Well this is day 2 at the AAS 229th meeting in Grapevine, Tx. This is the 2nd day of the meeting and I'll try to summarize again some of the discussions in the plenary sessions. First though I wanted to pass on an interesting article, passed on to me by Resident Astronomer Peggy, which describes how apparently for the first time, a fast radio burst has been identified and associated with a visible object. This pretty neat stuff and I guess a first. When I foun

d out about this, I looked up in the meeting catalog and found several upcoming sessions on fast radio bursts and I am trying to fit those into my schedule. For now you can follow up on the original article at:

http://news.nationalgeographic.com/2017/01/fast-radio-bursts-galaxy-frb-121102-black-hole-space-science/

Thank you for that Peggy!

While I was walking around in the exhibit hall, I was surprised to see someone I knew at the Planeview Telescope vendor booth. I stopped there just to window shop and dream of getting a Planewave telescope and discovered that Also Wants to Build a Cubesat, Randy Chung, was there displaying the 12U Cubesat with telescope mockup was there also. Cubesats come in small sizes, described as 1U, which is a cube 10 cm x 10cm x 10cm. A 12U form factor is essentially 12 times the volume of a 1U. They are so low cost and small and light weight that the Cubesats can hitch a ride on many commercial rocket launches into orbit because they can easily fit somewhere on the primary launch vehicle. Many organizations and universities and even high schools have built and launched Cubesats. The Cubesat mockup in the photo is shown with the proposed 21 cm mirror telescope. Randy used to attend the local Cubesat Meetup group with Wants to build a Cubesat, Dr Don, until Randy left and started this other venture.

Randy displays 12U cubesat telescope project that is teamed Planewave Telescope See www.spacefab.us for details |

Separately, another vendor that I always visit is the Cambridge University Press vendor area, usually operated by Vince Higgs. I looked over the 2nd edition of "Introduction to Cosmology" and after reviewing it and finding out that the author was going to be there in the afternoon, I decided to get the 2nd edition. With the AAS discount it was only $39, which is a real bargain for technical books. In addition, I got to meet the author and she signed my copy. I found her first edition one of the best introductory books on the market and she explained some of the new additions which were exactly in areas I wanted also. Now, I guess I'll just have to gift my first edition to one of our science squad members.

Barbara Ryden signs 2nd edition of her Introduction to Cosmology textbook for Palmia Observatory Resident Astronomer |

Ok, finally let me summarize one of the plenary sessions before I fall asleep. The one session I probably have time to summarize is also, as it turns out, one of the best presentations by Sean Carroll, that I have seen in a long time. Sean is professor at Caltech and popular speaker and author, all of whose books on science and general relativity, I have, and today his presentation was on "What we (don't) know about the beginning of the universe. His presentation was particularly significant for me because of my recent postings covering the asymmetry of time and the increase of entropy as time goes by. Well, Sean built on this whole concept and tied it all together into an interesting discussion of what can be meant by the beginning of time or the beginning of the universe in a Big Bang. His presentation was very clear and dramatic in the logic and conclusion and I can only hope to be able to summarize the discussion. So, let me summarize it in billeted sentence topics style since I am not going to be able to write this difficult subject up as prose. The key points I heard are:

- Something banged 13.8 billion years ago, but what?
- The universe seems to start at a singularity
- The early universe had low entropy, but how and why?
- Early entropy estimated at 10^88, now at 10^103 and in the distant future 10^123
- Consider Boltzmann concept of entropy as the number of possible macro states, summed up his formula
- Boltzmann tombstone has an equation on it. - Students should strive to do significant work that ends with an equation on their tombstone too
- Inflation, explains a lot, but is not connected to physical principles and does not explain where the low entropy comes from
- Conventional inflation theory seems to start with entropy 10^15, but can't explain why or how this. Umber comes about
- Popular explanations say that general relativity describes a singularity at the big band, but does not explain how or why
- We need a quantum theory of gravity or such to explain what happened at the Big Bang
- But maybe the Big Bang was not the beginning of the universe as we have come to assume
- Ways of avoiding the singularity include universes that bounce, cycle, hibernate, or reproduce
- Don' say the universe came into existence; it sounds like a process in time
- What caused the universe -- Wrong question - consider the following possibilities
- A bonding universe just continues from one bounce and beginning and crunch to the next
- A cycle universe could just come and go over time in a forever cycle
- The universe could have hibernating and then just expanded into our universe
- But these cyclic and hibernating universes have entropy catastrophe and entropy just keeps growing, and we don't see this
- Consider a reproducing universe where baby universes of low entropy are spawned off from the parent universe - by some mechanism
- The small size of these baby universes could have low entropy
- Spacetime quantum tunnels into these baby universes which disconnect from the parent universe
- We don't have any evidence for any of these approaches
- Go on to consider other concepts that have spontaneous compactification from simple dimension spaces to our three dimensions
- Easy to create time symmetric universes using this approach
- Time symmetrical theories are key to possible solutions
- Quantum mechanics is time symmetrical; the universe should be described by quantum mechanics not classical mechanics
- In Schrodinger equation has time as eternal and the states evolve either forward or reverse with respect to time, without beginning
- Maybe time is eternal, without beginning or end
- However, if the Hilbert space in which quantum mechanics states are defined is finite, then the same universe state will eventually recur
- This is not good; eventually could support Boltzmann brains and all sorts of unpleasant stuff
- But I'd the Hilbert space is infinite then no need to worry about recurrence.
- Another alternative is that time is emergent, not fundamental
- Consider the state where the universe Hamiltonian operates on the state and the result us zero
- This means the derivative of time does not show up in Schrodinger equation
- This is the Wheeler-deWitt equation as used by Hartle and Hawking
- The waveform does not evolve; time could exist but it would not be fundamental
- Sean likes the infinite Hilbert space approach
- Arranging the possibilities between time as emergent or fundamental and Hilbert space as finite or infinite yields four domains
- Pick your choice
- But what do we need to finally answer this set of questions
- We have heard of all theses approaches for years now
- Well, at least we have finally got to the point where we can start to ask these types of questions
- It's been less than a hundred years since we knew the universe was expanding -- don't get in a rush
- The big advances in quantum information theory and association with entanglement and association with gravity seems very promising

Wow, I am completely exhausted just trying to read through my pen scratches and notes and trying to understand all of this. I do like how the final answer seems to be one which can resolve these issues of entropy, the symmetry of time at the quantum level and the connection seemingly between quantum entanglement and information and gravity.

Maybe yo can figure it out. I hope Sean's lecture will show up on YouTube because I need to hear it again.

Until next time,

Resident Astronomer George

P.S. I forgot to bring the right charger cord for my Surface Pro and it's now out of juice and I and have been trying to write and edit this post on my IPad, which does not support many of the Blogger editing functions, so I hope this whole post shows up ok.

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