I What Insights on Time in Physics and Cosmology Emerged from the Pi Conference?

[windy miller]

The Pi just posted a bunch of videos from their conference on time
http://pirsa.org
A lot of the big names in cosmology were there: Sean Carroll, Lee Smolin, Abhay Ashtekar , Andy Albrecht, George Ellis etc
I have to say though I'm a little surprised at some of the questions. How is it i ( layman in this field ) knows that LQC isn't a cyclic model but Andy Albrecht one of the world experts ,doesn't? It makes me think there is far too much compartmentalisation in science, but maybe that's inevitable . Anyway this conference seemed to bring people together form different research programmes and is very interesting if you have the time.

 

[Chalnoth]

Why do you think LQC isn't a cyclic model?

 

[windy miller]

As I understand it , it gives corrections to the Gr at high curvature, replacing the big bang singularity with a bounce. it doesn't make predictions about dark energy turning around and causing a recollapse and hence it is not a cyclic model.

 

[Chalnoth]

As I understand it , it gives corrections to the Gr at high curvature, replacing the big bang singularity with a bounce. it doesn't make predictions about dark energy turning around and causing a recollapse and hence it is not a cyclic model.

https://arxiv.org/abs/1507.00226
https://arxiv.org/abs/hep-th/0407115

I believe a universe with a bounce is frequently called "cyclic" even if there isn't an infinite chain of cycles.

 

[windy miller]

I have no idea how it can possibly be appropriate to call a universe that contracts and then expands but never repeats this process a cyclic one. One that repeats the process sure, but one that doesn't? i don't see how that makes sense.

 

[windy miller]

https://arxiv.org/abs/1507.00226
https://arxiv.org/abs/hep-th/0407115

I believe a universe with a bounce is frequently called "cyclic" even if there isn't an infinite chain of cycles.

i think the papers you link are cyclic models but that is not mainstream LQC which predicts a one time bounce only.