Is there a support group for spouses of physicists?

[Tsu]

I think, pretty much - never mind. I tried to watch Integral's link to the PBS video, but I need to use Ivan's computer with the high-speed connection and that just isn't going to happen any time soon. I have so many questions, even I can't get them sorted out enough to make sensible posts. I can try to find more basic info about LQG and string theory somewhere on the net. Guess I'll first google "LQG for Dummies" first... Also probably "String Theory for Dolts". Once I have that all figured out, I'll be back with some questions. Maybe in my next life I'll be hard-wired for this stuff... (GOOD LORD! WHAT AM I WISHING FOR?)

Can anyone guide me to some sites about these two theories where they don't speak Greek? (you know, Greek - like 'sumthinorother diffeomorphism' - What the h*** IS THAT?)

Thanx anyway...

i should seek professinal help... i marry a nerd and i hang out with him and all his friends who just scramble my brains... YOU'RE ALL OUT TO GET ME, AREN'T YOU?! IT'S A CONSPIRACY! hmm... professional help it IS... Is there a 12-step group for physics wives?

 

[Evo]

Have you tried Brian Greene's Elegant Universe for string theory? Both the book and the TV show are perfect for laymen (like me). He explains things in a very simple and entertaining way.

Hyperspace - A scientific odyssey through parallel universes, time warps & the 10th dimension - by Michio Kaku

Other books -

Not really related, but he's hot (and funny), so you might be interested. He wrote "Faster than the Speed of Light" Joao Magueijo. I saw him on C-SPAN a little over a year ago, after I read an article on VSL. His website is http://theory.ic.ac.uk/~magueijo

Also, "The Fabric of Reality: The Science of Parallel Universes - And it's implications" by David Deutsch. He's more into multiverses and time travel, but an interesting read. http://www.qubit.org/people/david/David.html

People here may have differing opinions, they, having actual knowledge of these things, may say they're not worth the time spent reading them, so you may want to take whatever advice someone here gives on these over mine.

 

[marcus]

Originally posted by Tsunami
I think, pretty much - never mind...Is there a 12-step group for physics wives?

that's well written
in a dramatic many-voiced spontaneous-sounding style
and its quite funny
the idea of a 12step group-----actually it should be
what is called a "support group"----for physics wives is
first rate. there should be.

a friend of mine, solid state physicist, did a stint in holland at
philips eidhoven and fell in love with a lovely dutch girl
who lived in the town near the research labs, but
she had no idea of physics----she was good with languages---and
they moved to Los Alamos and lived completely among physicists
and their wives in a kind of suburb. She could have used a support group for physics wives. Should have had one really.
Finally she ran off with a geologist. He liked mountains,
which she could understand.

I don't think it is a very good idea for someone in your situation to try to learn LQG or string theory for that matter. Much rather learn German or sing in the campus glee club. Singing 4-part harmony is very useful---it makes people happy.

You are good with one-liners, so I think you are handy with language. Do you know some other languages besides English? If that's not too personal a question.

 

[jeff]

Originally posted by Tsunami I can't get them sorted out enough to make sensible posts. I can try to find more basic info about LQG and string theory somewhere on the net.

If you want to avoid wasting time on ideas that are popular in these sorts of low-brow public forums but not among physicists, forget about LQG.

 

[marcus]

Tsunami,

As you have doubtless gathered, I am real lowbrow and you are welcome to waste time trying to discuss anything you want with me, popular or not among whomever. As for research "demographics", here are numbers from a Los Alamos archive database. This relates to "popularity among physicists".

Numbers of scholarly preprints by year in Loop Gravity research topics
(keywords "loop quantum gravity", "spin foam", or "loop quantum cosmology")

2000 46
2001 48
2002 64
2003 70


--------------
Numbers of scholarly preprints by year in String research topics (keywords "string", "brane", "M-theory"


2000 1457
2001 1496
2002 1500
2003 1265

That is, those where the abstract summary of the paper has in it somewhere the word string, or the word brane, or the word M-theory.

More about this, and links to sources in the "Rovelli's program" thread serving as a Loop Gravity link-basket for want of sticky.

https://www.physicsforums.com/showthread.php?s=&postid=128448#post128448

Anecdotal evidence, in my experience, tends to confirm what you see in the numbers. I have repeatedly come across papers by authors who formerly did string research and have largely or entirely switched over.

 

[Tsu]

Evo,
I've been watching the Elegant Universe on-line (the link that Integral posted). Actually listening would be more like it, as I don't have enough of something computer (ask Ivan) for the video to come through. I need to go down to his office to watch it on his system - except that he uses it for work, which he is ALWAYS doing! Listening is fine, but I'm a visual person, so I miss the visuals.

Kaku is excellent. Hyperspace is what made me realize 'HEY! I CAN understand this stuff!' As long as I can stay away from the math and keep to the concepts (is that possible?) I'll be fine. I can't sit and read a lot of this stuff at one time because I end up with such a twisty-face trying to force an understanding that I end up with a headache! So I take it small chunks at a time - let it sink in and then go back for more. I know I'll never be able to understand it the way these folks do. They seem to be able to instinctively see, feel and understand it - like it's a PART of them. I've always envied that ability. I've always WANTED that ability! But... On the other hand, none of these folks are as good as I am at being ME, so...

Marcus,
Many-voiced? You mean, like - SCHIZOPHRENIC?! Funny you should use the word 'dramatic'. I was 'this close' (*shows miniscule space between fingers*) to auditioning for Tony and Tina's Wedding. And I do speak Spanish and love languages. I have MANY interests - including the directions that all sciences are heading - which is why I want to learn more about LQM & ST.

Jeff,
*blows raspberry* Killjoy. Then tell me, what ideas ARE popular among physicists these days? I'll google them, too! Might as well have a well-rounded perspective, right?

Anyway, thank you all for your posts. I've started my own list of links to hit whenever I get the intense desire to get all twisty-faced, but feel free to post any others that you think might be excellent for non-nerds like me trying to exist amongst you genious types. It will take me awhile to get through it all, but I'll pop in at times with a question or 50. Ivan is really excellent with answering my questions, but lots of times I want a different perspective. Frequently, someone will come up with some off-the-wall phrase that just pulls it all together for me. Why am I even here, you ask? Don't ask ME! Like I said, professional help is probably MORE than indicated here...

 

[Evo]

I watched Elegant Universe when it originally aired & went online & ordered the video. It's also available on DVD now. Worth the few bucks. You can order it here http://shop.wgbh.org/webapp/wcs/stores/servlet/CatalogSearchResultView?storeId=11051&catalogId=10051&langId=-1&pageSize=20&searchText=elegant+universe

Since I don't have a life (single & no desire to go hunting) I read at night in bed before I go to sleep, so I read a LOT! You're lucky to have Ivan, although he looks terribly pale...

 

[Nereid]

Scientific American?

SciAm has had quite a number of 'forefront of physics' articles in the past year or three, and there's nary a Greek letter or equation on any page. Furthermore, many of the articles are written by those regarded as leaders in their fields - Smolin, Greene, Tegmark, Kane (maybe not a leader?), Bekenstein, ... All articles have a "More to Explore" section too.

Many local libraries carry subscriptions, your budget may stretch far enough for you to take out one of your own, and there's a (fee-based) online service too.

 

[Ivan Seeking]

You all should feel honored!

She won't talk to me about physics any more.

well...only on rare occasion and only with her eyes closed and her face all scrunched up.

...sometimes she even makes funny sounds...like she's in pain...

 

[Tsu]

Originally posted by Ivan Seeking
You all should feel honored!

She won't talk to me about physics any more.

well...only on rare occasion and only with her eyes closed and her face all scrunched up.

...sometimes she even makes funny sounds...like she's in pain...

Yer so funny, honey. BUT, I DO *TOO* TALK TO YOU ABOUT PHYSICS! It's just that, after 20 years, I'm becoming a little weary of the direct-heat version of Scrambled-Eggs-For-Brains. I'd like to check out the microwave version for a bit.

I don't know how 'honored' they should feel, either. I would think 'annoyed' would cover it better. I half expect that they're thinking as they post a few links for me "Here. Read these, kiddo, and come back when you can talk more than nonsense."

Thanx for that link, Evo. I think that's probably the way for me to go. (*reaches for credit card* 'oh boy... more Hawaiian Miles!' )

Nereid, with that on-line service of SciAm, I would have access to past issues, right? And I could run searches on different topics through their archives? (*reaches for credit card AGAIN* 'oh boy... even MORE Hawaiian Miles!' I go visit my cousin again!)

THANX, EVERYONE! You can ignore me now if you want. (But if you don't want to, that's nice, too!)

 

[Nereid]

Nereid, with that on-line service of SciAm, I would have access to past issues, right?

That's true; or rather, it was the last time I looked (I now have my very own, personal subscription, which the mailman (oops! not PC - postperson? letterdeliverer??) kindly brings me every month.
http://www.sciam.com/
You'll have to put up with pop-up ads though.

 

[Tsu]

Originally posted by Nereid
That's true; or rather, it was the last time I looked (I now have my very own, personal subscription, which the mailman (oops! not PC - postperson? letterdeliverer??) kindly brings me every month.
http://www.sciam.com/
You'll have to put up with pop-up ads though.

Why do you choose hard copy over on-line service?

edit: WAIT! OF COURSE! You don't have a computer in your bathroom?

 

[selfAdjoint]

Originally posted by Nereid
That's true; or rather, it was the last time I looked (I now have my very own, personal subscription, which the mailman (oops! not PC - postperson? letterdeliverer??) kindly brings me every month.
http://www.sciam.com/
You'll have to put up with pop-up ads though.

Mail carrier. In the US.

 

[Nereid]

Originally posted by Tsunami
Why do you choose hard copy over on-line service?

edit: WAIT! OF COURSE! You don't have a computer in your bathroom?

Trains and boats and planes (laptop batteries only last so long). The back patio, with a glass of Prosecco (laptop screens can't compete with the Sun). In bed (laptops don't take too kindly to hitting the parque if you drop them while falling asleep). Etc (Evo would understand, so would SelfAdjoint and marcus).

 

[Evo]

Nereid, you're right about needing the paper copy. BTW, I got my first subscription to Scientific American when I was around 16. It's what got me interested in Quantum Physics. They sent me a free book one time called "Phenomena of Physics" or vice versa, and I got hooked.

Actually, I do take my laptop to bed with me. I have a big bed and lots of empty space and I don't move around in my sleep, so...

Sad huh?

 

[Tsu]

I have questions.

From this page by Smolin's site (I think that's where I am anyway )
http://www.edge.org/3rd_culture/smolin03/smolin03_p3.html

My questions are in red.

"The key thing that Amelino-Camelia and others realized is that we can use the universe itself as an experimental device to probe the Planck scale. There are three different ways the universe gives us experimental probes of the Planck scale. First, there are accelerators in distant galaxies What accelerators? What causes them? that produce particles with energies much higher than we can produce in even the largest human-made accelerators. Some of these ultra-high-energy cosmic rays have been observed hitting our atmosphere with energies more than 10 million times those we have ever produced. These provide us with a set of ready-made experiments, because on their way to us they have traveled great distances through the radiation and matter that fill the universe. Indeed, there are already surprises in the data which, if they hold up, can be interpreted as due to effects of quantum gravity.

Second, we detect light and particles that have traveled billions of light years on their way across the universe to us. During the billions of years they travel, very small effects due to quantum gravity can be amplified to the point that we can detect them."
What do we use to detect them?

 

[Nereid]

Tsunami quoted: First, there are accelerators in distant galaxies that produce particles with energies much higher than we can produce in even the largest human-made accelerators.
then she asked: What accelerators? What causes them? [/color]

In the words of Stecker (p6)*: "In most theoretical work in cosmic ray astrophysics, it is generally assumed that the diffusive shock acceleration process is the most likely mechanism for accelerating particles to high energy. (See, e.g., Jones (2000) and references therein.) In this case, the maximum obtainable energy is given by Emax = keZ(u/c)BL, where u ≤ c is the shock speed, eZ is the charge of the particle being accelerated, B is the magnetic field strength, L is the size of the accelerating region and the numerical parameter k = O(1)
(Drury 1994).[/color]" Very crudely, the same sort of thing that happens in accelerators at CERN, only over far, far larger distances, greater magnetic fields, or both (p7 has a good chart ("Hillas plot") showing the B-L relationship).

*reference to the Stecker paper in this marcus thread: https://www.physicsforums.com/showthread.php?s=&threadid=11309

Tsunami quoted: Second, we detect light and particles that have traveled billions of light years on their way across the universe to us. During the billions of years they travel, very small effects due to quantum gravity can be amplified to the point that we can detect them."
then she asked: What do we use to detect them?[/color]

CCDs at the focii of telescopes. Here's a thread - started by wolfram - on our very own PF on this topic:
https://www.physicsforums.com/showthread.php?s=&threadid=9367

I'm sorry to say that I've not followed up with an analysis of the HST images of distant supernovae (there are some excellent images, taken as part of the GOODS project: https://www.physicsforums.com/showthread.php?s=&threadid=11216)

 

[Tsu]

Nereid,
"the diffusive shock acceleration process" - caused by?

YIKES! This
https://www.physicsforums.com/showthread.php?s=&threadid=9367
will have to come later with a little stronger comprehension level.

What's a CCD?

 

[selfAdjoint]

Charge coupled device, I believe. Ultra sensitive electronic gizmo for detecting faint light "at the focus of large telescopes".

 

[Tsu]

Originally posted by selfAdjoint
Charge coupled device, I believe. Ultra sensitive electronic gizmo for detecting faint light "at the focus of large telescopes".

Excellent. Thank you.

From above:
"diffusive shock acceleration" - from a supernova? Are there other sources of cosmic rays that we measure?

 

[Nereid]

SelfAdjoint is right; they're the heart of your digital camera, and your videocam (and much else). Astronomers used to use photographic emulsion, on glass plates, but CCDs have now almost completely taken over (long list of reasons why).

In a nutshell, the 'wolfram thread' is about an analysis of a Hubble Space Telescope (HST) image of a relatively nearby supernova. One possible test of LQG is whether really distant 'point sources' (objects whose angular size is way below the resolving power of the telescope) become blurred. LQG predicts that they might; in effect, Planck-scale distortions can get amplified over billions of light-years to become detectable, by the HST.

The image of the nearby supernova is nice and sharp; but it's only a weak test of LQG.

What's really neat is that you, SelfAdjoint, marcus, wolfram, and I could do the tests ourselves - the relevant HST images are in the public domain, and the image analysis software is probably free too.

'PF members find evidence to support LQG' - it'd be a nice headline, don't you think?

 

[Tsu]

You guys are awesome. Thanks so much. Good, short concise answeres (so I can get back to my reading ) and NO MATH EQUATIONS. I like that!

Originally posted by Nereid
What's really neat is that you, SelfAdjoint, marcus, wolfram, and I could do the tests ourselves - the relevant HST images are in the public domain, and the image analysis software is probably free too.

'PF members find evidence to support LQG' - it'd be a nice headline, don't you think?

That would be SO COOL! I'll get started on that right away!

 

[Nereid]

Tsunami wrote: "diffusive shock acceleration" - from a supernova? Are there other sources of cosmic rays that we measure?

Again, very crudely:
- in interstellar and inter-galactic space there are electrons and ions (atoms with some electrons missing) floating around - a plasma
- there are also weak magnetic fields embedded in the plasma
- something like a supernova explosion causes the plasma to get compressed, as the electrons and ions screaming away from the explosion smash into the calm plasma that's there (this is the shock)
- within and around the shock front, the magnetic fields get all tangled up
- some electrons and ions get bounced back and forth between the tangled knots of magnetic fields (which also keep moving - the shock front isn't standing still!); each time they bounce, they gain energy (this is the diffusive acceleration)
- eventually, some break free and head on to the Earth.

What can accelerate charged particles to such high energies? Neutron stars (very high magnetic fields, short distances for acceleration), the hearts of active galaxies (magnetic fields as strong as CERN magnets; distances about the size of the solar system), to halos of Milky Way type galaxies (really weak magnetic fields; huge huge distances).

 

[Tsu]

Ooo. Good visuals, Nereid. Those help me a lot. Thanx! My bulb is getting brighter!

But my face is beginning to hurt. I'm takin' a break...

 

[Tsu]

Ya know - except for magnetic fields. For some reason, imaging magnetic fields in space in my own mind...doesn't work. I can't seem to 'see' it. Much less tangled up ones...

This is something that Ivan and I discuss quite a lot. You guys are just hard-wired to 'see' this stuff. I'm sick of being blind!

 

[Nereid]

What makes you think I'm a guy?

(Actually, this is the internet, and I'm a dog! Shh! )

 

[Ivan Seeking]

Originally posted by Tsunami
This is something that Ivan and I discuss quite a lot. You guys are just hard-wired to 'see' this stuff. I'm sick of being blind!

Don't get me into this...I still can't understand why everyone doesn't study physics. All other subjects are just a subset of physics anyway!

 

[Ivan Seeking]

Originally posted by Nereid
What makes you think I'm a guy?

Obviously Nereid is a guy's name.

 

[Nereid]

Originally posted by Ivan Seeking
Obviously Nereid is a guy's name.

As in "A sea nymph, one of the daughters of Nereus, who were attendants upon Neptune, ..."
http://www.hyperdictionary.com/dictionary/Nereid

 

[Ivan Seeking]

Uh oh...I'm not up on my sea nymphs!

Please forgive my ignorance.

 

[selfAdjoint]

Originally posted by Nereid
As in "A sea nymph, one of the daughters of Nereus, who were attendants upon Neptune, ..."
http://www.hyperdictionary.com/dictionary/Nereid

Or an annelid worm?

 

[Nereid]

Or a moon of Neptune ...
http://www.nineplanets.org/nereid.html

 

[Tsu]

Originally posted by Ivan Seeking
Don't get me into this...I still can't understand why everyone doesn't study physics. All other subjects are just a subset of physics anyway!

Yeah, yeah, yeah...
Nereid, I was using 'guys' generically. Would it help if I said 'youse guys'? (Like in 'HEY! Youse guys! What say we stop by Dauber's [Tav] catch a few beers, hey! ) 'Course, selfAdjoint might be the only one who understands this...

 

[selfAdjoint]

Originally posted by Tsunami
Yeah, yeah, yeah...
Nereid, I was using 'guys' generically. Would it help if I said 'youse guys'? (Like in 'HEY! Youse guys! What say we stop by Dauber's [Tav] catch a few beers, hey! ) 'Course, selfAdjoint might be the only one who understands this...

When I was in high school (1947-1951) "guys" could refer to a mixed gender group. Especially if you thought you were talking to a bunch of, you know, GUYS, and discovered there was a girl along too.

 

[Tsu]

Originally posted by selfAdjoint
When I was in high school (1947-1951) "guys" could refer to a mixed gender group. Especially if you thought you were talking to a bunch of, you know, GUYS, and discovered there was a girl along too.

It was the same when I was in high school in Wisconsin 20 years later. The part I thought YOU'D really understand was the 'YOUSE guys'. I never heard that term anywhere except your part of the country (Wisconsin, Minnesota, Michigan...does that term reach up into Canada, I wonder?). I always got a charge out of the Winsonsin 'accents' of my friends - they teased me unmercifully about my 'southern' accent [I was from CALIFORNIA! - where they got 'southern' I'll never know! Oh wait! I spent the summer in Texas before I started HS in Wisconsin! THAT'S where it came from! I'll be... I'm just a magpie when it comes to accents... ]).

Nevertheless... I DO appreciate all the help given by 'youse guys'(AND GALS)! Yer TOPS! Thanks BUNCHES!

 

[Tsu]

Well, HOT BANANA! I was rereading the thread that inspired me to start this one, and things were actually beginning to make sense. Maybe it's just because it's become more familiar... Guess I'll have to admit Ivan was right. I CAN learn this stuff if I really want to. I'm still going to hang on to my 'hard-wire' theory, tho. It's the math. The math drives me BONKERS!

 

[Tsu]

OK! I see that there are 302 views as opposed to 35 replies in this thread. Those of you who are popping in here to see just how dumb I can sound or if I fall on my face - start posting some links for me! Make yourself useful! I can laugh at myself all BY myself! I don't need your help! I NEED LINKS! (please and thank you)

cc: Background Independence for the local x-ray technologist

 

[Evo]

I would also appreciate any suggestions on reading.

 

[marcus]

Originally posted by Evo
I would also appreciate any suggestions on reading.

Tsunami calls for links and Evo seconds her request and asks, more generally, for suggestions on reading. I guess you may get quite a few.

But could you both tell us: links about what, reading about what?

The thread topic says "LQG and/or ST?"
-------------------------

I think what is essential about physics is not LQG/ST but the un-watered-down "Freshman Physics" they teach to prospective majors in the first and second years.

But also at a good university there may be popular "Poet's Physics" and "Introduction to Astronomy" courses that get at what is essential.
You can learn more physics, better motivated and with less pain, from an inspired General Astronomy lecturer than you can from a stodgy Freshman Physics prof. Because the colors a star glows help tell how far it is and somehow one cares about the star.

the problems and examples in Freshman Physics were established like a church "Canon" around a hundred years ago and have an antique feel. they use cars and airplanes instead of rowboats and wagons but its all the same.
--------------
the web has some fine animations that have to do with First Year Physics and Astronomy. moving pictures are a great aid to learning
--------------
the essence of physics is getting familiar with a certain style of
modeling nature with algebra and geometry. learing to visualize differential equations and to picture nature with visual and equational mathematics. You could get links about basic physics and astronomy.
----------------

Or would you rather pursue Quantum Gravity?

--------------------

Here is the essence of the crisis and turmoil around QG.

(Best thing would be to understand the historical context by reading the non-math parts of Rovelli's Chapter 2.)

It is really an historical thing---it is not the heart of what physics is, which doesn't change.

AE gave us TWO (not one) versions of Relativity. The 1905 version has a fixed crystalline beautiful 4-D geometry called Minkowski (the name is not beautiful, nor is the name "special relativity").

The second, the 1915 version, has no set geometry. Space is amorphous and dynamic.

Quantum Field Theory is built on the 1905 version. It is built on Minkowski space. this points to an historical fact of epic proportions. Fundamental physics has so far assimilated 1905 "special" but has not yet assimilated 1915 "general".
The Two Relativities are actually extremely different.

AE considered the 1915 Relativity his real accomplishment. It is where the real break with the Newtonian tradition comes. People argue about this but I think the case is pretty strong that he was right
and there is a deep fundamental divide there.

The upshot is that in all the theories of the matter they say
"Relativistic" Quantum Field Theory and they mean 1905.

But someone who calls himself a "Relativist" is a specialist in the 1915 general theory---which is the basis of cosmology. When Rovelli says "relativity" he explicitly tells you he does not mean the 1905 special. He just gets tired saying "general" all the time. Real relativity is general relativity (for people whose specialty it is).

Yet the rest of physics (e.g. particle physics) has not yet assimilated the space of general relativity.

Rovelli's book covers a lot of history (and philosophical issues too) and a lot of that non-math stuff is in Chapter 2. Also there is an appendix at the end entirely devoted to history.

I actually think it helps to get an historical perspective (without that a merely mathematical one is incomplete)

Maybe other people will have other suggestions of what to do first (if you really want to pursue the LQG/ST topic)

 

[8LPF16]

How about starting with a sound understanding of where the 2 competing theories are different, then how new theory (LQG) resolves the difference?

This is in contrast to learning completely, all three. By the time you finished, at least one would be "obsolete" by then.


LPF

 

[Evo]

Hi Marcus! Thank you so much for taking time for such a helpful response. I am more interested in String Theory, but I am running out of books to read that are at my level (I posted those in my first post in this thread). I thought the general consensus was that LQG was a waste of time, but I've been reading the thread concerning Thiemann and am wondering now if I should pay more attention to it.

I know most people that read this thread snicker when they see someone asking for something that explains String Theory, but without the math. I can understand the concepts, I am clueless on the math.

Maybe someone here should write a “String Theory for Dummies”. Brian Greene has recently brought a lot of attention to it for laymen.

Again, thank you for being so kind and willing to help this “dummie” out.

Originally posted by 8LPF16 - How about starting with a sound understanding of where the 2 competing theories are different, then how new theory (LQG) resolves the difference?

This is in contrast to learning completely, all three. By the time you finished, at least one would be "obsolete" by then.

Also excellent advice, thanks.

 

[selfAdjoint]

Where the competing theories are different. Well, the explorations of the last week have brought some clarity on that. They use math differently, and have different expectations of how the math is related to the physics. That is the basic difference. One side uses math bottom up, the other top down.

The string people use the same kinds of math = Lie Groups and Lie Algebras, that the LQG people do, but the string people are bottom up theorists; everything you do in algebra has to check point by point with the underlying representation of the string and its worldsheet.

The Virasoro algebra they talk about comes out of the basic way the the string physicists think about interacting strings, parallel to the way Feynman diagrams describe interacting particles. The whole argument between the string people and Thiemann is over the question of whether you can just free the results of this Virasoro thing from all the detailed and important ties it has to the rest of string theory and go off and "quantize" it by itself in upper algebra land. Thiemann stll maintains that what he is doing is valid, and that the criticisms are misunderstandings.

The LQG people claim that they have new methods, rigorously derived from mathematical practice, and validly available for describing nature. Every LQG publication including Rovelli's new book reaffirms that stance.

The string people claim the LQG methods miss the point about coupling tightly to nature (or failing nature then to basic constructs like strings and branes). They will admit that the LQG math may be valid (though they have their doubts...), but deny that anything the LQG program has pproduced can describe nature at all.

In all of this the fact that string theory itself has no verifiable predictions is lost (I thought they did but I was wrong). I am sadly sure that the kooks and cranks will be sneering about pots and kettles.

 

[jeff]

Originally posted by Evo
I thought the general consensus was that LQG was a waste of time, but I've been reading the thread concerning Thiemann and am wondering now if I should pay more attention to it.

Studying LQG isn't a waste of time, but studying only LQG is a mistake: There are reasons why physicists continue to show little interest in LQG. By all means satisfy your curiosity about LQG, but then move onto the stringy ideas that are actually driving current research, unless you don't feel it makes sense for a lay person such as yourself to take the opinion of the overwhelming majority of high energy theorists seriously.

 

[marcus]

Originally posted by Evo
...general consensus was that LQG was a waste of time,..

what you suggest about majority view (string being promising, loop not) was probably more true a few years back


now, I would say, LQG seems to be gaining visibility and interest----I know of several former string-theorists who have moved over into loop research (and I have not yet encountered a case of someone getting their degree in LQG and moving to string)

as of 4 or 5 years ago, like 2000, String research was vastly more voluminous----dwarfing the Loop research output---still does but to a lesser extent

back then, with some notable exceptions, loop people were rarely invited to speak at the same conferences, it was as if they did not exist

but since 2000 string research has slacked off some and loop has roughly doubled

and there is growing presence of loop research at conferences (some joint conferences), and books are appearing or will appear,

so there is a subtle shift in the picture----I have noticed it especially in the past couple of years.

However, there are still far more academic personnel, jobs, grants, research positions, available thesis advisors, etc. in string.
The loop "establishment" if you can call it that, is miniscule by comparison, nor has there been so much publicity (no Brian Greenes in the loop business)

dont know how one would measure such a "general consensus" as you call it. Probably it doesn't matter anyway. The directions in science are determined by active minorities, to a large extent, and sheer majority opinion is not too good an indicator. But I am not sure now that there even is such a "general consensus"

I noticed that the Novemeber issue of Physics World was about Quantum Gravity and they present it by 3 articles----one by a loop guy, one by a string guy, and one by a guy interested in how you can test theories by observation. That shows a balanced perspective that may be coming about.

the string guy was Susskind (one of the founders of string)
the loop guy was Rovelli (a loop founder)
the theory-testing guy was Amelino-Camelia (a quantum gravity phenomenologist, who has helped initiate that research line)

 

[jeff]

Originally posted by marcus
what you suggest about majority view (string being promising, loop not) was probably more true a few years back

I'm afraid that in fact just the opposite is true, as is easy to check for anyone with at least half a brain.

 

[8LPF16]

SelfAjoint,

quote "That is the basic difference. One side uses math bottom up, the other top down." unquote

succinct!

Could anyone offer a bite sized example of quantum geometry?
Is there a basic shape or "form"?


LPF



ps. "I am Not a frying pan!"

 

[jeff]

Originally posted by 8LPF16
SelfAjoint,

quote "That is the basic difference. One side uses math bottom up, the other top down." unquote

Wrong. The correct comparison is that in ST math follows the physics, as it should, whereas the physics (at best) follows the math in LQG. Also, reflecting the incredible richness of physical ideas in ST, the mathematics involved has far greater breadth and depth than in LQG, so much so that it's driving research in pure mathematics! Unlike with ST, you don't really need to know much to feel you understand LQG, which is the real reason for it's popularity outside the physics community.

 

[Evo]

SelfAdjoint, thank you too for a good basic description!

When you both speak of Rovelli's book, are you talking about "Quantum Gravity"? He has a PDF available for download on his site, if that is the one.

Marcus, I agree, I became interested in Quantum Physics in general MANY years ago, but I think it's time for me to back track and get a historical understanding. I think that may fill in some of the blanks.

Originally posted by Jeff - unless you don't feel it makes sense for a lay person such as yourself to take the opinion of the overwhelming majority of high energy theorists seriously.

Why would you think I would not want to know what the experts in their fields say? Ah Jeff, I may be lacking in knowledge, but I tend to seek out those that know what they are talking about, of course with so many opposing views, I will have to make my own decisions about which to believe and which to question.

Being such a novice at this, I will rely on "direction" from people that know what they are talking about, and as I learn more, I will figure out who they are.

 

[selfAdjoint]

Two good books on the history of 20th century quantum research are Inward Bound, by Pais (who also wrote books about Einstein and Bohr). That's fairly technical but pretty authoritative because he author is a physicist who knew all the parties and participated in the research. He really let's you feel how each new discovery was interpreted by the physicists of the time. It covers physics from the dawn of the 20th century up to the middle sixties. Thus it misses most of the great story of gauge theory, electroweak unification and QCD, leading to the Standard Model.

The other book may be out of print: The Second Creation, by two journalists whose names I forget. It is much less technical and focusses on the development of the standard model.

A really technical book, but wonderful in its way, is QED and the Men who Made it by Schweber. Did you know that Julian Schwinger was a boy genius? A real one who made productive contributions by the age of 17. The book will tell you all about those contributions, with lots of equations.

P.S. Yes, the book we are citing is the one with the PDF.

 

[jeff]

Originally posted by Evo
...I will figure out who they [people who know what they're talking about] are.

When it comes to LQG vs ST at PF, it's more a question of motives than knowledge - this isn't the physics community and people get "attached", to put it charitably, to theories for reasons that make no sense. So if you'd like to know what the true status of LQG is in the physics community, rather than waste time figuring out who at PF "knows what they're talking about", just visit the websites of 20 or 30 of the world's top university physics departments and see how often LQG is mentioned in the list of subjects being researched by their respective high energy theory groups. After you discover that the number is zero (or maybe one) come back here and ask the PF-LQG-cult members why they don't think it's fair to ever mention this? I mean, the first thing I ask about a complicated issue that I don't really understand but am interested in is, what do the experts think? Anyway, don't take my word for any of this, verify it on your own. Go visit the physics department home pages of stanford, mit, harvard, princeton, cal tech, chicago, berklee, columbia, cambridge, etc. Doing so certainly won't hurt your ability to judge who's posts need to be taken with more than a grain of salt, at least when it comes to this subject. After that, satisfy your basic curiosity about LQG, including why it's viewed as being so implausible by virtually everyone working in QG and HET.