What Causes the Big Crunch and How Does it Affect the Universe's Expansion?

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SUMMARY

The discussion centers on the Big Crunch theory, which posits that the universe's expansion may eventually reverse, leading to a contraction of space due to gravitational forces. Participants clarify that the Big Crunch would occur in a closed universe where the overall density is sufficient to halt expansion and initiate contraction. Key points include the role of dark energy in the universe's current expansion and the implications of gravitational interactions on space itself. The conversation highlights the need for a deeper understanding of concepts such as Friedmann's equation and the relationship between gravity and space.

PREREQUISITES
  • Understanding of the Big Bang and Big Crunch theories
  • Familiarity with Friedmann's equation and cosmological models
  • Knowledge of dark energy and its effects on cosmic expansion
  • Basic concepts of gravitational interactions in cosmology
NEXT STEPS
  • Study Friedmann's equation and its implications for cosmic models
  • Research the nature of dark energy and its role in the universe's expansion
  • Explore gravitational effects on space and matter in cosmological contexts
  • Investigate the current understanding of the universe's density and curvature
USEFUL FOR

Astronomers, physicists, and students of cosmology seeking to deepen their understanding of the universe's expansion and contraction dynamics, particularly those interested in gravitational theories and dark energy.

  • #31
To put it quite simply, if we assume that the Big Bang concept is correct, then space (and time) were created as a result of it. Space isn't a separate entity that simply is "out there". Space is a function of mass. Without the Big Bang, there is no space. Without mass, there is no space. Therefore, if one wants to postulate a "big crunch", it has to include the elimination of everything, mass, space, energy...everything.
 
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  • #32
Naty1 said:
note that frame dragging IS a theoretical phenomena; do not know if there is any experimental/obserbational evidence...
Hmm looks like there is some evidence for it after all.Have a look at the below link.
http://web.mit.edu/newsoffice/1997/blackholes.html"


Naty1 said:
too much speculation here...but the potential could, I guess, exist for everything to eventually end up as black holes, and over eons those smaller ones coalesce together...but as I understand things, that still doesn't collapse all space in the universe into a crunch from what is currently known...

On the other hand things/views/theories/insights change so I never say never...
i know but that it sounded good(it still does) when i first thought of it.thanks anyway
 
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  • #33
LBrandt said:
Space isn't a separate entity that simply is "out there". Space is a function of mass.

While I don't disagree with anything else you said, the above does not follow. You went from space to mass.
 
  • #34
Excellent name for a candy bar...on that I'm sure we all agree.
 
  • #35
Space without 'space' is illogical to me. I fail to see how 'quantum fluctuations' can arise in the absence of 'space'. I'm a fan, but, not a huge fan of 'creation ex nihilo'. But 'eternal space' is not a satisfactory alternative. There must be a better alternative.
 
  • #36
Sri...good find from MIT:

They showed that the matter's orbit in the accretion disk would wobble, much as a child's top wobbles when it slows down. The frequency at which it would wobble, based on their calculations, turned out to be the same frequency as the actual oscillations in intensity of the x-ray emissions previously measured by other researchers. They theorized that this wobble is evidence of frame-dragging, because the matter's orbit can only wobble if the space and time in which it exists are being dragged.

a possible verification of frame dragging?? So they think...
 
  • #37
Maybe the accretion disk is the gamma rays burst in young galaxies...
 

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