CMB at 50: Princeton early universe panel discussion

In summary: Neil Turok. In summary, this panel discussion discussed the pros and cons of inflation theory. Some people in the panel thought that inflation was too radical and didn't have enough evidence to support it, while others thought that inflation was a compelling story that needed to be taken seriously. There was also discussion of the possible implications of inflation on our understanding of the universe.
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palmer eldtrich
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An interesting discussion at this conference here:
http://physics.princeton.edu/cmb50/videos/20150612_session6_2.mp4
David Spergel said the next project should be to look for something called f and L or is is FNL?
Can someone explain what this is and what its significance is?

What did you guys think of the discussion?
I'm a bit annoyed someone like Alan Guth,Linde or Aguirre wasnt there to defend eternal inflation and no discussion of string gas or non singular bounce cosmologies.
 
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##f_{NL}## is a measure of non-gaussianity of the CMB anisotropies. See equation (5.2.10) in

http://www.damtp.cam.ac.uk/user/db275/Inflation/Lectures.pdf
 
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palmer eldtrich said:
An interesting discussion at this conference here:
http://physics.princeton.edu/cmb50/videos/20150612_session6_2.mp4
...
What did you guys think of the discussion?
...
Thought it was a great panel discussion: Mukhanov, Steinhardt, Turok, Freese, Penrose---with excellent comments from audience (Witten, David Spergel, Marc Davis...) and Brian Greene moderated very ably as well!
So lively and incisive that even though almost 2 hours I was motivated to watch from beginning to end.
Here's the main menu of the "CMB at 50" conference:
http://physics.princeton.edu/cmb50/program1.shtml
Here are some quotes from the panel:
http://physics.princeton.edu/cmb50/videos/20150612_session6_2.mp4

Neil Turok: “even from the beginning, inflation looked like a kluge to me… I rapidly formed the opinion that these guys were just making it up as they went along… Today inflation is the junk food of theoretical physics… Inflation isn’t radical enough – it’s too much a patchwork. It all rests on rare initial conditions… Akin to solving electron stability with springs… all we have is proof of expansion, not that the driving force is inflation… “because the alternatives are bad you must believe it” isn’t an option that I ascribe to, and one that is prevalent now… inflation is pretty but we should encourage young to think about its problems & be creative (not just do designer inflation)

David Spergel: papers on anthropics don’t teach us anything – which is why it isn’t useful.. sometimes we need to surrender (to anthropics) but that time is not yet now.

Slava Mukhanov: inflation is defined as exponential expansion (physics) + non-necessary metaphysics (Boltzmann brains etc)… we should separate inflation from the landscape… exponential inflation is very useful, the rest [of the metaphysical stuff] is not for scientific discussion… In most papers on initial conditions on inflation, people dig a hole, jump in, and then don’t succeed in getting out… unfortunately now we have three new indistinguishable inflation models a day – who cares?

Paul Steinhardt: inflation is a compelling story, it’s just not clear it is right… I’d appreciate that astronomers presented results as what they are (scale invariant etc) rather than ‘inflationary’… Everyone on this panel thinks multiverse is a disaster.

Roger Penrose: inflation isn’t falsifiable, it’s falsified… BICEP did a wonderful service by bringing all the Inflation-ists out of their shell, and giving them a black eye.

Marc Davis: astronomers don’t care about what you guys are speculating about at all (mulitiverses, pre-big bang, etc).
==endquote==
These excerpts appeared on Peter Woit's blog which also had other links and comments, there was also extensive live Twitter tweeting by people in the audience including David Spergel
 
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FAQ: CMB at 50: Princeton early universe panel discussion

1. What is CMB and why is it important?

CMB stands for Cosmic Microwave Background, which is the faint, uniform glow of electromagnetic radiation that fills the entire universe. It is important because it provides valuable information about the early universe, specifically the conditions that led to the formation of galaxies and other structures.

2. How was CMB discovered?

CMB was discovered in 1965 by Arno Penzias and Robert Wilson, two Bell Telephone Company scientists who were conducting experiments to detect radio waves from space. They found a persistent static signal that could not be explained, which turned out to be the CMB.

3. What does CMB tell us about the early universe?

CMB provides evidence for the Big Bang theory, as it is the remnants of the radiation that was released during the early stages of the universe. It also gives insight into the temperature and density of the universe at that time, as well as the distribution of matter and energy.

4. How has the study of CMB advanced our understanding of the universe?

The study of CMB has led to many important discoveries, including the confirmation of the Big Bang theory, the measurement of the age of the universe, and the discovery of dark matter and dark energy. It has also provided a wealth of data for scientists to further investigate the origins and evolution of the universe.

5. What are some current and future research efforts involving CMB?

Some current research efforts involving CMB include studying the polarization of the radiation to gain more insight into the early universe, and using CMB data to search for evidence of cosmic inflation. Future efforts may involve using more advanced technology and instruments to gather even more precise data about the CMB and its implications for the universe.

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