Smolin video LQG online course

[marcus]

I went back and edited post #45 and got rid of the error

Fine, we seem to have settled the homework problem.
I am wondering about moving on.

Question to f-h and selfAdjoint: have you watched Lecture #2?

...
...
Unless someone has another suggestion, let's all watch Lecture #2 and try to summarize what it is about.

...
...
(It is lecture #4 which is a review, and which we might skip.)

sorry about the mixup earlier today.

 

[selfAdjoint]

Fine, we seem to have settled the homework problem.
I am wondering about moving on.

Question to f-h and selfAdjoint: have you watched Lecture #2?

the last time we discussed practical matters, selfAdjoint system was crashing and it sounded painful to watch anything

then CD said he had files that could be downloaded, but i am not sure that would work for selfAdjoint or that he wants to go that route

Has anything happened in the meantime? Have you found a way to get around the problem?

Unless someone has another suggestion, let's all watch Lecture #2 and try to summarize what it is about.

I watched all of Part 2, but with the same difficulties; during the last half hour of the video yesterday I was only getting 2 or 3 minutes of viewing time between crashes. Also I had difficulty understanding Professor Smolin during this part of his talk, he often had his head turned away from the mike, and I didn't get all those equations he put on the three boards copied fully, so all I have is some very high level notes on why Euclidean QG is easier than Lorentzian QG and how the new equations are polynomial while the old naive way of quantizing produced very messy hard-to-handle equations. I would appreciate if anyone has better notes or a source for the official notes on that talk.

I am very open to CD's download procedure if he will indicate how I should go about it. I don't want to continue watching without trying to get something better.

 

[CD]

I sent you a pm containing the access information. Anyone else that would like to download a copy just pm me. If you have any problems let me know.

 

[marcus]

I sent you a pm containing the access information. Anyone else that would like to download a copy just pm me. If you have any problems let me know.

I would like to try it, if the memory requirement is not too large.
CD, does the file that we can download from you have only the sequence of blackboard still-frames, or is it the audio/video, or the whole thing?

It's not that I need to go this route, so if you only want people who don't have a good alternative, don't bother to send me the URL. The thing is, I am curious to try how it works.

 

[selfAdjoint]

does the file that we can download from you have only the sequence of blackboard still-frames, or is it the audio/video, or the whole thing?

It apparently has the video & audio, although I haven't tried it yet.

CD says he watches the video from his site and also has the perimeterstreaming site up to click through the slides.

 

[marcus]

It apparently has the video & audio, although I haven't tried it yet.

CD says he watches the video from his site and also has the perimeterstreaming site up to click through the slides.

Great! hope it works. Let's see if we can say anything about Lecture 2, then.

 

[selfAdjoint]

Successfully watched the first hour of Lecture Two, without slides (just didn't bother with them). I watched much of it twice and am now much clearer on what he was saying. My lack continues to be reproducing his board work in my notes, especially the index gymnastics that he went through so fast. From my memories of watching it at the Perimeter site I don't expect the slides to be much help.

One issue I would like to discuss is the degree-of-freedom counting which he used to show that SU(2) BF theory has no local degrees of freedom. I got the point that 18 equations in 18 unknowns determines a single solution (if nonsingular), and thereby uses up all the degrees of freedom available. It was the details of the counting that went by me, first three Fs and three Es and then... His audience seemed not only to be with him, but some of them were ahead of him. So this is apparently a prime way of reasoning about conjectured theories. Can we get up to it ourselves?

 

[CD]

I got 18 degrees of freedom from the 9 A's and 9 E's
then 3 equations from D_{a}E^a=0
and 9 equations from E^{i}_{ab}=\frac{1}{\lambda}F^{i}_{ab}
3 equations fixed by the gauge in A
3 equations from diffeomorphism invariance

Sorry about the equations here but I'm in a rush at the moment.

edit - updated to tex

 

[selfAdjoint]

I got 18 degrees of freedom from the 9 A's and 9 E's
then 3 equations from D_[a]E^a=0
and 9 equations from E^i_[ab]=1/@*F^i_[ab]
3 equations fixed by the gauge in A
3 equations from diffeomorphism invariance

Sorry about the equations here but I'm in a rush at the moment.

No prob about the equations, and thank you. What does the @ represent?

 

[CD]

I believe it was lambda in his equations. It was just introduced as a free parameter but eventually gets recoined as the cosmological constant.

It was something like
F_{ab}^{i} = -\frac{\Lambda}{3}\epsilon_{abc}E^{ci}
Then by breaking the gauge and setting the A's proportional to a delta we end up with a deSitter spacetime with cosmological constant lambda.

 

[f-h]

Perhaps it's noteworthy that he goes through all of this in greater detail in later lectures, (7, 8, 9) so there probably is little point in discussing it into great a detail. Lecture 2 is still mainly motivational.

 

[CD]

I placed an order for the Baez book. The paperback was listed on the publishers site for 45$ so I thought it was worth a shot. If it's not available oh well.
http://www.worldscibooks.com/physics/2324.html

 

[rtharbaugh1]

I got to watch lecture one and half of lecture two, in careful detail. I actually tried to transcribe what Smolin said! Is that a hockey stick on the table in front of him? I made a rude comment about hockey players once and would have to retract it if Smolin is a hockey player. I wish he had better handwriting.

However, I now find that I cannot get into the website. My browser says it is unavailable. Anyone else having this problem?

Thanks for the great link, at least while it lasted.

R.

 

[CD]

Streaming Presentations Unavailable Due To Maintenance
Presentations will be unavailable due to standard maintenance until Friday February 23, 2006 at 10am.

From the main perimeter site.

 

[rtharbaugh1]

Thanks! I am relieved. Now, what about that hockey stick? R

 

[Mike2]

However, I now find that I cannot get into the website. My browser says it is unavailable. Anyone else having this problem?

I'm still having trouble, and it's Saturday morning. Is the site working yet? Thanks.

 

[marcus]

I'm still having trouble, and it's Saturday morning. Is the site working yet? Thanks.

I saw somewhere that it would be down til Monday. AFAIK it is still down. Personally I will try again Monday. Hope it's up by then.

 

[selfAdjoint]

Just to let everybody know, I will be away from the computer from tomorrow morning February 25 till the evening of Monday March 6. So I won't be able to view Lectures 3 and up until that week.

See you all then.

 

[marcus]

Just to let everybody know, I will be away from the computer from tomorrow morning February 25 till the evening of Monday March 6. So I won't be able to view Lectures 3 and up until that week.

See you all then.

sounds like a trip----hopefully to somewhere warmer than the upper midwest Great Lakes region

to make a general request----last time I checked Perimeter streamer had not put up Lectures 11 and 12
and the site was still down for maintenance

(anyway that is what my computer thinks----it can't connect)

If anyone does try it, and happens to connect, please post the news here!

 

[selfAdjoint]

sounds like a trip----hopefully to somewhere warmer than the upper midwest Great Lakes region

To my son's house, to spend the week and attend the christening of his new daughter Elizabeth, born if you recall December 21 2005. He lives in a far Northern suburb of Chicago; the temp here is in the 20's (F), which is acceptible if not comfortable to a Wisconsin Cheesehead. We describe a day as "beautiful" not by the temperature but by whether it is sunny or not. That must seem counterintuitive out in La La Land.

When I was here over the Winter holidays, he didn't have a firewall on his new computer, and asked me not to log on to the net, for fear of viruses. Now he has one, so I can surf, but I still won't have an opportunity to watch the Smolin videos.

 

[beta3]

Hi guys, do the LQG videos work for you all? Or do you have currently problems too?

it doesn't for me, after the information bar is displaying 'Transitioning' for a few seconds, it goes back to ready, meaning it stopped (play button available, pause and stop not)

edit:

just discovered something interesting:
none of the videos is working for me, but when i right-click on the video window and choose error details, i get this:
WMP cannot play the file because the specified protocol is not supported. If you typed in the Open Url dialog box, try using a different transport protocol (for example, "mms:")

Why doesn't my windows media player (10, on windows xp) support the used protocol? It should be one that it's supporting, otherwise Internet Explorer wouldn't load the WMP ActiveX control (and i can see from the URL, that media player 'WM7' is specified)

 

[marcus]

Hi guys, do the LQG videos work for you all? Or do you have currently problems too?
...

they currently don't work for me. I just tried.
this is when I expected things to be back up (Monday 27 Feb)
after what they said would be routine maintenance.
but at least for my system----with which I earlier didnt have trouble getting them---they arent available

I don't know how to interpret----I think the whole Perimeter streaming media facility is not working.
I don't think it is special to me or to the Smolin lectures.
but I could be wrong.

If anybody finds something different, or gets a rise out of them, please post and let the rest of us know.

About the rest of the Perimeter site----the regular stuff not including the streaming video lectures----everything seems to be business as usual, I have no problems

 

[rtharbaugh1]

A day for disappointments, perhaps. FQX has, as promised, posted on their site a call for research proposals. Sadly, from my standpoint, they seem to be calling for academic professionals who may be tempted to do some work that is too edgy for DOE or other usual funding sources, but they are not encouraging people outside the academic establishment who might like to get a chance to bat, for once. Money and honors, as usual, flow toward those who already have them, not to those who may have some merit but go unrecognised. I had hoped for something else, from the original announcements.

Anyway, it may be a small alternative entertainment for those of us who are locked out of the Mediasite Presentation Catalog to visit FQX at:

http://www.fqxi.org/index.html

R

 

[marcus]

thanks Richard, I followed your link and found food for thought:
=====quote=====
Relevance: Proposals should be topical, foundational, and unconventional.

Topical: This Inaugural Request for Proposals is limited to research in physics (mainly quantum physics, high energy "fundamental" physics, and gravity), cosmology (mainly of the early universe) and closely related fields (such as astrophysics, astrobiology, biophysics, mathematics, complexity and emergence, and philosophy of physics), insofar as the research bears directly on questions in physics or cosmology. Although the distribution of funds across subject areas will be driven in large part by the quality of proposals received, a goal of the review process will be to fund diverse research topics that span the small and the large, and range from the elementary to the complex.

Foundational: This Inaugural Request for Proposals is limited to research with potentially significant and broad implications for our understanding of the deep or "ultimate" nature of reality.

Unconventional: This Inaugural Request for Proposals is intended to fill a gap, not a shortfall, in conventional funding. We wish to enable research that, because of its speculative, non-mainstream, or high-risk nature, would otherwise go unperformed due to lack of available monies. Thus, although there will be inevitable overlaps, an otherwise scientifically rigorous proposal that is a good candidate for an FQXi will generally not be a good candidate for funding by the NSF, DOE, etc. - and vice versa.

...
...

INITIAL PROPOSAL - DUE April 2, 2006 - Must include:
A 300 - 500 word summary of the project, explicitly addressing why it is topical, foundational and unconventional
A draft budget description not exceeding 200 words, including an approximate total cost and explanation of how funds would be spent
A Curriculum Vitae for the Principal Investigator, in PDF format, including:
Education and employment history
Five previous publications relevant to the proposed research, and five additional representative publications
Full publication list
======endquote======

I won't comment on the issue that you raised about restriction to Academia.

Whether or not that restriction makes sense (especially for their maiden venture) there are already quite a lot of people in Academia who have UNCONVENTIONAL ideas they want to work on that are not likely to get funded by either DOE or NSF.

By saying "non-mainstream, high-risk, speculative" they are already inviting a lot of rather unconventional stuff.

In the US research community almost any non-string Quantum Gravity is unlikely to get DOE or NSF funding and for this reason it could be considered as high-risk to embark on non-string QG research.

There is a lot else besides. They could find themselves getting plenty of proposals submitted----that they then have to review and decide which ones to invite to the second round submissions.

 

[Mike2]

they currently don't work for me. I just tried.
this is when I expected things to be back up (Monday 27 Feb)

The video is now working again. I just finished viewing part 3 in his intro to quantum gravity series. Cool.

 

[marcus]

The video is now working again. I just finished viewing part 3 in his intro to quantum gravity series. Cool.

thanks for passing on the news, Mike

 

[Mike2]

thanks for passing on the news, Mike

I just viewed Part 6 of his series. It is only 53 minutes long when most others are an hour and a half. At the end of Part 6 Lee comments on how many in his audience appear tiered. I guess I don't feel so bad. After viewing it, I too could hardly keep my eyes open. Why...? It seems Lee Smolin makes quite liberal use of his previous results, and I felt unprepared for it. He should give some more explicit warning that these results will be used later. And it wouldn't hurt to give a one or two sentence review of where that result came from as well. (Take notes in parts 4 and 5) Overall I appreciate his efforts, he seems to be doing a fine job. Although I wish his writing was a little more legible.

Does he plan on writing a book on this stuff later?

 

[marcus]

Does he plan on writing a book on this stuff later?

bravo to you Mike!
I am glad you are going through them and are up to Lecture 6

I watched #11 yesterday and thought it was the most interesting yet

It is quite hard work for me, and i don't follow everything. Also I have to go over and watch some again. Each viewing a little more is understandable.

In one of the lectures, I forget which, Smolin referred to "a book I am writing"
but it wasnt clear that the book was a textbook parallel to this series of lectures. the main topic of the book might be something else tangential.

He is writing a book. But I can't guarantee that the book is an "Introduction to Quantum Gravity"----in the sense of this series of lectures.

For a while I couldn't find lectures 11 and 12 because when I clicked on "Introduction to QG" I got the TOC page for Lectures 1-10 only. Duh!
then I realized that this was just PAGE ONE of the TOC
and I had to click a box to get page two! Maybe i am the only one in the world who doesn't always notice these things.

Anyway, today I plan to watch #12, while my wife is out at a handcraft bookbinding class----she does beautiful leather and ornamental cloth re-bindings of books she likes which are falling apart----and I will turn up the volume and kick back and enjoy

 

[CD]

For a while I couldn't find lectures 11 and 12 because when I clicked on "Introduction to QG" I got the TOC page for Lectures 1-10 only. Duh!
then I realized that this was just PAGE ONE of the TOC
and I had to click a box to get page two! Maybe i am the only one in the world who doesn't always notice these things.

Haha thank you! I had not noticed that there was a page two.

 

[Mike2]

bravo to you Mike!
I am glad you are going through them and are up to Lecture 6

I watched #11 yesterday and thought it was the most interesting yet

It is quite hard work for me, and i don't follow everything. Also I have to go over and watch some again. Each viewing a little more is understandable.

I think I'm going to have to go back to part 2 and this time take notes. My overall perspective gets lost in the immediate details. The TOC page refers to Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 as an accompanying text. I wonder if it includes all the wonderful math Lee shows on the board with Lagrangians, Hamiltonian, Poisson bracked, gauge fields, E and B fields, etc?

So marcus, what part does he start to actually quantize thing. Even up to part 6 he is still dealing classically. Thanks.

 

[garrett]

I can't confirm it contains all the math in Lee Smolin's lectures, as I haven't seen them all, but Rovelli's book does include Lagrangians, Hamiltonians, Poission brackets, gauge fields, spin networks, etc. It is very very good, and I recommend it highly. In my opinion it's the best book on quantum gravity. There's also an early draft available online for free:
http://www.cpt.univ-mrs.fr/~rovelli/book.pdf

 

[marcus]

I can't confirm it contains all the math in Lee Smolin's lectures, as I haven't seen them all, but Rovelli's book does include Lagrangians, Hamiltonians, Poission brackets, gauge fields, spin networks, etc. It is very very good, and I recommend it highly. In my opinion it's the best book on quantum gravity. There's also an early draft available online for free:
http://www.cpt.univ-mrs.fr/~rovelli/book.pdf

I defer to Garrett on this, Mike.

Two side remarks:

1. for a clear simple up-to-date summary of LQG including only the essential ideas, and a lot of pictures aimed at giving intuition, see
Rovelli's January 2006 LYON LECTURE----online are 59 slides

http://www.cpt.univ-mrs.fr/~rovelli/Lyon2006II.pdf

the link is at his website
http://www.cpt.univ-mrs.fr/~rovelli/rovelli.html

2. what Smolin keeps referring to during the first half-dozen lectures or so is sections of his own 2002 paper Quantum Gravity with a Positive Cosmological Constant hep-th/0209079

every so often he will say things like "today we cover sections 2 and 3 of the paper" or "now we are in section 4 of the paper"

sometimes on the blackboard he abbreviates the paper by writing "0209079"
and sometimes he refers to the paper in a kind of slang nickname way as
"\Lambda > 0"

standing for "...Positive Cosmological Constant"

in any case he says he is following that paper, at least in the early lectures

Although it is clear to him what the connection is, and how he is following the paper, the notation may not correspond in all details and I don't find that the paper necessarily helps. What I find myself doing is watching the video lectures repeatedly. second or third time through I grasp more.

 

[selfAdjoint]

Although I haven't been able yet to watch the later videos of Smolin's talk, I can say that I have found that repeated viewing really helps. Thinking back to the courses I took in grad school, I wish I had reviewable videos, or had had them then! I would be much better off today!

 

[rtharbaugh1]

The process of expansion or opening a node seems to me a sequence in which the observer's imaginary time line is projected through the node, thus making the node a step from which to then choose the other nodes with which it is connected as next possible steps. Note each transfer into a node (expansion of a node) can be thought of as the observer's regression into the world of that node. Some of the conditions for the node remain the same, but some may change as the observer chooses to negotiate through the matrix.

An old fashioned two step at light speed is continuous...otherwise the dance is discrete.

R.

 

[marcus]

Lectures 13 and 14, presented today, are now available on line

 

[CD]

Sorry I had midterms this week, but I'll try to get caught up more this weekend. Where is everyone in the series?

 

[marcus]

Sorry I had midterms this week, but I'll try to get caught up more this weekend. Where is everyone in the series?

I've viewed it up until Lecture #14. I get more out when I
go back and watch parts over again, so I will be reviewing

 

[selfAdjoint]

I'm still waiting to do three. I was away of course, and since I got back I've pampered myself by using my RealPlayer to play classical music radio station WFMT all day. It's really hard to turn off Mozart and Shostakovich for Smolin! And my bandwidth isn't enough to do both. Maybe over the weekend.

 

[marcus]

... It's really hard to turn off Mozart and Shostakovich for Smolin!.

a long-hair hedonist
and embarrassed to admit it!
probably lives somewhere in the Midwest where they feel guilty about too much pleasure

 

[marcus]

Lectures #15 and 16 are now online
according to what he said last week, Smolin should now quantize the Ashtekar variables in these lectures
(the previous two lectures developed the new-variables version of classical General Relativity)

when you get to the menu of the lectures, remember to flip to page 2 where there is a continuation of the menu

 

[marcus]

I've been watching Lecture #15.
it seems like the best yet
he's quantizing the classical theory and making a hilbert space etc.
giving intuition that had not come to me before

has anybody else been watching #15?
anybody else find it helpful too?

dynamics comes next week (#17,18)

Oriti just walked in, at the moment I was watching lecture #15

Oriti is supposed to give lecture #19 maybe also #20
because they get to spinfoam at that point

===================
BTW I've been learning to use the "slide list" menu option in sonicfoundry mediasite streamers

so I can watch particular parts of a lecture----or come back to where I had to stop the day before

if you are watching #15, well it has 64 slides
and a particularly cool part is right around slide 61 or 62
so suppose you want to go to that slide and start the whole thing there (instead of starting at the beginning)

you go to the slide list and you see numbers 1,2,...,7

each one of those baskets 1,...6 holds 10 slides
so they hold the first 60 slides
you click on 7 and you see thumbnails of slides 61,...,64
and you see which one you want and you click on "start from slide"
and it starts playing from that slide

has anyone else been using this feature? it really ups the efficiency of the whole process of watching

 

[Mike2]

I've been watching Lecture #15.
it seems like the best yet
he's quantizing the classical theory and making a hilbert space etc.
giving intuition that had not come to me before

What would really be cool is if someone would give a brief one paragraph summary of what will be covered in each part and even include some reference as to what course material will be covered.

 

[selfAdjoint]

What would really be cool is if someone would give a brief one paragraph summary of what will be covered in each part and even include some reference as to what course material will be covered.

Check out Christine Dantas' "The Hand of a Master" series of posts at http://christinedantas.blogspot.com/, She is doing just that, and she's up to Parts 5 and 6.

 

[Mike2]

Check out Christine Dantas' "The Hand of a Master" series of posts at http://christinedantas.blogspot.com/, She is doing just that, and she's up to Parts 5 and 6.

Thanks selfAdjoint.
It is also mentioned that one of the books used as reference is:
Gauge Fields, Knots, and Gravity (Series on Knots and Everything, Vol. 4) (Paperback)
by John C. Baez, Javier P. Muniain
at: https://www.amazon.com/gp/product/9810220340/?tag=pfamazon01-20

It is $500.00 each.

I wonder if the followning book might contain the same material:
Loops, Knots, Gauge Theories and Quantum Gravity (Paperback)
by Rodolfo Gambini
at: https://www.amazon.com/gp/product/0521654750/?tag=pfamazon01-20

 

[selfAdjoint]

Thanks selfAdjoint.
It is also mentioned that one of the books used as reference is:
Gauge Fields, Knots, and Gravity (Series on Knots and Everything, Vol. 4) (Paperback)
by John C. Baez, Javier P. Muniain
at: https://www.amazon.com/gp/product/9810220340/?tag=pfamazon01-20

It is $500.00 each.

I wonder if the followning book might contain the same material:
Loops, Knots, Gauge Theories and Quantum Gravity (Paperback)
by Rodolfo Gambini
at: https://www.amazon.com/gp/product/0521654750/?tag=pfamazon01-20

Yep, we all found out about that price for the Baez-Munian book It's because it is out of print and very much in demand. There is supposed to be a new edition coming out, but nobody knows when. I don't know the answer to your question about the Gambini book, sorry. Maybe Baez can tell us? He does check in here every now and then.

 

[marcus]

#17 and #18 of the Smolin Lectures are on line
(Hamiltonian constraint, area and volume operators)

this is from 22 March

on 29, next wednesday, Daniele Oriti will give the lecture, on spinfoam models (will have a review of Feynman diagrams)

the next week, 5 April, Viqar Hussain on black holes and elimating singularities

 

[Mike2]

Yep, we all found out about that price for the Baez-Munian book It's because it is out of print and very much in demand. There is supposed to be a new edition coming out, but nobody knows when. I don't know the answer to your question about the Gambini book, sorry. Maybe Baez can tell us? He does check in here every now and then.

I bought Rovelli's book, Quantum Gravity
at: https://www.amazon.com/gp/product/0521837332/?tag=pfamazon01-20
I was hoping it would help me with Smolin's video course. But chapter two of Rovelli's book starts out too dense for me. I'm getting lost in the indicies. Does anyone know a good primer for this notation he uses for GR? Thanks.

 

[garrett]

For a large and excellent treatment of GR, including index gymnastics, Wald is my favorite:
http://tinyurl.com/zs3u5

For a concise but thorough (and dense) online treatment, I like Peldan's review:
http://xxx.lanl.gov/abs/gr-qc/9305011

Indices are a bit like spoons in The Matrix... when you get really good at using and fully understanding them, there are no indices.

 

[rtharbaugh1]

Hi Mike2

I've been trying to get the indice idea from Baez on GR at

http://math.ucr.edu/home/baez/gr/outline2.html

but still getting stuck.

Thanks, Garret, for additional resources. I'll take a look at those.

R.

 

[rtharbaugh1]

#17 and #18 of the Smolin Lectures are on line
(Hamiltonian constraint, area and volume operators)

this is from 22 March

on 29, next wednesday, Daniele Oriti will give the lecture, on spinfoam models (will have a review of Feynman diagrams)

the next week, 5 April, Viqar Hussain on black holes and elimating singularities

Will this be broadcast in realtime? If so, what time CST? And how do I access it? I don't see it listed at the Mediasite link.

R.