No Boundary Condition Universe: Stephen Hawking

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Discussion Overview

The discussion revolves around the concept of the no boundary condition universe as proposed by Stephen Hawking, exploring its implications for the structure and fate of the universe. Participants examine whether the universe can be considered closed like Earth, the effects of dark energy, and the relationship between the Hartle-Hawking model and the origin of spacetime.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants suggest that if the universe is like a closed structure without boundaries, it may eventually collapse, contrasting this with the current observation of an accelerating expansion that implies an open universe.
  • Others question how the conclusion of eventual collapse follows from the premises of the no boundary condition proposal.
  • It is noted that an additional assumption may be present regarding the absence of dark energy in the Hartle-Hawking universe, and that a closed universe could still expand indefinitely if dominated by dark energy.
  • One participant raises a question about the implications of dark energy on the Hartle-Hawking model and the origin of spacetime, to which another participant responds that dark energy does not falsify the model nor affect the origin of spacetime.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the no boundary condition universe, particularly regarding the role of dark energy and the fate of the universe. The discussion remains unresolved with multiple competing views present.

Contextual Notes

There are limitations regarding assumptions about dark energy and its relationship to the Hartle-Hawking model, as well as the implications for the origin of spacetime that remain unclear.

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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