On Thursday, June 12, 2025 at 5:05:27 AM UTC-6 John Clark wrote:
On Thu, Jun 12, 2025 at 4:59 AM Alan Grayson <[email protected]> wrote: *> When viewing celestial objects, it's routinely claimed that what we observe, is how something looked in the past. * *Yes.* *The farther away it is, the further in the past is what the observation reveals.* *Yes.* *> But now you've turned this on its proverbial head; namely, the redshift observed is a measure of its recessional velocity NOW.* *Unless you're talking about very nearby galaxies such as Andromeda, which is actually blueshifted, cosmic redshift is NOT caused by the recessional velocity of something moving through space, it is caused by the amount of expansion of space itself that has occurred during the billions of years that it took the light to reach us. * That's one interpretation. Another is that the redshift from distant galaxies indicates a rapid expansion at the time of the BB. AG *>How are these contradictory interpretations resolved? TY, AG * *What contradictory interpretations? The light from distant galaxies is always damaged in one way or another, sometimes they run into dust clouds and only their infrared light makes it through, and sometimes the images of galaxies are distorted by gravitational lensing. But if we know there was a dust cloud between us and the galaxy then nobody believes the galaxy produced no optical or ultraviolet light, and if the light passed near a massive object then nobody believes the galaxy really had such a weird shape, we know the distortion was caused by a gravitational lens. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* zx5 -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/38d1bb06-0389-4f30-9404-84802ebceae8n%40googlegroups.com.
