Extent of space (APOD 23 Mar 2006)

[bystander]

Sorry, I truly believe that using infinity in empirical science is for those who's concept of the universe is overly simplified and haven't weighed the consequences of implying it to the "big" picture.

A static universe is all but proved to be false by observations of this last year (check the Noble Prize), if the universe not static it cannot be infinite.

Arguing that the universe has to be finite because you can't measure infinity is fallacious. Not being able to set a upper limit on the size of the universe does not preclude the ability to measure its parts and obtain empirical data. Nor does it preclude the possibility that the universe is expanding.

[Dr. Skeptic]

My argument is not only because ∞ can't be measured and is not part of empirical science, it that observation all point to the universe is not steady state, for a multitude of reasons if the universe is not steady state it is not ∞.

- The % of H and He
- The CMB
- Redshift
- The types, placement, age of galaxies throughout the universe
- ... and so on

[bystander]

I repeat, the inability to place an upper bound on the size of the universe does not preclude the possibility the universe is expanding (or even contracting). It does not require the universe to be in a steady state.

While we can place bounds on the size of the observable universe (even those bounds are contested), no one contends that's all there is. The best we can do is make extrapolations (guesses) about the size from uncertain data. Where's the empiricism in that?

[Dr. Skeptic]

Extrapolations are valid when derived between known empirical points.

If an extrapolation is derived between a known empirical point and an assumption, it's value is limited by the predictability of the assumption.

This is another major problem with science research and reporting where "extrapolations" ignore or attempt to hide open ended assumption.