Table of contents
Existence of the universe: an unavoidable tautology? Existence of the universe: an unavoidable tautology? Essentialism vs existentialism. Complements on the existence of the universe. Fundamental elements that allowed and determined the existence. Matter (and antimatter). The four interactions. The anthropic « principle ». The weak anthropic principle. The strong anthropic principle: The frustration of a lack of transcendent destiny? Foundation. Which destiny? Cosmology and the presence of thinking beings. Reminder. The universe: An incredible destructive capability that is matched only by its creative capability? Fragility or resilience of life? The immediate danger comes from inside. Thoughts on the nature of the existence of the universe. What general relativity says. Beyond the Standard Model of Physics. Isn’t knowing the origin of its own existence the prerogative of God? Conclusion: The limits of current thinking. Is a reductionist approach to intelligence and consciousness possible?. Some important structural problems. Does quantum mechanics illustrate the limit of scientific thought? Is science totally objective? The role of physicist thought in the (theoretical) representation of « physical reality ». Changing our way of thinking? Causality itself questioned! Hope remains.
Existence of the universe: an unavoidable tautology?
To the question of the existence of the universe, the answer is simple since, as part of this universe, if it did not exist, we would not be here to ask it.
The question of the existence, for us (from our point of view) of the universe, presupposes our existence, which as part of the universe implies its existence.
We will see in the next paragraph that existentialism generalizes this notion of existence.
Of course, if we did not exist, we would not be able to see either our non-existence or that of the universe.
So, the answer is a tautology. But isn’t that the only coherent answer we can give to this type of question, at least with our usual way of thinking?
Essentialism vs existentialism
This question of existence, especially our existence within other existences, has always been a favorite subject of philosophers.
The Platonic interpretation stipulating a world of ideas and its phenomenological realization in our sensible world (the physical world in which we live) justifies existence as an imperfect realization in the physical world, of the perfect entities of the world of ideas.
This world of ideas (essence), which is not accessible to us, therefore has a « divine » character in this approach.
Existentialism breaks with this character of precedence of essence over existence to affirm on the contrary that it is existence that prevails. Existence cannot be deduced, it is observed and this applies to all existence, not only to ours.
A sentence that can be heard as: « How lucky that life exists and precisely on Earth! » does not lack naivety and underlines the interest of existentialism!
Indeed, even if we think that the probability of the existence of life in the universe is very low, in a place where it exists and gave birth to intelligent beings, these beings should not be surprised that they exist and precisely where they are!
Notwithstanding with its the fact that it is the thuth, hypothesis of the existentialism is indisputable .
Let us emphasize that, by definition, existence requires a « consciousness » (necessarily a thinking being?) to observe it: we observe existence.!
Existentialism implies a « consciousness » in the universe to exist and therefore, in the materialist approach, there is a need for the universe to produce consciousness. In this materialistic approach, the universe is the « everything », a consciousness outside the universe is inconceivable.
In other words, what one could imagine as a universe (in the essentialist perspective), without an internal consciousness in this universe, for seeing its existence, does not exist in existentialism.
If the existentialist approach can leave the mind unsatisfied, because it can appear as a renunciation (we do not know how to answer the question of the source of our existence, we evade it and we stick to the observation) , its foundation is well supported.
This is the observation we have used, but if it is indisputable, it can leave unsatisfied because it can appear as a renunciation: we do not know how to answer the question of the source of our existence, we evade it and we stick to the observation.
But isn’t this dissatisfaction based on an implicit conception of a Platonic world? The existence of everything must be justified!
The question then arises is: is this justification really necessary?
After all, this world of ideas seems very fictitious, so it is not limited to seeing existence as a priority, because this is how reality is exposed!
This is the point of view of existentialists that, in a pithy way, can be summed up by: « see the existence, for its source or its cause, circulate, there is nothing to see! »
This attitude, which may seem like a pirouette to escape a problem (a loophole) is, despite everything, supported by a few arguments.
For example, the notion of precedence (the existence of a predecessor) implicitly invokes time (a chronology, one is prior to the other), which for the universe is problematic since the universe is a spacetime that does not require a predecessor.
Indeed, a spacetime is something that is more than a combination of time and space which are only its shadows. This criterion of chronology would not be therefore an external attribute of the universe but an internal parameter, which exists because part of something that already exists.
All this shows that we should not be fooled by implicit misleading habits of thought, at the risk of straying on a false track.
Complements on the existence of the universe
One could object that compared to the standard model where it is the universe that was created and evolving, we have only replaced this problem with another, the existence of the universe, of the same nature.
To this objection, we replied that spacetime deduced from Einstein’s equation describing the universe intrinsically has all the geometric properties required to explain the phenomenology that is described and observed.
By intrinsically, we mean that all these properties are « internal », no external element is required for the geometry of spacetime: it is self-sufficient! The only character we have added is its coupling with the human observer, itself internal to the universe, which provides a criterion for time orientation on geodesics, that the geometry of spacetime does not provide.
Therefore, to consider that the universe was created either ex nihilo or emerging from other pre-existing things, in which case we only postpone the problem, is a hypothesis, referring to elements that are external to it, therefore useless.
Fundamental elements that allowed and determined the existence
The universe we observe presents itself to us in great diversity.
Diversity in size, the universe with its very large structures such as galaxy clusters, galaxies and even stars and planets up to microscopic atoms, through the human scale.
Energy diversity: enormous for quasars, black holes, supernovas, stars, tiny for atoms and the chemical reactions that govern life as we know it.
Diversity of complexity: tiny for black holes described by few parameters up to the living world where the complexity can only be evaluated, as it is gigantic.
Its exhaustive description, which would be necessary for Einstein’s equation to give a rigorous solution, is operationally inaccessible. Drastic simplifications were necessary, justified by hypotheses (homogeneity, isotropy) to obtain approximate solutions, considered however significant, at least in the first order, even if we know that they are not rigorous.
Although we do not know everything, science will still have taught us, and this is not negligible, that it is a very limited number of elements that make it possible to generate all this diversity.
Matter (and antimatter)
Indeed, matter is composed of a very small number of elementary particles, divided into 3 families, the most common of which in our environment consists of 2 quarks (u, d), 1 electron, 1 neutrino. We must also consider their antiparticles (antimatter) but which are almost absent in our environment dominated by matter. This is an inventory, but would only be a backdrop (nothing would happen) without the interactions.
The four interactions
The interactions between these particles that will generate the « dynamics » of the systems. There are four of them.
Gravitational interaction: of infinite range that governs large structures.
Electromagnetic interaction: of infinite range that plays an important role in the environment at human scale, because responsible for the complex structure of the electronic layers of atoms that allows an important combinatorics generating a chemistry of molecules that we find, among others, in the living world. On a large scale, the universe being globally neutral, it is often dominated by gravitation.
Strong interaction: very short range. Active in the atomic nucleus and hadrons. It binds quarks into particles. For example, the proton consists of 2 quarks u and a quark d and the neutron consists of 2 quarks d and a quark u
Weak interaction: very short range. It allows quarks to change their « flavor », so a d quark can become a u quark and vice versa, so a proton can become a neutron and vice versa. This property allows a chemical element to change in nature as it is the number of protons in the nucleus that determines the chemical element.
In quantum field theory we associate particles called bosons with these interactions (except gravitation where it is hypothetical in the absence of a quantified theory)
Note that to explain the mass of massive particles it was necessary to add the Higgs boson, whose experimental confirmation is recent.
These few elements, alone allow, by the possible combinations, to generate all the diversity of the universe. These elements offer the possibility, but the realization of this diversity is done through Darwinian-type processes where errors and constraints of the environment and context play an important role.
Let us emphasize that in the description we have made of the diversity of the universe, in no case does the presence of an intelligent consciousness seem required. Life, which seems to result from a (happy?) combination of circumstances, plays no role in it.
As this observation is not such as to satisfy our minds, certain arguments have been proposed.
The anthropic « principle »
This principle, which it would perhaps be more coherent to call an anthropic « argument », is generally available in two versions:
The weak anthropic principle
He makes the observation that since we are here, it should not be surprising that in a reasonable description of cosmology, the parameters of the universe are compatible with our existence. This argument is not refutable and as such has no value since, like other hypotheses, it does not provide any information about the problem of our existence.
Its proponents often use it to study sensitivity to a variation in fundamental parameters, for example certain fundamental constants of physics, such as the velocity of light c, Planck’s constant  reduced
h = h/2π, the gravitational constant G , and others such as matter-energy density parameters. With regard to constants, apart from no dimensional constants (the fine structure constant is often cited as an example), as they depend on the choice of units, it is not their dimensioned value that is interesting  but their relations through phenomena and physical laws. The exercise is not without interest, but despite the conclusions that can be drawn about the criticality of this or that parameter, it does not bring, more than the others, any clarification on our existence.
The strong anthropic principle: The frustration of a lack of transcendent destiny?
In this strong anthropogenic principle, we also imply a destiny: The universe must produce beings like us. It is a philosophical principle not far, in its form, from considerations of a religious type, but it does not refer to any sacred text resulting from divine revelations.
Even if it tries to justify itself on certain scientific arguments, its deep foundation is a frustration based on the denial of a transcendent meaning to our existence. The cosmological description we have made has shown that while it has allowed the emergence of beings like us, they have played no active role in history. This shows that this emergence is incidental. Rightly or wrongly, this anxiety-provoking observation is unbearable for many human minds. No doubt that we have too high idea of ourselves for not accepting that we were not desired!
At the scientific level, this strong anthropic principle is nourished by the observation of the extreme complexity of life, its appearance and its specialization to lead, in a time not so long as that (less than the age of the Earth is a few billion years), to the very complex beings that are the animals of which we are part. So, according to the proponents of this principle, chance alone and the Darwinian mechanism are insufficient to explain our existence.
It remains to clarify the nature of the destiny invoked by the proponents of this principle. Indeed, for believers, obedience to sacred texts and the promise of eternal life give a course of action and meaning to their lives that go far beyond it. The fact that there are several religions is not an obstacle because the believer is convinced that only his belief reveals the truth. The success of religions comes from giving answers to these existential questions.  Whether perceived or not, their anthropomorphic character carries an appearance of evidence pleasing to our mind.
But for non-believers, without texts defining this and without eternal life, what meaning to give to their life which, in the narrative we have made, is incidental. So, failing to inherit a destiny and meaning to our life, we have no choice but to seek it in the immanence of our condition.  If the motivation is individual, the purpose will benefit from being relative to humanity which, in solidarity, perpetuates the lives of individuals by integrating them into its history.
This is the field of predilection of philosophers, among others, who since the dawn of time, have attached themselves to it, first by seeking the solution within ourselves, then by extending it to the level of humanity. There is no single answer as philosophy is not a science. The human, whether he wishes to be inspired by it or not, will have the choice. Any choice is reductive. But we know that truth is inaccessible by reason and that the only constructive response that can be given will necessarily possess the fragility of the human mind. 
Cosmology and the presence of thinking beings
Let us recall that the cosmological description we have made only partially deals with the appearance of humanity. It deals only with the cosmological and astrophysical conditions necessary for life as we know it to be possible. But between « possibility » and « realization » we need a process that makes the connection. The theory of evolution, where errors, chance, the environment and large numbers play a driving role, proposes a model that, describing evolution, from the most primitive living beings to us, reveals part of this link (we start from the living). Since, it only takes a favorable occurrence for precisely the result of this occurrence to raise the question, it is a possible lead.
The universe: An incredible destructive capability that is matched only by its creative capability?
The universe from which we get life can take it back as quickly as it gave it. Indeed, cosmic phenomena are extremely violent. The explosion, cataclysmic at the level of the universe, of the supernova that allowed the formation of the Sun has eradicated everything around it within a radius of hundreds of billions of kilometers. It would have pulverized the entire solar system if it had existed, and probably sown death far beyond. But it was this destructive cataclysm that allowed, among other things, the creation of the solar system in which an organized life could emerge. It is a process of life and death, of destruction and creation, quite general, which is also found on much more modest scales in other processes. This possibility of life is granted to us by the universe only for a time, which although very long on our scale , is limited because we know that the Sun in its final evolution, long before annihilating the Earth, will make it uninhabitable from its first spasms. Until then a lot can happen!
Fragility or resilience of life?
Alongside this cosmic deluge of energy, our earthquakes, tsunamis, cyclones, volcanic eruptions, falling asteroids and other terrestrial cataclysms, are imperceptible events at the scale of the universe. Our powerlessness vis-à-vis these events, where only information encouraging people to flee threatened regions can limit human damage, which is already progress, attests to our tiny capacity for action, even in the face of the slightest cosmic event.
The immediate danger comes from inside
The most immediate danger results from our own behavior . The reprieve offered by the universe seeming quite generous. Life has shown great resilience to major cataclysms suffered by the Earth, but this has led to drastic changes. Without this shielding us from astrophysical and terrestrial disasters, it is necessary to manage what depends on us before the situation gets out of control. Certainly, since today’s human societies have far greater capacities than dinosaurs to survive, even, more critical situations, this attests that life is less fragile than it seems. But in the face of such cataclysms, the price to pay, in survivors, conflicts and societal changes is likely to be very high.
Thoughts on the nature of the existence of the universe
What general relativity says
The arguments developed previously, if they were able to enlighten us on the concepts to be taken into account to better understand the phenomenology of the universe, did not give an answer to the nature of its existence.
The mathematical modeling of the solution proposed by general relativity is a geometric object called a manifold which, as already indicated, needs nothing but itself to be fully defined. In other words, the geometric object that models the whole thing that can be finite or infinite  has no exterior.
In this manifold that describes the possible universe, there is a singular point called singularity, which by the way, by definition, is not part of the manifold. It is a structure called « open ». We can get as close as we want to this point but we cannot reach it, it does not belong to the manifold
This singularity, which corresponds to t = 0, is called “the Big Bang” in the chronological model of cosmology (standard model). In the covariant model, this singularity exists, but it is interpreted differently. Physically, this means that the equations of physics are no longer valid in this singularity.
It is interesting to stress that the theory that adequately describes the chronology of the physical phenomenology of the universe, declares itself incompetent to describe the initial conditions, namely the big bang.
Attempts to describe physics near the singularity have been the subject of much work.
An interesting attempt called BKL, initials of its authors,  shows that in a homogeneous universe the universe becomes more and more chaotic when approaching the singularity, which means that nothing can be predicted about the state of the universe on the singularity.
These answers, while frustrating, are relevant. Indeed, to the question of initial conditions, the theory of general relativity responds with indeterminacy, consistent with the singular character of the problem.
That may be the only coherent answer that can be given.
To moderate the interest of this answer, it should be remembered that scientists consider that the theory of relativity, which is a classical theory that does not take into account quantum effects,  is not an effective theory to deal with these problems where the conditions are extreme.
Beyond the Standard Model of Physics
So they explored other theories. Among the theories explored over the past fifty years to address this problem, we find:
Loop quantum gravity which is derived from general relativity and which, by introducing a quantification of space, takes into account quantum aspects.
String theory (superstrings today) which is a theory of « everything » aiming to synthesize general relativity and quantum mechanics.
It is derived from particle physics where particles are no longer points but one-dimensional objects (strings that can be closed or open) or multidimensional (branes) whose vibration modes characterize the different types of particles.
These theories, which have made it possible to obtain some convincing results, such as the calculation of the entropy of a category of black holes, are not yet completed and it is not certain that they will ever be.
In any case, they did not clarify the initial conditions. Multiple hypotheses have been made, multiverse for example, but this remains speculative and only postpones the problem.
Isn’t knowing the origin of its own existence the prerogative of God?
When we consider all the knowledge acquired, in the field of astronomy since the geocentric model that still was the reference up to the 15th century, in the field of cosmology as we have described it and this from the years 1920-1930 and in the field of the quantum mechanics all along the 20th Century, just talking about the physical sciences, and today in the field of artificial intelligence whose use via the Internet has already begun to transform our world with its potential threats to humanity, we can be surprised that this has not brought us any answer about our existence. It’s as if this knowledge is useless!
Certainly, Darwin’s theory of evolution has enlightened us about our emergence. Today, in the chain of life, the progress of medicine in its ability to repair the human, evolves, through genetic engineering, towards a possibility to control the modification of the human, whereas until then it was nature which, at its own pace, took care of it. Who could be the human of tomorrow and what are the risks involved? Some see in this possibility a divine character.
While waiting to be gods, which some authors  like to imagine, it remains doubtful that it is a physical theory that answers the question of our existence. It is our mind that must probably be adapted to try to efficiently question this problem.
Conclusion: The Limits of Current Thinking
If we consider that before our birth we do not exist and that at our death we no longer exist, if we were alone on Earth or in the middle of nowhere, would we be aware of a before and after?
We would probably be aware of « existing » and no more.
Let us emphasize the structural similarity with the description of the universe by a manifold. In both cases phenomenology has no exterior. The existence of the mind has limits, conception and death, but does not exist outside these limits just like the universe that has no exterior (the outside does not exist). This morphism in phenomenology that emerges naturally is probably not fortuitous. Could it be a clue in the analysis of our existence?
It is because we are not alone, that we have external references, that we have the knowledge of a before and after to our existence. We see other living being born and dying, things deteriorating, in a context well marked by our existence and external events. So, to be consistent with the context that shapes our perception of the world, we must undoubtedly pose these problems in the context of an existence within a society. A hermit would probably ask it differently.
This awareness of existing should not hide from us that we are not pure spirits and that if the realization of existence and consciousness of existing is tangible, our body, which supports our mind, is made of atoms that existed before our existence. It is to the fundamental laws of physics, which allow the complexity of the living beings, that our body owes its existence.
Is a reductionist approach to intelligence and consciousness possible?
In a pure reductionist approach, we are led to assume that the properties, which allow a structured assembly of atoms such as our brain for example, to analyze nature and establish its laws, are inferred by the existence of these properties or at least the source of these properties at the most elementary level that is concerned, that is, the atom.
In this hypothesis, the assembly structure of atoms, all carriers of this property at the microscopic level, would for example be inferred by this property that would govern the assembly rules, which would give, by the means of the macroscopic structure of assembling atoms, intelligence and consciousness.
If atoms do not have this property, it will be necessary to ask how it is assigned.
Our even limited knowledge of quantum mechanics shows us that indeed atoms cannot naturally associate in any way to form molecules.
There are a limited number of possibilities allowed with more or less probability, a priori, and what we observe is the influence of the environment (the ecosystem) in the sense of what is « external » to the nature of the individual, even if he is physically inside as viral or bacteriological aggressors who will select what will happen and among the different productions those that will be the most viable in the environment considered.
These considerations, which are only hypotheses, show that, if the properties of the atom matter, they are not the only ones to be decisive and that we must then consider consciousness and intelligence as a property integrating its interaction with the societal environment and the ecosystem. It is perhaps in this direction that we must look for the source of emergence, which is usually attributed rather to a mysterious « external » property (emergence) that would be injected by the complexity of the assemblies.
The structure of neural networks that we are beginning to know better, shows that they are structures that initially naturally incorporate quite little information (in humans, by heredity they mainly incorporate vital information for an efficient metabolism) but that acquire their information through their interactions with the environment that includes it, through experience. It’s learning.
The elementary structure (the neuron) is structurally quite simple and it is the multiple interconnections developing a gigantic combinatorics between neurons, associated with the rules of activation / inhibition, that give this biological system its formidable efficiency, to the point that its computer modeling is currently the « Grail » of the most sophisticated algorithms.
Some important structural problems
Let us also emphasize that considering the problem of our existence in this reductionist context is to assume that the combination, even elaborate, of atoms constituting our body would explain the existence of these atoms! This seems structurally impossible to us.
An loophole would be that if it seems impossible to our brain, it is because, in its current level of learning, it has not been confronted with this situation. That’s how it works, it’s a “Spanish hostel”, you can find what you put in it. Rather than intelligence, let us call this « effective habits of thought ».
We will have the opportunity to indicate how modern physical theories have upset these habits of thought, which are considered essential (time, space, determinism). In this case we were (and still are) faced with incomprehensible or even inconceivable concepts (in the current state of our mental structures) which did not prevent us from building an effective representation (a theory).
This too seemed, a priori, impossible.
Thus, when Einstein, after many unsuccessful attempts in scalar solutions, considered, because he had not yet tried it, a geometric approach to gravitation, which, if not accepted by the scientific community at the time, was often qualified, with some respect, as a bold hypothesis, he did not really realize what conceptual break this would lead to: this is undoubtedly the mark of genius that has an element of irrationality.
Another proof that our mind, yet constrained by the concepts of space and time inherent in its nature, is able to overcome these limits and question them.
Recall that general relativity allows solutions where causality is violated and that other consequences on the orientation of time are theoretically possible, with the concept of negative energy (energy is the physical representation of time) even if it is not certain that the physical world, imperfect, allows them.
So, let’s not swear anything, even if we must admit it the task seems difficult.
A reasonable hypothesis is that these theories, which we currently do not understand, are effective because there is a formal (structural) morphism between these theories and the phenomena they describe and where they correctly predict the results of experiments.
To circumvent the current shortcomings of our mind (related to our formation and experience) that prevent us from directly studying these phenomena, let us take its formal representation (theory), which is available and intelligible, as an object of study and extract the formal characteristics (e.g. invariances).
This study of formalism that we have been led to build « empirically » for these theories to be effective, should allow us to extract information on the phenomena of the physical world they describe. This method of « best fit », less elegant than the classical method where a theory is deduced from founding principles, is part of an empirical pragmatic paradigm of remarkable efficiency, increasingly used in science.
This is a good way to get around our current intellectual inadequacies. We can hope that these are temporary, because our brain is an organ that does not impose, at least not itself, strict and impassable rules, but is a flexible, open and adaptive structure that incorporates data and algorithms (learning under constraint) to offer relevant answers to the safeguarding and well-being of the body in its environment. It is certain that for phenomena that it has not yet encountered in a binding way it does not have associated data and algorithms, hence its inadequacy.
However, let us moderate our optimism, because we must not lose sight of the fact that such an « empirical » method can incorporate « biases » as Bachelard pointed out, (an experiment is a materialized theory) that would reduce it to « a cooking recipe », which is better than nothing but which does not show all the chemistry behind it.
We will come back to this point
Does quantum mechanics illustrate the limit of scientific thought?
Having considered, the path that goes from the atom to the brain, in fact to intelligence, what can be said about the opposite path: What knowledge do we have about atoms?
R. Feynman liked to tell his students that they were not going to understand anything about what he was going to teach them and that he himself understood nothing about it. Beyond the provocative nature of the statement, which must be moderated by the facetious temperament of its author, this did not prevent him from making a masterful contribution to this discipline. Let us recognize that, if developing a theory that accounts well for phenomena to which we do not understand anything is even stronger than developing a theory where we understand something, it still leaves the scientist a little perplexed. 
Indeed, even more than general relativity, which if it implements counterintuitive concepts, remains a « classical » theory, quantum mechanics has given rise to multiple debates on its interpretation. When the scientists looked at the microscopic side, the view was not the one expected. Impossible to predict with scientific certainty the result of a measurement of an experiment. It has been necessary to build a new formalism.
The state of a system is represented by an unphysical wave function allowing to predict probabilities of measurement results, which are formally obtained by the application of mathematical operators, associated to physical quantities, on this wave function. The quantum world is viewed as a superposition of many possible states that when we go to make a measurement will give a result that is a value among the possible values whose probability depends on the wave function. Note that in order to obtain several physical parameters of the state by a measurement, it is necessary that the operators associated with the physical parameters commute. Otherwise, there is an indeterminacy relation, the Heisenberg indeterminacy relation, which limits the simultaneous knowledge of parameters .
This formalism gives a blurred picture of this microscopic world, where, for example, an electron in an atom, even in a state defined by its quantum numbers, is in the form of a cloud where a function defines its probability of presence, whose geometry depends on these quantum numbers, while moreover it has a proper kinetic momentum, (which is a rotation in classical representation) the spin. This has no classical geometric representation.
This formalism is effective because it makes (statistical) predictions that can be verified experimentally. As we have indicated previously, this means that a morphism should exist with physical reality.
Let us remember, as Bachelard said, that instruments bear the mark of the theories they are supposed to verify. This corresponds to a case where the structural limits of knowledge are reached.
Is science totally objective?
As suggested by what has been developed previously it is impossible to get rid of a part of subjectivity. In his analysis of the respective roles of theories, which he associates with rationalism, and experiments, which he associates with realism, in the scientific approach, Bachelard concludes that they are not totally independent. He states:
« It would not be difficult to show, on the one hand, that in his scientific judgments, the most determined rationalist daily accepts the instruction of a reality that he does not know thoroughly and that, on the other hand, the realist, the most intransigent, makes immediate simplifications, exactly as if he were admitting the informative principles of rationalism. Suffice to say that for scientific philosophy, there is neither realism nor rationalism, absolute and that we must not start from a general philosophical attitude to judge scientific thought… Thus, as soon as one meditates on scientific action, one realizes that realism and rationalism exchange their advice endlessly. This duality results from the fact that the philosophy of science is a philosophy that applies, it cannot keep the purity of a speculative philosophy. »
Bachelard argues that one cannot make an exclusive choice between the two, as they are not totally separable. He explains this point of view:
« Instruments are just materialized theories. The result is phenomena that bear the theoretical mark on all sides. After having formed, in the first efforts of the scientific mind, a reason in the image of the world, the mind activity of modern science is committed to building a world at the image of reason.
This results from the fact that science is a human activity. As such, it experiences all its constraints and limitations and necessarily includes a trace of them. 
The role of physicist thought in the (theoretical) representation of « physical reality »
In his article « Principle of Representation-Self-Duality Theoretical », Majid (Majid S. (1991), « Principle of Representation-Theoretic Self-Duality », Physics Essays, 4) proposes to represent realism and rationalism from the perspective of a formal duality and to use the appropriate mathematical formalisms to determine the constraints to reconcile the two points of view. Beforehand, he declares:
Theoretical physics is the search for a coherent complete set of fundamental laws of physics. We propose an approach to show that the ultimate structure, namely the set of laws to be taken into account by physicists, only reflects the structures authorized by the constraints of the physicist’s mind.
This can also be illustrated by a performance of a play where the author is generally not present on stage but is present in the text and staging.
The scientist is like that, his production is imbued with his being. Which makes say that when the human tried to grasp the ultimate secrets of nature, he found strange imprints: they were his own’s!
Illustration by the case of quantum mechanics
Quantum mechanics is an interesting illustration of this, because the formalism (wave function) used to describe a system does not give its state but a superposition of possible states. It is an experiment, a human action, which will produce a particular state among these possible states, according to a probability distribution.
Case of general relativity
There is no similar process in this theory. Einstein’s equation derives from a Lagrangian that involves an action of gravitation and an action of matter, perhaps it would be necessary to incorporate an action of the human mind, but in what form?
Changing our way of thinking?
But in a world that is experiencing a scientific and societal upheaval, of an unprecedented magnitude, whose effects and consequences are difficult to understand, but where humans are no longer passive either about their destiny or about their environment, it is clear that it is difficult to exclude anything!
A way out may lie in a change that will undoubtedly be an evolution of our way of thinking that will have to take into account the new « empirical » methods for some, which have allowed us to overcome, at least to a certain level, current inadequacies of our understanding, because if we consider it « reasonable » it is nevertheless only a kind of habit of thought shaped by our experience. 
Thus, as we have developed, on the only evidence which is the observation of our existence, as part of a larger entity that exists because of ours, which we call the universe, whose modeling uses an entity, spacetime, where time and space are no longer fundamental entities we arrive at a coherent conclusion (which does not mean that it is correct).
Spacetime exists, independently of anything else, as its mathematical representation shows. It does not require to have been created, in the sense where it is usually understood, in a given place and time, therefore from something that would incorporate these concepts of time and space because it is more (in fact, something else) than the time and space.
Spacetime incorporates space and time as shadows cast into our « physical » world (the material physical world in which we live), as Plato had described in his allegory of the cave.
This concept of spacetime is « inconceivable » because we think of it in time and space (in our physical world).
It is remarkable that, despite these « constraints » of our thought, it can offer us a coherent interpretation that, at least today, preempts these constraints but that we cannot understand and that leaves us dissatisfied.
Never the less, let us stress that a human activity (mathematics) allows us to go beyond the constraints of our human thought!
Causality itself questioned!
It turns out that this essential notion of physics, which has undergone many changes since the classical era when a universal absolute time and an absolute space provided a criterion of universal causality and then be reduced in general relativity to a « topological » criterion using the « cone » of light from an event A (an event B could have been caused by an event A only if the light from A reached B at the time or before B occurs), is itself questioned by phenomena such as black holes, for example, which are widely present in our universe.
The cosmic censorship conjecture tries to preserve its essential aspects by encapsulating the singularities in a horizon preserving physics from the break of causality that this singularity could generate, but on the one hand it is only a conjecture and on the other hand it preserves causality only outside this horizon, while spacetime also exists (is at least described mathematically) under the horizon.
What about causality inside the horizon where nothing protects physics from the devastating effects of the singularity? It is confirmed that mathematics predicts flagrant violations of causality in certain regions of Kerr’s black holes, for instance.
We can, of course, doubt their physical character and the fact that we cannot verify it experimentally, but let us not forget that these black holes themselves, whose proliferation can be seen in our universe, have long been mistaken for mathematical artifacts without a physical character.
We can also object that these mathematical black holes are ideal models of physical objects called black holes, but the existence of a horizon does exist in the images that we have recently obtained of these physical objects called black holes which, if they do not really conform to the mathematical model, look very similar to it!
Here again, our mind, yet structured by a concept like that of causality, invoking a temporal order, produces theories, which violate this temporal order. Even if it is not certain that these theories accurately reflect the physical world in which we live, is this not what could be called mental inconsistency?
Under these conditions the existence of the universe without a predecessor (without a « cause » and whose cause should be explained anyway and so on) no longer really seems like an absurd hypothesis because, obviously, according to our theories, certain parts of our universe behave in an unpredictable way.
If the conjecture (which is only a conjecture) of cosmic censorship is supposed to protect us it is at the cost of voluntary limitations in the exploration of our universe, because nothing prevents us from crossing the horizon of a black hole (especially hyper massive). What’s in it?
Whoever enters it will never be able to say it because he definitely leaves our outside world. Unlike in Schwarzschild’s black holes, his death is not certain, because in Kerr’s black holes we can go into an anti-universe or even be rejected in another universe disconnected from ours. How are these other universes? We have no idea, but it shows that the craziest hypotheses can be considered.
We could also mention quantum mechanics where it is determinism that is no longer valid.
This has been the price to pay, to develop theories that allow us to describe the physical world in which we live. If it turns out to be mysterious, it is, without a doubt, that our mind has not yet made the necessary path to adapt to it.
So, as we developed in a previous chapter, when we consider the renunciations that had to be inflicted on our mind to describe the relativity that destroyed our concepts of time and space that we thought were universal and related to the very nature of our mind and the even worse renunciations related to quantum mechanics where it is, in addition, the determinism that had to be abandoned, we see that we are not immune to a new upheaval of this type.
 The pulsation defined in radians per unit of time is used instead of the frequency. There are 2π radians per period.
 The arbitrariness of the units leads to the fact that for the study of the primordial universe, we often use the system of natural units where we pose c = 1, G = 1,
h = 1. Planck units (length, time, energy) are combinations of these constants constructed from dimensional analysis.
 This complexity comes from the structure of the outer layers of the atoms of the few dozen atoms useful to life, since it is at this level that atoms can assemble to form molecules. It is the electromagnetic interaction that is at work. So this possibility of evolution towards life comes from the elementary structure of matter described by quantum mechanics and the associated interactions. This structure, which existed from the beginning of the universe, was initially masked by the energy context. She began to reveal her creative power when her temperature dropped. Around 3000°K, this allowed the neutral atoms, where the nucleus was surrounded by its procession of electrons, to be stable. Then around 300 ° K, by stabilizing complex molecules, a combination of weakly bound atoms, this allows the very diverse chemistry of life: these molecules can easily bind with others or break.
 Note that, if theories invoking parallel universes, in incalculable numbers, give power back to chance, these theories are speculative, at least for the moment.
 Let us also emphasize the effectiveness of religions in federating a very large number of individuals of disparate interests around a doctrine in a group, thus giving it a power all the more important the larger the group. This was widely exploited by powerful lords, kings and rulers to found and ensure their dominion over individuals.
 The same goes for our body and intelligence. Genetic engineering allows humans to modify their bodies. Artificial intelligence and the networking of minds multiply our cognitive abilities.
 Humanist philosophies are well known, but they are not the only ones interested in communities. Let us point out that if we can limit the life of an individual, for humanity it is more problematic.
 Ancient Greek philosophers for example. « Know thyself! »
 Here we deal with the existence of the individual and humanity. Note the similarity with the description of the existence of the universe that we made. We have the same two approaches. One, classical, where one supposes something external to the object considered to explain phenomenology, the other where, on the contrary, where the object considered contains all the information and properties necessary for its explanation. We will come back to this in the conclusion.
 At the time of the explosion its instantaneous power can reach that of thousands of galaxies.
 The Sun is supposed to shine fairly stably for several billion years.
 For example, global warming, which is already probably in a non-linear phase today, which compromises any reliable prediction. In the past of life on Earth, many examples show that the uncontrolled development of a form of life leads inexorably to its extinction either by its waste or by a catastrophic event, which has the effect of promoting another form of life that will be subject to the same hazards.
 If we take the values of the coordinates as a reference, this does not generally make sense, because by changing the coordinates used, we can transform an infinite universe into a finite universe and vice versa. For this to have a physical meaning, the criterion under consideration must be of a physical nature.
 V. A. Belinsky, I.M. Khalatnikov and E.M. Lifschitz, 1970.
 It should be noted that to explain certain phenomena in the cosmological model, quantum effects, such as the spectrum of inhomogeneities, are taken into account, but this is not integrated into the theory.
 See the Book Homo Deus by Yuval Noah Harari. He evokes the possibility of « repairing » the human body in order to improve our health but also to increase its lifespan and also to modify it to adapt it more quickly to the changes of the world. By extrapolating to the extreme he evokes the possibility of eternal life which, of course, would pose societal, philosophical and scientific problems because not being pure spirits, we are materially dependent on the universe. Current cosmological predictions (big tear up) would be incompatible with our material existence. But this model only takes into account the gravitational interaction, the other three interactions, could, in this context, inhibit this effect locally. Physics is not finished and can hold surprises.
 Whose chemical properties depend on the number of protons of the nucleus which determines the number of electrons of the neutral atom and whose stability is ensured by the nuclear force. But it is the electronic layers that are at work for the chemical properties that characterize the link of this atom with its neighbors.
 He was awarded the Nobel Prize in 1965 for this.
 This may suggest a hidden underlying reality. Just because we have rules that describe phenomenology well does not mean that we know it well. Chemistry, with rules of valence to predict molecular combinations, has undergone remarkable development, for example. It is now known that this results from the structure of the electronic layers, especially external, of the atom.
 Operators A and B commute if the result does not depend on the order in which the operators are applied to the wave function. Today, the term indeterminacy is used. For instance for the momentum p and position x of an electron, whose associated operators do not commute, this is written ∆p ∆x ≥
 This makes it say that « When humans tried to unravel the ultimate secrets of nature, they found strange imprints: they were his own! »
 In each era we had to do this kind of thought. But when we read the predictions made over the next 50 years, we see that they have proved to be totally aberrant. Today, with the acceleration and magnitude of scientific, technical and societal change, which is difficult to integrate, it becomes even more problematic.
 We know more today about how our brain works. Studies show that he decides according to what he knows and that his reaction is questionable when new concepts are at stake.