# Another paper helping to clarify expansion-congrats, authors :-)

1. Jul 16, 2007

### marcus

another paper helping to clarify expansion--congrats, authors :-)

http://arxiv.org/abs/0707.2106

Coordinate Confusion in Conformal Cosmology
Geraint F. Lewis, Matthew J. Francis, Luke A. Barnes, J. Berian James
5 pages, accepted for publication in MNRAS Letters
(Submitted on 13 Jul 2007)

"A straight-forward interpretation of standard Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmologies is that objects move apart due to the expansion of space, and that sufficiently distant galaxies must be receding at velocities exceeding the speed of light. Recently, however, it has been suggested that a simple transformation into conformal coordinates can remove superluminal recession velocities, and hence the concept of the expansion of space should be abandoned. This work demonstrates that such conformal transformations do not eliminate superluminal recession velocities for open or flat matter-only FRLW cosmologies, and all possess superluminal expansion. Hence, the attack on the concept of the expansion of space based on this is poorly founded. This work concludes by emphasizing that the expansion of space is perfectly valid in the general relativistic framework, however, asking the question of whether space really expands is a futile exercise."

Last edited: Jul 16, 2007
2. Jul 17, 2007

### oldman

Last edited: Jul 17, 2007
3. Jul 17, 2007

### wolram

A ball rolling down a hill needs little explanation.
A ball moving because it is kicked needs little explanation.
Two balls moving apart from each other needs explanation, an explanation that can be understood in an (every day) way, cosmology seems to be only for (a group) of academics these days, with few tests to prove the theories.

Last edited: Jul 17, 2007
4. Jul 17, 2007

### marcus

distances increase, dammit

5. Jul 18, 2007

### Hell_SD

yeah i mean what's so hard to understand ???

...the balls aren't moving further apart, the distance between them is increasing

huh ???