No Boundary Condition Universe: Stephen Hawking

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SUMMARY

The discussion centers on Stephen Hawking's no boundary condition universe, which posits that the universe lacks boundaries in space-time, similar to the Earth. Participants debate whether the universe's current acceleration suggests it will expand indefinitely, indicating an open universe, or if it could eventually collapse, implying a closed structure. Key points include the role of dark energy in the Hartle-Hawking model, with consensus that its presence does not invalidate the model or affect the origin of space-time.

PREREQUISITES
  • Understanding of the Hartle-Hawking model
  • Familiarity with concepts of dark energy and vacuum energy
  • Knowledge of cosmological models (open vs. closed universe)
  • Basic grasp of space-time theories
NEXT STEPS
  • Research the implications of dark energy on cosmological models
  • Study the Hartle-Hawking model in detail
  • Explore the concept of vacuum energy in cosmology
  • Investigate the differences between open and closed universe theories
USEFUL FOR

Astronomers, physicists, and cosmologists interested in the fundamental structure of the universe and the implications of dark energy on cosmological theories.

us40
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Hello,
According to Stephen Hawking no boundary condition universe does not have any boundary in space time.If it is so then it is like earth.You can not go north to north pole.Earth does not have any edge or boundary.So universe is like closed structure like earth.Means after some times it collapse on its own and expansion stops.But acceleration of expanding universe suggest that universe may be expand for forever and that is open universe.So does it imply that universe had in past(before plank epoch) boundaries for space and time?
 
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us40 said:
Hello,
Means after some times it collapse on its own and expansion stops.
How does this follow from the premises of the proposal?
 
bapowell said:
How does this follow from the premises of the proposal?

http://web.uvic.ca/~jtwong/Hartle-Hawking.htm
 
Aha. There is an additional assumption here that there is no dark energy in the Hartle-Hawking universe. There is nothing wrong, however, with a closed universe dominated by vacuum energy (dark energy) that goes on expanding forever. In other words, it is incorrect to conclude an open universe from the fact that it is accelerating now, or indefinitely into the future.
 
bapowell said:
Aha. There is an additional assumption here that there is no dark energy in the Hartle-Hawking universe. There is nothing wrong, however, with a closed universe dominated by vacuum energy (dark energy) that goes on expanding forever. In other words, it is incorrect to conclude an open universe from the fact that it is accelerating now, or indefinitely into the future.

Thanks for reply..
But what my question is that if Hartle-Hawking model is wrong or finding of dark energy after that model does it has any effect on "origin of space-time"?
 
us40 said:
Thanks for reply..
But what my question is that if Hartle-Hawking model is wrong or finding of dark energy after that model does it has any effect on "origin of space-time"?
No. AFAIK the presence of dark energy does not falsify Hartle-Hawking nor does it have any specific implications for the origin of spacetime.
 

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