We often say that the primary reason why string/Mtheory is so essential for modern physics is that it is the only known – and most likely, the only mathematically possible – consistent theory of gravity. Everyone who believes that he or she can do stateoftheart research of quantum gravity without string theory is an unhinged crank, a barbarian, and a conspiracy theorist of the same kind as those who believe that Elvis Presley lives on the Moon.
But another reason why string/Mtheory is indispensable for the 21st century theoretical and particle physics is that many of the "ordinary", important, nongravitational quantum field theories and some of their nonfieldtheoretical but still nongravitational generalizations are tightly embedded as limits in string theory. In this way, a theory whose main strength is to provide us with robust quantum rules governing gravity is important for our knowledge of contexts that avoid gravity, too.
Because of the dense network of relationships within string theory that link ideas, concepts, and equations that used to be considered independent – and I mostly mean dualities but not only dualities – each of the "ordinary" nongravitational theories may be analyzed from new perspectives. In particular, extreme limits of the old theories in which a quantity is sent to infinity (or zero) could have been very mysterious but many of the mysteries go away as string/Mtheory allows us to use new descriptions.
Among the new insights that we're learning from the stringy network of ideas, rules, equations, and maps, we also encounter new quantum field theories – and some other nongravitational generalizations of these theories which are not quantum field theories – i.e. theories that are not fullfledged string vacua and that we shouldn't have overlooked in the past but we have. What are they?
In March, I discussed the maximally supersymmetric gauge theory in four dimensions. It's arguably the most farreaching or at least the most widely studied example of the point I made in the second paragraph.
The \(\NNN=4\) gauge theory in \(d=4\) is a gauge theory with 16 real supercharges. If you write it in terms of components, it's a gauge theory with a gauge group – it can be \(SU(N)\), \(O(N)\), \(OSp(2k)\), \(E_6\), or any other compact Lie group – which is coupled to four Weyl neutrinos in the adjoint representation of the same group and six Hermitian scalars in the same representation. When the interactions are appropriately chosen, we discover that the theory has those 16 supersymmetries even at the interacting level.
Nima ArkaniHamed would call this theory a harmonic oscillator of the 21st century. Andy Strominger reserves this term for black holes but it's true that these two theoretical constructs are perhaps even more important if they work as a team and they often do.
String theory tells us lots of things about the seemingly ordinary gauge theory which wasn't known to have any direct connection to strings. In fact, we have known for almost 15 years that this gauge theory is string theory. The \(SU(N)\) maximally supersymmetric gauge theory is totally equivalent to the superselection sector of type IIB string theory respecting the asymptotic conditions of \(AdS_5\times S^5\). This relationship is, of course, the most famous example of Juan Maldacena's AdS/CFT correspondence.
However, the remarkable relationship was found – and may be "almost proven" – by less shocking relationships between this gauge theory and string theory. In particular, the simplest representation of the gauge theory is the dynamics of D3branes in type IIB string theory at very long distances. Some properties of the gauge theory may be deduced out of this realization immediately. In particular, the theory inherits the \(SL(2,\ZZ)\) Sduality group – which includes the \(g\to 1/g\) exchange of the weak coupling with the strong coupling – from the full type IIB string theory. In the type IIB string theory, the Sduality group may also be motivated by representing type IIB string theory as a 12dimensional theory, Ftheory, compactified on a twotorus. This toroidal proof of the Sduality group may also be realized by another embedding: the gauge theory may also be viewed as a longdistance limit of the \(d=6\) \((2,0)\) superconformal field theory compactified on a twotorus; the logic is the same.
You should appreciate that the Sduality is an extremely complicated relationship if you want to construct it or prove it by hand. In fact, it replaces pointlike elementary oscillations that are weakly coupled with extended objects such as magnetic monopoles that are strongly coupled. They look like very different physical objects and the proof of the equivalence can't be made in perturbative expansion – because it is not a duality that holds orderbyorder in this expansion – but it's still true. But of course, all tests you can fully calculate work: the gauge theory seems to possess the nontrivial Sduality group. In its stringy incarnation, the Sduality may be seen within a second.
Also, Maldacena's holographic duality boils down to the construction of the gauge theory involving D3branes, too. The lowenergy limit of the D3branes' internal interactions has to be an interacting theory with 16 supercharges – because they aren't being broken by anything – and that has a field content that may be obtained from the counting of open string excitations attached to the D3branes. You will find out that the theory has to be a gauge theory with the degrees of freedom I enumerated above; the supersymmetries and consistency dictate the interactions uniquely. In the longdistance limit, only the massless open strings i.e. gauge fields and their superpartners matter; closed strings (especially gravity) is decoupled because the energy density per Planck volume is very low in this limit. So we really do have a nongravitational theory.
On the other hand, the D3branes in string theory are real objects, lively animals that manifest themselves in many other physical ways. In particular, they have a gravitational field that extends to the transverse dimensions. Much like D0branes would be particles that would behave as black holes, D3branes are extended versions of the same objects, extended black holes. We call them black branes or black \(p\)branes. They are black 3branes, in this case. Just to be sure, in the previous paragraph, I stated that the gravitational force between the open string interactions may be neglected; but the gravitational field from their substrate – the static D3branes in which the open strings live – still curves the 10dimensional spacetime of type IIB string theory.
A funny thing is that if you adopt the full 10dimensional perspective, the lowenergy excitations have another interpretation: they are physical states that are located near the event horizon of the black branes. The relationship between the adjectives "lowenergy" and "nearhorizon" holds because near the horizon, it's where the excitations that look "very red" from the global viewpoint (of an observer at infinity) may be created in generic processes. That's because of the gravitational red shift, of course.
If you ask which degrees of freedom are kept if you simply consider all lowenergy excitations of those 3branes, you have two methods to answer: you either realize that the 3branes may be described as D3branes whose dynamics is governed by interactions of open strings and the lowenergy limit of the open strings' interactions is nothing else than the gauge theory; or you may imagine that the D3branes are actual solutions of a gravitational theory – an extension of general relativity – and lowenergy states are the states of all objects that move near the event horizon.
Each of these operations is a valid method to isolate the lowenergy states; so the two theories obtained by these methods must be exactly equivalent. That's an elegant proof of the AdS/CFT correspondence, a nontechnical, nonconstructive proof that avoids almost all mathematics (although one should still add some mathematics in order to show that it really deserves to be called the "proof"). The nearhorizon geometry of the black 3branes is nothing else than \(AdS_5\times S^5\) and gravitational – well, type IIB stringy – phenomena within this spacetime must therefore be exactly described by a fourdimensional gauge theory.
Of course, this successful union of string theory and gauge theory may be extended to other gauge groups, less supersymmetric gauge theories corresponding to less symmetric compactifications of the gravitational side, and even to other dimensions. Lots of objects on both sides of the equivalence may be given new interpretations using the other description, and so on. But the main goal of this text is to describe new field theories and new nongravitational nonfield theories that arise from similar constructions. The most supersymmetric example of the first category is the socalled \((2,0)\) superconformal field theory in 6 dimensions.
M5branes and their dynamics
In the case of the D3branes above, we considered objects in string theory in ten dimensions. In the usual weakly coupled approach, these theories are parameterized by the string coupling constant \(g_s\) which is the exponential of the (stringy) dilaton; greetings. The coupling constant is adjustable in the simplest vacua; all values are equally good but the choice isn't a parameter representing inequivalent possibilities. Instead, because the coupling is an exponential of the dilaton and the dilaton is a dynamical field, different values of the coupling constant correspond to different environments that may be achieved in a single theory.
In realistic compactifications, a potential for the dilaton is generated (much like the potential for all other moduli) and string theory picks a preferred value of the string coupling which is at least in principle but – to a large extent – also in practice calculable (much like the detailed shape of the extra dimensions etc.).
However, there exists a vacuum of string/Mtheory that has no dilatonlike scalar field that would label inequivalent environments. Of course, it's the 11dimensional Mtheory. The field content of the elevendimensional supergravity only includes the graviton, some spin3/2 gravitino, and spin1 threeform generalizing electromagnetism. No spin0 scalar fields here.
That's kind of nice because the theories we may obtain from Mtheory in similar ways as the theories obtained from type II or type I or heterotic string theory have an unusual property: they have no adjustable dimensionless coupling constants. This is something we're not used to from the quantum field theory courses taught at schools. In those courses, we first start with a free theory and interactions are added as a voluntary deformation. All these interactions may be chosen to be weak because the coupling constants are adjustable and the free, noninteracting limit is assumed to be OK.
However, for theories obtained from Mtheory, we can't turn off the interactions at all! These theories inevitably force their degrees of freedom to interact with a particular vigor that cannot be reduced at all. Because the coupling constants may be measured as the strength of the "quantum processes" – how much the oneloop diagrams where virtual pairs exist for a while are important relatively to the treelevel "classical" processes – we may also say that the theories extracted from Mtheory are intrinsically quantum and they have no classical limit.
Are there any?
You bet. As I mentioned in my discussion of 11D SUGRA, the theory has to contain a threeform potential \(C_3\). One may add terms in the Lagrangian where \(C_3\) is integrated over a 3dimensional world volume in the spacetime. This term generalizes the \(\int \dd x^\mu A_\mu \) coupling of the electromagnetic fields with world lines of charged particles (in the limit in which they're treated as particles with clear world lines, not as fields). And indeed, Mtheory does allow such terms; the 3dimensional world volumes are those of M2branes, or membranes, objects with 2 spatial and 1 temporal dimensions.
Also, the exterior derivative of the \(C_3\) potential is a fourform \(F_4\) field strength. By using the epsilon symbol in eleven dimensions, this may get mapped to a Hodgedual sevenform \(F_7\) potential which is locally, in the vacuum, the exterior derivative of a sixform "dual potential" \(C_6\). So Mtheory also admits couplings of this \(C_6\) and indeed, the 6dimensional world volume we integrate over is the world volume of M5branes, the electromagnetic dual partners of M2branes.
Just like string theories contain fundamental strings, F1branes, and lots of heavy Dbranes of various dimensions, Mtheory contains no strings or 1branes but it has M2branes and M5branes which have different dimensions but are "comparably heavy" as long as their typical mass scale goes.
A nice thing is that just like you may study the longdistance dynamics of D3branes which led to the very important maximally supersymmetric gauge theory, you may also study the longdistance limit of the dynamics inside M2branes and M5branes. Both of them give you some new interesting theories. The theories related to the M2branes were the subject of the recent "membrane minirevolution"; this was my name for the intense research of some supersymmetric 3dimensional gauge theories extending the ChernSimons theory. Some new ways to see the hidden symmetries of these theories were found; the most obvious "clearly new" development of the minirevolution were the ABJM theories extending the longdistance of the membranes to more complicated compactifications. The membrane minirevolution has surprised many people who had thought that such M(ysterious) field theories would never be written in terms of ordinary Lagrangians. They could have been written. People could only discover these very interesting and special Lagrangians once they were forced by string/Mtheory to look for them.
When you consider the lowenergy limit of the M5branes, you get a sixdimensional theory: 5 dimensions of space and 1 dimension of time. It is useful to mention how spinors work in 6 dimensions. In 4 dimensions, the minimal spinor is a Weyl spinor (or, equivalently – when it comes to the counting of fields – the Majorana spinor). But there's only one kind: if you include a lefthanded Weyl spinor, the theory immediately possesses the Hermitian conjugate righthanded one, too. So you only need to know how many spinors your theory has. For example, the \(\NNN=4\) theory has supercharges that may be organized into 4 Weyl or Majorana spinors.
However, things are a bit different in \(d=6\). Because it is an even number, one still distinguishes lefthanded and righthanded Weyl spinors. But in spacetime dimensions of the form \(4k+2\), the lefthanded and righthanded spinors are actually not complex conjugates to each other. You may incorporate them independently of each other. The same comment holds for supersymmetries; if you want to accurately describe how the spinors of supersymmetric transform, you must specify how many leftmoving and how many rightmoving Weyl spinors there are in the list of supercharges.
In ten dimensions, we use the "shortened" terms type I, type IIA, type IIB for \((1,0)=(0,1)\) supersymmetric theories, \((1,1)\) supersymmetric theories, and \((2,0)=(0,2)\) supersymmetric theories, respectively. The permutation of the two labels is immaterial. The type I and type IIB theories are inevitably lefthandasymmetric i.e. chiral; type IIA is leftrightsymmetric i.e. nonchiral, as expected from the fact that it may be produced as a compactification of an 11dimensional theory.
In six dimensions, there's a similar classification. The \((1,1)\) theories are nonchiral and typically include some gauge fields. On the other hand, the \((2,0)\) theories are chiral. The \((2,0)\) theory we find in the longdistance limit of the M5branes is nonchiral not only when it comes to the fermions in the field content. Because the labels \((2,0)\) are "very asymmetric" between the first and second digit, the leftright asymmetry actually inevitably gets imprinted to the bosonic spectrum, too. If we're explicit, it's because the theory contains "selfdual field strength fields" i.e. 3form(s) \(H_3\) generalizing \(F_2\) in Maxwell's theory that however obey \(*H_3=H_3\). Note that this is possible in 6 dimensions but not in 4 dimensions because \((*)^2=+1\) in 6 dimensions but \((*)^2=1\) in 4 dimensions.
Because the \((2,0)\) theory must allow a generalization of the gauge field whose field strength is however constrained by the selfduality condition, it's hard to write an explicit Lagrangian definition of the theory, at least if we want it to be manifestly Lorentzsymmetric one. It's a part of the unproven lore that this can't be done. However, you must be careful about such widely held beliefs. In particular, the membrane minirevolution has shown that various Lagrangians that would be thought of as impossible are actually totally possible and you never know whether someone will find a clever trick by which this explicit construction may be extended to 6 dimensions.
So the sixdimensional theory can't be constructed as a "quantization" of a classical theory. It's a point that I discussed in less specific contexts in several recent articles about the foundations of quantum mechanics. We see many independent reasons why it's natural that no such "master classical theory" may exist in this case. First, the quantum theory requires the coupling constant to be "one" in some normalization: it can't be adjusted to be close to zero so studying the theory as the deformation of a free theory would be similar to studying \(\pi\) using the \(\pi\to 0\) limit. Second, we have mentioned that the theory contains selfdual fields and it's hard to write a Lagrangian for a potential if you also want its field strength to be selfdual. Third, and it is related, you would have a problem to write renormalizable interactions in a theory in 6 or more dimensions, anyway. A \(\phi^3\) cubic coupling for a scalar would be the "maximum" that would still be renormalizable but it would create instabilities. By denying that there exists a way to represent the full quantum field theory as a quantization of a classical theory (with a polynomial Lagrangian), string/Mtheory finds the loophole in all these arguments that a sloppy person could offer as an excuse that such a nontrivial 6dimensional theory shouldn't exist.
However, this theory still exists as an interacting, nongravitational theory with all the things you expect from a local quantum field theory. One may define local fields \(\Phi_k(x^\mu)\) and these fields have various correlation functions and may be evolved according to some welldefined Heisenberg equations, and so on. It may be hard or impossible to use the perturbative (and other) techniques we know from the gauge theory but the resulting product – Green's functions etc. – is conceptually identical to the product in the gauge theory. You may be ignorant about methods how to compute these physical answers in the \((2,0)\) theory; but one may actually prove – using the consistency of string theory as a main tool or assumption – that these answers exist and have the same useful properties as similar answers in gauge theory. However, in gauge theory, we may calculate a whole 1parameter or 2parameter family of the "collection of Green's functions"; the families are parameterized by the coupling constant (and the axion). In the \((2,0)\) case, there are no such parameters. It's just an isolated theory – one isolated set of Green's functions encoding all the evolution and interactions – without continuously adjustable dimensionless parameters.
Much like the \(\NNN=4\) gauge theory is equivalent to type IIB string theory in \(AdS_5\times S^5\) which we could have derived as the nearhorizon geometry of a stack of the D3branes, the \((2,0)\) theory in six dimensions may be shown to be equivalent to Mtheory on \(AdS_7\times S^4\), the nearhorizon geometry of a stack of the M5branes in Mtheory. Just to be sure, there is a similar case involving a 3dimensional ChernSimonslike theory andd Mtheory on \(AdS_4\times S^7\) – note that the labels four and seven got exchanged – which is the nearhorizon geometry of a stack of M2branes in Mtheory.
So while the perturbative, weakly coupled methods don't exist for this sixdimensional theory, the holographic AdS/CFT methods work as well as they do for the gauge theory. Also, this sixdimensional theory is as important for Matrix theory, a nongravitational way to describe some simple enough compactifications of string/Mtheory on flat backgrounds, as the gauge theory is. In particular, if you compactify the \((2,0)\) theory on a fivetorus (times the real line for time), you get a matrix description for Mtheory on a fourtorus.
Perturbatively, the \(\NNN=4\) gauge theory with the \(SU(N)\) gauge group seems to have the number of degrees of freedom – independent elementary fields – that scales like \(N^2\). That's because the adjoint representation may be viewed as a square matrix, of course. There are actually different, independent methods to derive this power law, too, in particular a holographic one that is based on the entropy of a dual bulk black hole.
The holographic methods may also be used for the M2based 3dimensional theory and the M5based 6dimensional theory. They tell you that the number of degrees of freedom in these two theories should scale like \(N^{3/2}\) and \(N^3\) in \(d=3\) and \(d=6\), respectively. The first case, a fractional power, doesn't even produce an integer but it has still been motivated in various ways.
The 6dimensional case is even more intriguing because the integral exponent does suggest that there could exist a "constructive explanation" – some formulation that uses fields with three "fundamental gauge indices", if you wish. Many authors have tried to shed light on this strange power law. A month ago, Sav Sethi and Travis Maxfield offered a brand new calculation of the "conformal anomaly" (what was interpreted as the number of degrees of freedom) which also produces the right \(N^3\) scaling.
There's still a significant activity addressing this 6dimensional theory and its less supersymmetric cousins. A few days ago, Elvang, Freedman, Myers, and 3 more colleagues wrote an interesting paper about the atheorem in six dimensions. You should realize that despite the absence of an oldfashioned, "textbook" Lagrangian classicalbased construction of the theory, the amount of knowledge has been growing for more than 15 years. Let me pick my 1998 paper with Ori Ganor as some "relatively early" research of physical effects that occur in this theory.
So the \((2,0)\) theory is conformal and therefore scaleinvariant (it is a "fixed point" of the renormalization group) which is why it may occur as the lowenergy limit of other physical theories in 6 dimensions; I will mention one momentarily. It has a qualitatively wellunderstood holographic dual and it appears in a matrix description of Mtheory on a fourtorus. Some fields, especially the "supersymmetry preserving ones", may be isolated and some of their correlation functions may be calculated purely from SUSY, and so on. The theory has various topological solutions that may be interpreted by various "perspectives" to look at this theory that string/Mtheory offers. This sixdimensional theory is also an "ancestor" of the maximally supersymmetric gauge theory; the \(\NNN=4\) gauge theory may be obtained from a compactification of the sixdimensional theory on a twotorus.
There are interesting modifications and projections of this theory, too. For example, there are \((1,0)\) theories in six dimensions which respect an \(E_8\) global symmetry. This global symmetry is inherited from the \(E_8\) gauge symmetry that lives on the domain walls (endsoftheworld) in Mtheory whenever the M5branes are places on such a boundary. I can't say everything that is interesting about this theory but be sure that there would be lots of other things just to enumerate – and lots of interesting details if I were to fully "teach you" about those things.
One of the broader points is that physics is making progress and finding "conceptually new ways" how to think about old theories, how to calculate their predictions, and how to related previous unrelated physical mechanisms and insights. Quantum field theory is essential in all this research; however, we know that quantum field theory isn't just some mechanical exercise starting from a classical theory and adding interactions to a free limit by perturbative interactions. There are lots of nonperturbative processes and insights that may be obtained without explicit perturbative calculations, too.
Little string theory
I have mentioned that the \((2,0)\) superconformal field theory discussed above was a quantum field theory whose Green's functions are as real as those coming from a gauge theory; they satisfy the same consistency, unitarity, and locality conditions, too. But it's a "fixed point", a scaleinvariant theory that may be identified as the "ultimate longdistance limit" of some other theories. Are there any other theories of this kind?
Yes, you bet. But the most interesting ones aren't gauge theories. They're "little string theories".
A little string theory is a type of a theory in spacetime that is something in between a quantum field theory in the spacetime; and the full gravitating string theory in the same spacetime. They're not local because we may say that their elementary degrees of freedom or elementary building blocks arise from strings much like in the full string theory; however, an appropriate limit is taken so that the gravitational force between the strings decouples.
This seemingly contradicts the lore that every theory constructed from interacting strings inevitably includes gravity; however, there's actually no congtradiction because while the little string theories contain strings and they are interacting theories, they actually cannot be constructed out of these "elementary strings" by following the usual constructive methods of the full string theory.
Fine, so what is the little string theory? The simplest little string theories carry the same \((2,0)\) supersymmetry in \(d=6\) as the superconformal quantum field theory I was discussing at the beginning. In fact, the longdistance limit of these little string theories (they are parameterized by discrete labels such as the number of 5branes) produce the superconformal field theory we have already discussed.
But these little string theories are not superconformal or scaleinvariant. In fact, they are not local quantum field theories at all. In this sense, they are just a generalization of a quantum field theory in a similar sense as the full string theory is a generalization of a quantum field theory. How can we obtain them?
The most straightforward way to obtain the \((2,0)\) superconformal field theories above were a stack of M5branes in Mtheory. Are there some other objects in string theory that are not M5branes but that look as M5branes in the lowenergy limit? The answer is Yes. Mtheory may be obtained as the strong coupling limit of type IIA string theory. Type IIA string theory also contains 5branes. But they are not D5branes which may be found in type IIB string theory; type IIB D5branes produce \((1,1)\) supersymmetric theories in six dimensions, not \((2,0)\): their world volume is exactly as leftrightsymmetric as the type IIB spacetime fails to be. There are also NS5branes in type IIB string theory which have the same SUSY as the D5branes, because of Sduality that relates them.
Type IIA string theory only contains Devenbranes, not D5branes, but it still allows NS5branes, the electromagnetic duals of fundamental strings. And while type IIA is leftrightsymmetric in the spacetime, its NS5branes are leftright asymmetric; not that there is an anticorrelation between the chirality of the spacetime and the chirality of the NS5brane world volume.
The dilaton of type IIA string theory has a value that depends on the distance from the NS5branes; this contrasts with the behavior of D3branes in type IIB string theory that preserve the constant dilaton (and string coupling) in the whole spacetime. This depends of the dilaton – it goes to infinity near the NS5branes' core – means that the ultimate lowenergy limit of the dynamics of NS5branes is the same one as it is for M5branes in Mtheory: the new 11th dimension really emerges if you're close enough to the NS5branes.
On the other hand, one may define a different scaling limit of dynamics inside the type IIA NS5branes in which the gravity in between the excitations of the NS5branes is sent to zero; but which is not the ultimate longdistance, scaleinvariant limit yet. Such a theory inherits a privileged length scale, the string scale, from the "parent" type IIA string theory. But it doesn't preserve the dilaton or the coupling constant because it's scaled to infinity.
The resulting theory of this limit, the little string theory, has no gravitational force but it has stringlike excitations. It is not a local quantum field theory but its low energy limit is a quantum field theory. The theory – which has a "qualitatively higher level of conceptual complexity than the \((2,0)\) superconformal field theory" – also enters Matrix theory; its compactification on a fivetorus is the matrix description of Mtheory compactified on a fivetorus. All the usual limits and dualities between the toroidally compactified string/Mtheoretical backgrounds may be deduced from the matrix description, too: these dualities may be reduced to relationships between their nongravitational matrix descriptions.
The little string theories have various other relationships to quantum field theories and vacua of the full string theory, too. Again, I can't say everything that is known about them and everything that makes them important.
Let me emphasize that none of these theories – neither the new superconformal field theories nor the little string theories – has any adjustable continuous dimensionless parameters. They still have discrete parameters – counting the number of 5branes in the stack and/or whether or not these 5branes were positioned at some endoftheworld boundaries or other singular loci in the parent spacetime. But the absence of the continuously adjustable parameters allows us to say that all these quantum theories are "islands" of a sort.
They're obviously important islands. If you want to study consistent nongravitational interacting theories in 6 dimensions, these islands may be as important as Hawaii or the Greenland or Polynesia or Africa – it's hard to quantify their importance accurately in this analogy. However, the importance is clearly "finite" and can't go to zero. Hawaii, the Greenland, Polynesia, or Africa inevitably enters many people's lives.
Finally, I want to end up with a more general comment. New exceptional theories that were previously overlooked but that obey all the "quality criteria" that were satisfied by the more wellknown theories; and all the new perspectives and "pictures" that allow us to say something or calculate something about these as well as the more ordinary theories are important parts of the genuine progress in theoretical physics and everyone who actually likes theoretical physics must be thrilled by this kind of progress and by the new "concise ways" how some previously impenetrable technical insights may be explained or proved.
There exists a class of people with a very low intelligence, no creativity, no imagination, and no ability to see the "big picture" who are only capable of learning some very limited rules and who are devastated by every new powerful technique or technology that physics learns. These human feces often concentrate around ShmoitandShmolin kind of aggressive sourball crackpot forums. I hope that all readers with IQ above 100 have managed to understand why the text above is enough as a proof of the simple assertion that all these ShmoitsandShwolins are just intellecutally worthless dishonest scum.
And that's the memo.
Ask Ethan #64: What happens to matter as the Universe expands? (Synopsis)

“The trees that are slow to grow bear the best fruit.” Molière So if the
Universe is expanding and cooling, what does that mean for the matter in
it? Sure...
6 hours ago
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