Is String Theory really a theory?

[whydoyouwanttoknow]

Hey guys. This is my first post.

I don't have any background in physics so please don't just throw equations and stuff at me and expect me to understand.

So is string theory really a theory? It seems to me that theories need to have evidence to back them up. You need to be able to look and see how it is applied. For the Big Bang theory we can see that the universe is expanding. For evolution we can see that new species arrive, there's mutations in genes, etc.

For string theory we have what?

Isn't it more of a conjecture or a philosophy?

Well just got to say that you guys seem pretty hardcore from what I've been reading. Hopefully I'll learn some stuff.

 

[jeff]

...you guys seem pretty hardcore...

When you're just a beginner, it's easy in this particular forum to get fooled into believing people here know more than they actually do. Truthfully there's hardly anyone here who knows what they're doing. Unfortunately some of them post with a misleading air of authority. So remember to ask questions in a way that forces them to give you clear, detailed and unambiguous physics answers, and not vague or overly broad statements which try to hide the fact that they don't really understand all relevant sides of the issue. Really try hard to recognize when someone is trying to brainwash you into worshipping the same gods they do so they can avoid discussions of ideas - I have in mind string theory - that they hate simply because they are too complex and technical for them to understand.

 

[notevenwrong]

Some other advice, watch out for the following all too typical behavior of string theory proponents:

1. Evasion of questions that they don't have an answer for, or for which the answer is embarassing to their cause. You don't seem to have gotten an answer to the question of whether string theory is really a theory in any conventional sense of the term. The reason
for this is the answer is that it's not, it's a set of ideas that people would like to believe can
someday be turned into a real theory. But they've been trying without success for twenty years. For more fun along these lines, try asking string theorists to write down the equations for string theory, or to give even one experimental prediction of string theory. You'll get all sorts of incorrect answers (equations whose solutions are known not to correspond to the real world, "predictions" about what might happen, not what will happen), obfuscation, and attacks on non-believers.

2. The arrogance of string theory advocates is pretty mind-blowing. Many of them are convinced that they are brilliant since they have learned something about string theory and that anyone who doesn't believe must just be too stupid to understand. I have a Ph.D in particle theory from Princeton and have taught graduate courses in mathematics and quantum field theory at Columbia, but I've more than once heard from undergraduate string theory fanatics who inform me that I'm just too stupid and ignorant to understand the true wonderfulness of string theory. Not all of them grow out of this youthful arrogance.

 

[sol2]

Some other advice, watch out for the following all too typical behavior of string theory proponents:

1. Evasion of questions that they don't have an answer for, or for which the answer is embarassing to their cause. You don't seem to have gotten an answer to the question of whether string theory is really a theory in any conventional sense of the term. The reason
for this is the answer is that it's not, it's a set of ideas that people would like to believe can
someday be turned into a real theory. But they've been trying without success for twenty years. For more fun along these lines, try asking string theorists to write down the equations for string theory, or to give even one experimental prediction of string theory. You'll get all sorts of incorrect answers (equations whose solutions are known not to correspond to the real world, "predictions" about what might happen, not what will happen), obfuscation, and attacks on non-believers.

2. The arrogance of string theory advocates is pretty mind-blowing. Many of them are convinced that they are brilliant since they have learned something about string theory and that anyone who doesn't believe must just be too stupid to understand. I have a Ph.D in particle theory from Princeton and have taught graduate courses in mathematics and quantum field theory at Columbia, but I've more than once heard from undergraduate string theory fanatics who inform me that I'm just too stupid and ignorant to understand the true wonderfulness of string theory. Not all of them grow out of this youthful arrogance.

Peter,

For one , I do not think you are stupid.

Could we not put this aside for a minute. I mean if we wanted too, could we not ask what your alliance is with Smolin, and whether this positon is more reputable? If we did this, and you answered, then we'd have to conclude there was some bias?

Well I know better then, to present such characteristics of people's nature in regards to theoretical positions then, because we indeed know the important criteria, and that has to do with experimentation, right? I assume everyone is on the same wave length? We have seen enough disrespect to the Grandfathers, even though we are building on their mistakes?

What are your thoughts on probing dimenisons in context of what I have shown in regards to the graviton(energy in energy out-where has it gone if not equal?) in regards to the colliders? Do you have another explanation?

 

[whydoyouwanttoknow]

What's a graviton?

Exactly. :D

 

[sol2]

What's a graviton?

Exactly. :D

A quantizied gravitational wave...

I'm not a string theorist...so if my answer is vague...

its for a good reason so you build with what you got, and see who siad what and hopefully...you come up with the right answer.

Maybe Jeff can respond as he pays a lot of lip service but does not contribute much. Or Peter, and we can expect a direct answer.

 

[whydoyouwanttoknow]

A quantizied gravitational wave...

I'm not a string theorist...so if my answer is vague...

its for a good reason so you build with what you got, and see who siad what and hopefully...you come up with the right answer.

Maybe Jeff can respond as he pays a lot of lip service but does not contribute much. Or Peter, and we can expect a direct answer.

Oh, I know that much. They're just a bit of wishful thinking at the moment though I believe because we know bugger all about gravity.

I think they just have a graviton because it would make sense.

 

[jeff]

Some other advice, watch out for the following all too typical behavior of string theory proponents:

1. Evasion of questions that they don't have an answer for, or for which the answer is embarassing to their cause. You don't seem to have gotten an answer to the question of whether string theory is really a theory in any conventional sense of the term. The reason
for this is the answer is that it's not, it's a set of ideas that people would like to believe can
someday be turned into a real theory. But they've been trying without success for twenty years. For more fun along these lines, try asking string theorists to write down the equations for string theory, or to give even one experimental prediction of string theory. You'll get all sorts of incorrect answers (equations whose solutions are known not to correspond to the real world, "predictions" about what might happen, not what will happen), obfuscation, and attacks on non-believers.

2. The arrogance of string theory advocates is pretty mind-blowing. Many of them are convinced that they are brilliant since they have learned something about string theory and that anyone who doesn't believe must just be too stupid to understand. I have a Ph.D in particle theory from Princeton and have taught graduate courses in mathematics and quantum field theory at Columbia, but I've more than once heard from undergraduate string theory fanatics who inform me that I'm just too stupid and ignorant to understand the true wonderfulness of string theory. Not all of them grow out of this youthful arrogance.

whydoyouwanttoknow,

All current approaches to the problem of how to quantize gravity or how to integrate all fundamental interactions into a single unified framework are more research program than theory. This is an inevitability when experiment isn’t able to keep up with imagination. The question is then how worthwhile a given research program is. This is a physics and not a politics question, and the one you should put to me, notevenwrong, and everyone else who posts in this thread.

 

[sol2]

Oh, I know that much. They're just a bit of wishful thinking at the moment though I believe because we know bugger all about gravity.

I think they just have a graviton because it would make sense.

On the contrary we know lots about gravity.

Check out Taylor and Hulse and tell me how this energy is being lost and you will understand why Mercury rotation give off information.

The question I ask Peter is legite, about energy in and energy out? Looking at the examples I just gave you, will help you undertand what I mean.

Hopefully Jeff or Peter will respond appropriately and not with some politcal jargon.

 

[marcus]

Some other advice, watch out for the following all too typical behavior of string theory proponents:

1. Evasion of questions that they don't have an answer for, or for which the answer is embarassing to their cause. You don't seem to have gotten an answer to the question of whether string theory is really a theory in any conventional sense of the term. The reason
for this is the answer is that it's not, it's a set of ideas that people would like to believe can
someday be turned into a real theory. But they've been trying without success for twenty years. For more fun along these lines, try asking string theorists to write down the equations for string theory, or to give even one experimental prediction of string theory. You'll get all sorts of incorrect answers (equations whose solutions are known not to correspond to the real world, "predictions" about what might happen, not what will happen), obfuscation, and attacks on non-believers.

2. The arrogance of string theory advocates is pretty mind-blowing. Many of them are convinced that they are brilliant since they have learned something about string theory and that anyone who doesn't believe must just be too stupid to understand. I have a Ph.D in particle theory from Princeton and have taught graduate courses in mathematics and quantum field theory at Columbia, but I've more than once heard from undergraduate string theory fanatics who inform me that I'm just too stupid and ignorant to understand the true wonderfulness of string theory. Not all of them grow out of this youthful arrogance.

Sol, I was really astonished when you replied to this with misinformed innuendo. AFAIK Peter has never once urged anybody to study Loop Quantum Gravity. I have never seen any signs of an "alliance" with Smolin.
You talk as if you thought there was a conspiracy to discredit String

I have followed Peter's blog since it's beginning several months ago and
his occasional criticisms of String hype, confusion, and triumphalism have been straight and disinterested-----not slanted towards the LQG alternative.

Peter is one of the few objective observers who speaks his mind and your unfounded hint that he might be a "crypto-Looper" with an ax to grind comes across to me as a smear tactic.

this is what I am referring to:
Sol: "I mean if we wanted too, could we not ask what your alliance is with Smolin, and whether this positon is more reputable? If we did this, and you answered, then we'd have to conclude there was some bias?"

I think you should retract that.

 

[jeff]

Jeff..pays a lot of lip service...

My experience at PF has taught me that the only questions worth my time in answering are those that are well-posed and addressed directly to me.

 

[sol2]

My experience at PF has taught me that the only questions worth my time in answering are those that are well-posed and addressed directly to me.

you mean...like about your knowledge of holography?

It's not nice to use other peoples excuses(Chroot)

 

[sol2]

Sol, I was really astonished when you replied to this with misinformed innuendo. AFAIK Peter has never once urged anybody to study Loop Quantum Gravity. I have never seen any signs of an "alliance" with Smolin.
You talk as if you thought there was a conspiracy to discredit String

I have followed Peter's blog since it's beginning several months ago and
his occasional criticisms of String hype, confusion, and triumphalism have been straight and disinterested-----not slanted towards the LQG alternative.

Peter is one of the few objective observers who speaks his mind and your unfounded hint that he might be a "crypto-Looper" with an ax to grind comes across to me as a smear tactic.

this is what I am referring to:
Sol: "I mean if we wanted too, could we not ask what your alliance is with Smolin, and whether this positon is more reputable? If we did this, and you answered, then we'd have to conclude there was some bias?"

I think you should retract that.

I know what Peter is like, and in the second paragraph I dismiss this feature. Please read again.

Well I know better then, to present such characteristics of people's nature in regards to theoretical positions then, because we indeed know the important criteria, and that has to do with experimentation, right? I assume everyone is on the same wave length?

Let's think about the beginning of this thread then and hoepfully people are not thinking I am hijacking because of a question asked. It has diverged now into something else? I have gone to the heart of the original question.

So is string theory really a theory? It seems to me that theories need to have evidence to back them up. You need to be able to look and see how it is applied.

Peter or Jeff can answer with "credibitly" as to what is being done in the colliders. String theory developed out of the need to comprehend where this energy was going, and pushing for great energy requirments, found limitations.

You talk as if you thought there was a conspiracy to discredit String

No, just putting everyine on the same playing field

Anyone can correct here. I'd appreciate it.

 

[notevenwrong]

could we not ask what your alliance is with Smolin

My interests and background are rather different than Smolin's. He has been doing quantum gravity from the beginning of his career more than 25 years ago (he and I
overlapped at Harvard where I was an undergraduate, he was a graduate student). He approaches quantum gravity often by trying to dig into the deep conceptual and philosophical problems that it raises. My background is in quantum field theory and mathematics, and to the extent that I think about quantum gravity it is from a particle physicist and mathematician's point of view, which is rather different than Smolin's. One thing he and I agree on though is that the current state of fundamental theoretical physics is quite disturbing, with a dangerous "group-think" about string theory. He and I have met and correspond every so often, but I correspond with a lot of people on these topics. The recent behavior of Susskind in response to Smolin's serious criticism of the unscientific nature of "anthropic" reasoning is an example of the all too common way in which some string theorists react to any criticism of what they are doing.

I'm not a proponent of LQG, although I find it a more promising idea about quantizing gravity than string theory. Unlike string theory it seems to me to be a healthy part of physics, with a reasonable number of people working on it and slowly making progress. Someday we'll know enough to see how well some of the LQG ideas work.
No one knows the right answer to the question of how to quantize gravity. Physics would be a lot healthier if there were many different research programs going on in this area, not just one huge dominant one with one small challenger.

 

[marcus]

I mean that kindly, sol. It would be better if you retracted the innuendo.

I think you have a problem with anyone criticising Leonard Susskind and the emotion shows when you use phrases like "respect for the Grandfathers" or "disresepect for the Grandfathers".

We should try to deal with this problem humanely.

I believe Susskind's influence is harmful to String research program---it distorts it, takes it in unscientific directions, and damages respect for it.
It is a case where one needs to amputate a limb to save the patient.
Someone in arXiv recently rejected a paper submitted by Susskind and IMO this did Susskind a great favor and was protective of String research interests.

Think about what that means. ArXiv never rejects stuff from established academic people but they made an exception in Susskind's case---probably the only time in the dozen or so years ArXiv has been running. He has gone wacko and must be muzzled for his own good and the good of String research.

But I also believe in respecting Grandfathers, and indeed even ordinary grandfathers and grandmothers! We should all treat each other with respect expecially distinguished old scholars. So what do you do?

For starters, sol, you could amputate the Anthropic Principle from your own thinking. It is the basic diseased member that needs excision. Susskind started damaging String interests the day he began appealing to it. It doesn't matter what you can say about different kinds of AP or different philosophical justifications for this version or that---the whole thing is in bad odor. It is, unfortunately, a question of biting the bullet.

the String/LQG debate is a whole other business, almost forgotten what with all this AP noise. Once Susskind is retired or under control we can all have a cup of tea and discuss the Loop vs. String prospects politely, as they did in Berlin last October.

 

[whydoyouwanttoknow]

So, um, the answer is that it's not a theory?

 

[marcus]

the P word: phenomenology

whydoyouwanttoknow,

All current approaches to the problem of how to quantize gravity or how to integrate all fundamental interactions into a single unified framework are more research program than theory...

Two separate aims jeff mentions.
A. quantize gravity
B. integrate all fundamental interactions

Loop people address problem A.
String people want to do B and get A as a bonus or byproduct.

What distinguishes a theory from a theory-under-development or a Bright Hope of a theory or, to put it more carefully a "research program" is
phenomenology: does it make predictions you can test?

the latest conference on this was in Poland in February 2004
the topic of WS-2004 was "Quantum Gravity Phenomenology"
It lasted 10 days from 4Feb to 14Feb and had talks by a dozen or more experts. Several people doing observational work---the best known
was Ted Jacobson. Lee Smolin, a theorist who has make some predictions
that the observation people are trying to shoot down, was there and
gave 3 of the talks. I will get the link.

Looking over the talks from this 10-day symposium is a good way to
gauge the progress in Loop Gravity from being just an untestable "research program" to becoming a real physical theory that can either be confirmed or proven wrong by astronomical observations (the leading type is gammaray burst astronomy, discussed at WS-2004).

[edit: here's the link to that symposium]
http://ws2004.ift.uni.wroc.pl/html.html
click on "lectures"

I don't say LQG has reached maturity, I am saying look for yourself and gauge the progress. (then equate it with String if you want to)

 

[sol2]

I think you have a problem with anyone criticising Leonard Susskind and the emotion shows when you use phrases like "respect for the Grandfathers" or "disresepect for the Grandfathers".

This reference is in regard to the predecessors who have lead our thinking.

Here we might inject, Penrose, or Wheeler, and even Kip? I think you have to be sixty and over to qualify

Einsteins position on EPR, and what did John Bell do for us? Now we have these crazy people who talk about quantum entanglement? And now imagine...teleportation

Theoretical positions change the way we percieve things, although indeed, must be grounded in some reality? In order to delve into those theoretcial positions it mght be a philosophy that begins the creation of this math or that math? There had to be some logical reasoning applied to the pursuate of any of these directions.

Again, Einstein did not like the spookiness, but things have changed. Penrose saw this when he presented the quanglement issue? I showed Wheeler's Geon, for this specific reason also. There was thinking behind these postions, although not always right, they lead to other conclusions

 

[sol2]

My interests and background are rather different than Smolin's. He has been doing quantum gravity from the beginning of his career more than 25 years ago (he and I
overlapped at Harvard where I was an undergraduate, he was a graduate student). He approaches quantum gravity often by trying to dig into the deep conceptual and philosophical problems that it raises. My background is in quantum field theory and mathematics, and to the extent that I think about quantum gravity it is from a particle physicist and mathematician's point of view, which is rather different than Smolin's. One thing he and I agree on though is that the current state of fundamental theoretical physics is quite disturbing, with a dangerous "group-think" about string theory. He and I have met and correspond every so often, but I correspond with a lot of people on these topics. The recent behavior of Susskind in response to Smolin's serious criticism of the unscientific nature of "anthropic" reasoning is an example of the all too common way in which some string theorists react to any criticism of what they are doing.

I'm not a proponent of LQG, although I find it a more promising idea about quantizing gravity than string theory. Unlike string theory it seems to me to be a healthy part of physics, with a reasonable number of people working on it and slowly making progress. Someday we'll know enough to see how well some of the LQG ideas work.
No one knows the right answer to the question of how to quantize gravity. Physics would be a lot healthier if there were many different research programs going on in this area, not just one huge dominant one with one small challenger.

Thanks Peter for being honest.

Did you see the importance of the question I asked in regards to a anomaly that exists in the colliders?

I am a outsider, looking in, and wondering what lead these thinkers to conclude these extra dimensions, and to demonstrate a philsophical position, is much more deeply considered, then being past off as, flights of fancy.

regards,

 

[sol2]

Two separate aims jeff mentions.
A. quantize gravity
B. integrate all fundamental interactions

The gravitational waves were already quantizied in the graviton.

I have concistently showed that the integral approach is being implored right now from a LQG perspective in Glast.

If you change the question around in terms of Gamma ray detection, you would ask, what is revealed in a photon interaction going through a gravitonic gathering?

But this could hurt Strings?

"If GLAST detects violations of lorentz invariance in the form of
energy-dependent photons velocity, in agreement with theoretical
calculations, such observations and such agreement would strongly
support LQG. It would also represent a severe problem for
string/m-theory, as string theory in its current formulation
presupposes lorentz invariance is an exact symmetry of nature, valid
at all scales.

http://en.wikipedia.org/wiki/Loop_quantum_gravity"

I must admit Urs wasn't to forth coming when I asked the question.

Can someone speak to the quoted paragraph?

We all know I have lots to learn

 

[sol2]

So, um, the answer is that it's not a theory?

I think we are still debating your question?

 

[Ontoplankton]

I believe Susskind's influence is harmful to String research program---it distorts it, takes it in unscientific directions, and damages respect for it.

(...)

He has gone wacko and must be muzzled for his own good and the good of String research.

And muzzling people "for the good of String research" isn't unscientific?

Susskind's recently expressed opinions may or may not turn out to be true, but they seem quite sane to me, and I'm glad he's expressing them. If there's a fatal problem with the anthropic principle, please show this using careful reasoning (more careful than Smolin's) rather than calling it names like "unscientific" and "cop-out".

 

[marcus]

And muzzling people "for the good of String research" isn't unscientific?
...

science is as science does
senior people are trying to get Susskind to shut up, I gather,
his own String colleagues are the ones who have to deal with the problem

I personally don't care. If I was narrowly "anti-String" then I would be enjoying every minute of the Susskind show and rejoicing in it. From the narrow standpoint of someone only interested in Loop Quantum Gravity and allied approaches to quantizing Gen Rel, I would be happy about everything that has happened in String since the Jan2003 Kachru paper, the 10¹⁰⁰ stringy Vacuums, Susskind's attempted salvage by Anthropery and the Landscape. It has been horrible for String and is apparently causing an exodus of researchers. My personal point of view is not that one-sided. I assume other stringfolk are pressuring him to stop
and I wish them all success.

whoever at arXiv suppressed Susskind's first response to Smolin did Susskind a favor---which he wasted by sending the paper out to a big email list so it became semipublic anyway (I haven't seen it)

arXiv is one of the central institutions of science---the "e-prints"---an organ of the new post-WWW science. arXiv did something unprecedented in muzzling Susskind in this case, and it is easily seen that it was done
in Susskind interest and in String interest. If you think that was "unscientific" then take it up with Ginsparg at arXiv (dont quarrel with me about it)----science has to be a self-regulating community and there are other considerations that must be balanced against free access to publication

 

[CJames]

I'm no physicist so this is a question not a statement. In "The Elegent Universe" Greene makes some mention of branes being used to explain black holes. They used the theory to build I five dimensional black hole, and then developed five dimensional relativity to see if the equations matched and they did. Is this the closest they have gotten to experimental prediction? They did, afteral, predict something before verifying it through conventional theory. If so, is this enough to start calling it a theory in progress rather than a well developed hypothesis or research project? Or would this even be enough to start calling it a theory?

Later.

 

[jeff]

Look, the issue has never been whether we need to invoke the anthropic principle or whether it indicates some basic flaw in string theory. The issue is that people are wasting time trying to solve problems that string theory in it's current state of development isn't ready for. So when you read discussions about the poor state of the collective "mental health" of the string community, it's not about their refusal to admit that string theory is somehow pathological - it clearly isn't - but rather that they need to stop trying to make huge conceptual leaps and instead work towards making more incremental and hence surer progress.

 

[marcus]

So, um, the answer is that it's not a theory?

Read jeff's post.
jeff is our unofficial string-spokesman here at PF
he says it is a "Research Program", as opposed to a theory
he indicates he believes, for various reasons, that it is a very promising program

String may in time become a well-developed scientific theory and
make unequivocal predictions of definite numbers that can be tested
In which case it will be possible to prove wrong.

the criterion of a scientific theory is that it bets its life on predicting
the outcome of future measurements
(if it can accommodate any future measurement it has no meaning as science----it is more of a daydream or a poem)

So when String becomes clear enough and definite enough that it could be shot down or refuted by some empirical observation it will be a scientific theory and it will be running the daily risk that this entails.

General Relativity was published in 1915 and by 1919 there was the first test, which could have invalidated it but didnt, and it continues to be testedeven today with things like Gravity Probe B satellite, and it could be found to be off by even a little----in the sixth decimal place, like----at any time but it hasnt yet. That is a theory.

 

[marcus]

... that string theory is somehow pathological - it clearly isn't - but rather that they need to stop trying to make huge conceptual leaps and instead work towards making more incremental and hence surer progress.

Yes
there was a good, lengthier, post by Lubos Motl to this effect
He said that the "string cosmology" stuff was premature
He said young researchers in the field should be advised not to
work on the more optimistic speculative things (I think he meant
"colliding braneworlds" and stringy multiverses and such) but instead
to grapple with basic problems. the post contained warnings and
he used the word "premature" more than once. I will try to find it
unless someone else can come up with a link.

In that same post, Lubos mentioned the need for "background-universal"
string models. Sounds encouragingly like background independent

On hearsay, I believe also that Lubos is very strong in rejecting Anthropery.

If we could filter out the voices of silliness we could hear the reasonable voice of string more clearly.

[edit: this blog has a pointer to a relevant Lubos post, and I see Peter was agreeing with Lubos there]
http://www.math.columbia.edu/~woit/blog/archives/000028.html

 

[sol2]

What are your thoughts on probing dimenisons in context of what I have shown in regards to the graviton(energy in energy out-where has it gone if not equal?) in regards to the colliders? Do you have another explanation?

Peter gave a response and was honest. If Jeff is suppose to be the official spokesperson, then he obviously hasn't given much here in PF to consider in regards to strings.

As a laymen I like to understand the experimental approach as well. Given indications here, from what has so far been considered(dimensions), although labelled whacky by a large segment, has something it is deriving itself from?

No? Yes?

The original question is still being poised, from the start of this thread. Is there scientific validation being looked at in the colliders?

 

[jeff]

Sol,

What's your first language?

 

[Gza]

I'm entering grad school within under two years, and still trying to figure out what I want to specialize in. I have been pretty fascinated by string theory and got a chance to take an undergrad class in it, which furthered my interest, but I am worried about what the state of it will be by the time I am a few years into research. If it hasn't given testable results in this many years, how many more years will people continue to hold onto it? Also, what fields are you guys currently specializing in?

 

[marcus]

... Also, what fields are you guys currently specializing in?

I'm a physics watcher and my special area of interest currently is Quantum Gravity Phenomenology.
This combines recent invovations in theory (extensions of special relativity to more than one invariant scale) with developments in instrumentation and satellite observatories such as GLAST, and PLANCK gammaray burst astronomy, ultra-high-energy-cosmic-ray, UHECR, astronomy, and other.

The latest conference on this was WS-2004 in Poland February 4-14
on the subject "Quantum Gravity Phenomenology"
Talks by a dozen or more experts included several people doing observational work

http://ws2004.ift.uni.wroc.pl/html.html
click on "lectures"

Steve Carlip, Roger Penrose and Carlo Rovelli were on the program committee: choosing the lecturers and which topics to cover.
Lee Smolin and Jerzy Kowalski-Glikman were among the theorists giving talks.
Observationalists Piran and Lipari gave talks on UHECR and Gamma Ray Burst astronomy.
The talks by these and other observational astronomers were
plentiful and of special interest. In (Loop especially) Quantum Gravity the trend is now to get busy with predicting and testing.
One wants to find LQG signatures in the spikes of gammaray bursts, for instance.
GLAST, the first gammaray array sensitive enough to see such things is not scheduled to fly until 2007 but in the meantime the observationalists are sort of "warming up" by doing whatever they can do with the instruments they have.

So that is a central interest for me. Exciting things are happening in Quantum Gravity, including the beginnings of prediction and testing, and i like to keep track of that.

I also have an interest in (Loop especially) Quantum Cosmology---basically the consequences of removing the big bang and black hole singularities by quantizing the relevant GR models.

 

[arivero]

I'm a physics watcher and my special area of interest currently is Quantum Gravity Phenomenology.

I keep wondering why you (and some other people which seems to have both the time and the interest) do not upgrade from "watcher" to "student" or something so.

 

[arivero]

So, um, the answer is that it's not a theory?

Hmm it depends. There is a "naive string theory", or "promised string theory", which was to have some nice properties (background-free to name one) letting us to justify mathematically the properties of the smallest elements of Nature. Such entity is not a theory but a goal. In pursuing it, the string practicioners were able to build a theory of perturbation for kaluza klein space-times with a matter content fixed by the theory. They did it twenty years ago; since then, the scientific discussion is about the utility of such object.

 

[marcus]

I keep wondering why you (and some other people which seems to have both the time and the interest) do not upgrade from "watcher" to "student" or something so.

a student may mature into a researcher and do original research in the chosen field

a watcher may aspire to gain historical perspective on the human quest for knowledge and perhaps to arrive at a journalistic account

it is a private-language distinction---I don't want to force it on anyone else and I am happy to be thought of as a student

Alejandro, have a good walking tour in the spanish country.

when you get back, here is a request

Could Meteor or you supply the original-language quote from Alfonso
(probably in 13th century Castilian)
"If I had been present at the creation, I would have given some useful hints on the ordering of the universe."

that guy was as smart as a cat, if he really said that,
and very right they called him Alfonso Sagio or whatever it was.

 

[Nereid]

String may in time become a well-developed scientific theory and make unequivocal predictions of definite numbers that can be tested In which case it will be possible to prove wrong.

the criterion of a scientific theory is that it bets its life on predicting the outcome of future measurements (if it can accommodate any future measurement it has no meaning as science----it is more of a daydream or a poem)

So when String becomes clear enough and definite enough that it could be shot down or refuted by some empirical observation it will be a scientific theory and it will be running the daily risk that this entails.

General Relativity was published in 1915 and by 1919 there was the first test, which could have invalidated it but didnt, and it continues to be testedeven today with things like Gravity Probe B satellite, and it could be found to be off by even a little----in the sixth decimal place, like----at any time but it hasnt yet. That is a theory.

[nitpick]A scientific theory *also* has to be consistent with all historical observations and experimental results (within its domain of applicability).[/nitpick]

This can be a truly awesome mountain to climb; many new theories do it by showing that they are consistent with well-established existing theories they hope to go beyond, to within the limits of experimental error, 'in the limit' of the domains of applicability (or best current tests) of those current theories.