rope and they can each, all handle being stretched apart a little. One day, they'll be too stretched and the atoms will fly apart.
There's the Big Rip astronomers talk about.
We can probably observe a kind of rope stretching today - the filaments that make up the structure of the universe we see in things like the Sloan Digital Sky Survey.
Any good?