No boundary condition

  • #1
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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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  • #2
bapowell
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Hello,
Means after some times it collapse on its own and expansion stops.
How does this follow from the premises of the proposal?
 
  • #4
bapowell
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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.
 
  • #5
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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"???
 
  • #6
bapowell
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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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