Graduate Decoding Hubble Data: Acceleration and Age of the Universe

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SUMMARY

The discussion centers on the interpretation of Hubble data regarding the acceleration and age of the universe. Participants clarify that the graph in question, which plots distance against velocity, is often misinterpreted; the correct origin is D=0 and v=0, not D=0 and t=0. The claim that Andromeda's distance of 2.5 million light years equates to its age is refuted, emphasizing that light from Andromeda was emitted 2.5 million years ago, not that the galaxy itself is that old. The conversation concludes with a critique of misconceptions surrounding dark energy and the Big Bang theory, highlighting the importance of understanding general relativity.

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meatym
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this graph: http://www.pnas.org/content/pnas/112/11/3173/F1.large.jpg?width=800&height=600&carousel=1
from: http://www.pnas.org/content/112/11/3173
can be found on many sites.
the origin is D=0 and t=0.
cosmology claims the universe is accelerating over time. the graph shows acceleration over distance, which is deceleration over time.
D = -Ct
andromeda's data shows it is 2.5 million light years away, so it is 2.5 million years old.
my engineering degree tells me that there is no dark energy nor a big bang.
 
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First of all, that plot is very old and currently only of historical value when it comes to understanding cosmology.

Second, it is only plotting quite nearby galaxies. You are never going to be able to distinguish an accelerating universe from a decelerating one with the data in that plot.

meatym said:
the origin is D=0 and t=0.
No it is not. You are misunderstanding the plot. The origin is D=0 and v = 0.

meatym said:
andromeda's data shows it is 2.5 million light years away, so it is 2.5 million years old.
This is just wrong and not a logical conclusion. The conclusion would be that the light you see from Andromeda now was emitted 2.5 million years ago. That does not mean that Andromeda did not exist before then. There is also a caveat to that and it is that in an expanding universe, the light travel-time vs distance does not work like that as space is expanding.

Furthermore, the local galaxy group (which both the Milky Way and Andromeda belong to) is gravitationally bound and therefore does not expand.

meatym said:
my engineering degree tells me that there is no dark energy nor a big bang.
Your engineering degree has then obviously not prepared you to understand how general relativity works.
 
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The OP is based on a misinterpretation, which has been corrected. Thread closed.
 
I always thought it was odd that we know dark energy expands our universe, and that we know it has been increasing over time, yet no one ever expressed a "true" size of the universe (not "observable" universe, the ENTIRE universe) by just reversing the process of expansion based on our understanding of its rate through history, to the point where everything would've been in an extremely small region. The more I've looked into it recently, I've come to find that it is due to that "inflation"...

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