Infinite Universe: What does it mean?

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The discussion centers on the implications of an infinite universe, particularly in the context of cosmological models that suggest an "open" universe with infinite spatial volume. Participants explore whether matter and energy exist beyond the observable universe and debate the validity of various assumptions regarding their extent. It is agreed that while the observable universe can expand indefinitely, the existence of matter beyond its limits remains uncertain. The conversation also touches on the concept of a universe that could be finite yet unbounded, challenging traditional notions of a center in the universe. Ultimately, the dialogue highlights the complexities of understanding the universe's structure and the limitations of current observational capabilities.
  • #31
marcus said:
... The Hubble radius is just a handle on the speed of expansion of distances. Expansion speed is proportional ...

Can I just confirm, if something sent a signal today, & it was greater than the Hubble radius from us, could it reach us?
 
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  • #32
Lino said:
Can I just confirm, if something sent a signal today, & it was greater than the Hubble radius from us, could it reach us?

Yes! and there is a nice reason! The Hubble radius is reciprocal to the percentage rate of distance growth, so as the growth rate declines the Hubble radius increases.

It is not a physical distance between definite things, so it is to subject to cosmological metric expansion. But it can increase.

So it can REACH OUT AND GATHER IN light which may be struggling to reach us but being carried slowly back by the expansion of distance.

If the light starts out a little bit outside the Hubble radius TODAY, and at first is being swept slowly back, it still may be inside TOMORROW'S Hubble radius.

Once a flash of light is safely within the Hubble radius it is home free, it will eventually make it.
 
  • #33
marcus said:
Yes! and there is a nice reason! ...
Wow! Thank you ... it reads correctly & sense-aguilie (?), but I need to think about it :)

Thanks Marcus.
 

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