Cyclical universe
If we assume that the universe alternates between expanding and collapsing phases, with the entropy gradient reversing during the collapse phase, the need for a time-asymmetric boundary condition is avoided since the evolution of the universe is time-symmetric overall.
For this solution to work however a "future hypothesis" is required that posits that, after increasing during the universe's expansion, entropy would reverse and decrease during the collapse phase ensuring a smooth, low entropy Big Crunch. This was suggested by cosmologist Thomas Gold, with such a universe being known as a "Gold Universe".
Λεπτομέρειες πλοηγού
(Βοήθεια)
-
The Arrow of Time  »The Arrow of Time 
The physics of time »The physics of time
The thermodynamic arrow »The thermodynamic arrow
Why do we see an entropy gradient? »Why do we see an entropy gradient?
Asymmetric boundary condition »Asymmetric boundary condition
Past hypothesis »Past hypothesis
Why low entropy in the past? »Why low entropy in the past?
Cyclical universe
No reason for entropy reversal »No reason for entropy reversal
+Σχόλια (0)
+Αναφορές (1)
+About