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Reference [1] presents evidence for magnetic field screening and “subtle” evidence for magnetic field expulsion in hydrides under high pressure, which is argued to support the claim that these materials are high temperature superconductors. We point out here that data presented in different figures of Ref. [1] are inconsistent (i) with one another, (ii) with other work by the same authors on the same samples [2, 3], and (iii) with the expected behavior of standard superconductors. This suggests that these magnetic phenomena reported for these materials are not associated with superconductivity, undermining the claim that these materials are high temperature superconductors.

The mathematical finding presented here undermines confidence in the claim that any of the experimental evidence reported in the published paper reflects the properties of real physical samples of CSH.

It has recently been reported that hydrogen-rich materials under high-pressure trap magnetic flux, a tell-tale signature of superconductivity (Minkov et al., Trapped magnetic flux in hydrogen-rich high-temperature superconductors, Ref. 1). Here, we point out that under the protocol used in these experiments the measured results indicate that the materials don’t trap magnetic flux. Instead, the measured results either are experimental artifacts or originate in magnetic properties of the sample or its environment unrelated to superconductivity. Together with other experimental evidence analyzed earlier, this clearly indicates that these materials are not superconductors.

During the past 9 years, extensive experimental evidence has been presented that is claimed to demonstrate that hydrogen-rich materials under high pressure are high temperature superconductors, as predicted by conventional BCS-electron-phonon theory. Foremost among the experimental evidence are electrical resistance measurements, claimed to show that the resistivity of these materials falls well below that of the best normal metals within experimental accuracy. Here I propose an alternative explanation for the vanishingly small resistance reported for these materials that does not involve superconductivity.

A magnetic field H is expelled from the interior of a metal becoming superconducting. Everybody thinks the phenomenon is perfectly well understood, particularly scientists with the highest H-index think that. I don't. I will explain why I believe that without Holes, conceptualized by Heisenberg in 1931 fifty years after Hall had first detected them in some metals, neither magnetic field expulsion nor anything else about superconductivity can be understood. I have been a Heretic in the field of superconductivity for over 30 years, and believe that Hans' little story about the emperor perfectly captures the essence of the situation. Here is (a highly condensed version of) the wHole story.

Recently, the discovery of room-temperature superconductivity was announced for a carbonaceous sulfur hydride (CSH) under high pressure [E. Snider et al., Nature 586, 373 (2020)]. The evidence for superconductivity was based on resistance and magnetic susceptibility measurements. In the figures showing the susceptibility it was stated that “the background signal, determined from a nonsuperconducting CSH sample at 108 GPa, has been subtracted from the data”. From a thorough data analysis we show that the data are incompatible with the notion that the susceptibility data are obtained from the “measured voltage” using a background correction. On the other hand, the data are compatible with the reverse procedure, namely the “measured voltage” is obtained by adding a “background signal” containing noise to what was reported as the background-corrected susceptibility. For all six of the reported pressures our analysis leads to the conclusion that: (i) the reported background-corrected susceptibility data are pathological, (ii) they were not obtained by the method described in this paper nor by any one of the alternative three methods that were subsequently provided by the authors and (iii) the “measured voltage” data are not raw data.

It is shown that the reported "Measured Voltage" detecting a superconducting transition at room temperature in CSH under 160 GPa pressure [1] was in fact not "measured" but instead calculated starting from a "User Defined Background".

By a recent count, there are 32 different classes of superconducting materials, only 12 of which are generally believed to be "conventional", i.e. described by the conventional BCS-electron-phonon theory of superconductivity. In this perspective I critically examine the successes and failures of the conventional theory to describe conventional superconductors, and discuss what is understood and not understood about hydrogen-rich materials claimed to be high temperature conventional superconductors under high pressure. I argue that the current state of affairs calls for dethroning the conventional theory of its privileged status and seriously explore the alternative possibility that a single theory, different from the conventional theory, may describe superconductivity of all materials in a unified way.

Prozorov and Bud’ko (On the analysis of the tin-inside-H3S Mössbauer experiment, 2022) recently analyzed the nuclear resonant scattering (NRS) experiment that reportedly demonstrated magnetic field exclusion in sulfur hydride under pressure (Science 351, 1303, 2016), and concluded that the experiment is consistent with the expected behavior of a type II superconductor. Here I point out that their analysis shows that the reported NRS measurements are incompatible with the recently reported magnetization measurements by Minkov et al. (Nat Commun 13, 3194, 2022), indicating that at minimum one of these two experiments does not support the claim that sulfur hydride under pressure is superconducting.

The Meissner effect, magnetic field expulsion, is a hallmark of superconductivity. Associated with it, superconductors exclude applied magnetic fields. Recently Minkov et al. presented experimental results reportedly showing "definitive evidence of the Meissner effect" in sulfur hydride and lanthanum hydride under high pressure [1], and more recently Eremets et al. argued that "the arguments against superconductivity (in hydrides) can be either refuted or explained" [2]. Instead, we show here that the evidence presented in those papers does not support the case for superconductivity in these materials. Together with experimental evidence discussed in earlier papers, we argue that this strongly suggests that hydrides under pressure are not high-temperature superconductors., 10 pages 7 figures

It has been suggested that the measured magnetic properties of hydrides under pressure claimed to be high temperature superconductors indicate that the materials are granular superconductors. Such materials will show reduced or no magnetic field expulsion under field cooling, and will trap magnetic fields when the external magnetic field is removed. They will also exhibit hysteretic behavior in magnetoresistance and other transport properties. Here we point out that hysteresis in transport properties has never been reported for hydrides under pressure. Its presence, with the expected features, would indicate that the materials trap magnetic flux, hence that they can sustain persistent currents without dissipation, something that all superconductors can do. Conversely, its absence would indicate that these materials are not superconductors.

Room temperature superconductivity has recently been reported for a carbonaceous sulfur hydride (CSH) under high pressure by Snider et al [1]. The paper reports sharp drops in magnetic susceptibility as a function of temperature for five different pressures, that are interpreted as signaling a superconducting transition. Here I question the validity and faithfulness of the magnetic susceptibility data presented in the paper by comparison with the measured raw data reported by two of the authors of ref. [2]. This invalidates the assertion of the paper [1] that the susceptibility measurements support the case for superconductivity in this compound.

Capitani and coworkers [1] reported that infrared optical reflectance measurements provided evidence for a superconducting transition in sulfur hydride [2] under 150 GPa pressure, and that the transition is driven by the electron-phonon interaction. Here we argue that the measured data did not provide evidence that the system undergoes a transition to a superconducting state, nor do the data support any role of phonons in driving a transition. Rather, the data are consistent with the system remaining in the normal state down to temperature 50K, the lowest temperature measured in the experiment. This calls into further question [3,4] the generally accepted view [5] that sulfur hydride under pressure is a high temperature superconductor., 3 pages, 3 figures. Nature Physics 2022

Ted Geballe has contributed enormously to the knowledge of superconducting materials during an illustrious scientific career spanning seven decades, encompassing groundbreaking discoveries and studies of both so-called conventional and unconventional superconductors. On the year of his 100th birthday, I would like to argue that all superconducting materials that Ted investigated, as well as those he did not, have one thing in common that is not generally recognized: hole carriers. This includes PbTe doped with Tl, for which Ted has proposed that superconductivity is driven by negative-U pairing. I will discuss why hole carriers are necessary for a material to be a superconductor, and the implications of this for the understanding of the fundamental physics of superconductivity.

By a recent count, there are 32 different classes of superconducting materials [Physica C: Special Issue, “Superconducting materials: conventional, unconventional and undetermined. Dedicated to Theodore H. Geballe on the year of his 95th birthday,” edited by J. E. Hirsch, M. B. Maple, F. Marsiglio (▪, 2015), Vol. 514, pp. 1–444.], only 12 of which are generally believed to be “conventional,” i.e., described by the conventional BCS-electron–phonon theory of superconductivity. In this Perspective, I critically examine the successes and failures of the conventional theory to describe conventional superconductors and discuss what is understood and not understood about hydrogen-rich materials claimed to be high temperature conventional superconductors under high pressure. I argue that the materials' evidence accumulated to date calls for dethroning the conventional theory of its privileged status and seriously explore the alternative possibility that a single theory, different from the conventional theory, may describe superconductivity of all materials in a unified way.

High-temperature conventional superconductivity in hydrogen-rich materials under high pressure has been reportedly found in twelve different compounds in recent years. However, the experimental evidence on which these claims are based has recently been called into question. Here we discuss the measurement of trapped magnetic flux, that should establish definitively that these materials are indeed high-temperature superconductors. Its absence should confirm claims to the contrary., Comment: minor changes; to be published in Physica C

In this comment by Leydesdorff, Bornmann and Opthof (Scientometrics https://doi.org/10.1007/s11192-019-03004-3 , 2019) the authors criticize the recently proposed $$h_{\alpha }$$ index (Scientometrics https://doi.org/10.1007/s11192-018-2994-1 , 2018) on the basis that “ $$h_{\alpha }$$ inherits most of the disadvantages of the h-index”, that it “can be extremely unstable”, and that “The empirical attribution of credit among co-authors is not captured by abstract models such as h, $$\bar{h}$$ , or $$h_{\alpha }$$ ”. I refute their arguments and present further evidence that $$h_{\alpha }$$ is a useful and essential complement to the h-index.

The $$\alpha$$ person is the dominant person in a group. We define the $$\alpha$$ -author of a paper as the author of the paper with the highest h-index among all the coauthors, and an $$\alpha$$ -paper of a scientist as a paper authored or coauthored by the scientist where he/she is the $$\alpha$$ -author. For most but not all papers in the literature there is only one $$\alpha$$ -author. We define the $$h_\alpha$$ index of a scientist as the number of papers in the h-core of the scientist (i.e. the set of papers that contribute to the h-index of the scientist) where this scientist is the $$\alpha$$ -author. We also define the $$h'_\alpha$$ index of a scientist as the number of $$\alpha$$ -papers of this scientist that have $$\ge$$ $$h'_\alpha$$ citations. $$h_\alpha$$ and $$h'_\alpha$$ contain similar information, while $$h'_\alpha$$ is conceptually more appealing it is harder to obtain from existing databases, hence of less current practical interest. We propose that the $$h_\alpha$$ and/or $$h'_\alpha$$ indices, or other variants discussed in the paper, are useful complements to the h-index of a scientist to quantify his/her scientific achievement, that rectify an inherent drawback of the h-index, its inability to distinguish between authors with different coauthorships patterns. A high h index in conjunction with a high $$h_\alpha /h$$ ratio is a hallmark of scientific leadership.

We find that the bulk moment of inertia per unit volume of a metal becoming superconducting increases by the amount $m_e/(\pi r_c)$, with $m_e$ the bare electron mass and $r_c=e^2/m_e c^2$ the classical electron radius. This is because superfluid electrons acquire an intrinsic moment of inertia $m_e (2\lambda_L)^2$, with $\lambda_L$ the London penetration depth. As a consequence, we predict that when a rotating long cylinder becomes superconducting its angular velocity does not change, contrary to the prediction of conventional BCS-London theory that it will rotate faster. We explain the dynamics of magnetic field generation when a rotating normal metal becomes superconducting., Comment: An error in Fig. 2 was corrected

Under the spell of BCS-electron–phonon theory [M. Tinkham, Introduction to Superconductivity, 2nd ed. (McGraw Hill, New York, 1996)], during the last 6 years experimentalists have purportedly discovered a plethora of high temperature conventional superconductors among pressurized hydrides [Pickard et al., Ann. Rev. Condens. Matter Phys. 11, 57 (2020) and R. F. Service, Science 373, 954 (2021)], and theorists have been busy predicting and explaining those findings [Lv et al., Matter Radiat. Extremes 5, 068101 (2020); Flores-Livas et al., Phys. Rep. 856, 1 (2020); and Boeri et al., J. Phys. Condens. Matter. (to be published)]. The alternative theory of hole superconductivity (see https://jorge.physics.ucsd.edu/hole.html for a list of references) predicts instead that no superconductivity can exist in these materials. In this Tutorial, I will first argue that, unclouded by the prejudice of BCS’s validity, the existing experimental evidence for superconductivity in pressurized hydrides does not withstand scrutiny. Once it is established that superconductivity in pressurized hydrides is a myth and not a reality, the claim to validity of BCS-electron–phonon theory as a descriptor of superconductivity of real materials will be forever shattered, and an alternative theory will become imperative. I will explain the fundamentals of the theory of hole superconductivity, developed over the past 32 years [see https://jorge.physics.ucsd.edu/hole.html and J. E. Hirsch, Phys. Lett. A 134, 451 (1989)], and why it is compelling. Crucially, it explains the Meissner effect, that I argue the conventional theory does not. It applies to all superconducting materials and provides guidelines in the search for high temperature superconductors that are very different from those provided by BCS-electron–phonon theory. Light elements are predicted to be irrelevant to warm superconductivity because according to this theory the electron–phonon interaction plays no role in superconductivity.

An electric current generates a magnetic field, and magnetic fields cannot exist in the interior of type I superconductors. As a consequence of these two facts, electric currents can only flow near the surface of a type I superconducting wire so that the self-field vanishes in the interior. Here we examine how an electric current flowing through the entire cross-section of a normal conducting wire becomes a surface current when it enters a superconducting portion of the wire. This geometry provides insight into the dynamics of magnetic flux expulsion that is not apparent in the Meissner effect involving expulsion of an externally applied magnetic field. It provides clear evidence that the motion of magnetic field lines in superconductors is intimately tied to the motion of charge carriers, as occurs in classical plasmas (Alfven's theorem) and as proposed in the theory of hole superconductivity [1] , in contradiction with the conventional London-BCS theory of superconductivity.

Over the past six years, superconductivity at high temperatures has been reported in a variety of hydrogen-rich compounds under high pressure. That high-temperature superconductivity should exist in these materials is expected according to the conventional theory of superconductivity, as shown by detailed calculations. However here we argue that experimental observations rule out conventional superconductivity in these materials. Our results indicate that either these materials are unconventional superconductors of a novel kind, which we term `nonstandard superconductors', or alternatively that they are not superconductors. If the former, we point out that the critical current in these materials should be five orders of magnitude larger than in standard superconductors, potentially opening up the way to important technological applications. If the latter, which we believe is more likely, we suggest that the signals interpreted as superconductivity are either experimental artifacts or they signal other interesting physics but not superconductivity., Comment: 11 pages, 13 figures

Alfven’s theorem states that in a perfectly conducting fluid magnetic field lines move with the fluid without dissipation. When a metal becomes superconducting in the presence of a magnetic field, magnetic field lines move from the interior to the surface (Meissner effect) in a reversible way. This indicates that a perfectly conducting fluid is flowing outward. I point this out and show that this fluid carries neither charge nor mass, but carries effective mass. This implies that the effective mass of carriers is lowered when a system goes from the normal to the superconducting state, which agrees with the prediction of the unconventional theory of hole superconductivity and with optical experiments in some superconducting materials. The 60-year old conventional understanding of the Meissner effect ignores Alfven’s theorem and for that reason I argue that it does not provide a valid understanding of real superconductors.

Alfven waves are transverse magneto-hydrodynamic waves resulting from motion of a conducting fluid in direction perpendicular to an applied magnetic field, that propagate along the magnetic field direction. I propose that Alfven-like waves can propagate along normal-superconductor phase boundaries in the presence of a magnetic field. This requires charge flow and backflow across the normal-superconductor phase boundary when the boundary moves, which is predicted by the theory of hole superconductivity but not by the conventional theory of superconductivity. The magnetic field and the domain wall energy provide elasticity, and the normal charge carriers’ effective mass provides inertia. It is essential that the normal state charge carriers are holes. I propose an experimental search for Alfven-like waves in superconductors.

Since their experimental discovery in 1989, the electron-doped cuprate superconductors have presented both a major challenge and a major opportunity. The major challenge has been to determine whether these materials are fundamentally different from or essentially similar to their hole-doped counterparts; a major opportunity because answering this question would strongly constrain the possible explanations for what is the essential physics that leads to high temperature superconductivity in the cuprates, which is still not agreed upon. Here we argue that experimental results over the past 30 years on electron-doped cuprate materials have provided conclusive answers to these fundamental questions, by establishing that both in hole- and electron-doped cuprates, superconductivity originates in pairing of hole carriers in the same band. We discuss a model to describe this physics that is different from the generally accepted ones, and calculate physical observables that agree with experiment, in particular tunneling characteristics. We argue that our model is simpler, more natural and more compelling than other models. Unlike other models, ours was originally proposed before rather than after many key experiments were performed.

In Nature 586, 373 (2020) [1], Snider et al announced the experimental discovery of room temperature superconductivity in a carbonaceous sulfur hydride under high pressure, hereafter called CSH. The paper reported sharp drops in the measured magnetic susceptibility as a function of temperature for five different pressures, that were claimed to be a superior test signaling a superconducting transition. Here I present several arguments indicating that the susceptibility data published in [1] were probably fraudulent. This calls into question the validity of the entire paper and its claim of detection of room temperature superconductivity. I also describe the roadblocks that I have encountered in reaching this conclusion. A variety of implications of this situation are discussed.

It was recently pointed out that so-called "superhydrides", hydrogen-rich materials that appear to become superconducting at high temperatures and pressures, exhibit physical properties that are different from both conventional and unconventional standard type I and type II superconductors [1,2]. Here we consider magnetic field expulsion in the first material in this class discovered in 2015, sulfur hydride [3]. A nuclear resonant scattering experiment has been interpreted as demonstration that the Meissner effect takes place in this material [4,5]. Here we point out that the observed effect, under the assumption that the system is in thermodynamic equilibrium, implies a Meissner pressure [6] in this material that is {\it much larger} than that of standard superconductors. This suggests that hydride superconductors are qualitatively different from the known standard superconductors {\it if} they are superconductors., 6 pages, 2 figures

It is generally believed that magnetization measurements on sulfur hydride under high pressure performed in 2015 [1] provided “final convincing evidence of superconductivity” [2] in that material, in agreement with theoretical predictions [3] , [4] . Supported by this precedent, drops in resistance that were later observed in several other hydrides under high pressure [ [2] , 5] have been generally accepted as evidence of superconductivity without corroborating evidence from magnetic measurements. In this paper we challenge the original interpretation that the magnetic measurements on sulfur hydride performed in 2015 were evidence of superconductivity. We point out that a large p a r a m a g n e t i c contribution to the magnetic susceptibility was detected below T c and argue that its temperature dependence rules out the possibility that it would be a background signal; instead the temperature dependence indicates that the paramagnetic behavior originated in the sample. We discuss possible explanations for this remarkable behavior and conclude that standard superconductors would not show such behavior. We also survey all the other published data from magnetic measurements on this class of materials and conclude that they do not provide strong evidence for superconductivity. Consequently, we call into question the generally accepted view that conventional superconductivity in hydrogen-rich materials at high temperature and pressure is a reality, and discuss the implications if it is not.

In Phys. Rev. Lett. 102, 197002 (2009) it was reported that the element Eu becomes superconducting in the pressure and temperature range [84-142GPa], [1.8-2.75K]. The claim was largely based on ac susceptibility measurements. Recently reported ac susceptibility measurements on a hydride compound under pressure that appears to become superconducting near room temperature (Nature 586, 373 (2020)) cast serious doubt on the validity of the results for Eu as well as for the hydride. Here I present results that shed new light on the true behaviour of Eu. It is argued that the experiments on Eu have to be repeated to either validate or rule out the claim that it is a superconducting element., Comment: arXiv admin note: This submission has been withdrawn by arXiv administrators due to inflammatory content and unprofessional language

It is generally believed that the laws of thermodynamics govern superconductivity as an equilibrium state of matter, and hence that the normal-superconductor transition in a magnetic field is reversible under ideal conditions. Because eddy currents are generated during the transition as the magnetic flux changes, the transition has to proceed infinitely slowly to generate no entropy. Experiments showed that to a high degree of accuracy no entropy was generated in these transitions. However, in this paper we point out that for the length of times over which these experiments extended, a much higher degree of irreversibility due to decay of eddy currents should have been detected than was actually observed. We also point out that within the conventional theory of superconductivity no explanation exists for why no Joule heat is generated in the superconductor to normal transition when the supercurrent stops. In addition we point out that within the conventional theory of superconductivity no mechanism exists for the transfer of momentum between the supercurrent and the body as a whole, which is necessary to ensure that the transition in the presence of a magnetic field respects momentum conservation. We propose a solution to all these questions based on the alternative theory of hole superconductivity. The theory proposes that in the normal-superconductor transition there is a flow and backflow of charge in direction perpendicular to the phase boundary when the phase boundary moves. We show that this flow and backflow explains the absence of Joule heat generated by Faraday eddy currents, the absence of Joule heat generated in the process of the supercurrent stopping, and the reversible transfer of momentum between the supercurrent and the body, provided the current carriers in the normal state are holes.

The theory of hole superconductivity predicts that in the reversible transition between normal and superconducting phases in the presence of a magnetic field there is charge flow in direction perpendicular to the normal-superconductor phase boundary. In contrast, the conventional BCS-London theory of superconductivity predicts no such charge flow. Here we discuss an experiment to test these predictions.

Joule heating is a non-equilibrium dissipative process that occurs in a normal metal when an electric current flows, in an amount proportional to the metal’s resistance. When it is induced by eddy currents resulting from a change in magnetic flux, it is also proportional to the rate at which the magnetic flux changes. Here we show that in the phase transformation between normal and superconducting states of a metal in a magnetic field, the total amount of Joule heating is determined by the thermodynamic properties of the system and is independent of the resistivity of the normal metal. Under the reasonable assumption that the magnetic field at the phase boundary is given by the thermodynamic critical field, we show that Joule heating occurs only in the normal region of the material, hence no Joule heating occurs in the superconducting region next to the phase boundary where normal current is expected to flow according to the conventional theory of superconductivity. We discuss the significance of this result.

Mutual extinction of light Active particle in a one-dimensional force field Simulating sleep apnea dynamics through random walk model Inconsistency of the conventional theory of superconductivity

A type I superconductor expels a magnetic field from its interior to a surface layer of thickness $\lambda_L$, the London penetration depth. $\lambda_L$ is a function of temperature, becoming smaller as the temperature decreases. Here we analyze the process of cooling (or heating) a type I superconductor in a magnetic field, with the system remaining always in the superconducting state. The conventional theory predicts that Joule heat is generated in this process, the amount of which depends on the rate at which the temperature changes. Assuming the final state of the superconductor is independent of history, as the conventional theory assumes, we show that this process violates the first and second laws of thermodynamics. We conclude that the conventional theory of superconductivity is internally inconsistent. Instead, we suggest that the alternative theory of hole superconductivity may be able to resolve this problem., Comment: Removed referees' comments to comply with arXiv policies

In a process where the temperature of a type I superconductor in a magnetic field changes, the conventional theory of superconductivity predicts that Joule heat is generated and that the final state is independent of the speed of the process. I show that these two predictions cannot be simultaneously reconciled with the laws of thermodynamics. I propose a resolution of this paradox., Comment: Final version. To be published in Europhysics Letters

Superconductivity at temperatures up to 190 K at high pressures has recently been observed in H 2 S and interpreted as conventional BCS-electron–phonon-driven superconductivity (Drozdov et al., 2014). Instead we propose that it is another example of the mechanism of hole superconductivity at work. Within this mechanism high temperature superconductivity arises when holes conduct through negatively charged anions in close proximity. We propose that electron transfer from H to S leads to conduction by holes in a nearly full band arising from direct overlap of S = p orbitals in a planar structure. The superconductivity is non-phononic and is driven by pairing of heavily dressed hole carriers to lower their kinetic energy. Possible explanations for the observed lower critical temperature of D 2 S are discussed. We predict that high temperature superconductivity will also be found in other sulfides under high pressure such as Li 2 S, Na 2 S and K 2 S .

We calculate the superconducting $T_c$ for a system which experiences Rashba spin-orbit interactions. Contrary to the usual case where the electron-electron interaction is assumed to be wave vector-independent, where superconductivity is suppressed by the spin-orbit interaction (except for a small region at low electron or hole densities), we find an enhancement of the superconducting transition temperature when we include a correlated hopping interaction between electrons. This interaction originates in the expansion of atomic orbitals due to electron-electron repulsion and gives rise to superconductivity only at high electron (low hole) densities. When superconductivity results from this interaction it is enhanced by spin-orbit coupling, in spite of a suppression of the density of states. The degree of electron-hole asymmetry about the Fermi surface is also enhanced., 8 pages, 8 figures

When a magnetic field is applied to a ferromagnetic body it starts to spin (Einstein-de Haas effect). This demonstrates the intimate connection between the electron's magnetic moment $\mu_B=e\hbar/2m_ec$, associated with its spin angular momentum $S=\hbar/2$, and ferromagnetism. When a magnetic field is applied to a superconducting body it also starts to spin (gyromagnetic effect), and when a normal metal in a magnetic field becomes superconducting and expels the magnetic field (Meissner effect) the body also starts to spin. Yet according to the conventional theory of superconductivity the electron's spin only role is to label states, and the electron's magnetic moment plays no role in superconductivity. Instead, within the unconventional theory of hole superconductivity, the electron's spin and associated magnetic moment play a fundamental role in superconductivity. Just like in ferromagnets the magnetization of superconductors is predicted to result from an aggregation of magnetic moments with angular momenta $\hbar/2$. This gives rise to a "Spin Meissner effect", the existence of a spin current in the ground state of superconductors. The theory explains how a superconducting body starts spinning when it expels magnetic fields, it provides a dynamical explanation for the Meissner effect, and it explains how supercurrents stop without dissipation, all of which we argue the conventional theory fails to explain. Essential elements of the theory of hole superconductivity are that superconductivity is driven by lowering of kinetic energy, which we have also proposed is true for ferromagnets], that the normal state charge carriers in superconducting materials are holes, and that the spin-orbit interaction plays a key role in superconductivity. The theory is proposed to apply to all superconductors., Comment: this paper was written before the latest progress reported in arXiv:1808.02857

I discuss the process of magnetic field generation in rotating superconductors in simply connected and multiply connected geometries. In cooling a normal metal into the superconducting state while it is rotating, electrons slow down or speed up depending on the geometry and their location in the sample, apparently defying inertia. I argue that the conventional theory of superconductivity does not explain these processes. Instead, the theory of hole superconductivity does. Its predictions agree with experimental observations of Hendricks, King and Rohrschach for solid and hollow cylinders., Comment: A section was added (IX)