archived as http://www.stealthskater.com/Documents/Pitkanen_36.doc (also …Pitkanen_36.pdf) => doc pdf URL-doc URL-pdf

more from Matti Pitkänen is on the /Pitkanen.htm page at doc pdf URL

note: because important websites are frequently "here today but gone tomorrow", the following was archived from http://matpitka.blogspot.com/2010/01/lubos-motl-provided-his-own-answer-to.html on January 19, 2010. This is NOT an attempt to divert readers from the aforementioned website. Indeed, the reader should only read this back-up copy if the updated original cannot be found at the original author's site.

24 Fundamental Questions for Elementary Physicsby Dr. Matti Pitkänen / January 28, 2010

Postal address:Köydenpunojankatu 2 D 1110940, Hanko, Finland

E-mail: matpitka@luukku.comURL-address: http://tgdtheory.com

(former address: http://www.helsinki.fi/~matpitka )"Blog" forum: http://matpitka.blogspot.com/

Lubos Motl provided his own answers to Sean Carroll's 24 questions. Lubos answered these questions as a superstring fanatic. In the following, I will do the same as a TGD fanatic;-).

Lubos' answers appear in blocked text . My own answers follow his.

1. What breaks electroweak symmetry?

In contemporary physics, there are many questions that are too deep to be sensibly asked: we don't have the right tools and language to constructively think about them. There are many unanswered questions that are deep but that can already be asked. But there are also questions that have been answered, that are tautological, that are too shallow or too vague, that make some incorrect assumptions, or that have other reasons not to be interesting. Sean Carroll's "24 Questions" mostly belong to the latter category.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

The electroweak symmetry is broken by the Higgs field's vacuum expectation value.

The unitarity of the WW scattering implies that a new term with a scalar exchange has to contribute below a TeV (a contribution from the exchange of a Higgs particle). This is no speculative physics. Steven Weinberg got most of his Nobel prize in 1979 for this insight.

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TGD

The corresponding particle has to be relatively stable and its mass must be in an accessible interval to make it work. It will be seen at the LHC. Somewhat more speculatively, there may be several such Higgs fields (like in SUSY) or this Higgs field may be composite (like in technicolor). But these are technical additions that are not strictly necessary to answer the question above. The bulk of the question was answered by the first sentence.

Lubos gives the textbook answer -- i.e., the electroweak symmetry is broken by the Higgs field's vacuum expectation value. TGD allows the Higgs but reduces the description of the symmetry breaking to a much deeper level. CP2 geometry breaks the electroweak symmetry. For instance, color partial waves for different weak isospin states of imbedding space spinors have hugely different masses. The point is that the electroweak gauge group is the holonomy group of spinor connection and not a symmetry group unlike the color group, which acts as isometries.

For physical states are massless before p-adic thermal massivation due to the compensation of conformal weights of various operators. The most plausible option is that both the non-half integer part of vacuum conformal weight for particle and Higgs expectation are expressible in terms of the same parameter which corresponds to a generalized eigenvalue of the modified Dirac operator. Higgs expectation-massivation relation is transformed from causation to correlation.

2. What is the ultraviolet extrapolation of the Standard Model?

This question is amusing and the probable reason why it was asked was that the author didn't understand and doesn't understand the meaning of the word "extrapolation". The answer to the question in this form is, of course, "the Standard Model".

By a definition of "extrapolation", the formulae from the Standard Model are taken to be valid in all regimes regardless of the energy. In fact, the Standard Model may really be extrapolated up to the Planck scale as long as the Higgs mass belongs to a realistic range.

What Carroll probably wanted to ask is what is the ultraviolet "completion" of the Standard Model -- i.e. what theory replaces it when its extrapolation breaks down (just the opposite than what he asked). This is way too general a question because it essentially says "tell me everything about new physics". Supersymmetry, grand unified theory, Kaluza-Klein theory, etc. are all likely to be a part of the answer.

At any rate, this more ambitious question -- at this limited level of detail -- can also be answered and the most correct answer is string theory. However, it is even more certain that the question in the form that was asked is trivial and the answer is, once again, "the Standard Model".

Lubos violently explains that "UV extrapolation" in the above statement should be replaced with "UV completion". I would replace it with "the unified theory of fundamental interactions". Lubos, of course, answers as a proponent of string theory. The problem is that there is practically an infinite number of completions so that the predictivity is lost.

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TGD geometrizes the symmetries of the Standard Model and reduces them to the symmetries of Classical number fields. Also octonionic infinite primes, one of the most exotic notions inspired by TGD, code standard model symmetries. The most general formulation of the World of Classical Worlds is as the space of hyper-quaternionic of co-hyper-quaternionic subalgebras of the local hyper-octonionic Clifford algebra of M8 or equivalent M4× CP2.

The answers by both Lubos and me involve also supersymmetry but in a different sense. In TGD framework, the oscillator operators of the induced spinor fields define the analog of the space-time SUSY so that the algebra of second quantization is replaced with N = ∞ SUSY. This requires a modification of SUSY formalism. But N=1 SUSY associated with the right handed coveriantly constant neutrinos emerges as preferred sub-SUSY and counterpart of N=1 SUSY. The construction of infinite primes also involves supersymmetry.

3. Why is there a large hierarchy between the Planck scale, the weak scale, and the vacuum energy?

These are, of course, two most famous hierarchy problems of current physics.

The Planck-weak hierarchy is most likely stabilized by supersymmetry. The stabilization is necessary but not sufficient a condition for the hierarchy to occur. Supersymmetry probably plays some role in the smallness of the cosmological constant in the Planck units (the other problem included in this question).

However, the "truly tiny" observed value of the vacuum energy can't be derived at this moment. It is unclear whether a "canonical" dynamical explanation exists. It is plausible (but not guaranteed) that the anthropic explanation is everything one can obtain. It is surely true that if the cosmological constant were vastly different, Life similar to ours couldn't exist.

Individual vacua allow one to calculate all these values. Some of the vacua give answers that are vastly different from the observed hierarchies while some of them may give answers that are close or exactly equal to the observed figures.

These are the two most famous hierarchy problems of current physics as Lubos notices. In TGD framework, the Planck scale is replaced with CP2 length scale which is roughly by a factor 104 longer than the Planck length scale. Instead of the Planck length, it might be more appropriate to talk about gravitational constant which follows as a prediction in TGD framework.

p-Adic length scale hierarchy is needed to understand the hierarchy of mass scales. The inverse of the mass-squared scale comes as primes which are very near to octaves of a fundamental scale. Powers of 2 near Mersenne primes or Gaussian Mersennes are favored. This predicts a scaled-up copy of hadron physics which should become visible at the current LHC. Quite generally, unlimited number of scaled versions of Standard Model physics are possible in principle.

The vacuum energy density is the basic problem of superstring approach. How desperate the situation is becomes clear from the fact that rhetoric tricks such as the anthropic principle are considered seriously. Empirical findings (for some reason neglected by colleagues) suggests that cosmological constant depends on Time. In TGD framework, the cosmological constant is predicted to depend on the p-adic length scale of the space-time sheet and behaves roughly like 1/a2 where a is cosmic time

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identified as light-cone property time. Actually, the time parameter a is replaced by a corresponding p-adic length scale. The recent value is predicted correctly under natural assumptions.

What "dark energy" is becomes a second question. TGD suggests the identification as a matter at space-time sheets mediating gravitational interaction having gigantic values of Planck constant implying extremely long Compton lengths for elementary particles. This guarantees that the energy density is constant in excellent approximation. If gravitational space-time sheets correspond to dark magnetic flux tubes (i.e., expanded cosmic strings), the mysterious negative pressure can be identified Classically in terms of magnetic tension. If one takes seriously the correlation of the intelligence of conscious entities with the value of the Planck constant, these gravitational space-time sheets can be God-like entities.

4. How do strongly-interacting degrees of freedom resolve into weakly-interacting ones?

In Quantum Field Theory, the number of particles is not conserved. So particles of any kind can "transmute" into particles of other kinds as long as the strict Conservation Laws are obeyed.

The "character" of the final particles doesn't have to coincide with the "character" of the initial ones. For example, a strongly interacting pion may decay into 2 photons and/or various combinations of leptons that are only interacting by the electroweak interactions. There's nothing unusual to it. They decay via a virtual W boson or similar channels. This has been understood for more than 70 years (for example, recall Fermi's theory of beta-decay).

Lubos regards this question as strange and expresses this using colorful rhetoric. Maybe Carroll refers to QCD and hadronization. M8-M4× CP2 duality relates low energy and higher energy hadron physics to each other in TGD framework and corresponds group theoretically to SU(3)-SO(4) duality where SO(4) is the well-known strong isospin symmetry of low-energy hadron physics.

Or maybe Carroll talks about the technical problem of calculating the behavior of strongly interacting systems. Nature might have solved the latter problem by a phase transition increasing Planck constant so that perturbation theory based on larger value of Planck constant works. The particle spectrum however changes and system becomes anyonic in general.

5. Is there a pattern/explanation behind the family structure and parameters of the Standard Model?

Yes, of course.

Obviously, the multiplicity of leptons and quark families may only be derived from a "deeper" principle in the framework of string theory. Whoever is hoping that a non-stringy framework could ever shed light on any of these big questions is fighting a lost battle. It's simply not possible to avoid string theory in answering any of these questions.

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The number of families may be calculated in various stringy constructions by well-understood mathematical algorithms. In the most Classical case of heterotic strings on Calabi-Yau manifolds (with the identified spin/gauge connections), the number of families equals one-half the Euler character of the Calabi-Yau.

Analogous-but-different formulae exist in other frameworks and more complicated vacua (e.g., braneworlds, vacua with fluxes, M-theory, F-theory). Also, Yukawa couplings, gauge couplings, masses, and other parameters may in principle be calculated although the calculation depends on the scenario. The right question that summarizes these unknown things is: Which limit of string theory (heterotic, IIA, M-theory, F-theory) is most useful (weakly coupled) to describe the reality?

I can only echo Lubos "of course there is". In superstring models, the large number of explanations tells that the real explanation is lacking. In TGD framework, fermion families correspond to various genera for partonic 2-surfaces (genus tells the number of handles attached to sphere to get the 2-dimensional topology). There is an infinite number of genera. But the 3 lowest genera are mathematically very special (hyper-ellipticity as a universal property) which makes them excellent candidates for light fermion families. The successful predictions for masses using p-adic thermodynamics and relying strongly on the genus dependent contribution from conformal moduli support the explanation.

Bosons correspond to wormhole contacts and are labeled by pairs of general implying a dynamical SU(3) symmetry with ordinary bosons identified as SU(3) singlets. SU(3) octet bosons (perhaps making themselves visible at today's LHC) are predicted and serve as a killer test.

The symmetries of the Standard Model reduce to the geometry of CP2 having a purely number theoretical interpretation in terms of the hyper-octonionic structure. Number theory fixes through associativity condition the dynamics of space-surfaces completely (hyper-quaternionicity or its co-property in appropriate sense).

6. What is the phenomenology of the "dark" sector?

Dark matter has the well-known gravitational effects on the galaxies etc. that forced the physicists to discover it a few decades ago. Besides that, various decays appear with some frequency.

And the dark matter particles (such as neutralinos) can participate in a limited number of additional types of interactions. Assuming the standard MSSM neutralino realizations (or other scenarios for that matter), these things are mostly understood. Dark matter accounts for a higher percentage of the mass of the Universe than the visible matter. But that doesn't mean that it has a more interesting phenomenology.

Even if the MSSM were wrong, it's pretty obvious that it is the other way around. Besides the basic gravitational impact and some decays and perhaps pairwise annihilation, dark matter probably doesn't exhibit too much interesting behavior. At least, that's the thing we should conclude -- in a preliminary way -- based on our knowledge and basic principles such as Occam's razor.

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Lubos sees the "dark matter" as something relatively uninteresting. Just some exotic weakly-acting particles. How incredibly blind a theorist accepting 11-D space-time and landscape having absolutely no empirical support can be when it comes to actual experimental facts!

In TGD framework, "dark matter" means a revolution in the world view. Its description relies on the hierarchy of Planck constants requiring a generalization of the 8-D imbedding space M4 × CP2 to a book-like structure with pages partially characterized by the value of Planck constant. The most fascinating implications are in Biology. Also, the implications for our view about the nature of consciousness and our position in World Order are profound.

7. What symmetries appear in useful descriptions of nature?

One must be careful what types of symmetries we are talking about. Only global unbroken symmetries are "really objective" features of the reality. It's very likely that we have found the full list and it includes the CPT-symmetry, Poincaré symmetry (including Lorentz, translational, and rotational symmetries), and the U(1) from the conservation of the electric charge.

Additional symmetries may exist. But they are broken (i.e. non-linearly realized) SUSY and the electroweak symmetry. SU(3) is confined and there may exist additional confined groups. But the presence of gauge groups really depends on the description and it is never a sharply defined Physics question whether a symmetry in a description is "useful".

Asking whether something is "useful" doesn't belong to Physics, it's a "meta" question related to our strategy whose purpose is for us to be more capable to ask and answer other, more objective questions. Different dual descriptions of the same physics usually have different gauge symmetries and there's no contradiction here.

Also, perturbative string field theory may be usefully formulated with the help of an infinite-dimensional gauge symmetry principle (at each point). Such gauge symmetries may be pretty in formulations of physical theories. But they're not really necessary for Physics. They are not physical because physical states must be singlet under all gauge groups (so physical objects know nothing about the representation theory of these groups).

It's conceivable but far from guaranteed that a generalization of our knowledge about symmetries will lead to further progress in the understanding of the fundamental laws of Physics.

As Lubos says, one must be careful what types of symmetries we are talking about. Lubos says "Only global unbroken symmetries are 'really objective' features of the reality. It's very likely that we have found the full list and it includes the CPT-symmetry, Poincare symmetry (including Lorentz, translational, and rotational symmetries), and the U(1) from the conservation of the electric charge."

By adding color symmetry and separate baryuon and lepton conservation, one obtains the symmetries of Quantum-TGD. This prediction follows from number theoretical vision alone.

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Lubos mentions dualities relating descriptions based on different symmetries. In TGD, M8-M42

duality manifests as the dual descriptions of hadrons using low-energy hadron phenomenology (SO(4))and parton picture at high energies (color SU(3)).

There are good reasons to believe that the TGD Universe is able to emulate almost any gauge theory for which gauge group is simply a laced Lie group and stringy system (Mc-Kay correspondence, inclusions of hyper-finite factors and the book-like structure of generalized imbedding space). These symmetries would be however engineered rather than fundamental symmetries.

8. Are there surprises at low masses/energies?

Probably no. One can ask this kind of question in any context. For example, are there surprises when the number of baryons becomes comparable to the number in the stars?

Surprises only occur when they occur. The most likely answer to the question above (and any other question about the surprises) is No. If that wasn't the case, the new things couldn't be surprises according to a rational evaluation of their surprising power.

Various hints indicating that there could be such surprises (e.g., alternative dark-matter-free explanations of dark-matter effects, or MOND alternatives to dark matter and dark energy, and so on) have been heavily disfavored by recent observations. The most likely possible new physics at low ("officially understood" mass scales) may be axions or some light gravitinos etc. But they wouldn't be "real" surprises because they've been studied as legitimate possibilities.

We can't be quite sure, but I would bet 10-to-1 against completely new surprises at low masses that don't follow among the names above and similar particles, fields, and effects that have been intensely studied in the seriously considered literature.

The question of the type above is manifestly not useful because it is -- by its very design -- trying to go beyond any level of understanding we would achieve at any point. But interesting questions only reside at the boundary of our understanding. Not far beyond it.

Lubos believes that there are no surprises without realizing that we ourselves are the most surprising surprise. The eye is not able to see itself without a mirror. The fact is that Standard Physics cannot say anything really interesting about Life and Consciousness. p-Adic physics, hierarchy of Planck constants, Zero Energy Ontology, etc. -- I believe that all of these are necessary if one really wants to understand living matter.

9. How does the observable Universe evolve?

Thanks for asking. Very well.

The standard model of Cosmology (including dark matter and dark energy) is almost certainly enough to account for every major cosmological observation we have

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made or we are making. We pretty much know the evolution from a tiny fraction of a second after the Big Bang -- and maybe even the GUT scale length after it -- until the Present.

It is very likely that the Universe will continue in the accelerating expansion and come closer to an empty de Sitter space.

Lubos believes in standard cosmology described by General Relativity as such. TGD predicts a quantum version of standard cosmology. Smooth cosmological evolution is replaced by a sequence of rapid expansion periods serving as space-time correlates for quantum jumps increasing Planck constant for appropriate space-time sheets. This applies in all length scales.

One especially fascinating application is to the evolution of the Earth itself. The Expanding Earth hypothesis finds a physical justification and one ends up to an amazingly simple and predictive vision about pre-Cambrian and Cambrian periods. This includes both Meteorology, Geology, and Biology.

Zero Energy Ontology strongly suggests that the proper quantum description is in terms of the moduli space for "causal diamonds" (i.e., CDs identified as intersections of Future and Past light-cones). The entire Future light-cone labeling the "upper" tips of CD and analogous to Robertson-Walker cosmology is replaced with a discrete set of points. In particular, the values of cosmic time come as octaves of basic scale for a given value of the Planck constant.

The spectrum of Planck constants means that all rational multiples of CP2 time scale are possible in principle. Cosmic evolution as endless re-creation of the Universe can be seen as the emergence of CDs with larger-and-larger size.

10. How does gravity work on Macroscopic scales?

It is described by General Relativity. For many purposes in Astrophysics and Cosmology, we may replace this theory due to Einstein by its Newtonian approximation.

Obviously, the harder question is how gravity works at microscopic and ultra-microscopic scales. Changes to Newton's law at accessible microscopic scales would suggest additional large or curved space-time dimensions. But we know from the newest experiments that they shouldn't be larger than 10 microns-or-so.

Modifications of gravity at the ultra-microscopic, Planckian scales is what quantum gravity is all about. String theory tells us that gravity can't be separated from other forces (and forms of matter) in this extreme regime. However, it also tells us that gravity works according to the older established approximate theory ( Einstein's theory) at microscopic scales. Otherwise we wouldn't consider it as a theory of quantum gravity.

General Relativity is part of the description. But Zero Energy Ontology and the hierarchy of Planck constants bring in new elements.

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The gigantic values of gravitational Planck constant make possible Astroscopic quantum coherence for the dark matter at magnetic flux tubes mediating gravitational interaction and explain dark energy. Quantum-Classical correspondence suggests that the exchanges of virtual particles has a Classical description allowed by Einstein's tensor.

In the case of a planetary system, a possible manifestation is the observation of Grusenick that a Michelson interferometer rotating horizontal plane produces a constant interference pattern. But in a vertical plane, the interference pattern varies during rotation. If this is real, this find is revolutionary! It might also directly relate also to the finding that the measured values of gravitational constant varies within 1 percent. There has been no reaction from Academic circles.

The assumption that gravitation in long length scales has been understood more-or-less completely is the basic dogma of string theorists. This despite the fact that the list of anomalies and intriguing regularities is really long. It is much more rewarding to impress colleagues with long and complex calculations than using one's professional lifetime to a risky attempt to solve a real problem.

11. What is the topology and geometry of space-time and dynamical degrees-of-freedom on small scales?

When this question is separated from the things that are known, it becomes fully equivalent to the question asked at the end of the Answer #5: What is the most weakly coupled description of string theory to describe the reality?

It's important to notice that the geometry only becomes "objective" if it is large and Classical. The geometry and topology of small (especially Planckian) manifolds is a question that doesn't have a unique answer because of dualities. There exist lots of dualities that imply that string theories on entirely different geometric backgrounds are completely equivalent to each other.

Also, the additional "Planckian" degrees-of-freedom may be -- and are somewhat likely to be -- non-geometric. They don't allow one a useful reformulation in terms of a finite number of fields on a Classical geometry. The question above is incorrectly asked because it makes a somewhat unlikely assumption that the Classical geometry is guaranteed to be useful at the scales where new degrees-of-freedom resembling "new dimensions" emerge.

In TGD framework, "on small scales" can be dropped from the question. Many-sheeted space-time, hierarchy of Planck constants, p-adic space-time sheets serving as correlates of cognition and intentionality, Zero Energy Ontology -- all these mean a dramatic generalization of the view about space-time in all length scales and a profoundly new way to interpret what we observe.

If TGD is correct, we really "see" the dark matter in Biology. And we really "see" p-adic physics via its interaction giving rise to effective p-adic topology of real space-time sheets leading to extremely successful predictions for elementary particle masses.

Quantum group enthusiasts believe that space-time time becomes non-commutative in Planckian length scales. Some theoreticians believe that some kind of Planckian discreteness emerges. In TGD framework, quantum groups emerge as a natural part of description in terms of a finite measurement resolution and in all length scales. Discretization appears as a space-time correlate for a finite

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measurement resolution but not as an actual discreteness. The finite resolution of cognition and sensory perception implies also an apparent discreteness. Also, the hierarchy of infinite primes suggests description in terms of hierarchy of discrete structures.

At the fundamental level, everything is however continuous in real or in p-adic sense in accordance with the generalization of number concept involving both fusion of real and p-adic number fields to a larger super structure and providing single space-time point with infinitely rich number theoretic anatomy. The talk about infinite primes (infinite only in real sense) sounds very unpractical. But to my great surprise, infinite primes lead to highly detailed predictions for the spectrum of states and quantum numbers.

12. How does quantum gravity work in the real world?

Very well, thank you for asking.

One can show that quantum gravity (i.e. string theory) fully reduces to the conventional effective theories (especially effective quantum field theories) in the context of the "real world" (i.e., relatively long-distance and low-energy phenomena). As we have already mentioned in Answer #10, that was the first test that made us de facto sure that we actually know what the right theory of quantum gravity is.

Lubos restates the basic belief of string theorists that Einstein's equations follow at long length scale QFT limit of superstring models. In TGD framework, Einstein's equation hold true too at this limit. But quantal aspects are also present. The hierarchy of Planck constants -- in particular gigantic values of the gravitational Planck constant at dark magnetic flux tubes mediating gravitational interaction -- are essential for the gravitational physics of dark matter.

There are also several delicate effects (such as the Allais effect) suggesting that the ultra-conservative view of Lubos is wrong. With all respect, the builders of quantum gravity theories should really consider returning to the roots and also a serious consideration of experimental data. Otherwise they continue to produce useless formalism without any connection with the observed reality.

13. Why was the early Universe hot, dense, and very smooth but not perfectly smooth?

Again, the answer to this question is well-known in the (by far) most likely picture of the early Universe we know.

Flatness and relative smoothness of the Universe today requires cosmic inflation. In inflationary cosmology, the smoothness arises from the gigantic exponential expansion of the Universe during the inflationary era. The inflation is terminated by reheating and the structures start to form later by the gravitational clustering and collapse.

It's important to appreciate that the cosmic inflation achieves the right outcome independently of the detailed state of the Universe that existed before the inflation. And we actually don't know what the state of the Universe right before the inflation

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was. It's pretty likely that the inflationary regime is directly adjacent to the Planckian regime of the Universe.

And in the Planckian regime, we actually can't say that the Universe was "too smooth but not perfectly smooth". There's no sensible definition of the word "smooth" that would allow us to say that the pre-inflationary Universe was smooth. Otherwise, the hotness and high density of the Planckian world is a trivial result of dimensional analysis: things had to be Planckian. And both the Planckian density and the Planckian temperature are extremely high relatively to the densities and temperatures that we know from our lives.

The standard answer echoed by Lubos is in terms of inflationary cosmology. In TGD framework, very early cosmology is cosmic string dominated. Space-time sheets appear later (at certain proper time distance from light-cone boundary). Inflationary cosmology is replaced with a sequence of expansion periods during which the cosmology is quantum critical at appropriate space-time sheets. No scales are present and 3-space is flat. The critical cosmology (which is unique apart from a parameter telling its duration) describes the situation. This is an extremely powerful prediction following from the imbeddability to M4× CP2 alone. Quantum criticality implies the universality of the dynamics during expansion periods.

The 'Big Bang' is replaced by a "silent whisper amplified to a Bang" since the energy density of cosmic strings behaves as 1/a2 where a denotes the proper time of light-cone. The moduli space of CDs suggests a cartesian product of M4×CP2 labeling the lower tips of CDs with its discrete version labeling the upper tips of CD. One must ask whether a CD corresponds to a counterpart of the 'Big Bang' followed eventually by a 'Big Crush'.

14. What is beyond the observable Universe?

The same kind of the Universe as the visible one.

It's extremely likely that what we see does qualitatively continue a huge distance beyond the cosmic horizon we can observe today and the appearance of the cosmic horizon is just a "technicality" caused by our Universe's finite age (so far). This answers the question above.

We could try to go even further. Beyond the Universe that looks similar to ours. There could be some non-uniformities or domain walls separating us from other patches of the eternally inflating Universe. And there could exist segments of the Universe or Multiverse that are completely causally disconnected from our region of space-time.

If that's so, these questions won't ever become a part of the empirical science. Otherwise, when we talk about the "whole" Universe or Multiverse including the completely disconnected patches that we can never observe and we will never observe, I find it obvious that we must say that all the vacua (and their excitations) connected in all conceivable ways that satisfy the equations of string theory do exist "somewhere".

Clearly, such an extended Universe is too big. And to get closer to what was known as Physics, we must refocus on those segments of the Multiverse and/or the

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landscape that are closer to our world (either in the space-time or in the configuration space).

"What is beyond the Universe observable to us" would be a more precise formulation.

The hierarchies of Planck constants and p-adic length scales; the hierarchy of conscious entities in which we correspond to one particular relatively low lying level; the hierarchy of infinite primes mathematically similar to an infinite hierarchy of second quantizations; the infinitely complex structure of single space-time point realizing algebraic holography -- I find myself standing at the shore of an infinitely vast sea.

The fundamental symmetries are the basic elementary particle quantum numbers are universal. This by the simple requirement that the geometry of the World of Classical Worlds exists mathematically and has number theoretic interpretation.

15. Why is there a low-entropy boundary condition in the past but not the future?

The Second Law of Thermodynamics abruptly answers both questions. These issues have been discussed on this (my) blog very many times. After all, the question above is incorrectly formulated too.

There are no "boundary conditions in the Future". By its very definition, the Future is whatever will evolve from the Past (through the Present) and nothing else. If you first decide what the Future has to be and then calculate the Present or the Past (as in various doomsday scenarios), you're a victim of a wishful thinking or a bigot with an agenda, not a rationally-thinking person.

The boundary conditions (usually known as the "initial conditions") can only be defined in the Past. Boltzmann's H-theorem and equally strong derivations then imply that the Future is guaranteed to have a higher entropy than the Past. (i.e., That the Past is guaranteed to have a lower entropy than the Future.)

The fact that the Past has a low -- and essentially vanishing -- entropy is a tautology. We simply want to find the "oldest" or "most fundamental" explanation of our origin. So our theories are obliged to go as far into the Past as they can. Because the entropy is a non-decreasing and mostly increasing function of time, this criterion means to reduce the initial entropy to the lowest allowed value (essentially zero).

While it's trivial to see that the entropy of the initial state is low or zero (by the definition of the term "initial state of the Universe"), it's much less clear what the relevant state actually was. It is even mysterious what the right degrees-of-freedom in which the initial state should be described are: it would be much more scientifically interesting to ask this question than Carroll's tautological question.

But once again, this question is equivalent to the other questions above about the nature of the Planckian regime. Once the right degrees-of-freedom are known and the full calculational framework is understood, the question about the identity of the initial state may be answered by a form of the Hartle-Hawking state. But we obviously don't

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know how to calculate the full answer in the right stringy framework today (as opposed to some mini-superspace approximations).

The form of the question reflects the erratic identification of the experienced time appearing in the Second Law with the Geometric-Time appearing as one space-time coordinate. After 32 years of research, this identification looks to me incredibly stupid. But it is made by most of my colleagues despite the fact that these times are completely different. Irreversibility contra reversibility, only the recent moment and past contra entire eternity, etc. Here only Consciousness theory could help. But the "patient" stubbornly refuses to receive the "medication".

Lubos, however, intuitively realizes that Future and Past are not in symmetric position in the Second Law. But he is unable to ask what this means. He really believes that the Boltzmann equations are all that is needed and never consider the possibility that these wonderful equations might make sense only under certain conditions.

In TGD framework, the geometric correlate for the arrow of Subjective-Time which by definition is always the same (consciousness as sequence of quantum jumps with the Past identified as quantum jumps that have already occurred and contribute to conscious experience) can in principle have both directions. Phase conjugate laser beams provide a basic example about the situation in which the Second Law applies in "wrong" direction of geometric-time. Also, self assembly for biological molecules can be interpreted in this manner. Hierarchy of Planck constants implies that for given CD, Boltzmann's equations make sense only for smaller CDs inside it. In living matter, the Boltzmannian description fails.

In TGD framework, the concept of low entropy boundary condition does not make sense. The subjective evolution applies the evolution of entire CD of cosmological size quantum jump by quantum jump. Boltzmann's equations apply only in scales considerably shorter than cosmological time. What is clear is that one can speak only initial condition rather than boundary condition.

It is however not clear whether one can speak about the evolution of entropy as a function of cosmic time if identified as a coordinate of the imbedding space. Quantum-Classical correspondence might allow also the mapping of subjective time evolution to a Geometric-Time evolution with respect to cosmic time. The low entropy of the very early Universe could correspond to that assignable to cosmic strings. The energy density of cosmic strings goes down as 1/a2 and entropy density as 1/a so that for a given co-moving volume the entropy approaches to zero.

The structure of moduli space of CDs suggests that positive of the upper tip of CD relative to the lower one defines a discretized cosmic time and the space-time correlate for entropy corresponds to the growth of entropy of CD as a function of this time in an ensemble of CDs. The asymmetry between tips could be seen as a correlate for the arrow of time.

Carroll's idea about boundary conditions in future might make sense in the following: In Zero Energy Ontology, one has pairs of positive and negative energy sense. There is a large temptation to think that there are 2 choices for the tip which corresponds to the discrete version of the Future light-cone.

16. Why aren't we fluctuations in de Sitter space?

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Because to create our brains, one needs to arrange something like 1026 molecules into pretty organized configurations. As understood by Boltzmann in the 19th century, the probability that such an organized object (whose entropy is 1026 times Boltzmann's constant) occurs as a random fluctuation is comparable to exp(-1026) which is completely negligible relatively to the probability of our origin that actually has a non-random reason (and a detailed, sensible evolution).

The creation of a Macroscopic organized object out of chaos is so unlikely that the probability is -- for all practical purposes -- zero anywhere and everywhere. Any calculation that ends up with a "reasonably finite" probability for such a crazy event is a result of trivial mistakes. Especially an incorrect multiplication of the tiny probability by the (infinite) volume of the space-time etc.

Probabilities can't be artificially "inflated" by multiplying them with incorrect infinite factors. Especially if you don't do the same thing with the probabilities of the "alternative" (namely right) explanations. Probabilities of events must always be normalized together with their alternatives so that the sum equals one. And a spontaneous creation of a Macroscopic organized system is always much less likely than the appearance of evolution composed out of a few steps whose probabilities are comparable to one.

Also, probabilities can't ever be proportional to the (expected) space-time volume in the Future because the Future is unknown at this moment. By the basic rules of causality, it can't affect the Present (or a rational calculation of probabilities at the Present). They are always calculated as functions of our observations of the Past using theories which were also induced from observations of the Past. The knowledge about the Future can't ever be independently used in any rational argument because this knowledge doesn't exist. The Future will actually depend on random events and we may only predict their probabilities by the rules of Quantum Mechanics. That's also why it's wrong to multiply probabilities by space-time volumes (or numbers of observers) in the Future.

We only "directly" know something about the Past. And there is only one finite Past. 13.7 billion years of it. There was one long process of evolution that ended with people like us (among other things). And this evolution is surely much, much more likely than a spontaneous creation of a Macroscopic organized brain by a factor of exp(1026) or so (not far from a googolplex).

If you want to read a whole book filled with similar silliness -- a book that denies the very basic and self-evident facts mentioned above -- please buy Sean Carroll's From Eternity to Here. ;-)

If I have understood correctly the emotional rhetoric of Lubos, the idea of Carroll seems to be that intelligent life is just a random fluctuation rather than a long lasting evolution. For some reason, he locates this fluctuation in de Sitter space. In Standard Physics framework, this view is however more-or-less unavoidable. The colleagues should really use some of their time to learn what we understand and do not understand about Consciousness and the brain to realize that the physics they understand really fails to describe the physics of Life.

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Also, Lubos is so fixated in his materialistic and reductionistic dogmas that he is unable to propose anything constructive. For instance, he does not ask how this undeniable evolution is possible in the framework of Standard Physics.

In TGD framework, the hierarchy of Planck constants meaning a hierarchy of Macroscopic quantum phases and hierarchy of time scales of memory and intentional action leads to a coherent overall view about what Life is. Zero Energy Ontology provides a concrete realization how volition is realized in accordance with the laws of Physics and makes possible a continual re-creation of the Universe.

17. How do we compare probabilities for different classes of observers?

Probabilities are numbers between 0 and 1. So they are compared in the same way as any other pair of real numbers. For example, 0.6 is greater than 0.5. It's questionable whether it's useful to compare probabilities of entirely different things. But there's no doubt that we know how to do it. I may have misunderstood the question. But in its current form, it is genuinely idiotic, right?

I suspect that this silly question originated from some misconceptions described in Answer #16: Sean Carroll may have wanted to artificially inflate probabilities by "acknowledging" some properties of the observers etc. But rational observers calculate probabilities of physical phenomena according to objective algorithms that don't depend on the observers or their class at all.

So if the question was supposed to be "how should we imprint our identity (the class of observers of our kind) into our calculations of probabilities of events", the obviously right answer is that it shouldn't be imprinted at all. Proper laws of Physics -- those that can hopefully be obtained by a legitimate scientific process -- work for the people in China, the Vatican, as well as the extraterrestrial aliens. Nothing that depends on the citizenship of the observer belongs to Physics. Or Science, for that matter.

I do not repeat the violent reaction of Lubos to this question. I am myself not at all sure whether I can catch the meaning of this question. Maybe I could interpret in terms of finite measurement resolution.

Different measurement resolutions give rise to different M-matrices and probabilities. The comparison would require rules allowing to compare these probabilities. This comparison requires relationship between M-matrices at the quantum level; probabilities are not enough. Renormalization group evolution as function of measurement resolution could provide the answer to ho compare the probabilities.

18. What rules govern the evolution of complex structures?

The detailed evolution of all complex structures is governed by the microscopic laws that govern the elementary building blocks applied to a large number of ingredients.

Various kinds of behavior may be described approximately but there's no universal answer to the question "which approximations are both accurate enough and useful".

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Generally, we are often interested in the evolution of "collective coordinates" and approximate degrees-of-freedom that are constructed out of the full ensemble of the degrees-of-freedom.

Such "simplified descriptions" of systems often approximately follow the most general type of behavior that is compatible with the existing symmetries and other qualitative constraints. Most typically, effective Quantum Field Theories and other "critical phenomena" may govern such behaviors.

One can systematically expand the full equations governing the subset of the degrees-of-freedom in a derivative expansion around the strict long-distance limit. There are many kinds of such behaviors because this question really covers all of sciences. It's way too inclusive a question to be useful. It's likely that only "scaling limits" of various kinds may give us effective descriptions that can become "arbitrarily accurate". All other approximate descriptions of complex systems are vague and their inaccuracies are inherently finite.

The textbook answer of Lubos is "The detailed evolution of all complex structures is governed by the microscopic laws that govern the elementary building blocks applied to a large number of ingredients".

The TGD-inspired answer is based on the acceptance of fractal hierarchies -- i.e., reductionistic dogma is replaced with fractality. The laws at various levels are essentially similar. But every level brings something new (e.g., the Mandelbrot fractal set does not look exactly the same in the new zoom). It is not possible to reduce the behavior at higher levels that at the lowest level.

The hierarchy of infinite primes characterizes this idea number theoretically and -- as there are reasons to believe -- also physically. The construction of hyper-octonionic infinite primes is structurally similar to a second quantization of an arithmetic Quantum Field Theory with states labeled by primes (rational, quaternionic, or octonionic). There is infinite hierarchy of second quantization with many particle states of the previous level becoming single particle states of the new level. At each level, one has infinite primes analogous to free many particle states plus primes analogous to bound states.

One new element of emergence is association statistics. Permutations and associations are basic stuff of number theory and algebra. Quantum commutativity -- invariance of the physical state under permutations in quantum sense leads to Fermi-, Bose- and quantum group statistics in effectively 2-D situation. Quantum associativity requires association statistics with respect to different associations of particles (i.e., replacing A(BC) with (AB)C can induce multiplication with +1,-1, or more complex phase).

At space-time level, the hierarchy of space-time sheets is the counterpart for this hierarchy. p-Adic length scales define one hierarchy. Also, space-time sheets characterized by a large value of Planck constant emerge as systems migrate to the pages of the "Big Book" partially characterized increasing value of Planck constant and at which matter is "dark" relative to the observer with standard value of Planck constan which corresponds to rational number equal to 1.

There is also a hierarchy of cognitive descriptions of the physical system. The higher the level in the hierarchy, the more abstract the description is and the less details it has. This is like the view of Boss of a big company as compared to that of a person doing something very concrete job.

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p-Adic physics turns upside the reductionistic hierarchy proceeding from short to long scales. What is infinitesimal p-adically is infinitely large in a real sense. This p-adic aspects is necessarily if we want to understand intentional systems able to plan their own behavior. p-Adic effectively topology means precise long-range correlations and short-range chaos which indeed characterizes the behavior of living matter. One can also say that p-adic physics provides the IR completion of Physics.

19. Is Quantum Mechanics correct?

Yes it is, thanks for asking.

All imaginable attempts to show that a non-Quantum Mechanics could replace Quantum Mechanics as an explanation of the observed phenomena have been de facto ruled out. All kinds of hidden-variable theories have been shown impossible. Incompatible either with direct observations of entanglement or indirectly with observations of locality and Lorentz invariance or incompatible with basic consistency rules such as the rules for the sum of all probabilities (unitarity).

Also, all existing motivations to look for theories that violate the postulates of Quantum Mechanics have been shown unsubstantiated even though it wasn't clear from the beginning.

To present a major example, it's been shown that the string-theoretical dynamics of black holes in the "quantum regime" (including black hole evaporation and the flow of the information) is fully compatible with all the universal postulates of the black hole. In 2010, the search for a non-Quantum explanation for the phenomena that need Quantum Mechanics is equivalent to the full denial of 100 years of all the key evidence in Physics.

Quantum Mechanics is not wrong. It however requires, however, a profound generalization if we want to understand Life.

Also the gravitational anomalies and unexpected regularities at the level of planetary system suggest a generalization. The Planck constant must be replaced with a hierarchy of Planck constants realized in terms of the "Big Book". Positive Energy Ontology must be replaced with Zero Energy Ontology for which states correspond to physical events in standard positive energy ontology.

S-matrix is replaced with its "complex square" root (i.e., M-matrix) having interpretation as square root of density matrix and making Thermodynamics part of Quantum theory. This generalization answers several frustrating questions raised in standard ontology.

A further important modification is the introduction of the notion of finite measurement resolution realized in terms of inclusions of hyper-finite factors and having discretization as space-time correlate.

20. What happens when wave functions collapse?

Nothing objective happens.

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A wave function is nothing else than a tool to predict probabilities. It is no real "wave". When such an object "collapses", the only thing that it means is that we learned something about the random outcomes of some measurements so we may eliminate the possibilities that -- as we know -- can no longer happen.

For our further predictions, we only keep the probabilities of the possibilities that can still happen (i.e. those that are compatible with the facts about the events that have already taken place).

Everyone who thinks that "something real happens" when a wave function collapses -- that a wave function is on par with classical waves (such as electromagnetic waves) -- has misunderstood the basic meaning of Quantum Mechanics.

The answer of Lubos is from the few pages of the standard Quantum Mechanics textbook devoted to the measurement problem. "A wave function is nothing else than a tool to predict probabilities; it is no real wave. When such an object "collapses", the only thing that it means is that we learned something about the random outcomes of some measurements so we may eliminate the possibilities that -- as we know -- can no longer happen. For our further predictions, we only keep the probabilities of the possibilities that can still happen."

This answer brings in "we" but says nothing about what this "we" might be. This "We" remains an outsider to the physical world. Here we encounter the amazing ability of even admittedly intelligent persons to not see the problem although it is staring directly at their face.

In TGD framework, wave function collapse is involved with quantum jump re-creating the quantum universe. Speaking about space-time correlates, this means that the entire space-time surface (or rather their quantum superposition) is replaced with a new one. Both Geometric-Ppast and -Future are replaced with a new one in a quantum jump. There is no conflict with deterministic field equations (in generalized sense in TGD framework) since the non-determinism relates to Subjective-Time identified as a sequence of quantum jumps rather than with Geometric-Time appearing at the Classical field equations and Schrödinger equation.

Negentropy Maximization Principle (stating the reduction of entanglement entropy in quantum jump is maximal) implies standard quantum measurement theory. There are fascinating possibilities opened by the fact that for rational (and even algebraic entanglement) probabilities, number theoretic analogs of Shannon entropy make sense and allow negentropic entanglement (emergence of information carrying stable quantum entangled states).

21. How do we go from the quantum Hamiltonian to a quasi-Classical configuration space?

A Classical configuration space is only useful when we can describe the Hilbert space using a basis of simultaneous eigenstates of a collection of observables.

If the "configuration space" is a good concept, the spectrum of these observables must be continuous and the Hamiltonian must be equal to a function of these observables (up to small terms of the order of Planck's constant). That's when a

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Classical limit occurs and the derivation of Classical physics from the full Quantum laws is a well-known procedure in this case.

Semi-Classical physics is a standard undergraduate material and decoherence covers all the issues about the "conceptual" transition from the Quantum framework (including interference and quantum probability amplitudes) to the Classical framework (without interference, with at most Classical probabilities, and with emergent determinism).

Most of the well-known Quantum theories have actually been constructed in the opposite way (as "quantizations" of a Classical starting point). However, one must realize that such a Classical theory doesn't have to exist for a given Quantum theory. There are many Quantum theories that don't have any Classical limit. At least not in their most interesting regimes.

The real world is a Quantum system. The existence of Classical limits is just a "bonus". And all Classical theories we may find useful are always just approximations.

A more appropriate question would be "How to go from a Quantum description to a Classical description".

Hamiltonian formulism relies on Newtonian time and is given up already in Special Relativity. In General Relativity, General Coordinate invariance makes Hamiltonian formalism even more un-natural.

In Zero Energy Ontology, the basic mathematical object coding for the predictions of the theory is M-matrix characterizing the physics inside given CD. It decomposes into a product of positive square root of diagonal density matrix and unitary S-matrix. The latter characterizes given CD and need not have any natural representation as an exponentiation of infinitesimal Hermitian operator (i.e., the Hamiltonian).

This kind of picture is also in conflict with General Coordinate Invariance. In p-adic context, unitary evolution becomes highly questionable also for number theoretical reasons. The counterpart of exponential function in p-adic context does not have the properties as it has in real context and the natural unitary operators involve roots of unity typically requiring algebraic extension of p-adic numbers and therefore have no description as unitary time evolutions.

In the formalism without the Hamiltonian, observables are replaced with algebras of various symmetries. Various super-conformal symmetries make these algebras infinite-dimensional. The modified Dirac equation brings in second quantization which reduces to an infinite-dimensional analog of space-time SUSY algebra.

How Classical physics emerges from Quantum theory is, of course, extremely important un-answered question although Lubos claims the opposite. This emergence has 2 meanings corresponding to Geometric-Time and Subjective-Time.

1. Consider first Geometric-Time. In TGD framework, the space-time surface is a preferred extremal of Kahler action and analogous to the Bohr orbit. Classical physics in the geometric sense becomes an exact part of Quantum physics and the geometry of the World of Classical Worlds. This is forced by the General Coordinate Invariance alone.

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Even more preferred space-time surfaces correspond to maxima of the Kahler function identified as value of Kahler action for a preferred space-time surface. In mathematically non-existing path integral formalism, stationary phase approximation gives something believed to be enough for Classical physics in this sense.

2. Lubos talks also about decoherence as a mechanism leading to Classicality. This notion applies when one speaks about Subjective-Time. When the time scale of observer is long as compared to the time scale of observed events (i.e., the CD of observer is much larger than those of observed systems so that quantum statistical determinism applies), decoherence taking place in sub-quantum jumps guarantees that all phase information is lost and quantum mechanical interference effects are masked out. The World looks classical in Boltzmannian sense but only for an observer looking the situation from a longer time scale.

22. Is physics deterministic?

No, Classical determinism has been proven invalid in our Universe.

Once again, our Universe follows the principles of Quantum Mechanics. Questions #19, #20, and #22 are clearly equivalent and they're not real questions. The purpose of these sentences ending with a question mark is to promote mystifications about fundamental science and fog surrounding the most solid pillars of modern Physics. Fog that is based on no rational evidence, neither empirical nor theoretical whatsoever.

Determinism is not valid in a Quantum universe as Lubos states. But Determinism is valid at the level of field equations. These statements are contradictory unless one realizes that there are two different Times.

To understand these two Times and their relationship, one is forced to make the observer a part of the Universe instead of being outsider. That is to develop a Quantum theory of Consciousness. Amusingly, Lubos admits the non-determinism is a fact but denies that Schrödinger amplitudes -- which must behave non-deterministically in standard ontology -- are real.

23. How many bits are required to describe the universe?

Currently around 10100.

This entropy is dominated by the large black hole entropies. Before we knew about them, we thought that the number was closer to 1090, dominated primarily by the cosmic microwave background. Still, a description in terms of 10100 bits is inevitably an effective, approximate one. To describe the phenomena in our de Sitter space "exactly", one needs those 10120 bits that holographically live on the de Sitter cosmic horizon (it's approximately the area of the cosmic horizon in the Planck units).

As the entropy of our Universe is increasing, the answer is clearly getting closer from 10100 to 10120. The evolution is seemingly non-unitary because the Hilbert space

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couldn't grow. But this only corresponds to the emergence of the previously unknown information from the de Sitter horizon.

However, it's likely that a finite number of bits (such as 10120) is probably inadequate to describe the de Sitter space fully in the quantum framework. The full theory almost certainly needs to work with infinitely many bits because there's no preferred finite number of bits. 10120 is just a truncated subset that is good enough for the effective estimates of information but bad enough for the detailed evolution.

However, it is questionable whether such a complete theory makes any sense in de Sitter space. The phenomena in de Sitter space can have an inherent unpredictability due to the unpredictable thermal noise coming from the horizon. One must realize that the time spent with the research of "overly accurate" questions about de Sitter space could be a wasted time because no solid interesting answers may exist. It's plausible that solid formulae only emerge in the limit when the space becomes effectively infinite.

Currently around 10100 says Lubos. For me, both the question and its answer are nonsense for the same reason as some other questions above. That people waste their time with this kind of questions shows how desperately Physics needs an extension to a theory of Consciousness. This is also required by Neuroscience and Biology.

Lubos identifies this number as the entropy of the observed Universe. The notion in principle makes sense. But not the identification. In TGD framework, the entropy is also dependent on the resolution used. The better the measurement resolution, the larger the number of degrees-of-freedom and the larger the entropy.

24. Will elementary physics ultimately be finished?

Yes.

It will either be finished when a complete formulation of the elementary laws is found by the scientists. Or by the death of the mankind (or other lifeforms in the Universe). Or by its de facto death when people's intellectual qualities will sufficiently deteriorate so that they will no longer work on it.

The answer depends on what one means with "elementary particle" and what one means with "finished"!

TGD predicts in principle an infinite hierarchy of scaled versions of what we have used to call elementary particle physics corresponding to hierarchies of p-adic length scales and Planck constants. The hierarchy of infinite primes suggests a generalization of elementary particle in which many particle states of given hierarchy level (i.e., space-time sheets) become single particle states of the new level (space-time sheets topologically condensed at large space-time sheets).

The same Universal mathematical description applies at all levels. But always something new emerges.

Therefore, my answer is a realistic "No".21

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