On Tuesday, August 19, 2025 at 2:10:49 AM UTC-6 Alan Grayson wrote:
On Monday, August 18, 2025 at 3:59:43 AM UTC-6 Alan Grayson wrote:
On Monday, August 18, 2025 at 12:20:41 AM UTC-6 Alan Grayson wrote:
On Sunday, August 17, 2025 at 9:40:16 PM UTC-6 Brent Meeker wrote:
On 8/17/2025 6:26 PM, Alan Grayson wrote:
On Sunday, August 17, 2025 at 2:00:28 PM UTC-6 Brent Meeker wrote:
On 8/16/2025 4:37 PM, Alan Grayson wrote:
On Saturday, August 16, 2025 at 12:56:53 PM UTC-6 Brent Meeker wrote:
On 8/16/2025 12:27 AM, Alan Grayson wrote:
On Monday, August 11, 2025 at 10:21:16 PM UTC-6 Alan Grayson wrote:
On Sunday, August 10, 2025 at 8:23:53 PM UTC-6 Alan Grayson wrote:
On Sunday, August 10, 2025 at 5:51:31 AM UTC-6 John Clark wrote:
On Sun, Aug 10, 2025 at 6:01 AM Alan Grayson <[email protected]> wrote:
On Saturday, August 9, 2025 at 5:45:01 AM UTC-6 John Clark wrote:
*Until very recently the most distant object our telescopes can see had a
redshift of about 14, but very recently there are reports that the James
Webb telescope has seen point-like objects that seem to have a redshift of
25! Whatever these objects are they contain little or no dust as you'd
expect because dust requires elements other than hydrogen and helium which
need to be made in stars, but if we really are looking at an object that
has a red shift of 25 then we're looking at something that existed before
stars did. If confirmed that would be a pretty profound discovery, and
about the only thing that could explain them are Primordial Black Holes
created during the first nanosecond after the Big Bang.*
*JWST Found Objects at Insane New Distances (Redshift of 25?!)*
<https://www.youtube.com/watch?v=saL_1R1WitA&t=797s>
*> How is the red shift related to the velocity of light? How large must it
be to equal c? TY, AG *
*Because space is expanding and accelerating, galaxies that have a redshift
greater than about 1.7 are today moving away from us faster than the speed
of light, so we can never reach them or even send a message to them, they
are beyond our causal horizon; however today we can still see them because
at the time the light from them was emitted the galaxy was closer to us
than it is now, and back then it was receding away from us slower than it
is now, slower than the speed of light. For the same reason today we can
even detect the Cosmic Microwave Background even though it has a redshift
of about 1100, but we could never send a message or influence anything that
happens that far away.*
*John K Clark See what's on my new list at Extropolis
<https://groups.google.com/g/extropolis>*
TY. If it's not too much trouble, can you show me how you do that
calculation? AG
What is the physical interpretation of the huge red shift of the CMB? It
can't mean extreme recessional velocity since it's here, everywhere, in
every direction. AG
Since the CMB isn't receding, what is the physical interpretation of its
huge red shift? AG
It's all relative. We're receding, if you insist on "somebody is
receding". The bit of the CMB we see is a further away bit every day. Its
photons have traveled to us thru space that has been expanding as they
traveled.
Brent
Since I am free to choose any observer is receding, I did. But more
important is your model of the photon. Since the wave property of light is
an ensemble property, what allows you to claim they lose energy as the
universe expands? AG
Suppose you and a pro-baseball pitcher are standing alongside a road
playing catch. When you catch his fastball it has an energy of 70J and
stings thru you glove. Now his throw is little off and instead going to
you, it is caught by a kid in a passing car going the same direction as the
throw. But when the kid catches it bare handed it doesn't even hurt
because it's only got an energy of 2J. How did the ball loose energy?
Brent
Good question. The ball caught by the observer in the moving car didn't
lose all of its kinetic energy, and kept moving with the car after being
caught, whereas all the kinetic energy of the ball was disappated into
recoil, sound waves, and heating of the material in the glove, when the
ball was fully stopped by the guy on the ground catching the ball. Now
that I've answered your question, tell me how a point particle, the photon,
can get it wave stretched by an expanding universe. AG
You didn't answer it correctly. You overlooked the impetus the ball adds
to the car increasing the energy of the car/ball system.
*I gave you a good approximate answer. You're just nitpicking. The ball
never comes to a complete rest wrt the ground when caught by the observer
in the moving car. Hence, this is the main source of the "loss" in kinetic
energy. What part of my explanation do you not understand? AG *
That the photon gets its wavelength stretched during it's long travel from
the CMB is obvious in the inflating balloon model. As space expands it
stretches the photon traveling thru it.
*This is not an explanation. An individual photon has no identifiable wave.
Wave extend to spatial infinity. You're just repeating something you've
heard before, and believe. AG*
*Since photons travel at light speed, from the pov of external observers,
using the LT, they have zero length. So, when you speak of their wave
lengths, do you really know what you're referring to? AG*
Brent
*I sympathize. It's a monumental task to show, how something without
length, a photon, can be stretched. AG *
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