"Are There Ultimate Laws of Physics?" by Sankar Das Sarma

July 2, 2020

My colleague Maissam Barkeshli pointed out a wonderful 2-year old article by Robert Dijkgraaf in the Quanta Magazine (June 4, 2018).

The article in Quanta is provocatively titled "There are no laws of physics: There's only the landscape" (Quanta Magazine Online June 4, 2018). In this blog, I will take a break from the scientifically frustrating topic of covid-19, the subject of my first 6 blogs, and venture into the intellectually depressing topic of there being no laws of physics, Einstein is turning in his grave, and so is Dirac, who apparently said that all of chemistry can be derived just from his equation. Looking back, I am sure that this story is apocryphal; Dirac was far too smart and far too reticent to make such a remark.

I agree wholeheartedly with Robert, who is as good an expositor of science as there can be. I literally believe that there are no ultimate laws of nature to be discovered, not by string theorists, not by condensed matter physicists (such as myself), and not by anybody. The human brain is finite, although it has a huge capacity, and the universe in some sense is infinite, as it apparently keeps on expanding faster and faster. There is no chance of our figuring out the ultimate laws of nature that control the universe using our finite brains, so we might as well accept that the universe does not follow, in the strictest sense, any ultimate laws. The more we learn about the universe, more new laws should emerge as has happened continuously during the last 400 years since Newton/Kepler/Galileo. Before that, we made little systematic progress in understanding the physical world, and scientific knowledge in the modern sense did not really exist. What is amazing is the fact that we can make sense of some aspects of this infinite universe through our laws of physics. It may have been Feynman (another great scientist who was also a great expositor) who first said it; the issue is not how clever we humans are in figuring out how nature works, it is how clever nature is in following our laws!

What we call laws of physics, whether they are Newton's laws of mechanics and gravitation, Maxwell's equations for electricity and magnetism, Einstein's theory of special and general relativity, Schrodinger's and Dirac's equations in quantum physics, or even the string theory, are all effective descriptions of nature at various levels. They are all internally consistent mathematically and (hopefully) eventually consistent with human experience as observed in laboratory experiments. This is all they are, nothing more. Nature is infinite, and as our experience matures, our laws must evolve as there is no ultimate law waiting to be discovered in the end. Just an increasingly complex effective description that works (in a precise sense) to allow us to describe nature at a reasonable level and helps us improve human life by contributing to technology. It is like the peeling of an infinite onion, the more we peel, the more there is to peel.

It is interesting to note that even a hundred years ago the physical laws were many and were all directly connected with the successful description of some concrete aspects of the natural world. Some examples are Planck's law, Hooke's law, Stoke's law, Faraday's law, Lenz's law, Boyle's law, Dulong-Petit law, Wiedemann-Franz law, and so on. Laws of physics as an all-encompassing ultimate theory using fundamental forces and reductionist building blocks is a powerful intellectual bias that developed only over the last 100 or so years. Einstein contributed mightily to physics becoming a subject focused on investigating the ultimate quasi-religious question of whether God had any choice in designing the universe! No wonder Einstein, as great as he was, spent the last 30 years of his life wasting away on the futile search for an impossible unified field theory as the ultimate theory of everything.

Laws of nature, in the strictest ultimate sense, do not exist. We have only internal mathematical consistency and explanations of facts. In very good theories, this consistency is very tight, not allowing a huge number of tuning parameters. String theory is a very successful theory in terms of its consistency and mathematical tightness; it is indeed rather magical the way gravity and quantum mechanics exist equivalently within it. However, string theory has so far been ineffective in predicting facts, particularly new facts that can be tested in laboratories.

For example, a great worthy early goal of the string theory in providing explanations for the many tuning parameters of the standard model still remains elusive. I am unimpressed by its claim of having 'predicted gravity', which was an acceptable claim in 1984, but no longer in 2020. String theory so far has remained like a proverbial highly promising brilliant assistant professor whose promise is always in the future. I am not criticizing string theory, I am a big fan of its mathematical tightness and I agree that someday it may turn out to be the next great thing in explaining facts. But 40 years is a very long time to wait for 'someday'. Now, with supersymmetry itself in doubt as a fact, I am not sure that conclusions based on the string theory should be aggressively discussed. String theories have led to some remarkable insights, e.g., a deep unexpected connection between gravity and conformal field theories, the so-called AdS/CFT duality. These are extraordinarily powerful concepts, although it is unclear right now if this by itself leads to any new physical laws.

My focus is the so-called 'landscape' problem in string theories, where literally zillions of universes (~ 10^500, the number is so large that it seems obscene) are acceptable solutions of the theory. If true, one can declare victory as one of those zillions of universes must be our universe, and all one needs to do is to somehow find that particular solution to figure out our existence. Of course, this is an impossible task because of the exceptionally large number of possible universes existing in the landscape, and all with their own distinct laws. This scenario is often called the multiverse.

The other way of looking at it is that all possible laws, conceivable and inconceivable, are allowed in some possible universe, and laws of physics are no longer meaningful or unique from a fundamental sense, since they depend entirely on where in the multiverse landscape one is looking. It is ironic that the theory of everything turned out to imply an 'everything' (i.e. the landscape), which is exponentially larger than any 'everything' anybody could have imagined before. The search to predict the fundamental constants like the fine structure constant ('alpha') starting from a parameter-free ultimate theory is ending up showing that essentially all values of fundamental constants are allowed in different universes in the vast landscape. This landscape/multiverse scenario is perhaps philosophically similar to invoking God, as homo sapiens have been doing for a very long time, claiming that everything is the way it is because this is what God wishes, God works in a mysterious way. Instead of God, we appeal to a landscape. Both make predictions impossible, and the concept of fundamental natural laws becomes moot.

It is possible that progress will come in the future as deep patterns are discovered in the landscape, some large parts of the landscape may turn out to be useless swamps, and other parts may turn out to be connected with each other in subtle ways not discernable today. Perhaps someday far in the future, the landscape will start making sense. If so, string theory will then be a true theory of everything.

One possible conclusion, therefore, is that the conventional reductionist approach of particle physics, where natural laws are increasingly focused on smaller and smaller building blocks (molecules/atoms/nuclei/quarks/electrons/neutrinos, etc..) and fundamental forces (gravity, electromagnetism, nuclear weak and strong forces) acting between the building blocks, is no longer a fruitful objective way of looking at the physical world. There are no fundamental building blocks and no fundamental forces, and as such there are no laws. The only thing we are left with is the landscape, where the 'laws' depend on the specific universe one is dealing with. This is so mind-bogglingly complex that the whole idea of natural laws must be modified. An apparently strange end to a worthy journey which started with atoms as hypothetical indivisible constituents of matter 2500 years ago and witnessed a great recent triumph in the experimental discovery of the Higgs particle in 2012.

In the end, our physical laws are only 'boundary conditions', and not intrinsic at all, depending entirely on where in the landscape we happen to be! Einstein's lofty quest to find out if God had any choice ends in a rather crafty God who made every possible choice and designed an unimaginably complex landscape with all possible universes.

As a theoretical condensed matter physicist I do not find the 'landscape' scenario discouraging at all. The fact that there are essentially infinite number of possible laws only makes doing science more exhilarating because exploring the landscape will remain an active and creative activity forever, theoretical physics can never end because the landscape is simply too vast. I already know from my 40 years of experience in working on real-life laboratory physical phenomena, such as superconductivity, magnetism, metal-insulator transition, phase transition, quantum Hall effects, superfluidity, etc., that the whole idea of an ultimate law based on an equation using just the 'building blocks' and 'fundamental forces' is unworkable and essentially a fantasy. It may work in some limiting cases (one example is QED, which I discuss separately below), but in general the problems one wants to solve are just too complex to be solved by starting with a fundamental reductionist equation from first principles. Predictions based on a fundamental equation are impossible because of the great complexity of the possible solutions. We might as well then invoke a God to explain things, which will be a perfect explanation (the ultimate Theory of Everything) with no predictive power.

In condensed matter physics we actually have such a single 'fundamental' equation, an ultimate law, which leads to ALL the complex phenomena and phases of matter that we find in the natural world around us. This equation is simply the Hamiltonian (i.e. the energy functional) of the system in terms of the underlying electrons and nuclei (which are the building blocks for condensed matter) with the fundamental force being the electrical Coulomb interaction between the building blocks. That is it. That simple. Of course, the complexity comes from the fact that a cubic centimeter of matter will typically have 10^23 of these building blocks, and we cannot solve this equation from first principles at all. If we could, we would find every possible phenomenon and every possible phase of matter, those already seen and those yet to be discovered.

Suppose we find a way to exactly solve the fundamental equation of condensed matter physics for a macroscopic piece of matter containing 10^23 or more atoms. This will not help in our understanding at all since this 'solution' would be a set of at least 10^23 complex numbers at every instant of time giving us the quantum mechanical wave function of the system. Looking through 10^23 complex numbers at each instant of time is obviously an impossible task unless we know exactly where to look so that we can discern the patterns in the system to figure out what is going on. This will necessitate our knowing precisely what to look for so that we simply do not get lost in a 'solution' with no meaningful information. Or rather so much information that we have no idea how to do anything with it.

This is why in condensed matter physics we must first have some idea of what we are looking for using effective descriptions of the physical system. Unless we have some ideas about the patterns we are looking for, even having an 'ultimate solution' (i.e. the complete wave function of the system as a function of time) of the fundamental equation takes us nowhere. Thus, progress in condensed matter physics comes always from knowing where in the vast condensed matter landscape one is interested in, and then building effective descriptions focusing on the phenomena and patterns in that specific part of the landscape. No good would come out of a complete solution of the fundamental equation since it would simply have hopelessly detailed and mostly useless information about the whole landscape which is simply too complex for us to handle.

This is our condensed matter 'phase and phenomena' landscape. This landscape has in principle every possible arrangement of these 10^23 atoms and electrons, leading to all possible phenomena. We could just declare victory and stop doing condensed matter physics even if we cannot solve our fundamental equation to derive the results. The beauty of condensed matter physics is to build simple effective models which capture some low energy approximate descriptions of this extraordinarily complex landscape of phenomena and phases, leading to useful predictions and explanations. The famous BCS theory underlying superconductivity is an effective theory where almost everything about this ultimate equation is discarded except for a tiny piece involving an effective interaction between a fraction of the electrons around the Fermi surface and the thermally excited background lattice (called 'phonons') of the nuclei. This was so exquisite and subtle an effective theory that it took almost 50 years between the laboratory discovery of superconductivity in 1911 and its eventual approximate BCS theoretical description in 1957.

All attempts to understand superconductivity during 1911-1957 using the first principles approach to the fundamental equation failed until the BCS theory came along to show us which part of the hugely complicated fundamental Hamiltonian is relevant for explaining superconductivity. BCS theory acted as a detailed map guiding us directly to the part of the condensed matter landscape where superconductivity resides, the full fundamental equation did not allow that possibility because of its complexity.

In condensed matter physics, we do not have the choice of giving up simply because our fundamental reductionist equation has too many possible solutions, as it most certainly does. That would be akin to throwing away the proverbial baby with the bath water. For us, condensed matter physicists, the entire physics is to explore the nook and crannies of the landscape, because those are the phenomena that must be understood. The appeal of condensed matter theory is the chance to embrace and explore the details of the landscape using the flashlights and maps of effective field theories, not reductionist microscopic equations using building blocks and Coulomb forces as our tools.

Sometimes the word 'emergence' is used to emphasize the fact that collective many-body properties of many particles interacting with each other are very difficult to predict based on the reductionist approach using building blocks and fundamental forces, they must be guessed using a variety of effective theories using coarse-grained approximate descriptions. This requires a great deal of careful creative thinking in order to obtain the appropriate emergent properties, a brute force reductionist approach almost never works. The BCS theory is a great example of such an effective theory.

Another example is the existence of liquids in nature, it is easy to guess the existence of solids (at low temperatures) and gases (at high temperatures) based on the fundamental equation, but liquids existing at intermediate temperatures are an emergent collective phase that are difficult to guess theoretically. Another amazing collective emergent property, not predicted theoretically, is the quantum Hall effect with its perfectly quantized electrical resistance in a tiny transistor, which turns out to be a very subtle topological phenomenon lurking in a non-obvious manner in the condensed matter landscape.

It is instructive to expand on the idea of liquids as an emergent property. Suppose we have 10 molecules interacting through some force (e.g. Lennard-Jones potential) in an isolated closed off box. We will take molecules as the building blocks and the effective inter-molecular force as the fundamental interaction for this example. If we cool this box down to very low temperatures, the molecules will stop moving around randomly (temperature is nothing other than the measure of the average speed of the molecular motion in a system) and create a solid with a well-defined volume and shape. If we heat the box up to very high temperatures, the random fast chaotic molecular motion, with the molecules colliding repeatedly with each other and with the walls of the box, will lead to a gas, which has neither a fixed volume nor a fixed shapeÑit just fills up the container. These two limiting phases are obvious: low temperature solid and high temperature gas. We know that most materials also have an intermediate liquid phase in between the solid and the gas, but it is not so easy to define exactly when that happens. A liquid has a well-defined volume (or density, to be precise), so it is more like a solid in that sense, but it has no well-defined shape, it simply takes the shape of the container you put it in, so in that sense it is like a gas.

At what stage does a system become a liquid? Clearly, with very few molecules, the concept of a liquid phase is not meaningful, we only have a gas and a solid at high and low temperatures. As we increase the number of molecules, eventually the liquid phase is an emergent collective property of macroscopic materials, but exactly when such an intermediate phase between a gas and a solid emerges is not so easy to define in a precise manner. Clearly, 10 water molecules will not form liquid water that we are all familiar with at room temperatures, but 10^25 water molecules will fill a glass as a liquid, which we can drink. If liquids did not exist at all in a hypothetical world, it would have been very difficult, if not impossible, to predict them just from a microscopic reductionist ultimate law. This is the enigma of emergence at the heart of condensed matter physics. Strange and unexpected phases and phenomena exist in the vast condensed matter landscape, which are almost impossible to envision or predict based on a fundamental ultimate law. There are ideas that space-time itself may be an emergent behavior somehow, but this is pure speculation with no concrete theories supporting it. Human consciousness is also thought to be an emergent collective behavior of the whole brain; we have no idea exactly how and why.

There are some parallels between the string multiverse landscape and the condensed matter phenomena and phase landscape. Both provide essentially impossible technical challenges to theorists. Only very small regions of the landscape can be explored using weak-coupling perturbation theories, the standard tool of theoretical physics. In most condensed matter systems, the electrical Coulomb interaction between electrons is not parametrically small in any sense, and therefore, perturbation theory is inapplicable except in asymptotic regimes of little physical interest. Almost none of the important emergent interacting collective phases and phenomena in condensed matter physics was theoretically predicted, most of them are essentially experimental discoveries of serendipity. This includes, among others, high-temperature superconductivity, as well as integer and fractional quantum Hall effects.

It may be worthwhile to emphasize that, in spite of many similarities, there is a key difference between the string theory multiverse landscape and the condensed matter phase/phenomena landscape. In the string multiverse, we are forever confined to our specific universe by accidental boundary conditions beyond our control. This particular universe, one out of apparently ~ 10^500 possible universes in the landscape (all with their own individual fundamental laws), has the standard model with its hadrons and leptons, it has the Higgs particle (as well as W and Z particles), it has QED with alpha~ 1/137 defining the electromagnetic interaction, and so on. This is the only universe experimentally accessible to us no matter how high in energy our accelerators take us to. We can never learn anything experimental about the other 10^500 universes, we are stuck to just one specific universe where we happen to be in the landscape purely accidentally. This seems to be a somewhat depressing situation as we are simply prisoners of the boundary conditions we did not get to choose.

By contrast, the condensed matter phase/phenomena landscape is, in principle, experimentally accessible to us in its totality. Perhaps we need much lower temperatures, much higher magnetic fields, much higher pressures and so on than what is technologically possible today, but there is no limit to our exploration of the condensed matter landscape, it is just out there with its almost infinite possible phases and phenomena waiting to be discovered. New discoveries in the condensed matter landscape are guaranteed forever because technological improvements will allow us to explore the landscape in greater and greater details, but the landscape being essentially infinite, we will never run out of new phenomena and phases.

We are by no means stuck to just the phenomena already discovered and already imagined or predicted. The future of condensed matter physics is never-ending since our landscape, while being complex and vast, is forever accessible. Sometimes we may have to wait for a long time for exploring parts of the landscape. One example is the Bose-Einstein condensation (BEC), a highly coherent quantum phase of matter akin to a laser beam made of atoms rather than light, which was predicted in the 1920s, but was discovered in the laboratories only in the mid-1990s (a 70-year waiting period, much longer than the Higgs particle, which took 50 years for its discovery) when experimental techniques to cool atomic gases to temperatures as low as nanokelvins were eventually developed. Another example is the existence of non-Abelian quasiparticles, which are neither fermions nor bosons (the two types of fundamental particles defining the standard model), which have been predicted to exist in certain low-dimensional condensed matter systems. They have not been directly experimentally discovered yet in spite of rather intense search over the last 10-15 years. I am convinced, however, that they exist and will be found in the laboratories although I do not know how long it will take, I certainly hope that it is not 70 years. When found, these non-Abelian quasiparticles would enable a particular kind of fault-tolerant quantum computation, called 'topological quantum computation', which would not require extensive error correction protocols for its operation.

An obvious fact is that the condensed matter landscape is independent of the existence or not of the string theory multiverse landscape. The condensed matter landscape would be unaffected if the string theory landscape disappears tomorrow because of some spectacular new theoretical breakthrough, and the condensed matter landscape of phenomena and phases was here long before string theorists started discussing the multiverse landscape. The fundamental equation of condensed matter involves electrons, nuclei, and electromagnetic interactions, which are completely unaffected even by discoveries within the standard model, let alone developments in string theories. The discovery of quarks, W and Z particles, and the Higgs particle did not in any way affect condensed matter physics since all of these are involved with very high-energy intra-nuclear physics, which is not relevant for condensed matter phases and phenomena. One of the basic pillars of theoretical physics is that physics at one energy or length scale is typically not affected by physics at very different length and energy scales. For example, we do not need to apply quantum mechanics to do weather forecasting, and the complex civil engineering of building skyscrapers does not require any information about the arrangement of quarks inside the nuclei. This independence of the condensed matter landscape from the ultimate laws of particle physics makes condensed matter physics both particularly rich and particularly subtle. The existence or not of super-symmetry, important as it is in understanding the hierarchy problem in the standard model of particle physics, will have no direct bearing on condensed matter physics. Indeed, the experimental discovery of the Higgs particle in 2012 was an earth-shattering event in particle physics (just imagine what would have happened if the Higgs did not show up in the LHC experiments), but had no direct effect whatsoever in condensed matter physics.

One of the most important and theoretically mysterious aspects of the condensed matter phase/phenomena landscape is the emergence of biological life, and perhaps even more significantly, conscious intelligent life (such as ourselves) somewhere in that landscape. A part of this landscape, human beings, likely to be a set of measure zero in the landscape filled with lifeless phenomena and phases, gets to think about the landscape itself! What we humans refer to as 'consciousness' may very well be the ultimate emergent collective behavior (in the brain), which most likely will forever remain inaccessible to reductionist 'ultimate' laws of physics. This seems miraculous and probably explains why religion has been so central to such a large number of humans for a very long time. It is much easier to just give up and think of a supreme being ordaining everything than to actually accept that the landscape is exponentially large, allowing many unpredictably complex possibilities, even conscious life itself. Apparently, there are close to 10 million known species of life on the earth, and this is a very small fraction of the actual number of species, a recent publication speculates that it may take 1000 years just to identify all the species!

All of these biological species are controlled by precisely the same fundamental reductionist condensed matter equation involving electrons, nuclei, and Coulomb interactions as inanimate objects such as metals and magnets are. In that sense, from the viewpoint of theoretical physics, life, even conscious intelligent human life capable of blogging and idly speculating on the nature of physical laws, is just an emergent collective property of the fundamental equation, residing somewhere within our vast landscape of phenomena and phases exactly the same way as superconductors, magnets, liquids, crystals, glasses, and all other materials that condensed matter physicists study in the laboratory. It is humbling to realize that the basic law underlying humans is the same as that controlling a magnet.

However, this knowledge is also manifestly useless because every human knows that human beings are qualitatively different from magnets. This, in a nutshell, is the problem of insisting on a fundamental ultimate law. It is unclear that the enigma of consciousness, which we all feel, but is hard to describe, will ever be quantitatively explained by an ultimate law using building blocks of electrons and nuclei (let alone, leptons and hadrons) interacting through fundamental forces. We may discover in the end that such a law is irrelevant for answering some of the most important questions one may have. Such an ultimate law would tell us nothing about how to cure stage-4 terminal cancer or how to eliminate the covid-19 pandemic. It most certainly will not tell us how to eliminate poverty in the world, cure all the childhood diseases, end violence, or improve human tolerance for each other.

Finally, I will comment on QED, undoubtedly the most successful fundamental theory homo sapiens have ever created. Experiment and theory agree to better than 10 decimal place in QED, this is an astonishing achievement of human intellect. The great success of QED is, however, purely accidental and dependent entirely on the basic QED interaction strength alpha~ 1/137 being small. This enables one to expand the fundamental equation in powers of alpha, and keep only the first few powers in a systematic manner. Why is alpha small? We have no idea, it is an experimental fact that alpha is small. Actually, alpha is not a constant at all, it changes with energy (slowly), and it happens to be small only at our usual energy scales. If you go to very (unimaginably) high, but still finite, energy scales, alpha actually diverges, making the premise of the whole QED theory questionable. This problem has the historical name of Landau pole or Moscow zero. The spectacular success of QED is based only on the accidental fact that alpha at ordinary energy scales happens to be very small (~ 1/137) in our universe. We have no way of predicting alpha from any deeper fundamental theory, all we can say is that it just so happens that we are accidentally in that universe in the landscape where alpha~1/137.

Another strange aspect of QED is that the perturbation series in powers of alpha is actually only asymptotic, and diverges logarithmically when the series is extended to high powers of alpha. Because of the very small value of alpha (~1/137), this does not pose any problem to the theoretical physicists in our universe, but you should feel sorry for the universe where alpha~ 1 since the perturbation series then would fail already at the first order in alpha (more on this point below). Thus, the spectacular agreement between theory and experiment in QED, which is based entirely on a systematic perturbative expansion in alpha, is a pure matter of luck since alpha is not ordained to be 1/137 because of any fundamental reasons, it just happens to be 1/137 in our universe. The deep sounding question of why alpha is 1/137 allowing QED to be the most successful theory ever is moot because it is simply a boundary condition defining our universe.

It may be intellectually unsatisfactory that our laws (e.g. the precise value of the fine structure constant) are simple accidents (or boundary conditions) of where our universe happens to be in the landscape, but we must live with it. There cannot be any reductionist fundamental explanation for it any more than for why I suddenly chose to write a blog on the topic of the existence or not of physical laws today! Even our most successful reductionist theory (QED) is suspect and not quite internally consistent on its own. This is not just a matter of academic interest. Condensed matter physics has systems (e.g. graphene) whose underlying theory is very similar to QED except that the effective alpha can easily be larger than one (and in some experimental situations, it can be much larger than one). What happens then? The great success of QED goes out of the window because a weak-coupling perturbation theory as in regular QED fails, and we are suddenly in a universe within the landscape where alpha being 1 or even 20 becomes possible. (How one does theoretical physics in a situation where alpha is much larger than one is a highly technical subject beyond the scope of the current blog, but obviously, a perturbation-theoretic approach is not the appropriate starting point.) Such is the complexity/richness of condensed matter physics where the landscape itself, with all its incredible details, is the interesting physics, not the end of physics. I spend much of my time exploring the landscape figuring out which parts of it are manifesting themselves in the current laboratory experiments, and which parts should be observable in future experiments. Phenomena and phases, once thought impossible (or totally unknown), reside in the landscape, and sometimes in our imagination, but most often, sheer serendipity lead to their discoveries. Exploring the phase/phenomena landscape is what condensed matter physics is all about.

Returning to the theme of the ultimate laws of physics, one may argue that quantum mechanics itself is such a law since it has been hugely successful for close to 100 years with no experimental violations. Quantum mechanics is actually more like a set of rules (or a grammar) that we physicists use to express our laws rather than being an ultimate law itself. In addition, in quantum mechanics (or, more generally, in quantum field theories), space and time are variables which are put in by hand and are not emergent. Presumably, space and time should come out naturally from an ultimate law of physics, and not put in by hand as independent variables. It is difficult to imagine that a thousand years from now, physicists will still use quantum mechanics as the fundamental description of nature as we do today; something else should replace quantum mechanics by that time just as quantum mechanics itself replaced Newtonian mechanics. Of course, I have no idea what that something else might be, but I see no particular reason that our description of how the physical universe seems to work should reach the pinnacle suddenly in the beginning of the 21st century, and become stuck forever at quantum mechanics. Note that my firm belief that quantum mechanics, as we know now (1925-2020), cannot be the ultimate law has nothing to do with all the pseudo-philosophical hand-wringing associated with Schrodinger's cat or Wigner's friend and so on, I am neither concerned about the wave function collapse nor about entanglement here. I simply find it difficult to believe that suddenly physics has discovered the final law during my lifetime, and physicists 10,000 years from now would still be using anything remotely similar to the quantum mechanics of today to make sense of the physical world around them. This is simply too depressing a thought to me, just imagine if I were trying to figure out non-Abelian Majorana zero modes and topological superconductivity using the arguments of Aristotle (or even Newton)! Newton's laws were extraordinarily successful for three hundred years, but we had to go beyond them as we learned more about the universe, and the same should happen with quantum laws some day in the future. Of course, any such unknown new theory of the future must build on and incorporate the physics of quantum mechanics, just as quantum mechanics built on and incorporated classical mechanics (for example, quantum mechanics uses the same variables such as space, time, momentum, angular momentum, energy, etc. as classical mechanics does, but with reinterpreted meaning and completely different dynamical laws). Our understanding of the physical world must continue indefinitely unimpeded by any temporally fixed discovery of an ultimate law. Search for a unique ultimate law for the physical world is a fantasy.