Exploring Time in Physics and Cosmology: Insights from the Pi Conference

In summary, the Pi recently posted multiple videos from their conference, featuring notable figures in cosmology such as Sean Carroll and Abhay Ashtekar. The conference sparked discussions about LQC not being a cyclic model and raised questions about compartmentalization in science. However, mainstream LQC predicts a one-time bounce without predictions about dark energy causing a recollapse. Some papers suggest a universe with a bounce can still be considered cyclic, but it may not necessarily repeat the process.
  • #1
windy miller
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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.
 
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  • #2
Why do you think LQC isn't a cyclic model?
 
  • #3
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.
 
  • #4
windy miller said:
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.
 
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Likes Fervent Freyja
  • #5
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.
 
  • #6

1. What is time in physics?

Time in physics is a fundamental quantity that is used to measure the duration or sequence of events. It is often described as the fourth dimension, and is considered to be a fundamental aspect of the universe.

2. Can time be measured accurately?

Yes, time can be measured accurately using a clock or other timekeeping devices. In physics, time is measured in seconds, and atomic clocks are the most accurate time-keeping devices currently available. However, there are theories in physics that suggest time may not be as constant as we perceive it to be.

3. How does time relate to space in physics?

In physics, time and space are considered to be interconnected and inseparable. This concept is known as spacetime, and it is the framework in which all physical events occur. Time is often considered the fourth dimension in this framework, with the other three dimensions being length, width, and height.

4. Can time travel be possible?

According to current theories in physics, time travel is not possible. However, there are some theories, such as the theory of relativity, that suggest the possibility of time dilation, where time may appear to pass differently for objects moving at different speeds. However, this is not the same as traveling through time as portrayed in science fiction.

5. How does time relate to the beginning of the universe?

In cosmology, time is often discussed in relation to the beginning of the universe. The Big Bang theory states that the universe began as a singularity, and time itself began at this point. Before the Big Bang, there was no concept of time as we understand it. However, there are still ongoing debates and theories about the exact beginning of time and the universe.

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