Strings represent a theoretical concept possibly useful to provide a mathematical description of a certain subset of natural phenomena. Modern physics does not talk about "substance" (such as ether, heat,...), anymore; i.e., we do not ask what things like particles, fields or strings are made of. Instead, these notions refer to theoretical concepts that appear as mathematical objects in some of our theories. The success of these concepts is gauged according to whether those theories yield accurate descriptions of natural phenomena, or not. - For the time being, string theory isn't really a THEORY, but, rather, a surprisingly coherent set of rules enabling the experts to perform many amazing calculations and mathematical operations. It retrodicts a large set of physical phenomena from a fairly unified point of view; but it has not made any specific predictions that could serve to prove it wrong or right.

Hi!

First, note that string theory as of today is primarily a theoretical framework. There are some key notions about the "string" though.

1) As per the main stream theory, the average size of a string should be close to the Planck length, which is about 10^-33 cm. This implies that strings are too small to be observed (directly, or indirectly) by any relevant physics, or even in particle colliders and therefore it is physically irrelevant.

2) In the article link (below), you can find that the author says that strings are made of point-like objects which he refers to as string bits. He further draws analogies with the light-cone description of the string. 

3) Leonard Susskind in his online lecture series (you can find it on youtube) says the constituents of the string are parameter-dependent of the respective theory.

4) Strings cannot be decomposed into anything further, so it is the strings which make-up everything else. Thus, strings are the most fundamental objects in this material universe.

5) A greater deal of the problem is due to the language framework to which "your" mind is used to.

6) My personal intuition says that be it particles or strings (if they exist), they are nothing but "knots"  in space. Knots of varying degree give rise to different particles and their respective properties.

http://arxiv.org/abs/hep-th/9405069

Thank you. I'm reading Susskind's " the Black hole Wars' in which he discusses string theory enough to apply to black holes but your answer fans my greatest fear ...

We have wave functions and probabilities that are hard to square with anything real and now strings and even new point objects...

your reference assumes even deeper point like objects as more fundamental. But was not the whole idea of strings to get away from the point object abstraction?

Are we still scientists?

Now I learned strings are made of string bits. From above: "It should be emphasized that the system described by our model hamiltonian is a collection of nonrelativistic point particles (“String Bits”) moving in one less spatial dimension than the strings do. The longitudinal dimension... is nonexistent for string bits and only appears with

string formation". This string bit moves on only one light cone coordinate x0 + x1. These become "strings" by entering in the other light cone coordinate x0 - x1. This is why strings are considered (spatial?) 1-dimensional. Next, on page 3: "Superstring theory has supersymmetry and is consistent only in space-time

dimension D = 10"  Why not This, together with a graviton is a state of a closed string is enough to know about strings. 

#########

I wonder that they work on the light cone with nonrelativistic point like particles and simple Schrödinger equations. I'm not impressed from this QFT Hamiltonion (standard) with a +- delta function shaped potential V. +-: repulsive/attractive.

Dear Remi:

Thanks for the funny comment, but it applies to all science today!

People had made similar funny comments to Einstein's general theory of relativity as well until it was experimentally proven. It is a common practice. Irrespective of whether we succeed or fail, we have to keep trying not because it is a great thing to do, but rather that is the only available option. Many intelligent minds have devoted their life to string theory research, this is enough for me to take them seriously. Thousand years ago, none in the human race could have imagined about computers, mobiles and space explorations. String theories predictions are hard to test using the present day technology, this is why alternate modifications such as Loop quantum gravity have been proposed to give testable predictions. Sooner or latter either the theory will be proved right or wrong. And if not right, it will pave the way for an even better theory just like negative results of Michelson-Morley results triggered the research of special theory of relativity.

 @ Vikash Pandey:

“Thousand years ago, none in the human race could have imagined about computers, mobiles and space explorations”. You underestimate our ancestors, they had better means around: they had ghosts (like us in elementary particles), among them an “holy one”, they would instantaneously accept that we have now (a minimum of 130) “god’s particles” and move even “faster than light” (these CERN neutrinos). About “space” they knew everything (Tommaso d’Aquino). And “space exploration” was no problem (Dante). They had dark matter – from the devil, and they did not need “mobiles” because they flew around with the help of angels (or devils). For the big bang they had the genesis and they knew exactly from St. John what happens in the end. For “computers” they took oracles.

This thread has became more funny than it was supposed to be, but i like it!

OK we can gripe about the state of physics but it is more productive to try to fix it.So it may be hype and grants, but as Vikash says a lot of smart people are spending time. What problem drove them to postulate strings? Reaching the dead end of the point particle assumption.

It is obvious that a lot of imagination has crept into physics and it is becoming important to both carefully classify the mental concepts as mental concepts not physical reality and keep the connection between our mental concepts and directly observable experiments or thought experiments intact.

That is why I ask this question "what are strings?" I'm looking for a material, something I could in principle grab. Could "action" be such a material?

Is it the vibrations themselves that are the material. Do we just say strings because we need to visualize something to hang the vibrations onto?

What about the 11 dimensions. Are these to be considered as 11 dimensional containers in which strings vibrate, or are these dimensions mathematical book keeping dimensions like the 3 angular dimensions in particle kinematics, or time, that cannot be implemented physically as space?

Dear Wolfgang, I wished they were fractal dimensions nested inside the 4D space-time. In the figure below, please consider the larger cube as the 3D space moving in a real line (like the physical space-time), and consider the two cubes inside as nested fractal dimensions where second and third-order patterns of vibration are represented.

@ Alfredo Pereira Junior,

Let me add a minor point to it. There are few researchers who are already working on the idea you have stated. The field of research is called scale relativity (see attached link). But, as expected some researchers are praising their efforts while others are criticizing them.

@ Wolfgang Baer

The motivation behind string theory can be found through the attached link.

Also, another point on a deeper aspect of what you had commented earlier. Can you really distinguish between mental concepts and physical reality? Think a while before you comment on it. 

The "physical reality" you are referring to is nothing but a mental construct of yours (ours), just like blueness of the sky. It could be a physical reality for you, but is there a sky in the first place?

This is why in my first comment I had added a point that language/thinking framework plays a major role in shaping your research outlook. Hans Bethe has also said..something like.. Stop asking what was before big bang, why it occurred.. and so on..This is what it is and what we know as of today..

But we humans have a tendency of digging in deep - a choice possibly which we enjoy more than anything else (at least physicists) and so is the inspiration behind string theory and scale relativity and so on,..

http://whystringtheory.com/#motivation

https://en.wikipedia.org/wiki/Scale_relativity

In quantum field theory elementary particles assume zero volume. They are described as mathematical points. Anybody can understand that it is certainly an approximation. The interaction vertices are also mathematical points. Therefore uncertainty in position is zero. So uncertainty in momentum is infinite. Measurable physical quantities such as total cross sections and decay rates, involving momentum integrals, thus become infinite (in other words they blow up). One introduces a momentum cut-off, but if you cut-off momentum at a certain maximum value, then according to the uncertainty principle, you are also accepting a finite size of elementary particles. This leads to a contradiction. This is the main problem.

To correct this one has to consider extended structures to describe elementary particles. In string theory one considers a string like (one dimensional) object which exists in more than 4 dimensions. Various vibrational modes of this fundamental object are identified as elementary particles. Therefore, in this point of view, elementary particles possess a finite size (string length) and also they cease to be the most fundamental building blocks of all matter.

Strings represent a theoretical concept possibly useful to provide a mathematical description of a certain subset of natural phenomena. Modern physics does not talk about "substance" (such as ether, heat,...), anymore; i.e., we do not ask what things like particles, fields or strings are made of. Instead, these notions refer to theoretical concepts that appear as mathematical objects in some of our theories. The success of these concepts is gauged according to whether those theories yield accurate descriptions of natural phenomena, or not. - For the time being, string theory isn't really a THEORY, but, rather, a surprisingly coherent set of rules enabling the experts to perform many amazing calculations and mathematical operations. It retrodicts a large set of physical phenomena from a fairly unified point of view; but it has not made any specific predictions that could serve to prove it wrong or right.

Dear Vikash, Many thanks for the tip about Scale Relativity! It helps with my philosophical projects. I notice that the hypercube concept has also been used in computation (see attached - a free access paper). Many thanks again!

Dear Alfredo,

Thanks for your feedback. I will read the file you have sent. I am personally more inclined towards scale-relativity and/or knot theory of space. One of the pioneers of scale relativity is Nottale and in one his works he derived Schrodinger's equations just by the geometrical notion of fractal space-time. 

By the way, not sure why my post regarding the scale relativity was down-voted by somebody. It could be that someone did not liked the philosophical content of that post. It is Ok to raise questions but not demoralizing.

Dear Vikash, I would like to suggest to Research Gate managers (if they are reading this message) to make down-votes not anonymous.

@Vikash ; thank you for the references. Yes i agree "The "physical reality" you are referring to is nothing but a mental construct of yours (ours)" but it is a mental construct that is attached to some external reality and the connection as well as the ultimate nature of that reality is what we are exploring. See https://www.ted.com/talks/donald_hoffman_do_we_see_reality_as_it_is?language=en ,

we must take the mental construct seriously

@Biswajoy; a good description of the infinity problem and how the finite size of strings solve the problem. thank you.

@ christian ; I got my PhD in physics at UC Berkeley with 6 Noble prize winners were on staff - the last reasonable answer for me personally was " electrons are made of charge and mass" and are held together by some charge-mass, mass charge forces which I believe can be related to the weak and strong forces.

Could strings be made of "action" (Wirkung)  or at least be considered a visualization of action.?

@ Jurg martin : That string theory " retrodicts a large set of physical phenomena from a fairly unified point of view;" That means we compact our description of nature in more elegant forms, which can be valuable, no problem there. But have we forgotten something in the compaction process?

Concepts must be incorporated in real memories (symbols) which have real interactions with other real memories and ultimately symbols of testable 1st person sensations. If substance does not occur in the new fundamental entities "strings" how is it it introduced in their macroscopic combinations? 

I'm eating an apple. Its substance, not its Platonic concept,  keeps me alive. Man does not live by concepts alone. Where does the substance come from?

@ Vikash : Some people deny the existence of mind. Until we have a good theory that integrates  mind and body "naive reality" is the most practical stance one can take in our society. I would not worry about a downgrade.

Please, post comments that have something to do with the question that is being asked, rather than anything else, for example remarks on Bell type experiments, etc.! Concerning the question asked by Wolfgang Baer, one may say that "strings are made of strings", and that they represent objects in a theoretical/mathematical framework that may describe some aspects of reality - they are NOT elements of reality.

Could strings be made of action?

If I think of a lump of action, h,  then it can be stretched and formed in any combination of conjugate variables E*dt, px*dx, etc. as many dimensions as ones problem has. It could be short and energetic or long and skinny going around the whole universe.

Action is a kind of fundamental material  of events.

If I new where and when all the actions (h's) took place I'd have a complete database describing the result of all experiments and experiences, and therefore the basis for all theories including string theory if it is ever tested.

If strings are not a form of action, Then we have one concept, action,  that has fundamental properties and is fairly concrete should it not at least be related to the string concept that, from the answers above,  seems to me to be a mathematical construct still hoping to become fundamental and concrete.

HUMMM: By concrete I mean well entrenched in useful theories and experiments. Action is still an abstraction and must be hosted in some visualizable activity, but we are familiar with  those visualizations.

Dear Wolfgang, what would be the connection of your concept of action with Frank Wilczek concept of "Wavicles"? Please see the link below.

https://www.youtube.com/watch?v=q63CnyBu3nQ

@ wolfgang

Look up harmonic quintessence on google

Fundamental strings are a new invention-the last statement is correct. Whereas in classical physics, a material string can be shown to be made of molecules and, at a finer scale, these of atoms, these of nuclei and electrons and the former of protons and neutrons and these of quarks (of course the motion of quarks and electrons can't be described classically, but it's the identification of degrees of freedom of the medium that matters here-the classical approximation to the motion of molecules is relevant)-so, in principle, the macroscopic motion of the classical string can be described as the collective motion of these constituents, for fundamental strings, that enter the picture when trying to describe quantum and gravitational effects, it turns out that they can be described consistently only in terms of other extended objects-that, in fact, are not, exclusively, one-dimensional.

This isn't that unprecedented: when light was recognized to have wave properties, experience with other waves (sound, water) made the search for a medium for such waves-for classical constituents, whose complicated individual motion could be described as a collective motion, that  would give rise to the ``simpler'' motion of a wave-look reasonable. It took some effort to realize that electromagnetic waves can't be described as the collective excitations of the constituents of any medium-and, in fact, the entities that could be identified as particles, whose collective behavior might be identified as that of electromagnetic waves turned out to be photons, that aren't classical objects at all. 

It's an interesting historical fact that, while a medium for wave propagation was readily assumed, the atomic structure of matter was quite hotly debated and the ``physical reality'' of the degrees of freedom used by Boltzmann in his statistical approach to thermodynamics was considered far from obvious.   (Many years later, the ``physical reality'' of quarks, as constituents of hadrons, was, similarly, debated.) It should be realized that it wasn't obvious, at the time, that a classical medium for electromagnetic waves couldn't exist, or that Boltzmann's statistical approach did describe physical objects-it was the result of sharp arguments, that led to decisive experiments, by Michelson and by Perrin, that clarified matters-though it did take some effort to convince people what the experiments actually meant. Einstein's thesis, apparently, was on the subject, cf. http://arxiv.org/pdf/physics/0504201.pdf for he obtained an estimate of Avogadro's number-and, of course, what's relevant is that it's finite.

Alfredo: The video was hard to hear but I did not hear anything about wavicles more about the Higgs field as the cosmic molasses. However what I know of wavicles is that it combines particle and wave properties in a kind of combination that incorporate the wave particle duality. It is a visualization and whatever its motions are it is a form of  action. Action is the material the rate the material flows through the Now plane is its energy.

if I visualize strings, the visualization is made of something, like ink on a piece of paper. The meaning of that elongated ink line means something - it could mean that some action happened along that line.

Andrew: Never heard of harmonic quintessence and I found the paper Harmonic Quintessence and the Derivation of the Charge and

Mass of the Electron and the Proton and Quark Masses

Its 50 pages long and will need study but looks good. Thank you. .

The introduction of the single harmonic quintessence oscillator suggests to me that action is involved. A single oscillation of a light wave happening is always one quanta of action. perhaps your oscillator is then again a visualization of action, i.e. a form of action.

Is the visualization of a single quintessence oscillation to be related to the visualization of a string?

Fundamental strings don't exist *in* spacetime-they *define* spacetime, since the closed string spectrum does contain a massless, spin-2 excitation, that can be identified with the graviton. This was the remark made by Joel Scherk in his 1974 paper, http://inspirehep.net/record/838 and developed  in  papers with John Schwarz, http://inspirehep.net/record/89538 and http://inspirehep.net/record/90403 that resolved the problem of the missing, massless, spin-2 resonance of dual models of hadrons, by interpreting  it as the graviton. 

spacetime,matter and the forces of Nature are all made form the same stuff, String/Harmonic quintessence

Is relative to the "point", it represents a long and thin appearance, every moment in the vibration.

"Please explain briefly HOW does a closed string or graviton create space and time? "

The string action (which is proportional to the area of world sheet) is,

S=(1/4πα')  ∫ dσ dτ √h hnm ∂m Xμ ∂n Xμ

Here the space-time coordinates Xμ are treated as fields in a two dimensional field theory. The partial derivatives are w.r.t. coordinates σ and τ on the string world sheet, and hmn is the two dimensional metric defined on the string world sheet. Equations of motions are obtained when this action is stationary. We thus obtain the required dynamics of Xμ variables, which are space-time dimensions. This is what we were seeking. Space time coordinates Xμ are therefore called the target space.

The expression I have written above is Nambu-Goto action. A more sophisticated action is written by Polyakov, which is classically equivalent to Nambu Goto action, however which is more appropriate for the study of quantum behaviour. 

Ref:

Y. Nambu, Lectures at Copenhagen Symposium (1970).

T. Goto, Prog. Theo. Phys.46 (1971) 1560.

this string actually exists in eleventh dimensions , this theory consider that this string vibrating and at each frequency produce type of particles so "comes from nothing but its every thing" , and it consider that the super-symmetry model applied very will and no one can say that this theory is right or wrong 

@Sami Mukhiemer. Very well: I know what this is: a curve in R(n):R --> R(n);  t: --> f(t). Here, locally R(n). Now, what exactly "vibrates" in R(n)? Is this vibrating object restricted to a subspace R(n-p)? Sometimes it is called a "loop" This should be a 1-dimensional manifold too. What is the problem to write down a simple representation of a string in terms of plain linear algebra? 

Since Max Planck we know that in every Planck volume VP of space

there is an enormous amount of energy:

2 E m c P P = ⋅ (1)

Empty space which origins from quantum vacuum of

Planck metrics has it energy density ρPE which is:

ρ PE P P = ⋅ ( ) / V m c

####################

this is your  beginning of 1 UDE: Planck never said this. your assumption is flat wrong.

with a wrong assumption everybody can "prove" everything!

The strings concept seems to make the math. model overall more consistent. But for that one needed to go all the way into the 11th dimension, and gain that additional freedom.

Also, helps the old issue of  the wave-particle duality.

I think of strings as non-trivial solutions to the Einstein vacuum field equations (zero mass/energy stress tensor).  Only in higher dimensions do non-trivial (e.g. other than flat spacetime) solutions exit.   Intuitively, this implies that complex, knotted, curved spaces can exist when there is no energy or matter on the Planck-scale (Lp ~10^{33}  cm) that fluctuate on a Planck time (tp ~ Lp / c ~ 10^[-43} sec).

 I have a theory that traces the origin of universe to an infinite, indivisible, motionless field of consciousness (Spirit). When this field begins to move, it generates waves and apparently splits into quanta of consciousness called Savitons. This is the birth of energy. Just as the waves in the ocean does not have independent existence, in the same way Savitons do not have independent existence from the indivisible ocean of consciousness. String theorists should try to associate these Savitons with their strings and see how it works for them. So the beginning of the universe is cool. When there is friction between moving Savitons, it generates heat and the result is big bang explosion.

Another problem with the string theory is lack of experimental verification. My theory can also help the string theorists in this area because existence of infinite field of consciousness can be experienced and is verifiable. I quote here from The Gospel of Sri Ramakrishna:

To a devotee Sri Ramakrishna said: It has been revealed to me that there exists an Ocean of Consciousness without limit. From It come all things of the relative plane, and in It they merge again. These waves arising from the Great Ocean merge again in the Great Ocean. I have clearly perceived all these things.

https://en.wikipedia.org/wiki/Ramakrishna

Article Unified field of consciousness

Article Periodic quantum gravity and cosmology

dear Dr. Vikram Zaveri,  your assumption: "... that traces the origin of universe to an infinite, indivisible, motionless field of consciousness (Spirit)" is not new at all, it is absolutely common and called "idealism": Plato created this kind of philosophy. Next was Kant. In Husserl's solipsism there was 1 thought the creator of "everything". Most prominent till today is C.G. Jung, a psychoanalyst, who states a parallel world of COMMON consciousness, you call it "ocean". You may believe this but in this believe there is no room for mathematics and no engineering at all. And if you enter an airplane even you hope that our materialistic aerodynamical laws work. Now the conclusion: since ages mankind was successful in creating techniques for survival, we didn't need common (universal) consciousness. Why introduce useless presumptions.

Dear Wolfgang,

I see that your question has stimulated a lot of discussion ... around a subject that should be well understood ! I mean a complete mathematical model of physical systems is nothing else than mathematics. More precisely whether a mathematical model is self contained it must justify with a geometric structure any physical object. This was well understood by some great minds like Albert Einstein. In fact he was not personally satisfied by his GR. Really in his PDE there is the term on the left that is pure geometry, but the term on the right comes from the phenomenology. The Einstein's dream was exactly to discover a more general theory that should made by pure geometry. This was also well understood by J.A. Wheeler in his Geometrodynamics. On the other hand theories where appear so-called physical constants cannot be considered complete. They must necessarily suppose the existence of a more general geometric formulation, where physical constants are justified. This can be also understood by considering the Gödel's incompleteness theorems ...

With respect to the specific question of this thread the natural answer is that whether the 'String Theory' and 'M-theory' should be complete theories they should be made only by geometric objects. Unfortunately this is not the case ... since they are classical theories that require to be quantized.

However, nowadays there exists my quantum gravity theory that is just a pure geometric theory and contains as particular case String Theory and M-theory.

Thus we can state that String-Theory and M-Theory can be completed by my quantum gravity theory.

For interested users: http://www.sciencedirect.com/science/article/pii/S1468121812000491.

All the best,

Agostino

String theory looks at the universe as symphony and the laws of Physics as the harmonies. Strings vibrate in a ten-dimensional world. A point in 3-D Euclidean space is a complicated geometrical structure existing in six dimensions, which are wrapped on the scale of the Planck length (1.6 × 10-35 metres). Vibrations of these  very tiny threads of energy describes particles and fields. The strength of the vibrations is what is described as mass, and distinct patterns of vibrations create four fundamental forces.

? Dr. Biswajoy Brahmachari: Why tiny? you say E3xT6 .(T=torus). The scale is arbitrary, we don't "see" these tori, It wouldn't matter 1m!

By the way, on  E3xT6 .is nothing complicated, locally it is E9 anyway!

Dear Dr. Anton Schober, your comments about assumptions and presumptions does not take into account the fact that the theory is verifiable. The idea of origin of universe cannot be a new idea. It has to be as old as the universe itself. Everything that man creates begins with an idea. This is also true for the creation of the universe. You talk

about Plato (428 - 348 BC) and C. G. Jung (1875 - 1961 ), but I say that this idea is on record much before Plato and Jung. It is described in detail by Sri Krishna (3139 BCE). But this idea existed much before Krishna and is well recorded in Upanishads and Vedas. Sri Ramakrishna (1836 - 1886) was one of the many great prophets who verified this idea (1865) when C. G. Jung wasn't even born. When man creates something he sits down with his calculators and computers and does lots of calculations. But I don't think any one made any mathematical calculations before creating the universe.

My impression of the strings in string theory is that they are the "visual" part of a model. The model is a mathematical representation of reality. The "strings" involve a space-time of 10 dimensions, 7 of which, are curled up into such a small "volume" that they are not observed in experiments. I could not find anywhere an explanation of what the strings are. My hope is that string theory can be mathematically reduced to a theory in 4 dimensional space-time. Perhaps we might find that they are the abstract part of a real physical entity formulated in 4 dimensional space-time such as the electromagnetic field.   

Why tiny? you say E3xT6 .(T=torus). The scale is arbitrary, we don't "see" these tori, It wouldn't matter 1m!

I suppose according to string theory, we cannot observe compactified dimensions simply because radius of compactification is very tiny. Smallest possible length is the Planck length, which corresponds to the highest possible energy, ie, 1019 GeV. If radius of compactification was large (compactification scale < 100 GeV), experiments would have detected them by now.

See for example the following review by Alex Pomerol.

http://pdg.lbl.gov/2013/reviews/rpp2013-rev-extra-dimensions.pdf

Dear E.J Zampino, I like your suggestion. Although I am not an expert in the mathematical formalism required in this area (I am a philosopher), I have proposed the hypercube analogy (the 4D spacetime corresponds to the larger cube's 3D in time, and the additional dimensions are compressed as fractal dimensions inside the cube); please take a look at my previous messages in this thread. and to article "Towards a Model-Based Philosophy of Nature" (in my RG page). A colleague also suggested that this kind of model relates to Scale Relativity theory. On the other hand, another colleague told me privately that H. Weyl argued against the very idea of scale relativity. I would like to know more about this kind of solution - if RG colleagues have references, please post here or send to me privately. Many thanks in advance!

Dear Christian, 

As usual I should be wrong, but I conceive the extra dimensions as components of a state space that encode the qualities of objects and processes (both "Primary" and "secondary" qualities). In other words, the patterns of vibration that are represented in the extra dimensions are not further dimensions of physical space. Physical space has only three dimensions and physical time has only one. The other dimensions represent the factors that generate qualities such as color, sound, odor, etc. These qualities belong to objects and processes inside the 4D physical spacetime. In other words, the extra dimensions are not orthogonal to the 4D spacetime, but are embedded in it. I am talking as a philosopher, not as a mathematical physicist, but I am looking for a physicist like you or the new Kepler to make sense of the above intuitions.

@ Alfredo,

In your post above, you have basically mentioned the essence of higher dimensional aspects of string theory.

And, regarding scale relativity, this theory is still in the developing phase, many brilliant minds are working on it as well as it has invited criticisms, which is inherent to any scientific theory.

As a scientist doing mathematical modeling all my life, I agree with Dr. Fröhlich that strings are only mathematical objects.

But I disagree that modern physics does not talk about "substance" (such as heat,...).

On a macro level,  latent heat, specific heat, etc. are used in math. models a lot, eg., in the Stefan problem for phase transitions.

Natalia you misunderstand the meaning of "substance" !

For example heat is never defined for itself, but only as a form of energy in thermodynamics, by some mathematical formulas. Science associates symbols to physical concepts and try to find relations between them. The knowledge of substances will be never revealed by Science.

Regards,

Agostino

Dear Natalia and Agostino, '"substance' is a term that derives from Aristotelian philosophy, but its meaning has been changing along the times. Today we could better use the term "qualitative patterns" to refer to the reality that is expressed by the strings. Vibrational patterns could be encodings of the qualities of things and processes we experience - these qualitative aspects were not properly addressed by Modern science. I can argue that this concept of qualitative patterns could be the original meaning intended by Aristotle, but this argument requires a criticism of the historical usage of the term.

Dear Dr. Prastaro:

Yes, I did not emphasize the word "substance", as , e.g., in chemistry. You are correct, of course, heat is a form of energy. But in this context "substance" was used as an antonym to purely "mathematical objects". Something substantial,  whose effect you can feel  in the physical world. Sorry for miscommunication.

Convention does not allow free thought, so conventio-anal answers get up voted and free thought down voted.

The substance (quite right Natalia)  which makes up strings has a velocity which is tachyonic - discuss.

Why is it that just about every thread of discussion or debate disseminated in the "scientific community" by ResearchGate goes astray, after a fairly short time? Why are we confronted so often with contributions of poor taste like the one of Andrew Worsley? Why should we discuss the nature of heat - a concept originating in thermodynamics - in a thread devoted to string theory? I confess that I find most of the debates I find in RG rather frustrating.

To return to the original question, let us recall that, in many of our physical theories formulated on a space-time with space- and time-translation symmetry, energy and momentum are conserved quantities, i.e., properties of states of a system that do not change in time. In contrast, objects such as fields or strings are used to provide a local description of the degrees of freedom of a physical system in terms of which the dynamics of the system can be formulated. They are local quantities and, thus, have an entirely different character as compared to global "state quantities" such as energy and momentum. I repeat my earlier statement when I say that fields and strings are objects appearing in a mathematical description of natural processes rather than elements of reality! Those processes may indeed concern "things you may sense directly" - at least if you have access to a suitable laboratory or observatory. The potential value of string theory is in its "explanatory power" - more appropriately: in its descriptive power. It remains to be seen whether string theory is a successful description of natural processes that unifies quantum theory with a relativistic theory of gravitation.

That fields, particles and strings and branes, are objects that appear in  a mathematical description of natural processes doesn't imply that they are not elements of reality, however-any more or less than the degrees of freedom imagined by Boltzmann, for the statistical description of thermodynamics, can be identified as molecules and atoms or the quarks of Gell-Mann and Zweig. That Maxwell's ether isn't an element of reality, however, can be given a precise meaning-that distinguishes Poincaré's approach, for instance, from Einstein's. This recalls discussions, also,  between Heisenberg and Einstein and others in Heisenberg's memoirs, ``Physics and beyond'' (``Schritte über Grenzen'' or ``Der Teil und das Ganze'' are the two original titles it was published as). 

On the other hand, it may be that it is possible to identify other degrees of freedom, strings and branes are collective excitations of-just like classical waves can be considered as a, convenient, mathematical, description of the complicated motion of molecules, that can be considered classical at that level of description.

In Physics, "elements of reality" are called "signals" and "events". It would go too far to explain how one may define "signals" and "events" precisely. Suffice it to say that these are the things one can observe or measure. If you are willing to grant me this point of view then quarks - to mention one example - are not "elements of reality", but mathematical constructs appearing in a highly successful theoretical description of particle processes; (namely QCD). To stick to this example, "elements of reality" in particle physics experiments are the tracks one can recognize in suitable detectors (formerly on photographic plates), the deposition of charge or heat one can measure in other  detectors, a flash of light emerging from a detector screen, etc. Such signals are then interpreted - in our theories - in terms of processes involving degrees of freedom called quarks and gluons, etc. Although Bohr was rather vague or confusing in some of his thoughts, he understood the distinction between "elements of reality" and theoretical constructs invented to interpret them very precisely.

Many thanks-however isn't there a certain degree of arbitrariness involved here? One can observe, in deep inelastic scattering, that the protons do interact with probes  in ways that are consistent with their having point-like constituents-so one can, in fact,  measure events of quarks; while these, indeed, are not so obvious at lower energies-where, indeed, a description of hadronic resonances in terms of strings does seem useful, though it does have its limitations (the absence of a massless spin-2 resonance being one of them). In this particular case, indeed, the description in terms of strings is a convenient, mathematical,  parametrization of the complicated dynamics of quarks and gluons.

Dear All,

let me underline the following interesting words by Jurg:

' The potential value of string theory is in its "explanatory power" - more appropriately: in its descriptive power. It remains to be seen whether string theory is a successful description of natural processes that unifies quantum theory with a relativistic theory of gravitation.' 

In fact the great importance of the String Theory (ST) and M-theory (MT) was to emphasized the role that extended objects (extendons) has in particle physics. 

Unfortunately, the methods used were not completely adapted to solve this task. Principally for the fact that (ST) and (MT)  remain classical theoies, hence they must quantized to be applied to quantum particles. But in my quantum gravity theory (QGT) extended objects are rightly interpreted thanks to a new geometric theory of quantum (super) PDEs. In fact nowadays one can surely state that (QGT) completes (ST) and (MT) in the Goedel sense.

Regards,

Agostino

Dear Dr, Frölich, please clarify if for you the observer and his/her mental states are physical events.

@Agostino Prástaro · 29.32 · 41.83 · Sapienza University of Rome

Natalia you misunderstand the meaning of "substance" !

For example heat is never defined for itself, but only as a form of energy in thermodynamics, by some mathematical formulas.

what's the difference between S = Q/T and R = U/I? We have states and observables. Only these observables are in these formulas. But solid/liquid/gas? This is "state" and Q makes state transfer similar U, which in addtion depends on an open energy scale. There is a long list of "energies", many of them quasi undefined like "vacuum"- or "dark" energy. If something is missing? define a new energy! After all this, what is wrong about thinking of "substances", weakly defined entities, like "energy" . 

@Anton Schober

It my be you equivocate the meaning of my post. By the way I repeat:

Science associates symbols to physical concepts and try to find relations between them. The knowledge of substances will be never revealed by Science.

Probably we say the same thing ...

Regards,

Agostino

dear Agostino Prástaro, "symbols to physical concepts" and "The knowledge of substances" is more or less the same, just medieval philosophy (scholastic). In modern physics we have states (in thermodynamics, classical- and quantum mechanics) and observables. Further, all mathematical physics is trivial from the mathematical point of view: mathematically well known (tedious) stuff.

Dear Christian, in mathematics there are only two kinds of problems: the solved ones and the unsolved. The solved are trivial, and the nonsolved become trivial after they are solved.

(so far I understand math physics as trivial, we are like pupils, wondering by calculating a(b+c))

@ Baumgarten, @Amrit @ Schober: So strings, fermions, bosons, wave functions are all inventions and mathematical constructions of the Human mind, that do not  exist out there but are instrumentalist entities that happen to give predictive answers. OK many people agree all of quantum theory falls into the same category.

However lets consider a string or branes, or for that matter world lines that are often drawn on a space time diagram to represent a locus of “action”. We can argue whether energy, action, or momentum are mental abstracts or whether they should be given a greater ontological status. But let’s change the question and avoid that philosophical dog fight, by accepting each of our preferences and only ask for comparisons

 Are strings of string theory made of action when action is accepted at the same ontological level as energy, momentum, or deBroglie waves?

Dear Wolfgang, could it be action of elementary energy forms?

Dear Anton, and then there are those problem where axiomatization isn't enough to fully describe a solution: those are the essence of Kurt Godel's theories.

(I'm far from being a matgematician, and hence, I'm prone to mistakes. Hence, any correction will be most welcome)

Consider this conversation, for instance, my persona. You know how my face looks like. You can get a feel of my writing style, or even my personality. You can even know my alma mater institution. But, for instance, you don't know if I am married, or if I drive a car, or my favourite color. You can't deduce such things from the information you have - the axioms. So, while you know many things about me: a specimen of the homo sapiens sapiens species, brown hair, etc, etc, which may classify me, your axioms are not enough to define me. This incompleteness theorem has deep consequences, and the interesting thing about it is that is none trivial, but you do have a result - that your result is incomplete. A bir stupid, perhaps - and many people will see this as the philosopher's stone for local realism and hidden variables - but it isn't actually. You just have a very non trivial result. And the best thing? You see this everyday.

So, forgive me if I am mistaken, but I just wanted to give my two cents and add the following: Triviality and axiomatization are two different concepts.

No action is the material of events. Energy is the rate of action happening in the time direction, Momentum is the rate of action happening in the spatial direction, or angular, or any Quantity parameter. So you would have to add a time interval during which the elementary energy forms happen to get action.

Action can just lie there on a map the rate at which one experiences it depends upon the observers direction through space time on the map.

@Anton Schober

1) About states and observables. You can change name but the meaning remains.

Science associates symbols to physical concepts and try to find relations between them. The knowledge of substances will be never revealed by Science.

2) About triviality of the mathematical physics. Probably you refer to your production in this sector. [I have seen on RG two your papers in mathematical physics ...] But serious works in mathematical physics are more hard to do than solve mathematical problems only ! In fact in order to solve problems in mathematical physics one must first to find the right mathematics, that in general necessitates to be invented yet. Then to develop this mathematics and to solve with this mathematics physical problems. Finally to test these mathematical models with experiments !

Look to the Science history and you will understand that the greatest scientists built their mathematics.

By conclusion you have a too naive point of view !

All the best,

Agostino

Dear Wolfgang, your answer is not clear to me.

You wrote: 

"No action is the material of events."

Alfredo: This statement seems to be in contradiction with what comes later in the message:

(Wolfgang) Energy is the rate of action happening in the time direction, Momentum is the rate of action happening in the spatial direction, or angular, or any Quantity parameter. So you would have to add a time interval during which the elementary energy forms happen to get action.

Alfredo: OK, so I add time to the elementary waveforms and get action. This is what I want. No need of a "material" at this moment. Matter can be conceived as a kind of action, not action as a kind of matter!

@Christian: I’m impressed, the best definition of physics I ever heard. The world is too complex for understanding it, say on a satisfactorizing level. If there would be nothing, we would understand this, however by saying why is nothing?

In mathematics however, everthing is clear and simple, it exists like a tru parallel universe.

Without math a physicist is lost, but the reverse is not the case.

Caro Agostino, “But serious works in mathematical physics are more hard to do than solve mathematical problems only” Very tru, but “problem solving” is like highschool calculations called “math”, but it isn’t.

A mathematician may worry about: is there an infinity of twin primes? Now assume, physicists working on Planck scale need to know, what is the highest twin prime below 10100?. Of course, very hard work, however, trivial work.

Dear Anton,

I find a big stupidity this absurd competition between Mathematics and Mathematical Physics that you aim to force us to follow ...

In fact I work in both sectors and I found hard to produce serious works whether in Mathematics or Mathematical Physics. To be more clear I do not distinguish between Mathematics and Mathematical Physics. This distinction can be made at the experimental level only ... but this is another story !

Regards,

Agostino 

Dear Agostino, " ... that you aim to force us to follow ..." I force nobody to anything. I'm amazed in my daily life by following these discussions, I'm happy in case my math comes to a decent result, and as a physicists I'm aware that I'm part of this universe and understand to a certain amount some basic rules around us.

"To be more clear I do not distinguish between Mathematics and Mathematical Physics". Well done, Dr. Prástaro!

Dear Anton,

I am glad to see that our minds converge on Mathematics and Mathematical Physics.

My best regards,

Agostino

Is not mathematics in physics always a kind of metaphor? patterns such as super symmetry , or the periodic table, or Dirac's Equation, can lead us to gaps and holes that are in fact sometimes found on nature(positrons). However only PLatonists believe there is an intrinsic metaphoric phenomena in nature for every symbolic phenomena in mathematics. I myself consider it wise to let experimental verification define the domain of applicability i.e. of Mathematical physics. 

Does this mean Strings, being mathematical objects, have no physical meaning until connected by experiment to physical phenomena? If so why are we even calling string theory a physical theory? Is there not some initial guess as to what these Strings could be physically based at least on some thought experiments?

Dear Wolfgang,

it appears more a question of words than of substance. By the way, my quantum gravity theory (that if you like can be considered a quantum completion of String Theory) is well experimentally verified for all phenomena that are just known. In advance it opens new windows on new results that to be experimentally verified it is necessary to develop experiments to higher energy levels. Therefore, my quantum gravity theory can merit the title of physical theory ...

My best regards,

Agostino

@Wolfgang Baer

What if the strings are thoughts themselves?

It appears to me that string theory is a model: a mathematical representation of reality. The reality is the four fundamental forces of nature.  The model involves the  4 dimensional space-time and the additional compactified space of multiple dimensions. So the strings are a model. The only way to verify if the model can actually represent the fundamental forces of nature is by experiment ( in the lab) or by observations (Astrophysics). It's got to predict observables. If it cannot ever predict observables then it is not a theory, Theories have to have the possibility of being falsified. If they are invulnerable for all time, then perhaps they are models only.   

 Thought is a force, as is gravitation or repulsion.

                                                -Swami Vivekananda

                                     (The complete works, v.1, p.201)

https://www.google.co.in/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=swami%20vivekananda%20complete%20works

I will see this question in this way, with this (cite the following):

 [...] Strings in string theory also seem to possess a rather complicated and certainly non-trivial suite materials-like properties such as length, rigidity, tension, and others (e.g. some analog of angular momentum?). [...]

Only with such material-like properties they can be taken in serious (non abstract) consideration for me. For example, the string's tension means that if  a string physically there exists then such string must have some internal forces of tension which can not be no gravitational force, no EM, no weak or strong forces (no one of the fundamental physical forces). Then which one? Another new fundamental force must be.  But in that case we are going toward this circular paradox:  such a new fundamental force must be a new quantum force and so must have the intermediator- bosons, and hence the string will not be more an ELEMENTARY particle as initially assumed to be !

Hence, any non-point like representation of an ELEMENTARY particle (1D, 2D or 3D in our open 3D space) can have only the Einstein's self-gravitational force inside its space distribution (by considering original GR based on time-space curvature originated by particle's energy, i.e., without any existence of  the intermediator-bosons (the gravitons)) , and this string's internal tension can not be a self-gravitational force (otherwise this string would briefly be transformed into a 3-D cloud. That is, the stability of an elementary particle can be based only on its internal self-gravitational force like in our macro-universe we have for the stars: the energy contained in this non point-like elementary particle necessarily makes curved time-space inside the particle and (very) locally around it ( a micro-island time-space curvature around the particle), and this curvature generates the self-gravitational force inside and around the particle. In an analog way as the self-gravitational force generated by the energy contained in any star (the Sun for example) is the reason of the star's stability (ideally spherically symmetric density of its matter/energy.

Consequently, the physical structure of an elementary particle (similarly to any star or macro-object) must be composed by the energy-density delimited (for any fixed instance of time) in a micro 3D (open) space.  In such a way we have the continuous and full integration of the micro and macro physical worlds. Obviously, we need an completion of QM (which in current Schrodinger-based theory is a STATISTICAL theory, appropriate to ensemble interpretation, but non appropriate to represent an INDIVIDUAL elementary particle).

Who is interested in this new part of conservative extension of the Standard QM Model, can find all info in my recently published books (visit my Home-page, http://zoranmajkic.webs.com).

Zoran Majkic, In following theory, energy of charge causes severly curved space time compared to which the curvature contribution of gravity is negligible. In this QM theory radial distance and the velocity does not have a STATISTICAL interpretation.

Article Hydrogen spectra using Einstein's field equations

Try to think carefully through your proposals before you publish them online! Otherwise, you will only increase the confusion that already prevails in the modern world!