Is there a support group for spouses of physicists?

[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.

 

[Evo]

Self Adjoint - Thank you! I will look into these! I really cannot express how much I appreciate the extra effort that you and Marcus have taken to come down to my level and offer material that I may be able to comprehend.

I know most of the people here are so far beyond where I am that it is difficult to envision what I need.

You two are AWESOME! I know smiley faces are beneath you "smart guys", but it does express my gratitude for what you have done for me.

 

[Evo]

Originally posted by jeff
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.

Yes, I agree that people do get very attached to what they believe, and I will seek out these other opinions. But I feel that you tend to "talk above" me rather than talk "to me" on my level, well maybe that's asking a bit too much, kind of like me talking optical networks to a kindergartener. But Marcus in his first post on this thread stated that popular opinion was against LQG and much more slanted towards ST. Isn’t this in support of what you are saying?
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/showth...8448#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]

This is the BEST thread!

Evo, thanks for taking over for me and posting my thoughts and feelings! I will PM you the first chance I get. *aside to other posters here - you know, Evo and I were separated at birth! We are SO (oddly) alike in SO many things... She expresses us better, tho!* I have been hammered at work and haven't had time to do a lot of additional study on ST/LQG theories. I have another week or two before I can get back into it hot and heavy.

Marcus and selfAdjoint, thanks so incredibly much for your posts. You guys are the BEST! While I may not be posting much here right now, I AM reading and keeping up (well, sort of... like I said, I'm hammered at work). Please keep this going while I'm 'out of site'!

Jeff! You're next! Be ready! (sorry! I can't live without smilies!) Fun and laughter are the best parts of life! Trust me on this one. If you ever have to have a cat scan or a barium enema - you're going to want someone like ME doing it! Yes, I've been told I can make even a barium enema a FUN experience! (What a claim to fame, ya? )

 

[jeff]

Originally posted by Tsunami
Jeff! You're next! Be ready!

Originally posted by Tsunami
If you ever have to have a...barium enema...

Originally posted by Tsunami
I've been told I can make even a barium enema a FUN experience!

 

[Tsu]

ROTFLMAOAPMP!

Oh, jeff. *wiping tears from my eyes* You are FUNNY! There's hope for you nerds, yet! I'm looking forward to quizzing you about ST, if you have time. I promise not to 'dry tip' you if you do!

 

[Tsu]

Well, I'm completely loaded up with material. I expect to be reading for MONTHS! The thing is - I can find all kinds of stuff on the net about ST (for dummies), but not much on LQG. Oh well... I'm getting there. I have some books and videos chosen and in my basket at the PF Bookstore, I just have one more book to choose and then I'm outta there! Am I doing this backwards? (as usual) Would I understand LQG better (easier) if I first got a good handle on ST?

Jeff! Straighten me out here, tho! 'String Theory' refers to the original bosonic string theory? And supersymmetry was added to these theories to become 'Superstring Theory'? And what was added to what to become M-Theory (which is on the back burner until I figure out the first two)? And LQG has taken ST stuff and gone off in another direction? I'm also confused with the number of dimensions in each. Can you help? Will finally getting to watch Elegant Universe straighten this out for me? If so, you can ignore this question. In another week (or three ) I'll be back in here with more questions.
THANK YOU!

 

[ranyart]

Originally posted by Tsunami
Well, I'm completely loaded up with material. I expect to be reading for MONTHS! The thing is - I can find all kinds of stuff on the net about ST (for dummies), but not much on LQG. Oh well... I'm getting there. I have some books and videos chosen and in my basket at the PF Bookstore, I just have one more book to choose and then I'm outta there! Am I doing this backwards? (as usual) Would I understand LQG better (easier) if I first got a good handle on ST?

Jeff! Straighten me out here, tho! 'String Theory' refers to the original bosonic string theory? And supersymmetry was added to these theories to become 'Superstring Theory'? And what was added to what to become M-Theory (which is on the back burner until I figure out the first two)? And LQG has taken ST stuff and gone off in another direction? I'm also confused with the number of dimensions in each. Can you help? Will finally getting to watch Elegant Universe straighten this out for me? If so, you can ignore this question. In another week (or three ) I'll be back in here with more questions.
THANK YOU!

Tsunami, before the Wave comes crashing down on jeff maybe you should consider Ed Witten:http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=ea+Witten,+Edward

also here:http://www.sns.ias.edu/~witten/

Not only is he a much pleasant person, he is instrumental in throwing String Theory into the 21st century!

 

[Tsu]

Originally posted by ranyart
Tsunami, before the Wave comes crashing down on jeff maybe you should consider Ed Witten:http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=ea+Witten,+Edward

also here:http://www.sns.ias.edu/~witten/

Not only is he a much pleasant person, he is instrumental in throwing String Theory into the 21st century!

You mean the TSUNAMI (wave)?? (ok. i'll stop now.)

So which one of those 25 items at the first site would you suggest? Few of them appear to be written in English (read NON-physicist language) and the ones that look as though they might be, aren't. I don't speak Physicsese.

The second one looked more promising until I started the second paragraph of the first article. It's frustrating and discouraging if you're not a 'real' scientist. Remember! You're dealing with a true Physics Dummy here! But I WANT TO KNOW WHAT IT'S ALL ABOUT!

Besides, I promised Jeff I wouldn't 'dry tip' him if he helped me out a little bit with ST.

Let me ask you this, though. If science finally decides that 'this' (ST or M-Theory or LQG) is 'the one' - what's that going to tell us? How the universe began? What banged? Did God do it or is it just random-chance chaos at work? The recipe for primordial soup? WHAT?

 

[arivero]

Originally posted by Tsunami
Let me ask you this, though. If science finally decides that 'this' (ST or M-Theory or LQG) is 'the one' - what's that going to tell us? How the universe began? What banged? Did God do it or is it just random-chance chaos at work? The recipe for primordial soup? WHAT? [/B]

You could want to check the table in page 60 of http://arxiv.org/ps/hep-th/0303185

As for philosophical results, notice the title of quant-ph/9802020 from Carlo Rovelli.

 

[marcus]

Originally posted by arivero
You could want to check the table in page 60 of http://arxiv.org/hep-th/0303185

As for philosophical results, notice the title of quant-ph/9802020 from Carlo Rovelli.

I have edited the links that Alejandro gave to make
sure they work for my (sometimes reluctant) browser
http://arxiv.org/hep-th/0303185
http://arxiv.org/quant-ph/9802020


"Incerto tempore, incertisque loci": Can we compute the exact time at which a quantum measurement happens?
Carlo Rovelli
6 pages
Published in "Foundations of Physics" 28 (1998) 1031-1043

----quote from Rovelli's abstract----
Without addressing the measurement problem (i.e. what causes the wave function to "collapse", or to "branch", or a history to become realized, or a property to actualize), I discuss the problem of the timing of the quantum measurement: assuming that in an appropriate sense a measurement happens, when precisely does it happen? This question can be posed within most interpretations of quantum mechanics. By introducing the operator M, which measures whether or not the quantum measurement has happened, I suggest that, contrary to what is often claimed, quantum mechanics does provide a precise answer to this question, although a somewhat surprising one.
------end quote-----

The other link Alejandro gives here is to the table on page 60
of "How far are we from the quantum theory of gravity?"

This table summarizes the results of section 8 of that paper
"How well do the theories answer the questions?"
This section compares String and Loop systematically point by point.
The author does research in both fields and knows both theories first-hand, so it's an interesting comparison.
Section 8 begins on page 59 (right before this table) with
a profound and thought-provoking truth uttered by Jean Cretien, the Prime Minister of Canada.

-------------
Rovelli's Latin quote "At a random time and in a random place"
is from Lucretius "De Rerum Natura"
-------------
One may assume that Smolin likes Loop Gravity since he is one of its founders. But the fact remains that he has published a number of String papers, has a detailed knowledge of both fields, and
even wrote a Stringy paper last month.
His "How far are we..." tries to make a balanced objective comparison.
That is what the table on page 60 tries to do.
Some String/Brane theorists may complain it doesn't make their theory look good enough. They could try making their own table.
Smolin's recent string paper, with Magueijo, was
hep-th/0401087.

 

[arivero]

Originally posted by marcus

http://arxiv.org/abs/quant-ph/980202
"Incerto tempore, incertisque loci":
Published in "Foundations of Physics" 28 (1998) 1031-1043

Actually, the main clue is the title itself. Sorry the pedantic mode, but as you can know, I like very much to overuse some classics.
With this quote, Rovelli refers to a late anarchist author, Titus Lucretius

corpora, quom deorsum rectum per inane feruntur
ponderibus propriis, incerto tempore ferme
incertisque locis spatio depellere paulum
tantum quod momem mutatum dicere possis

Er... did I say an-archist? Well it is true that Lucretius's book was used last December in a bomb sent from Bologna to Brussels EuroJustice department, and it is also true that the current translation to Spanish is due to an anarchist-biased philologist. But I probably mean to say a-tomist. Really, it is the only whole surviving text on ancient atomic theory, although it does not work out the mathematical issues.

Also Lee Smoolin chooses this word to title his divulgation article in Scientific American this January: Atoms of Geometry

Ancient atomic theory has two variants. A static one, devised to calculate volume of any figure, and a dynamical one, aimed to absorb the arguments of Zeno without requiring the limit procedure Newton uses. To this end, the world is considered to be a foam or lattice of vacuum separated by atoms, or a set of atoms separated by vacuum, and then a lost rule to refine the lattice. The only information contained in atoms is rhythm (?), contact and direction, so -I guess- they can not be divided because they do not carry, by themselves, spatial information. Duality is important to Democritus, and he uses a wordplay to remark it, calling sometimes "muth-on" and "on", say no-zing and zing, to vacuum and atoms respectively. Note that we have respected the nomenclature "-on" to name elementary particles.

LQG postulates a intriguing quantum of area, because it is not a solid chunk of space, but simply the fact that if you measure an area, the result will always be above this value. Just as in special relativity any measurement of speed is always below c.

Speaking of that, old atomic theory also tells that there is a maximum speed, anhyperbleton and that atoms should move freely at this speed but that a hidden cause, perhaps a sort of imperceptible interaction with vacuum or with other atoms, will ultimatelly cause the bouncing and scattering that let us to define matter. This imperceptible deviation, or clinamen, is the one alluded in the verses used by Rovelli

 

[marcus]

Originally posted by Tsunami
...Let me ask you this, though. If science finally decides that 'this' (ST or M-Theory or LQG) is 'the one' - what's that going to tell us? How the universe began? What banged? Did God do it or is it just random-chance chaos at work? The recipe for primordial soup? WHAT?

I am still mulling over what it was Alejandro meant when he
pointed you to the table on page 60 of
"How far are we from the theory of quantum gravity?"

I believe it was because Smolin has thought deeply about
just what it is that a quantum theory of gravity (if we finally
settle on one) should tell us.

What questions should a satisfactory theory of gravity answer?

Smolin thinks carefully about this and lays out the questions.

that is what allows him to compare progress at answering them and to judge "How far" we still are.
-------------

Smolin also has a short 4-page section right at the beginning
"Physical questions the theories should answer"
this is pages 10-14
it says what questions a satisfactory quantum theory of gravity]
should answer

so hey! that answers your question, Tsunami!
Alejandro's link was very much to the point, which i did not see
immediately (par for the course, I often have to look twice at things)
------------------

 

[arivero]

Originally posted by marcus
I am still mulling over what it was Alejandro meant when he
pointed you to the table on page 60 of
"How far are we from the theory of quantum gravity?"

Well, I can be dark, but I am not Heraclitus! The table shows an evaluation of the questions that Loop Quantum Gravity actually aims to answer, and Tsunami was just asking what's that [theory] going to tell us?

 

[marcus]

Originally posted by arivero


Also Lee Smoolin chooses this word to title his divulgation article in Scientific American this January: Atoms of Geometry

...
LQG postulates a intriguing quantum of area, because it is not a solid chunk of space, but simply the fact that if you measure an area, the result will always be above this value. Just as in special relativity any measurement of speed is always below c.

Speaking of that, old atomic theory also tells that there is a maximum speed, anhyperbleton and that atoms should move freely at this speed but that a hidden cause, perhaps a sort of imperceptible interaction with vacuum or with other atoms, will ultimatelly cause the bouncing and scattering that let us to define matter. This imperceptible deviation, or clinamen, is the one alluded in the verses used by Rovelli

the mediterranean world is at the root of science and we will not be surprised if Lucretius said some things that again Rovelli says

but Smolin's article was "Atoms of Space and Time" I think and
not geometry---although spacetime and geometry is maybe the same thing.

thanks for the latin text. it is amazing that there was an ancient idea of a speed limit
because the modern speed limit idea only goes back to AE's paper of
1905---an-hyper-bleton is a funny word
"not-more-speedy(entity)"?

 

[arivero]

You are right, Atoms of Space and Time. I was quoting from memory.

The atomist abhors infinity even more strongly that Aristotle abhors vacuum. So for them it was logical to put a maximum to speed, but they looked for this funny name to avoid paradoxes, I supposse. The word appears in an extant letter of Epicurus, if I remember well.

I have brought here Lucretius because he partly tryes to answer the more metaphysical questions of Tsunami, which obviously are not going to be addressed in a paper of physics.

 

[marcus]

Originally posted by arivero

Ancient atomic theory has two variants. ... The only information contained in atoms is rhythm (?), contact and direction, so -I guess- they can not be divided because they do not carry, by themselves, spatial information. ...


LQG postulates a intriguing quantum of area, because it is not a solid chunk of space, but simply the fact that if you measure an area, the result will always be above this value. Just as in special relativity any measurement of speed is always below c.

...

it seems to me to be a good idea to compare ancient physics theory
(Lucretius c.100BC to c.50BC?) to LQG

I think by "rythm" you mean rhythm, peculiar English spelling.

I did not know that Lucretian atoms contained rhythm information, associating existence with vibration frequency, on some level. an idea also associated with modern physics.
lots of surprises this morning.

the key word always seem to be "measurement"
if one part of the universe measures another part, then...
every puzzle seems sometime to come down to this

so for example: space is not made of lumps, but if you
measure the surface area or volume of something the result must be from
a discrete set of possibilities
like drops of dew on the spider's thread

 

[marcus]

always exciting to read and think about your posts A.R.
now I feel as if I have drunk too many cups of coffee
but it is just the philosophical considerations not the caffeine

must attend to mundane chore and return to this later

 

[arivero]

crosslink

A subthread on Lucretius and family has been open at
https://www.physicsforums.com/showthread.php?s=&threadid=14281

 

[glitterboi]

G-day. I read through all the posts and ah have quantized your mind. ;)

You're natually people-oriented and curious about them [pyschology I wager]. You may be better off learning a unpopular protoscience - Numerology. this way you gain an insightful understanding of the differences between you and the physics freaks and labcoats. then you could also be more educated in realizing how important numbers and symbols (which are embedded numbers also) in the world around us and related it is to everything.

Brain hard-"wired" differently: From my impression, you need finely tuned processing speed, laser precision focus, and specialized perception depth to really comprehend [theoretical] physics or the mysteries of life. Some people can be taught to understand it while others are naturally capable and will exceed those who can only be taught.

this capability belongs to a number in Numerology - 7. Theoretical physics exemplify this vibration. here's a snippet:

7-Mind, you are the searcher and the seeker of the truth.
You have a clear and compelling sense of yourself as a spiritual being. As a result, your life path is devoted to investigations into the unknown, and finding the answers to the mysteries of life.
You are well-equipped to handle your task. You possesses a fine mind; you are an analytical thinker, capable of great concentration and theoretical insight. You enjoy research, and putting the pieces of an intellectual puzzle together. Once you have enough pieces in place, you are capable of highly creative insight and practical solutions to problems.
-Decoz master numerology program 6.0

Notice, it mentioned "great" concentration. a highly understatement. It is the best and unmatched among the basic numbers from 1 - 6 and 8- 9.

If you're interested, I'll provide more information.

Marcus: Would you indulge me? I gather you have this vibration somewhere in your birthdate or your names or both. I like to test Numerology's postulates given above because I rarely run across 7s except from reading their theophysics.

later

Originally posted by Tsunami
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?

 

[Nereid]

Welcome to Physics Forums glitterboi!

Would you mind if I suggest that there's a very good sub-forum here for Numerology and related topics? It's called Theory Development, and if you post there I'm sure you'll find many folk who are interested in discussing your ideas (and they can be quite energetic about it too).

Personally, I'd prefer that this thread remains on the topic of LQG and/or ST, and unless I'm mistaken, numerology is not part of either.

Thank you in advance for your cooperation.