Inflation in Barcelona
I have been traveling to Barcelona on and off for 10 years and this time I find the whole world has discovered the easygoing charms of the city. The hotel prices have shot up and the queues at meal-times are unbelievable. But this post is not about that kind of inflation.
A conference was held in Barcelona to celebrate 25 years of the theory of cosmological inflation. Most of the pioneers Guth, Linde and Starobinsky gave talks giving their insights at hindsight on the subject. Starobinsky was serious as always, Linde was not as always but it was Guth who had the most impact. Guth spoke about the conceptual problems that still exist in the theory. The standard picture where a scalar field rolls down a potential while the universe expands exponentially with time is an over-simplification. Quantum mechanics applied to the universe allows the scalar field to have some probability of moving up the potential rather than rolling down. The parts of the universe where the scalar field moves up inflates faster and occupies a larger volume of the universe than the parts of the universe where the field rolls down. So the universe continuously branches off into sections which are inflating. So inflation once started never stops -some part of the universe is always inflating.Guth showed one problem with this inflating multiverse is that it is dominated by young universes- like in a pond where algae double every day will have 50% of the algae whose age is only 1 day. So the probability that this multiverse will have universe like ours is very small and that's something that needs explaining.
There is the anthropic principle that says that in the multiuniverse there will be some universes where the constants of nature would be accidentally such as to support life which gives our universe the appearance of creation by intelligent design.
To my mind the million dollar question is whether this multiverse has some observable signature maybe in the cosmic microwave background .
I have been traveling to Barcelona on and off for 10 years and this time I find the whole world has discovered the easygoing charms of the city. The hotel prices have shot up and the queues at meal-times are unbelievable. But this post is not about that kind of inflation.
A conference was held in Barcelona to celebrate 25 years of the theory of cosmological inflation. Most of the pioneers Guth, Linde and Starobinsky gave talks giving their insights at hindsight on the subject. Starobinsky was serious as always, Linde was not as always but it was Guth who had the most impact. Guth spoke about the conceptual problems that still exist in the theory. The standard picture where a scalar field rolls down a potential while the universe expands exponentially with time is an over-simplification. Quantum mechanics applied to the universe allows the scalar field to have some probability of moving up the potential rather than rolling down. The parts of the universe where the scalar field moves up inflates faster and occupies a larger volume of the universe than the parts of the universe where the field rolls down. So the universe continuously branches off into sections which are inflating. So inflation once started never stops -some part of the universe is always inflating.Guth showed one problem with this inflating multiverse is that it is dominated by young universes- like in a pond where algae double every day will have 50% of the algae whose age is only 1 day. So the probability that this multiverse will have universe like ours is very small and that's something that needs explaining.
There is the anthropic principle that says that in the multiuniverse there will be some universes where the constants of nature would be accidentally such as to support life which gives our universe the appearance of creation by intelligent design.
To my mind the million dollar question is whether this multiverse has some observable signature maybe in the cosmic microwave background .
posted by Subhendra at 6:04 PM
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