Hubble

[Beestie]

I do wonder about one thing.

What if what we think is happening is not what's really happening? What if the universe isn't accelerating outward? If our observations are wrong about that then there is no need to create 'dark energy' to come up with the missing force to explain the observed acceleration.

Light can play games as it traverses over vast distances. And isn't red shift the only real 'evidence' of the increasing acceleration? And unless we are exactly in the center of the universe, wouldn't celestial objects at similar distances in opposite directions display differing degrees of red shift or, if they are moving with a lateral component, substantially less red shift?

I checked out a book to read the other day - I actually requested it be delivered to my branch: Warped Passages by Lisa Randall. Problem is, its 512 pages of thick, dense material and I just can't manage a book that big right now so I grudgingly returned it and its been nagging at me ever since.

I bet there's some good information in there. She's leaning towards the multi-dimensional model which ties in with string theory and all that. I've read some good articles about that but have to confess that I don't think I really get it.

[ZenGum]

First, let me say, i think I am getting out of my depth here. I studied philosophical metaphysics, I teach critical thinking. Astrophysics and cosmology are just hobbies. But .... here goes:

Originally Posted by Beestie

I do wonder about one thing.

What if what we think is happening is not what's really happening? What if the universe isn't accelerating outward? If our observations are wrong about that then there is no need to create 'dark energy' to come up with the missing force to explain the observed acceleration.

That would be called "being wrong". Learned that in Philosophy of Science.

Light can play games as it traverses over vast distances. And isn't red shift the only real 'evidence' of the increasing acceleration? And unless we are exactly in the center of the universe, wouldn't celestial objects at similar distances in opposite directions display differing degrees of red shift or, if they are moving with a lateral component, substantially less red shift?

The red shift is mostly uniform in all directions, increasing with apparent distance. It is primarily NOT due to galaxies rushing apart through space, but due to space itself stretching. Remember the balloon inflating.
If you want you can draw a smiley face on a ballon and watch how it stretches uniformly as the balloon inflates. We are at any randomly chosen point on that image. All points are moving away from us, in proportion to the distance they already are from us.

I checked out a book to read the other day - I actually requested it be delivered to my branch: Warped Passages by Lisa Randall. Problem is, its 512 pages of thick, dense material and I just can't manage a book that big right now so I grudgingly returned it and its been nagging at me ever since.

I bet there's some good information in there. She's leaning towards the multi-dimensional model which ties in with string theory and all that. I've read some good articles about that but have to confess that I don't think I really get it.

That does sound a bit weighty. Try that New Scientist article, and browse through the links of related articles. There are always plenty and most are digestible, bite-size and fairly accessible. I think they have a cosmology page to organise all of them. You won't get all the discussion all at once, but that is probably a good thing.

[glatt]

Originally Posted by ZenGum

Remember the balloon inflating.
If you want you can draw a smiley face on a balloon and watch how it stretches uniformly as the balloon inflates. We are at any randomly chosen point on that image. All points are moving away from us, in proportion to the distance they already are from us.

When I took astronomy in college, this concept really blew me away. It's so counter-intuitive when you are thinking about it, but if you grab an actual balloon and do it, you can see it happening clearly.