Expert: Paul Wagner - 8/19/2011

Question
QUESTION: Hello, i get the concept of the expanding universe, raisins in the rising dough, no center of the universe, etc. to explain that the universe appears to be expanding from any point.  Yet i also can't help but think that, even with normal expansion of matter from an origin point (an actual "explosion-type" universe), all galaxies would still appear to be receding from all others.  That is, since galaxies with greater velocity would be further out, and any galaxy at any point would be increasing its distance from the origin at a faster rate than any galaxy further in, wouldn't all galaxies appear to be receding from each other, and hence be red-shifted just as in the expanding universe model?  Moreover, wouldn't the more distant galaxies (with greater velocities) have greater red-shifts in some sort of proportion to their distance away?  Thank you.

ANSWER: Hi Michael

Yep-this is true, exception for localized gravitational issues, even galaxies close to us are slowly moving away....and the ones that are farther away from us appear to be moving away faster. And you can see that in their red shifts.

Paul Wagner

---------- FOLLOW-UP ----------

QUESTION: Thank you for your response, Paul.

I'm not sure if my question was posed correctly.  What i mean to ask is, wouldn't we get red shifts for all galaxies even simply with an explosion-type universe (without positing an expanding-universe, i.e. expanding space-time model)?

Answer
HI Michael

I don't have a degree in astro-physics...so there may be others on this board more qualified to respond.  But as I understand things, the "explosion" type universe would show red-shifts that indicate all matter is emanating from a single point, while what we apparently see in our studies is that all matter is expanding in all directions--not just from a single point.

Paul Wagner