The present day standard cosmological model is a great theoretical achievement. This chapter surveys the main themes that have arisen and issues that are still oustanding.

The standard model of cosmology is acclaimed in physics as accurate, robust, well-tested, our best scientific theory of the cosmos, but it has had serious anomalies for a while, including the Hubble tension, anomalous galaxies, and the completely unexplained nature of dark energy and dark matter. And lurking behind it all is the lack of a unified theory: General Relativity (GR) and quantum mechanics (QM) are inconsistent. Now startling new observations by the James Webb Space Telescope (JWST) in (...) 2022 of the early universe present the strongest challenge yet to the standard model, and whispers have started that this shows there is something wrong with the fundamental theory, General Relativity itself. This would be a crisis for cosmology. But haven’t they tested this theory already, and shown it is correct? How could it turn out wrong at this late stage? Here we compare the standard cosmology with an alternative fundamental theory, that has a strikingly different overall cosmological behavior: a simple cyclic expansion function. It is simple and deterministic. There are only two or three general parameters. The interesting result is that this alternative cosmology: (A) closely matches the expansion observed and modelled through the CDM standard model, now going back to red-shifts of 5-15; and (B) it also predicts unexpected early galaxy formation now being reported by the JWST. The point here is not to try to prove this alternative theory however, but rather show how it compares to the conventional cosmology. This show us clearly how weak the empirical evidence for the standard model really is against a counterfactual fundamental theory. Some results established in science are robust against theory change, but we find the standard cosmological model and the implications drawn from it are not robust at all. (shrink)

I review some theoretical ideas in cosmology different from the standard “Big Bang”: the quasi-steady state model, the plasma cosmology model, non-cosmological redshifts, alternatives to non-baryonic dark matter and/or dark energy, and others. Cosmologists do not usually work within the framework of alternative cosmologies because they feel that these are not at present as competitive as the standard model. Certainly, they are not so developed, and they are not so developed because cosmologists do not (...) work on them. It is a vicious circle. The fact that most cosmologists do not pay them any attention and only dedicate their research time to the standard model is to a great extent due to a sociological phenomenon . We might well wonder whether cosmology, our knowledge of the Universe as a whole, is a science like other fields of physics or a predominant ideology. (shrink)

The main foundations of the standard \CDM model of cosmology are that: the redshifts of the galaxies are due to the expansion of the Universe plus peculiar motions; the cosmic microwave background radiation and its anisotropies derive from the high energy primordial Universe when matter and radiation became decoupled; the abundance pattern of the light elements is explained in terms of primordial nucleosynthesis; and the formation and evolution of galaxies can be explained only in terms of gravitation within (...) a inflation + dark matter + dark energy scenario. Numerous tests have been carried out on these ideas and, although the standard model works pretty well in fitting many observations, there are also many data that present apparent caveats to be understood with it. In this paper, I offer a review of these tests and problems, as well as some examples of alternative models. (shrink)

Cosmology, the study of the universe, has a past, which is reviewed here. The standard model—the Big Bang, or the hot, dense early universe that is still expanding—is based on observations that are basically consistent but which require additional input to improve the agreement. Out of the early universe came the galaxies and stars that shine today. The future of the universe depends on the density of matter: too much mass leads to the Big Crunch; too little leads (...) to eternal expans ion and cooling. The dark‐matter problem prevents us from knowing which will be the fate of the universe. Thelimits of what may be called “scientific” are addressed. (shrink)

Cosmology, the study of the universe, has a past, which is reviewed here. The standard model—the Big Bang, or the hot, dense early universe that is still expanding—is based on observations that are basically consistent but which require additional input to improve the agreement. Out of the early universe came the galaxies and stars that shine today. The future of the universe depends on the density of matter: too much mass leads to the Big Crunch; too little leads (...) to eternal expans ion and cooling. The dark‐matter problem prevents us from knowing which will be the fate of the universe. Thelimits of what may be called “scientific” are addressed. (shrink)

Dark matter is a fundamental component of the standard cosmological model, but in spite of four decades of increasingly sensitive searches, no-one has yet detected a single dark-matter particle in the laboratory. An alternative cosmological paradigm exists: MOND (Modified Newtonian Dynamics). Observations explained in the standard model by postulating dark matter are explained in MOND by proposing a modification of Newton's laws of motion. Both MOND and the standard model have had successes (...) and failures – but only MOND has repeatedly predicted observational facts in advance of their discovery. In this volume, David Merritt outlines why such predictions are considered by many philosophers of science to be the 'gold standard' when it comes to judging a theory's validity. In a world where the standard model receives most attention, the author applies criteria from the philosophy of science to assess, in a systematic way, the viability of this alternative cosmological paradigm. (shrink)

I argue that some important elements of the current cosmological model are 'conventionalist’ in the sense defined by Karl Popper. These elements include dark matter and dark energy; both are auxiliary hypotheses that were invoked in response to observations that falsified the standard model as it existed at the time.

In a recent article Merritt has claimed that current observational data provide “severe tests” falsifying the standard cosmological model. Based on Popper’s idea of conventionalism, he concludes that the introduction of some essential components of the standard cosmological model—including dark matter and dark energy—are a consequence of conventionalist stratagems. In this article, I provide more recent discoveries and discussions showing that the standard cosmological model is not built on any conventionalist stratagem.

This thesis provides an introduction to the physics of the Standard Model and beyond, and to the methods used to analyse Large Hadron Collider (LHC) data. The 'hierarchy problem', astrophysical data and experiments on neutrinos indicate that new physics can be expected at the now accessible TeV scale. This work investigates extensions of the Standard Model with gravitons and gravitinos (in the context of supergravity). The production of these particles in association with jets is studied as (...) one of the most promising avenues for researching new physics at the LHC. Advanced simulation techniques and tools, such as algorithms allowing the computation of Feynman graphs and helicity amplitudes are first developed and then employed. (shrink)

In this paper I take a sceptical view of the standard cosmological model and its variants, mainly on the following grounds: (i) The method of mathematical modelling that characterises modern natural philosophy-as opposed to Aristotle's-goes well with the analytic, piecemeal approach to physical phenomena adopted by Galileo, Newton and their followers, but it is hardly suited for application to the whole world. (ii) Einstein's first cosmological model (1917) was not prompted by the intimations of experience (...) but by a desire to satisfy Mach's Principle. (iii) The standard cosmological model-a Friedmann-Lematre-Robertson-Walker spacetime expanding with or without end from an initial singularity-is supported by the phenomena of redshifted light from distant sources and very nearly isotropic thermal background radiation provided that two mutually inconsistent physical theories are jointly brought to bear on these phenomena, viz the quantum theory of elementary particles and Einstein's theory of gravity. (iv) While the former is certainly corroborated by high-energy experiments conducted under conditions allegedly similar to those prevailing in the early world, precise tests of the latter involve applications of the Schwarzschild solution or the PPN formalism for which there is no room in a Friedmann-Lematre-Robertson-Walker spacetime. (shrink)

In spite of successful tests, the standard cosmological model, the $$\varLambda$$ CDM model, possesses the most problematic concept: the initial singularity, also known as the big bang. In this paper—by adopting the Kantian difference between to think of an object and to cognize an object—it is proposed a degree of scientificity using fuzzy sets. Thus, the notion of initial singularity will not be conceived of as a scientific issue because it does not belong to the fuzzy (...) set of what is known. Indeed, the problematic concept of singularity is some sort of what Kant called the noumenon, but science, on the other hand, is constructed in the phenomenon. By applying the fuzzy degree of scientificity in cosmological models, one concludes that cosmologies with a contraction phase before the current expansion phase are potentially more scientific than the standard model. At the end of this article, it is shown that Kant’s first antinomy of pure reason indicates a limit to our cosmological models. (shrink)

This comprehensive textbook is devoted to classical and quantum cosmology, with particular emphasis on modern approaches to quantum gravity and string theory and on their observational imprint. It covers major challenges in theoretical physics such as the big bang and the cosmological constant problem. An extensive review of standard cosmology, the cosmic microwave background, inflation and dark energy sets the scene for the phenomenological application of all the main quantum-gravity and string-theory models of cosmology. Born of the author's (...) teaching experience and commitment to bridging the gap between cosmologists and theoreticians working beyond the established laws of particle physics and general relativity, this is a unique text where quantum-gravity approaches and string theory are treated on an equal footing. As well as introducing cosmology to undergraduate and graduate students with its pedagogical presentation and the help of 45 solved exercises, this book, which includes an ambitious bibliography of about 3500 items, will serve as a valuable reference for lecturers and researchers. (shrink)

I discuss how modern cosmology illustrates under-determination of theoretical hypotheses by data, in ways that are different from most philosophical discussions. I emphasise cosmology's concern with what data could in principle be collected by a single observer ; and I give a broadly sceptical discussion of cosmology's appeal to the cosmological principle as a way of breaking the under-determination.I confine most of the discussion to the history of the observable universe from about one second after the Big Bang, as (...) described by the mainstream cosmological model: in effect, what cosmologists in the early 1970s dubbed the ‘standard model’, as elaborated since then. But in the closing Section 4, I broach some questions about times earlier than one second. (shrink)

According to the standard interpretation of Einstein’s field equations, gravity consists of mass-energy curving spacetime, and an additional physical force or entity—denoted by Λ (the ‘cosmological constant’)—is responsible for the Universe’s metric-expansion. Although General Relativity’s direct predictions have been systematically confirmed, the dominant cosmological model thought to follow from it—the ΛCDM (Lambda cold dark matter) model of the Universe’s history and composition—faces considerable challenges, including various observational anomalies and experimental failures to detect dark matter, dark (...) energy, or inflation-field candidates. This paper shows that Einstein’s Equivalence Principle entails two possible physical interpretations of General Relativity’s field equations. Although the field equations facially appear to support the standard interpretation—that gravity consists of mass-energy curving spacetime—the field equations can be equivalently understood as holding that gravitational effects instead result from mass-energy accelerating the metric-expansion of a second-order spacetime fabric superimposed upon an absolute, first-order Euclidean space, resulting in the observational appearance of spacetime curvature. This alternative interpretation of relativity is shown to be empirically equivalent to the standard interpretation of relativity, albeit with a changing value for Λ (which is similar to how Λ is understood in the conception of Λ as ‘quintessence’, but in this case takes Λ to be gravity). The reconceptualization is then shown to potentially resolve major observational anomalies for the ΛCDM model, including recent observations conflicting with ΛCDM predictions, as well as failures to directly detect dark matter, dark energy, and inflation field/particle candidates. (shrink)

I discuss how modern cosmology illustrates underdetermination of theoretical hypotheses by data, in ways that are different from most philosophical discussions. I confine the discussion to the history of the observable universe from about one second after the Big Bang, as described by the mainstream cosmological model: in effect, what cosmologists in the early 1970s dubbed the ‘standard model’, as elaborated since then. Or rather, the discussion is confined to a (very!) few aspects of that history. (...) I emphasize that despite the underdetermination, a scientific realist can, and should, endorse this description. (shrink)

Certain results of observational cosmology cast critical doubt on the foundations of standard cosmology but leave most cosmologists untroubled. Alternative cosmological models that differ from the Big Bang have been published and defended by heterodox scientists; however, most cosmologists do not heed these. This may be because standard theory is correct and all other ideas and criticisms are incorrect, but it is also to a great extent due to sociological phenomena such as the "snowball effect" or "groupthink". (...) We might wonder whether cosmology, the study of the Universe as a whole, is a science like other branches of physics or just a dominant ideology. (shrink)

In the paper we show that modern cosmology has a status of effective theory of the Universe similarly to the standard models in particle physics. We illustrate that the source of such a point of view is the fact that the complete theory of the Universe (TOE) should be complicated enough to derive observables. The role of epistemological emergence in the context of cosmological models (Cold Dark Matter vs. Lambda Cold Dark Matter) is also investigated. We demonstrate that (...) while the effective theories of the Universe are not conceptually simple and elegant, their strength lies in the predictive accuracy and data fitting required for the model testing. (shrink)

Cosmological questions (e.g., how far the world extends and how it all began) have occupied humans for ages and given rise to numerous conjectures, both within and outside philosophy. To put to rest fruitless speculation, Kant argued that these questions move beyond the limits of human knowledge. This article begins with Kant’s doubts about cosmology and shows that his arguments presuppose unreasonably high standards on knowledge and unwarranted assumptions about space-time. As an analysis of the foundations of twentieth-century cosmology (...) reveals, other worries about the discipline can be avoided too if the universe is modeled using Einstein’s general theory of relativity. There is now strong observational support for one particular model. However, due to underdetermination problems, the big cosmological questions cannot be fully answered using this model either. This opens the space for more speculative proposals again (e.g., that the universe is only part of a huge multiverse). (shrink)

The concept of the universe is used in physical cosmology differently from the usual meaning of the term, naively considered as the entire reality. Traditionally, thinking about the whole led to logical contradictions. Taking as reference the Kantian antecedent, different contemporary philosophical notions of the universe are analysed in the first part of this paper, including realist and constructivist approaches, as well as a notion of the universe as a physical object. In the second part, the specific notion from the (...) standard physical cosmology is discussed. Although modelling the universe as a physical system provides a specific way to define some global properties, the universe as a whole remains empirically inaccessible. Hence, the discussion about the under-determined global properties depends ultimately on philosophical preferences. Under these circumstances, it is argued that the realist interpretation of such properties becomes problematic because it leads to unstable conclusions. Finally, it is argued that the notion of the universe as conceived in standard cosmology is not necessarily consistent with an approach that considers it to be a physical object. (shrink)

Inflationary cosmology won a large following on the basis of the claim that it solves various problems that beset the standard big bang model. We argue that these problems concern not the empirical adequacy of the standard model but rather the nature of the explanations it offers. Furthermore, inflationary cosmology has not been able to deliver on its proposed solutions without offering models which are increasingly complicated and contrived, which depart more and more from the (...) class='Hi'>standard model it was supposed to improve upon, and which sever the connection between cosmology and particle physics that initially made the inflationary paradigm so attractive. Nevertheless, inflationary cosmology remains a promising research program, not least because it offers an explanation of the origin of the density perturbations that seeded the formation of galaxies and other cosmic structures. Tests of this explanation are underway and may settle the issue of whether inflation played an important role in the early universe. (shrink)

Summary Cosmology has always been different from other areas of the natural sciences. Although an observationally supported standard model of the universe emerged in the 1960s, more speculative models and conceptions continued to attract attention. During the last decade, ideas of multiple universes (the ‘multiverse’) based on anthropic reasoning have become very popular among cosmologists and theoretical physicists. This had led to a major debate within the scientific community of the epistemic standards of modern cosmology. Is the multiverse (...) a scientific hypothesis, or is it rather a philosophical speculation disguised as science? This paper offers a review of the recent and still ongoing controversy concerning the multiverse, emphasizing its foundational nature and relation to philosophical issues. It also compares the multiverse controversy to some earlier episodes in the history of twentieth-century cosmology when particular theories and approaches came under attack for betraying the ideals of proper science. (shrink)

Several features of cosmology are of striking philosophical interest. Unlike other branches of physics which deal with kinds of occurrences and relations, cosmology investigates only one unique entity, the physical universe. Hence the science cannot avail itself of standard inductive procedures which depend on the assembling of samples. Cosmologists are therefore obliged to choose between two other procedures. Mr. Bondi calls them the "extrapolative" and the "axiomatic-deductive" lines of thought. The former starts from physical laws known to hold of (...) terrestrial or near-terrestrial phenomena. It then tries to frame an answer to the question: "What is the largest set of phenomena to which these laws can be applied consistently and successfully?" The result of this approach has been the construction of a number of "models" of the universe at large, each patterned on verified laws of physics. The axiomatic-deductive approach starts from certain a priori assumptions which are held to underlie any physical science whatever and which are equivalent to certain suppositions about the structure of the universe. From these assumptions, together with special axioms adopted for the purpose, the laws of cosmology are deduced. Then the deductions are checked with the observational data. Here again, various models of the cosmos have resulted. (shrink)

Recently the cosmological evolution of the universe has been considered where 3-dimensional spatial topology undergone drastic changes. The process can explain, among others, the observed smallness of the neutrino masses and the speed of inflation. However, the entire evolution is perfectly smooth from 4-dimensional point of view. Thus the raison d’être for such topology changes is the existence of certain non-standard 4-smoothness on R4 already at very early stages of the universe. We show that the existence of such (...) smoothness can be understood as a byproduct of the quantumness of the origins of the universe. Our analysis is based on certain formal aspects of the quantum mechanical lattice of projections of infinite dimensional Hilbert spaces where formalization reaches the level of models of axiomatic set theory. (shrink)

Cosmological ideas influenced every aspect of traditional Chinese culture, from science and medicine to art, philosophy, and religion. Although other premodern societies developed similar conceptions, in no other major civilization were such ideas so pervasive or powerful. In The Development and Decline of Chinese Cosmology, John Henderson traces the evolution of Chinese thought on cosmic order from the classical era to the nineteenth century. Unlike many standard studies of premodern cosmologies, this book analyzes the origins, development, and rejection (...) of these models, not just their structure. Moreover, while historians often limit their studies of cosmic order to specialized fields like the history of science, Henderson examines how the cosmological ideas formulated in late classical times permeated various facets of Chinese life, from high philosophy to popular culture. (shrink)

Paul Feyerabend argued that theories can be faced with experimental anomalies whose refuting character can only be recognized by developing alternatives to the theory. The alternate theory must explain the experimental results without contrivance and it must also be supported by independent evidence. I show that the situation described by Feyerabend arises again and again in experiments or observations that test the postulates in the standard cosmological model relating to dark matter. The alternate theory is Milgrom’s modified (...) dynamics. I discuss three examples: the failure to detect dark-matter particles in laboratory experiments; the lack of evidence for dark-matter sub-haloes and the dwarf galaxies that are postulated to inhabit them; and the failure to confirm the predicted orbital decay of Milky Way satellite galaxies and other systems due to dynamical friction against the dark matter. In each case, Feyerabend’s criterion directs us to interpret the experimental or observational results as an indirect refutation of the standard cosmological model in favor of Milgrom’s theory. (shrink)

In recent years, apparently the Big Bang as described by the Lambda CDM-Standard Model Cosmology has become widely accepted by majority of physics and cosmology communities. Even some people have concluded that it has no serious alternative in horizon. Is that true? First, as we argued elsewhere, Big Bang story relies on singularity. In other words, when we are able to describe the observed data without invoking singularity, then Big Bang model is no longer required. Therefore, here (...) we explore a few alternative stories other than Big Bang story, which most cosmologists believe it is the nearest to Biblical account of creation. We would argue that re-reading of Genesis 1:2 will lead us to another viable story, albeit the alternative has not been developed rigorously as LCDM theories. We also briefly discuss a fluid Maxwell equations of Prof. Tsutomu Kambe based on vortex sound theory. (shrink)

Dark matter is an essential ingredient of the present Standard Cosmological Model, according to which only 5% of the mass/energy content of our universe is made of ordinary matter. In recent times, it has been argued that certain cases of gravitational lensing represent a new type of evidence for the existence of DM. In a recent paper, Peter Kosso attempts to substantiate that claim. His argument is that, although in such cases DM is only detected by its (...) gravitational effects, gravitational lensing is a direct consequence of Einstein's Equivalence Principle and therefore the complete gravitational theory is not needed in order to derive such lensing effects. In this paper I critically examine Kosso's argument: I confront the notion of empirical evidence involved in the discussion and argue that EEP does not have enough power by itself to sustain the claim that gravitational lensing in the Bullet Cluster constitutes evidence for the DM Hypothesis. As a consequence of this, it is necessary to examine the details of alternative theories of gravity to decide whether certain empirical situations are indeed evidence for the existence of DM. It may well be correct that gravitational lensing does constitute evidence for the DM Hypothesis—at present it is controversial whether the proposed modifications of gravitation all need DM to account for the phenomenon of gravitational lensing and if so, of which kind—but this will not be a direct consequence of EEP. (shrink)

In Logik der Forschung (1934) and later works, Karl Popper proposed a set of methodological rules for scientists. Among these were requirements that theories should evolve in the direction of increasing content, and that new theories should only be accepted if some of their novel predictions are experimentally confirmed. There are currently two, viable theories of cosmology: the standard cosmological model, and a theory due to Mordehai Milgrom called MOND. Both theories can point to successes and failures, (...) but only MOND has repeatedly made novel predictions that were subsequently found to be correct. Standard-model cosmologists, by contrast, have almost always responded to new observations in a post-hoc manner, adjusting or augmenting their theory as needed to obtain correspondence with the facts. I argue that these methodological differences render a comparison of the two theories in terms of their ‘truthlikeness’ or ‘verisimilitude’ essentially impossible since the two groups of scientists achieve correspondence with the facts in fundamentally different ways, and I suggest that a better guide to the theories’ progress toward the truth might be the methodologies themselves. (shrink)

The high precision attained by cosmological data in the last few years has increased the interest in exact solutions. Analytic expressions for solutions in the Standard Model are presented here for all combinations of Λ = 0, Λ ≠ 0, κ = 0, and κ ≠ 0, in the presence and absence of radiation and nonrelativistic matter. The most complete case (here called the ΛγCDM Model) has Λ ≠ 0, κ ≠ 0, and supposes the presence (...) of radiation and dust. It exhibits clearly the recent onset of acceleration. The treatment includes particular models of interest such as the ΛCDM Model (which includes the cosmological constant plus cold dark matter as source constituents). (shrink)

The paper presents the methodology of effective theories as a strategy used in the process of development of modern physics to reach a final theory. We present the definition and characteristic features of an effective theory, as well as the answer to the question of whether and what kind of scenario of reaching a final theory is realized by contemporary physics. We argue that the process of development of physics in the direction of a final theory is potentially final, i.e. (...) expressible in the conceptual schema of effective theories and as such it is convergent to a final theory. In each effective theory there are physical constants, however, whose status differs from logical constants. They have a dimension and are used to compare physical quantities. The structure of relevant effective theory can be interpreted in the epistemological framework of approximated truth theory. In the case study of cosmological models, the sequence of models is convergent to potentially true model. The Standard Cosmological Model is the theory of the structure and dynamics of the Universe. (shrink)

Scientific cosmology is an empirical discipline whose objects of study are the large-scale properties of the universe. In this context, it is usual to call the direction of the expansion of the universe the "cosmological arrow of time". However, there is no reason for privileging the ‘radius’ of the universe for defining the arrow of time over other geometrical properties of the space-time. Traditional discussions about the arrow of time in general involve the concept of entropy. In the (...) class='Hi'>cosmological context, the direction past-to-future is usually related to the direction of the gradient of the entropy function of the universe. But entropy is a thermodynamic magnitude that is typically associated with subsystems of the universe: the entropy of the universe as a whole is a very controversial matter. Moreover, thermodynamics is a phenomenological theory. Geometrical properties of space-time provide a more fundamental and less controversial way of defining an arrow of time for the universe as a whole. We will call the arrow defined only on the basis of the geometrical properties of space-time, independently of any entropic considerations, the "cosmological arrow of time". In this paper we will argue that: (i) it is possible to define a cosmological arrow of time for the universe as a whole, if certain conditions are satisfied, and (ii) the standard models of contemporary cosmology satisfy these conditions. (shrink)

Conventional particle theories such as the Standard Model have a number of freely adjustable coupling constants and mass parameters, depending on the symmetry algebra of the local gauge group and the representations chosen for the spinor and scalar fields. There seems to be no physical principle to determine these parameters as long as they stay within certain domains dictated by the renormalization group. Here however, reasons are given to demand that, when gravity is coupled to the system, local (...) conformal invariance should be a spontaneously broken exact symmetry. The argument has to do with the requirement that black holes obey a complementarity principle relating ingoing observers to outside observers, or equivalently, initial states to final states. This condition fixes all parameters, including masses and the cosmological constant. We suspect that only examples can be found where these are all of order one in Planck units, but the values depend on the algebra chosen. This paper combines findings reported in two previous preprints (G. ’t Hooft in arXiv:1009.0669 [gr-qc], 2010; arXiv:1011.0061 [gr-qc], 2010) and puts these in a clearer perspective by shifting the emphasis towards the implications for particle models. (shrink)

We argue that the Standard Model in the Higgs phase does not suffer from a “hierarchy problem” and that similarly the “cosmological constant problem” resolves itself if we understand the SM as a low energy effective theory emerging from a cutoff-medium at the Planck scale. We actually take serious Veltman’s “The Infrared–Ultraviolet Connection” addressing the issue of quadratic divergences and the related huge radiative correction predicted by the SM in the relationship between the bare and the renormalized (...) theory, usually called “the hierarchy problem” and claimed that this has to be cured. We discuss these issues under the condition of a stable Higgs vacuum, which allows extending the SM up to the Planck cutoff. The bare Higgs boson mass then changes sign below the Planck scale, such that the SM in the early universe is in the symmetric phase. The cutoff enhanced Higgs mass term as well as the quartically enhanced cosmological constant term provide a large positive dark energy that triggers the inflation of the early universe. Reheating follows via the decays of the four unstable heavy Higgs particles, predominantly into top–antitop pairs, which at this stage are massless. Preheating is suppressed in SM inflation since in the symmetric phase bosonic decay channels are absent at tree level. The coefficients of the shift between bare and renormalized Higgs mass as well as of the shift between bare and renormalized vacuum energy density exhibit close-by zeros at about \ and \, respectively. The zero of the Higgs mass counter term triggers the electroweak phase transition, from the low energy Higgs phase and to the symmetric phase above the transition point. Since inflation tunes the total energy density to take the critical value of a flat universe and all contributing components are positive, it is obvious that the cosmological constant today is naturally a substantial fraction of the total critical density. Thus taking cutoff enhanced corrections seriously the Higgs system provides besides the masses of particles in the Higgs phase also dark energy, inflation and reheating in the early universe. The main unsolved problem in our context remains the origin of dark matter. Higgs inflation is possible and likely even unavoidable provided new physics does not disturb the known relevant SM properties substantially. The scenario highly favors to understand the SM and its main properties as a natural structure emerging at long distance. This in particular concerns the SM symmetry patterns and their consequences. (shrink)

We review the observational foundations of the ΛCDMΛCDM model, considered by most cosmologists as the standard model of cosmology. The Cosmological Principle, a key assumption of the model is shown to be verified with increasing accuracy. The fact that the Universe seems to have expanded from a hot and dense past is supported by many independent probes . The explosion of detailed observations in the last few decades has allowed for precise measurements of the (...) class='Hi'>cosmological parameters within Friedman–Lemaître–Robertson–Walker cosmologies leading to the ΛCDMΛCDM model: an apparently flat Universe, dominated by a cosmological constant, whose matter component is dominantly dark. We describe and discuss the various observational probes that led to this conclusion and conclude that the ΛCDMΛCDM model, although leaving a number of open questions concerning the deep nature of the constituents of the Universe, provides the best theoretical framework to explain the observations. (shrink)

It is taken for granted that the explanation of the Universe’s space-time dimension belongs to the host of the arguments that exhibit the superiority of modern (inflationary) cosmology over the standard model. In the present paper some doubts are expressed . They are based upon the fact superstring theory is too formal to represent genuine unification of general relativity and quantum field theory. Neveretheless, the fact cannot exclude the opportunity that in future the superstring theory can become more (...) physical. Hence this paper does not aim to query neither string cosmology, nor superstring theory; it asks for “tolerance in the matters cosmological”. It advices the researchers not to dwell on the common way of unification and to take into consideration the other ways as well. (shrink)

The subject matter of the article is a standard cosmological model of the Universe. Contemporary opinion regarding origin, structure, and evolution of the Universe is of great interest. The answer to the question of the Universe origin is given by the Big Bang Theory. Is it possible to be sure in this theory correctness, which persuading of the Universe origination from the singularity fluctuation, when the World had appeared from nowhere, that is from abstract nothingness, further accelerated (...) expansion of the Universe following the Big Bang, and its development up to present with inexplicable source of energy for that. However, in the extreme end of the meta-universe the speed of stellar formations runaway is about the light velocity. Further, there is a new problem, the finiteness of the Universe. There are two counter-opinions, if the expanding Universe is finite or infinite. A very important question arises here, the question regarding isolatedness of the Universe as a system. The problem of the Universe heat death is closely connected with it. For this reason it is the time to discuss the Universe entropy. There is a short description of notions and problems with reference to this branch of knowledge, as well as of Doppler and Ritz effects alongside with Habble Law. The authors’ detailed interpretation of an entropy is also suggested. The analysis of the existing model is followed by the idea of the authors about the Universe organization. The style of the article is popular-science. In the first part of the article the existing concept of the Expanding Universe Theory and the dynamical Friedmann-Lemaitre models are described; it deals with the existing concept of the Big Bang Theory as well as the dark energy and the dark matter notions. In the second part the author gives detailed interpretation of an entropy. In the last part the problem of theoretical basis and fact nonconformity within the Expanding Universe Model Theory and the authors’ idea about the Universe organization are considered. (shrink)

Studying astroparticle physics sheds new light on scientific explanation and on the ways in which cosmology is empirically underdetermined or not. Astroparticle physics extends the empirical domain of cosmology from purely astronomical data to “multi-messenger astrophysics”, i.e., measurements of all kinds of cosmic rays including very high energetic gamma rays, neutrinos, and charged particles. My paper investigates the ways in which these measurements contribute to cosmology and compares them with philosophical views about scientific explanation, the relation between theory and data, (...) and scientific realism. The “standard models” of cosmology and particle physics lack of unified foundations. Both are “piecemeal physics” in Cartwright's sense, but contrary to her metaphysics of a “dappled world” the work in both fields of research aims at unification. Cosmology proceeds “top-down”, from models to data and from large scale to small-scale structures of the universe. Astroparticle physics proceeds “bottom-up”, from data taking to models and from subatomic particles to large-scale structures of the universe. In order to reconstruct the causal stories of cosmic rays and the nature of their sources, several pragmatic unifying strategies are employed. Standard views about scientific explanation and scientific realism do not cope with these “bottom-up” strategies and the way in which they contribute to cosmology. In addition it has to be noted that the shift to “multi-messenger astrophysics” transforms the relation between cosmological theory and astrophysical data in a mutually holistic way. (shrink)

No other scientist may have had a greater impact on modern cosmology than the Belgian physicist, astronomer and priest Georges Lemaître. In 1927 he predicted the expansion of the universe on the basis of the cosmological field equations; and four years later he proposed what he called the primeval-atom hypothesis, the first version of the later big bang universe. In all his work on cosmology the cosmological constant Λ played a significant role. A recognized expert in the theory (...) of general relativity, Lemaître also contributed significantly to the theoretical clarification of local and global singularity problems. Still, when he died in 1968, at a time when the standard big bang model celebrated its first victories, he was largely forgotten or recalled only as a somewhat shadowy figure of the past. This essay reviews in a historical context the scientific work of Lemaître with particular attention to his seminal contributions in the decade between 1925 and 1934. (shrink)

The Big Bang singularity in standard model cosmology suggests a program of study in ‘early universe’ quantum gravity phenomenology. Inflation is usually thought to undermine this program’s prospects by means of a dynamical diluting argument, but such a view has recently been disputed within inflationary cosmology, in the form of a ‘trans-Planckian censorship’ conjecture. Meanwhile, trans-Planckian censorship has been used outside of inflationary cosmology to motivate alternative early universe scenarios that are tightly linked to ongoing theorizing in quantum (...) gravity. Against the resulting trend toward early universe quantum gravity phenomenology within and without inflation, Ijjas and Steindhardt suggest a further alternative: a ‘generalized cosmic censorship’ principle. I contrast the generalized cosmic censorship principle with the logic of its namesake, the cosmic censorship conjectures. I also remark on foundational concerns in the effective field theory approach to cosmology beyond the standard model, which would be based on that principle. (shrink)

There is a paradox in the standard model of cosmology. How can matter in the early universe have been in thermal equilibrium, indicating maximum entropy, but the initial state also have been low entropy (the “past hypothesis"), so as to underpin the second law of thermodynamics? The problem has been highly contested, with the only consensus being that gravity plays a role in the story, but with the exact mechanism undecided. In this paper, we construct a well-defined mechanical (...) model to study this paradox. We show how it reproduces the salient features of standard big-bang cosmology with surprising success, and we use it to produce novel results on the statistical mechanics of a gas in an expanding universe. We conclude with a discussion of potential uses of the model, including the explicit computation of the time-dependent coarse-grained entropies needed to investigate the past hypothesis. (shrink)

Understanding of principles forms the basis of mastering Greek Philosophy. This article focuses on the idea of Principled Knowledge. Plato, too, seems to hold that grasping a body of knowledge requires a grasp of its principles. One example is the Republic where Socrates explains the image of the line. He has divided the line into two sections, the intelligible and the perceptible. The Timaeus, like the Republic, emphasizes the need for us to grasp the proper principle of our disciplines of (...) study. The major principles enlisted in the Timaeus are as follows: Being is that which is graspable by intelligence with an account ; becoming is that which is graspable by opinion with unreasoning perception. Everything that comes into being has a cause. When a craftsman uses an eternal model, his product is necessarily fine ; if he uses a generated one, the product is not fine. The article further elaborates upon the standards of the cosmological argument and the most proper principle of coming into being which Socrates argues is the prelude. (shrink)

I try to revive, and possibly reconcile, a debate started a few years ago, about the relative roles of a bare cosmological constant and of a vacuum energy, by taking the attitude to try to get the most from the physics now available as established. I notice that the bare cosmological constant of the Einstein equations, which is there ever since GR emerged, is actually constrained (if not measured) indirectly combining the effective cosmological constant observed now, as (...) given by ΛCDM Precision Cosmology, with the cumulative vacuum contribution of the particles of the Standard Model, SM. This comes out when the vacuum energy is regularized, as given by many Authors, still within well established Quantum Field Theory, QFT, but without violating Lorentz invariance. The fine tuning, implied by the compensation to a small positive value of the two large contributions, could be seen as offered by Nature, which provides one more fundamental constant, the bare Lambda. The possibility is then discussed of constraining (measuring) directly such a bare cosmological constant by the features of primordial gravitational wave signals coming from epoch’s precedent to the creation of particles. I comment on possibilities that would be lethal, that is if the vacuum does not gravitate. This last issue is often raised, and I discuss the current situation about. Finally a hint is briefly discussed for a possible “bare Lambda inflation” process. (shrink)

The Robertson–Walker (RW) metric allows us to apply general relativity to model the behavior of the Universe as a whole (i.e., cosmology). We can properly interpret various cosmological observations, like the cosmological redshift, the Hubble parameter, geometrical distances, and so on, if we identify fundamental observers with individual galaxies. That is to say that the interpretation of observations of modern cosmology relies on the RW metric. The RW model satisfies the cosmological principle in which the (...) 3-space always remains isotropic and homogeneous. One can derive the cosmological redshift relation from this condition. We show that it is still possible for us to obtain consistent results in a specific time-varying speed-of-light model without spoiling the success of the standard model. The validity of this model needs to be determined by observations. (shrink)

A case study of quantum mechanics is investigated in the framework of the philosophical opposition “mathematical model – reality”. All classical science obeys the postulate about the fundamental difference of model and reality, and thus distinguishing epistemology from ontology fundamentally. The theorems about the absence of hidden variables in quantum mechanics imply for it to be “complete” (versus Einstein’s opinion). That consistent completeness (unlike arithmetic to set theory in the foundations of mathematics in Gödel’s opinion) can be interpreted (...) furthermore as the coincidence of model and reality. The paper discusses the option and fact of that coincidence it its base: the fundamental postulate formulated by Niels Bohr about what quantum mechanics studies (unlike all classical science). Quantum mechanics involves and develops further both identification and disjunctive distinction of the global space of the apparatus and the local space of the investigated quantum entity as complementary to each other. This results into the analogical complementarity of model and reality in quantum mechanics. The apparatus turns out to be both absolutely “transparent” and identically coinciding simultaneously with the reflected quantum reality. Thus, the coincidence of model and reality is postulated as necessary condition for cognition in quantum mechanics by Bohr’s postulate and further, embodied in its formalism of the separable complex Hilbert space, in turn, implying the theorems of the absence of hidden variables (or the equivalent to them “conservation of energy conservation” in quantum mechanics). What the apparatus and measured entity exchange cannot be energy (for the different exponents of energy), but quantum information (as a certain, unambiguously determined wave function) therefore a generalized law of conservation, from which the conservation of energy conservation is a corollary. Particularly, the local and global space (rigorously justified in the Standard model) share the complementarity isomorphic to that of model and reality in the foundation of quantum mechanics. On that background, one can think of the troubles of “quantum gravity” as fundamental, direct corollaries from the postulates of quantum mechanics. Gravity can be defined only as a relation or by a pair of non-orthogonal separable complex Hilbert space attachable whether to two “parts” or to a whole and its parts. On the contrary, all the three fundamental interactions in the Standard model are “flat” and only “properties”: they need only a single separable complex Hilbert space to be defined. (shrink)

The \CDM cosmological model is remarkable: with just six parameters it describes the evolution of the Universe from a very early time when all structures were quantum fluctuations on subatomic scales to the present, and it is consistent with a wealth of high-precision data, both laboratory measurements and astronomical observations. However, the foundation of \CDM involves physics beyond the standard model of particle physics: particle dark matter, dark energy and cosmic inflation. Until this ‘new physics’ is (...) clarified, \CDM is at best incomplete and at worst a phenomenological construct that accommodates the data. I discuss the path forward, which involves both discovery and disruption, some grand challenges and finally the limits of scientific cosmology. (shrink)

If we live on the weak brane with zero effective cosmological constant in a warped 5D bulk spacetime, gravitational waves and brane fluctuations can be generated by a part of the 5D Weyl tensor and carries information of the gravitational field outside the brane. We consider on a cylindrical symmetric warped FLRW background a U self-gravitating scalar field coupled to a gauge field without bulk matter. It turns out that brane fluctuations can be formed dynamically, due to the modified (...) energy–momentum tensor components of the scalar-gauge field. As a result, we find that the late-time behavior could significantly deviate from the standard evolution of the universe. The effect is triggered by the time-dependent warpfactor with two branches of the form \}\) constants) and the modified brane equations comparable with a dark energy effect. This is a brane-world mechanism, not present in standard 4D FLRW, where the large disturbances are rapidly damped as the expansion proceed. Because gravity can propagate in the bulk, the cosmic string can build up a huge angle deficit by the warpfactor and can induce massive KK-modes felt on the brane. Disturbances in the spatial components of the stress-energy tensor cause cylindrical symmetric waves, amplified due to the presence of the bulk space and warpfactor. They could survive the natural damping due to the expansion of the universe. It turns out that one of the metric components becomes singular at the moment the warp factor develops an extremum. This behavior could have influence on the possibility of a transition from acceleration to deceleration or vice versa. (shrink)