We understand each other then.It's like having an ant walk down a rubber band, and as you stretch the rubber band you argue that the velocity of the ant is slowing, and even reversing, because its distance to the end of the rubber band is increasing. — staticphoton
I agree. I only interjected because you didn't say 'inertial' the first time (below), and light moves at different speeds as measured by most (all?) non-inertial frames. You also didn't say 'in a vacuum', but most people know that restriction.The fact is that the speed of light, measured from ANY inertial frame of reference (any velocity), is constant. — staticphoton
From the perspective of any observer in any frame of reference, all photons travel at the speed of light — staticphoton
The selected quotes from the above physicists concern infinity, which I did not mention in my comment. I did reference infinite time.
My comment concerned chatGPT's response to a reference to an 'edge', which implies a spatial boundary with matter, light, and stars on one side and nothing on the other. He does say that such a thing isn't well defined. Again, I don't disagree with any of his responses.
There are models of finite size universes, but most/all(??) of them curve in on themselves, much like Earth having finite surface area without anywhere having an edge. It was the reference to that edge at which I balked. — noAxioms
Let me clarify by a simple thought experiment:
I start out driving along a straight road to a destination 1,000 miles away. To an external observer I drive at a steady 100 mph, with the distance between my front bumper and my destination shrinking at 100 mph. — jgill
However, I was unaware that clocks tick slower in my car than outside stationary clocks, — jgill
so at the end of one hour I pass the 200 mile road post, and think, wow, I am going really fast, twice the speed limit! But that’s not possible. — jgill
So, my destination is approaching my car at that speed. But that’s not possible either. So I surmise that I am driving at the speed limit and the distance between my car and my destination is shrinking that fast as well. Hence, the rate of change of the distance between car and destination is changing more than I originally assumed. — jgill
To an external observer the actual space between vehicle and destination is not contracting, but the distance between them is. It's a playground for metrics. — jgill
Thanks. Pretty heady stuff for one unversed in physics . . . :cool:
6hReplyOptions — jgill
I knew what I was supposed to do ( :zip: ) but I didn't, I couldn't. I was compelled tostaywrite. — :cool:
Are you folks in astro? I'm graduating with an MS in astro in a matter of weeks (though starting PhD bridge... probably in the fall, I'm taking spring off). Right now I'm researching galaxy quiescence at 0.6 < z < 2.5 and hopefully publishing morphological metrics from CANDELS soon. Happy to see others at least with a cosmo background here — Astro Cat
We call it "high noon" because of the high star formation rates, but there's still plenty of quenching especially at the "nearer" z (but that's the point, I end up making a lot of figures splitting into four redshift bins of equal comoving space against different metrics so you can kind of "watch" galaxies march towards quiescence under different definitions and with different metrics: sersic n vs. z, axial ratio vs. z, sersic n vs. axial ratio, UVJ in different redshift bins, SFR vs. compactness). I only wish it were possible to more easily cognize a higher dimensional plot so put more of them together in a single plot lol.
I actually haven't had the pleasure to use ANY JWT data even for fun, I've been so busy with CANDELS. :( (They are lovely to look at, though!)
Pleasure to meet you — Astro Cat
Similar to staticphoton, I do something else (low level database implementations) but I read what I need to in order to support or criticize various philosophical views. It is something new to me to interact with somebody actually working in the field.Are you folks in astro? — Astro Cat
I've seen 3D plots done with a tool that allows manual rotation/PoV/zoom controls. It conveys a lot more info than the 2D plots, and it works real time. Not sure of the tool used to build it, but I have played with the controls. The one I saw plotted all the nearby large galaxies' peculiar movements for the last 6 BY or so, including Virgo SC but I think not going so far as the great attractor. The plot negated expansion, so it looks like we're headed for Virgo, but of course we'll never get there. It really helped me see our own movement and Andromeda chasing us from behind. Our peculiar motion is actually away from it.I only wish it were possible to more easily cognize a higher dimensional plot so put more of them together in a single plot lol. — Astro Cat
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