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  • 51.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    “Quantum machine” to solve quantum “measurement problem”?2014Report (Refereed)
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  • 52.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    "Quantum machine" to solve quantum "measurement problem"?2015In: Advanced Studies in Theoretical Physics, ISSN 1313-1311, E-ISSN 1314-7609, Vol. 9, no 5, p. 233-236Article in journal (Refereed)
    Abstract [en]

    Recently a study of the rst superposed mechanical quantum object(\machine") visible to the naked eye was published [1]. However, as weshow, it turns out that if the object would actually be observed, i.e.would interact with an optical photon, the quantum behavior shouldvanish. This, the actual observation, has long been suspected in manyinterpretations of quantum mechanics to be what makes the transitionquantum ! classical, but so far it has not been available for direct ex-perimental study in a mechanical system. We show how any interaction,even a purely quantum one, of sucient strength can constitute a physi-cal \measurement" - essentially the emergence of an eectively classicalobject - active observation thus being a sucient but not necessary cri-terion. So it seems we have in this case of the \quantum machine" aunique possibility to study, and possibly solve, the long-standing \mea-surement problem" of quantum mechanics.

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  • 53.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Reality or Locality? Proposed Test to Decide How Nature Breaks Bell's Inequality2012In: Physics Research International, ISSN 2090-2220, E-ISSN 2090-2239, Vol. 2012, article id 352543Article in journal (Refereed)
    Abstract [en]

    Bell's theorem, and its experimental tests, has shown that the two premises for Bell's inequalitylocality and objective realitycannot both hold in nature, as Bell's inequality is broken. A simple test is proposed, which for the first time may decide which alternative nature actually prefers on the fundamental, quantum level. If each microscopic event is truly random (e.g., as assumed in orthodox quantum mechanics) objective reality is not valid whereas if each event is described by an unknown but deterministic mechanism (hidden variables) locality is not valid. This may be analyzed and decided by the well-known reconstruction method of Ruelle and Takens; in the former case no structure should be discerned, in the latter a reconstructed structure should be visible. This could in principle be tested by comparing individual hits in a double-slit experiment, but in practice a single fluorescent atom, and its (seemingly random) temporal switching between active/inactive states would possibly be better/more practical, easier to set up, observe, and analyze. However, only imagination limits the list of possible experimental setups.

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  • 54.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Relativitetsteorin på 15 minuter: allt är inte alls relativt2007In: Allt om Vetenskap, ISSN 1652-3318, no 10, p. 106-109Article in journal (Other (popular science, discussion, etc.))
  • 55.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Reply to comment on 'A Simple explanation of the nonappearance of physical gluons and quarks'2003In: Canadian journal of physics (Print), ISSN 0008-4204, E-ISSN 1208-6045, Vol. 81, p. 893-894Article in journal (Other academic)
    Abstract [en]

    This is the reply to a comment by Andreas Aste on a previous article of mine in Can.J.Phys. The counter-arguments used by Aste utilize a mathematical limit without physical meaning. We still contend that in QCD, the particles ``gluons'' and ``quarks'' are merely artifacts of an approximation method (the perturbative expansion) and are simply absent in the exact theory.

  • 56.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Strängteorin på 15 minuter - Teorin om allt... eller inget?2008In: Allt om Vetenskap, ISSN 1652-3318, no 2, p. 104-108Article in journal (Other (popular science, discussion, etc.))
  • 57.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Svarta hål på 15 minuter - Fysikens slut?2008In: Allt om Vetenskap, ISSN 1652-3318, no 5, p. 104-108Article in journal (Other (popular science, discussion, etc.))
  • 58.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The 10 Biggest Unsolved Problems in Physics2015Report (Refereed)
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  • 59.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The 10 Biggest Unsolved Problems in Physics2015In: International Journal of Modern Physics and Applications, ISSN 2381-6945, Vol. 1, no 1, p. 12-16Article in journal (Refereed)
    Abstract [en]

    In 1900, the British physicist Lord Kelvin declared: “There is nothing new to discover in physics. All that remains is to more accurately measure its quantities.” In the same year quantum physics was born and three decades later it, and Einstein’s theory of relativity, had completely revolutionized and transformed physics. Today, hardly anyone would dare say that our knowledge of the universe, and everything in it, is almost complete. On the contrary, every new discovery appears to open a Pandora’s Box of larger and deeper issues. I have selected some of today’s biggest unsolved riddles in physics. Just like Moses, I stop arbitrarily at 10. Here follow these “Ten Com...plications” with a brief explanation/justification. They may be seen as a roadmap for future important work.

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  • 60.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The 11-year magnetic Solar Cycle: Chaos control due to Jupiter2020Manuscript (preprint) (Other academic)
    Abstract [en]

    The observed magnetic field of the Sun is believed to originate from a "dynamo-effect" in its convective surface layer. However, there is no natural 11-year timescale in such models. We show that this major magnetic solar cycle naturally may arise through magnetic "chaos- control" of the inherently chaotic solar dynamo, mainly due to Jupiter.

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  • 61.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The 11-Year Magnetic Solar Cycle: Chaos Control Due to Jupiter2022In: Solar system research, ISSN 0038-0946, E-ISSN 1608-3423, Vol. 56, no 3, p. 191-194Article in journal (Refereed)
    Abstract [en]

    The observed magnetic field of the Sun is believed to originate from a “dynamo-effect” in its convective surface layer. However, there is no natural 11-year timescale in such models. We show that this timescale in the mean naturally and automatically arise through magnetic “chaos-control” of the inherently chaotic solar dynamo, mainly due to Jupiter, while also conforming to real and observed sunspot characteristics.

  • 62.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The fundamental structure of matter1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The subject of this thesis is "the fundamental structure of matter, that is, the quest of understanding the deepest level of the physical world, and the interactions relevant at that level. The hope is that, as one goes deeper, the laws are going to be simpler, not necessarily in mathematical terms, but in conceptual terms. The goal is fewer and fewer ad hoc assumptions, inspiring and driving the pursuit for the fundamental structure of matter. The thesis consists of an introductory part, giving a broad overview of where the subject stands today, and of a more detailed part, containing our own contributions to the advances of this knowledge. Six reproduced papers are appended at the end. There we treat the fundamental structure of matter on three different levels. The first three papers are concerned with the inner structure of particles (hadrons) that interact via the strong nuclear force. Here we have investigated the interactions of the so-called quarks inside hadrons, taking into account also their spin structure. Besides protons and neutrons, we have also studied more exotic particles containing quarks, so-called mesons, that are only produced in high-energy collision processes. Om a more fundamental, but speculative, level we have constructed a new model for an underlying substructure common to both quarks and leptons (particles unaffected by the strong interaction), i.e., all particles that build up matter. We also investigate some of the physical consequences of this model, particularly the possibility of radiative neutrino decay. On the large scale, we analyse the origin of the so-called dark matter in the Universe, which we propose is composed out of enormous lumps exclusively made of quarks, without any "normal" hadrons. We also explore the connection of this phenomenon to the mysterious bursts of gammarays seen in astrophysics.

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  • 63.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The Klein-Alfven Cosmology Revisited2019Manuscript (preprint) (Other academic)
    Abstract [en]

    The Klein-Alfven model is based on the pragmatic belief that alsocosmology, just like all other elds of physics, should be based onphysical laws independently tested in the laboratory. It actually hasa number of attractive features, described in this article. As almostall matter in the known universe is in the plasma state, the modelis by necessity based on both gravity and electromagnetism, and asmost cosmic plasmas are inhomogeneous and magnetized, it is auto-matically inhomogeneous (as is the real universe). It is not perfect(no models are), but many of the outstanding unsolved \problems" ofthe contemporary standard big bang-model of cosmology are eithersolved/sidestepped by, or non-existent in, the Klein-Alfven model.One should remember that the standard model of cosmology also isjust that - a model, and highly idealized at that, with many ad hocingredients and a large number of free parameters and hypotheticalingredients that are xed only through comparison with cosmologicaldata in a global best-t fashion. It is not, and should never be con-sidered to be, sacrosanct. If a comparable number of man-hours hadbeen invested in the direction of the Klein-Alfven model it is plausi-ble that it would describe the real observed universe as good as, oreven better than, the big bang-model - with much fewer speculativeadditions to known physics.

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  • 64.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The Klein-Alfvén cosmology revisited2019In: Journal of Physics Communication, E-ISSN 2399-6528, Vol. 3, no 11, article id 115001Article in journal (Refereed)
    Abstract [en]

    The Klein-Alfvén model is based on the pragmatic belief that also cosmology, just like all other fields of physics, should be based on physical laws independently tested in the laboratory. It actually has a number of attractive features, described in this article. As almost all matter in the known universe is in the plasma state, the model is by necessity based on both gravity and electromagnetism, and as most cosmic plasmas are inhomogeneous and magnetized, it is automatically inhomogeneous (as is the real universe). It is not perfect (no models are), but many of the outstanding unsolved 'problems' of the contemporary standard big bang-model of cosmology are either solved/sidestepped by, or non-existent in, the Klein-Alfvén model. One should remember that the standard model of cosmology also is just that—a model, and highly idealized at that, with many ad hoc ingredients and a large number of free parameters and hypothetical ingredients that are fixed only through comparison with cosmological data in a global best-fit fashion. It is not, and should never be considered to be, sacrosanct. If a comparable number of man-hours had been invested in the direction of the Klein-Alfvén model it is plausible that it would describe the real observed universe as good as, or even better than, the big bang-model—with much fewer speculative additions to known physics.

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  • 65.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The magical “Born Rule” & quantum “measurement”: Implications for PhysicsManuscript (preprint) (Other academic)
    Abstract [en]

    The arena of quantum mechanics and quantum field theory is the abstract, unobserved and unobservable, M-dimensional formal Hilbert space not equal to spacetime. II. The arena of observations and, more generally, of all events (i.e. everything) in the real physical world, is the classical 4-dimensional physical spacetime. III. The "Born Rule" is the random process "magically" transforming I. into II. Wavefunctions are superposed and entangled only in the abstract space I., never in spacetime II. Attempted formulations of quantum theory directly in real physical spacetime actually constitute examples of "locally real" theories, as defined by Clauser & Horne, and are therefore already empirically refuted by the numerous tests of Bell's theorem in real, controlled experiments in laboratories here on Earth. Observed quantum entities, i.e. events, are never superposed or entangled as they: 1) Exclusively "live" (manifest) in real physical spacetime, 2) Are not described by entangled wavefunctions after "measurement", effectuated by III. When separated and treated correctly in this way, a number of fundamental problems and "paradoxes" of quantum theory vs. relativity (i.e. spacetime) simply vanish, such as the black hole information paradox, infinite zero-point energy of quantum field theory and quantization of general relativity.

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  • 66.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The Magical “Born Rule” and Quantum “Measurement”: Implications for Physics2023In: Foundations, E-ISSN 2673-9321, Vol. 3, no 4, p. 634-642Article in journal (Refereed)
    Abstract [en]

    I. The arena of quantum mechanics and quantum field theory is the abstract, unobserved and unobservable, M-dimensional formal Hilbert space ≠ spacetime. II. The arena of observations—and, more generally, of all events (i.e., everything) in the real physical world—is the classical four-dimensional physical spacetime. III. The “Born rule” is the random process “magically” transforming I into II. Wavefunctions are superposed and entangled only in the abstract space I, never in spacetime II. Attempted formulations of quantum theory directly in real physical spacetime actually constitute examples of “locally real” theories, as defined by Clauser and Horne, and are therefore already empirically refuted by the numerous tests of Bell’s theorem in real, controlled experiments in laboratories here on Earth. Observed quantum entities (i.e., events) are never superposed or entangled as they: (1) exclusively “live” (manifest) in real physical spacetime and (2) are not described by entangled wavefunctions after “measurement” effectuated by III. When separated and treated correctly in this way, a number of fundamental problems and “paradoxes” of quantum theory vs. relativity (i.e., spacetime) simply vanish, such as the black hole information paradox, the infinite zero-point energy of quantum field theory and the quantization of general relativity.

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  • 67.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The proton as a laboratory for the fundamental structure of matter1996Licentiate thesis, comprehensive summary (Other academic)
  • 68.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The "Proton Spin Crisis" - a Quantum Query2010In: Progress in Physics, ISSN 1555-5534, E-ISSN 1555-5615, Vol. 3, p. 51-52Article in journal (Refereed)
    Abstract [en]

    The "proton spin crisis" was introduced in the late 1980s, when the EMC-experiment revealed that little or nothing of a proton's spin seemed to be carried by its quarks. The main objective of this paper is to point out that it is wrong to assume that the proton spin, as measured by completely di erent experimental setups, should be the same in all circumstances, an assumption explicitly made in all present theoretical treatments of the "crisis". As spin is a genuine quantum property, without any objective existence outside its measuring apparatus context, proper account of quantum mechanical measurement theory must be taken.

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  • 69.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The 'Proton spin crisis': A Quantum query2003Report (Other academic)
    Abstract [en]

    The "proton spin crisis" was introduced in the late 1980s, when the EMC-experiment revealed that little or nothing of a proton's spin seemed to be carried by its quarks. The main objective of this paper is to point out that it is wrong to assume that the proton spin, measured by completely different experimental setups, should be the same in all circumstances.

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  • 70.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The Quantum Measurement Problem2021In: International Journal of Quantum Foundations, E-ISSN 2375-4729, Vol. Supplement 3, no 2, p. 29-32Article in journal (Refereed)
    Abstract [en]

    The quantum measurement problem is the most fundamental question of all: How the ghostly quantum mechanical coexistence of many mutually incompatible possibilities result in the concrete reality of the normal world, even though we and our measuring instruments are all made of atoms obeying quantum mechanics. In this brief article we lay down the criteria for such a mechanism.

  • 71.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The Quantum Measurement Problem2020Manuscript (preprint) (Other academic)
    Abstract [en]

    The quantum measurement problem is the most fundamental question of all: How the ghostly quantum mechanical coexistence of many mutually incompatible possibilities result in the concrete reality of the normal world, even though we and our measuring instruments are all made of atoms obeying quantum mechanics. In this brief article we lay down the criteria for such a mechanism.

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    The Quantum Measurement Problem
  • 72.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Universum för nyfikna: och andra populärvetenskapliga essäer2023Book (Other (popular science, discussion, etc.))
  • 73.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Why Gravity is Non-Quantum2022Manuscript (preprint) (Other academic)
    Abstract [en]

    The comprehensive analysis of Niels Bohr shows that the classical world is a necessary additional independent conceptual structure not derivable from quantum mechanics. The results of measurement mustalways be expressed classically. Furthermore, neither linear "decoherence", nor any other unitary linear models/interpretations can ever result in the observed nonlinear classical physics. As we will see, the invariant objective classical events constituting the dynamically nonlinear spacetime of general relativity is this classical structure. Hence,classical gravitation is required to make the abstract and purely formal, perfectly linear, quantum mechanical eternal coexistence of many mutually incompatible possibilities into the concrete reality of the observed nonlinear world. It also means that "Quantum Gravity" is a pseudo-problem, a mirage, "Quantum Spacetime" an oxymoron.

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  • 74.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Why Gravity is Non-Quantum2023In: International Journal of Quantum Foundations Supplement, E-ISSN 2375-4729, Vol. 5, no 1, p. 1-6Article in journal (Refereed)
    Abstract [en]

    The comprehensive analysis of Niels Bohr shows that the classical world is a necessary additional independent conceptual structure not derivable from quantum mechanics. The results of measurement must always be expressed classically. Furthermore, neither linear “decoherence”, nor any other unitary linear models/interpretations can ever result in the observed nonlinear classical physics. As we will see, the invariant objective classical events constituting the dynamically nonlinear spacetime of general relativity is this classical structure. Hence, classical gravitation is required to make the abstract and purely formal, perfectly linear, quantum mechanical eternal coexistence of many mutually incompatible possibilities into the concrete reality of the observed nonlinear world. It also means that “Quantum Gravity” is a pseudo-problem, a mirage, “Quantum Spacetime” an oxymoron.

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  • 75.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Dols Duxans, Jaime
    Svensson, Martin
    Nonlinear Effects of Gravity in CosmologyManuscript (preprint) (Other academic)
    Abstract [en]

    We investigate some nonlinear effects of gravity in cosmology. Possible physically interesting consequences include: non-requirement ofdark matter and dark energy, asymmetric gravitational matter-creation,emergent homogeneity/isotropy & asymptotic flatness, resolution of“cosmic coincidence” Ωm∼Ω, effective cutoff of gravitational inter-action at the scale of cosmic voids.

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  • 76.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Dols Duxans, Jaime
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Svensson, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nonlinear Effects of Gravity in Cosmology2018In: Advanced Studies in Theoretical Physics, ISSN 1313-1311, E-ISSN 1314-7609, Vol. 12, no 4, p. 157-172Article in journal (Refereed)
    Abstract [en]

    We consider some nonlinear effects of gravity in cosmology. Possible physically interesting consequences include: non-requirement of dark matter and dark energy, asymmetric gravitational matter-creation, emergent homogeneity/isotropy & asymptotic flatness, resolution of "cosmic coincidence" Omega_m \sim Omega_lambda, effective cutoff of gravitational interaction at the scale of cosmic voids.

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  • 77.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Francois, Stephane
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Testing Quantum Gravity2016Report (Refereed)
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  • 78.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Francois, Stephane
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Testing Quantum Gravity2017In: International Journal of Modern Physics D, ISSN 0218-2718, Vol. 26, no 12, article id 1743003Article in journal (Refereed)
    Abstract [en]

    The search for a theory of quantum gravity is the most fundamental problem in all of theoretical physics, but there are as yet no experimental results at all to guide this endeavor. What seems to be needed is a pragmatic way to test if gravitation really occurs between quantum objects or not. In this paper, we suggest such a potential way out of this deadlock, utilizing macroscopic quantum systems; superfluid helium, gaseous Bose–Einstein condensates and “macroscopic” molecules. It turns out that true quantum gravity effects — here defined as observable gravitational interactions between truly quantum objects — could and should be seen (if they occur in nature) using existing technology. A falsification of the low-energy limit in the accessible weak-field regime would also falsify the full theory of quantum gravity, making it enter the realm of testable, potentially falsifiable theories, i.e. becoming real physics after almost a century of pure theorizing. If weak-field gravity between quantum objects is shown to be absent (in the regime where the approximation should apply), we know that gravity then is a strictly classical phenomenon absent at the quantum level.

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  • 79.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lindkvist, Jesper
    Inhomogeneous structure formation may alleviate need for accelerating universe2010In: The Open Astronomy Journal, E-ISSN 1874-3811, Vol. 3, p. 145-149Article in journal (Refereed)
    Abstract [en]

    When taking the real, inhomogeneous and anisotropic matter distribution in the semi-local universe into account, there may be no need to postulate an accelerating expansion of the universe despite recent type Ia supernova data. Local curvatures must be integrated (over all space) to obtain the global curvature of the universe, which seems to be very close to zero from cosmic microwave background data. As gravitational structure formation creates bound regions of positive curvature, the regions in between become negatively curved in order to comply with a vanishing global curvature. The actual dynamics of the universe is altered due to the self-induced inhomogeneities, again more prominently so as structure formation progresses. Furthermore, this negative curvature will increase as a function of time as structure formation proceeds, which mimics the effect of "dark energy" with negative pressure. Hence, the "acceleration" may be merely a mirage. We make a qualitative and semi-quantitative analysis, for pedagogical reasons using newtonian gravity corrected for special relativistic effects (which works surprisingly well) to corroborate and illustrate/visualize these statements. This article may be seen as an attempt to communicate to a larger number of people the necessity of starting to take seriously the real, observed inhomogeneous distribution and the nonlinearities of nonperturbative general relativity, and their impact on the dynamics and behavior of the cosmos instead of allowing an oversimplified cosmological model to generate a consensus world-view of a cosmos allegedly dominated by mysterious dark energy.

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  • 80.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Olevik, David
    Luleå University of Technology.
    Türk, Christian
    Luleå University of Technology.
    Wiklund, Hanna
    Luleå University of Technology.
    Comment on "Measurement of quantum states of neutrons in the Earth's gravitational field"2003In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 68, no 10, p. 1087011-13Article in journal (Other academic)
    Abstract [en]

    In the paper by Nesvizhevsky et al. [Phys. Rev. D 67, 102002 (2003)], it is argued that the lowest quantum state of neutrons in the Earth's gravitational field has been experimentally identified. While this is most likely correct, it is imperative to investigate all alternative explanations of the result in order to close all loopholes, as it is the first experiment ever claimed to have observed gravitational quantum states. Here we show that geometrical effects in the experimental setup can mimic the results attributed to gravity. Modifications of the experimental setup to close these possible loopholes are suggested.

  • 81.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ponga, Anna
    LTU.
    Pulsars: Cosmic permanent “neutromagnets”?2011In: ISRN Astronomy and Astrophysics, ISSN 2090-4738, E-ISSN 2090-4746, Vol. 2011, no Article ID 378493Article in journal (Refereed)
    Abstract [en]

    We argue that pulsars may be spin-polarized neutron stars, that is, cosmic permanent magnets. This would simply explain several observational facts about pulsars, including the “beacon effect” itself, that is, the static/stable misalignment of rotational and magnetic axes, the extreme temporal stability of the pulses, and the existence of an upper limit for the magnetic field strength, coinciding with the one observed in “magnetars.” Although our model admittedly is speculative, this latter fact seems to us unlikely to be pure coincidence.

  • 82.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sandin, Fredrik
    Preon stars: a new class of cosmic compact objects2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 616, no 1-2, p. 1-7Article in journal (Refereed)
    Abstract [en]

    In the context of the standard model of particle physics, there is a definite upper limit to the density of stable compact stars. However, if a more fundamental level of elementary particles exists, in the form of preons, stability may be re-established beyond this limiting density. We show that a degenerate gas of interacting fermionic preons does allow for stable compact stars, with densities far beyond that in neutron stars and quark stars. In keeping with tradition, we call these objects "preon stars", even though they are small and light compared to white dwarfs and neutron stars. We briefly note the potential importance of preon stars in astrophysics, e.g., as a candidate for cold dark matter and sources of ultra-high energy cosmic rays, and a means for observing them.

  • 83.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sandin, Fredrik
    Preonstjärnor - en ny sorts himlakropp?2005In: Populär astronomi, ISSN 1650-7177, Vol. 4, no 8, p. 8-13Article in journal (Other (popular science, discussion, etc.))
  • 84.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sandin, Fredrik
    Stor som en kula men tyngre än jorden: Svenska forskare kan ha upptäckt de första kompakta objekten i universum på sjuttio år2005In: Forskning & Framsteg, ISSN 0015-7937, no 7, p. 40-43Article in journal (Other (popular science, discussion, etc.))
  • 85.
    Hansson, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Zernell, Lasse
    Allt om Vetenskap.
    Preonstjärnor - Äntligen något nytt på himlen2008In: Allt om Vetenskap, ISSN 1652-3318, no 8, p. 82-89Article in journal (Other (popular science, discussion, etc.))
  • 86. Houra-Yaou, L.
    et al.
    Kessler, P.
    Parisi, J.
    Murgia, F.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    A Generalization of the Brodsky-Lepage formalism1997In: Proceedings: International Conference on the Structure and the Interactions of the Photon (Photon 97) including the 11th International Workshop on Photon-Photon Collisions / [ed] A. Buijs; F.C. Erne, World Scientific and Engineering Academy and Society, 1997Conference paper (Refereed)
    Abstract [en]

    We present an approach that generalizes in a natural way the perturbative QCD formalism developed by Brodsky and Lepage for the study of exclusive hadronic processes to the case of $L\neq 0$ mesons. As an application of our approach we consider here the production of meson pairs, involving tensor and pseudotensor mesons, in photon-photon collisions.

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  • 87. Houra-Yaou, Ladonne
    et al.
    Kessler, Paul
    Parisi, Joseph
    Murgia, Francesco
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Production of meson pairs involving L not = 0 mesons in photon-photon collisions1998In: Workshop on Diquarks III: Villa Gualino, Torino, Italy, 28 -30 October 1996 / [ed] Mauro Anselmino, Singapore: World Scientific and Engineering Academy and Society, 1998, p. 70-80Conference paper (Refereed)
    Abstract [en]

    We present a formalism for studying the exclusive production or decay of mesons with any value of the internal orbital angular momentum L. As an application, we discuss the production of meson pairs (involving tensor and pseudotensor mesons) in photon-photon collisions.

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    FULLTEXT01
  • 88. Houra-Yaou, Ladonne
    et al.
    Kessler, Paul
    Parisi, Joseph
    Murgia, Francesco
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Production of meson pairs, involving tensor and pseudotensor mesons, in photon-photon collisions1997In: Zeitschrift für Physik C Particles and Fields, ISSN 0170-9739, E-ISSN 1431-5858, Vol. 76, no 3, p. 537-547Article in journal (Refereed)
    Abstract [en]

    Starting from a bound-state model of weakly bound quarks for (q [`(q)]) mesons, we derive a formalism for computing the production or decay of such mesons, whatever the value of their internal orbital angular momentum L. That approach appears as a natural generalization of the Brodsky-Lepage formalism (valid only for L=0) that has been widely used in recent years for the computation of exclusive processes in perturbative QCD . We here apply it to the production, in photon-photon collisions, of: i) tensor-meson pairs; ii) pseudotensor-meson pairs; iii) hybrid pairs made of a pion and a pseudotensor meson. The numerical results we obtain allow for some hope of experimentally identifying such pairs, in the charged channels, at high-energy e+e- colliders of the next generation, provided integrated luminosities as high as » 1040 cm-2 can be reached.

  • 89. Nicolaidis, A.
    et al.
    Tsirigoti, G.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    TeV neutrinos in a dense medium1999Report (Other academic)
    Abstract [en]

    The dispersion relation of energetic (few TeV) neutrinos traversing a medium is studied. We use the real time formalism of thermal field theory and we include the effects from the propagator of the W gauge boson. We consider then the MSW oscillations for cosmic neutrinos traversing the Earth, adopting for the neutrino parameters values suggested by the LSND results. It is found that the $\nu_\mu$ flux, for neutrinos passing through the center of the Earth, will appear reduced by 15% for energies around 10 TeV.

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    FULLTEXT01
  • 90. Olevik, David
    et al.
    Turk, C.
    Luleå University of Technology.
    Wiklund, H.
    Luleå University of Technology.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Critique of an experiment regarding quantum states in a gravitational field and possible geometrical explanations1992Report (Other academic)
    Abstract [en]

    We discuss an experiment conducted by Nesvizhevsky et al. As it is the first experiment claimed to have observed gravitational quantum states, it is imperative to investigate all alternative explanations of the result. In a student project course in applied quantum mechanics, we consider the possibility of quantummechanical effects arising from the geometry of the experimental setup, due to the "cavity" formed. We try to reproduce the experimental result using geometrical arguments only. Due to the influence of several unknown parameters our result is still inconclusive.

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    FULLTEXT01
  • 91. Sandin, Fredrik
    et al.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Observational legacy of preon stars: Probing new physics beyond the CERN LHC2007In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 76, no 12Article in journal (Refereed)
    Abstract [en]

    We discuss possible ways to observationally detect the superdense cosmic objects composed of hypothetical subconstituent fermions beneath the quark/lepton level, recently proposed by us. The characteristic mass and size of such objects depend on the compositeness scale, and their huge density cannot arise within a context of quarks and leptons alone. Their eventual observation would therefore be a direct vindication of physics beyond the standard model of particle physics, possibly far beyond the reach of the Large Hadron Collider (LHC), in a relatively simple and inexpensive manner. If relic objects of this type exist, they can possibly be detected by present and future x-ray observatories, high-frequency gravitational wave detectors, and seismological detectors. To have a realistic detection rate, i.e., to be observable, they must necessarily constitute a significant fraction of cold dark matter.

  • 92. Sandin, Fredrik
    et al.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The observational legacy of preon stars: probing new physics beyond the LHC2007Report (Other academic)
    Abstract [en]

    We discuss possible ways to observationally detect the superdense cosmic objects composed of hypothetical sub-constituent fermions beneath the quark/lepton level, recently proposed by us. The characteristic mass and size of such objects depend on the compositeness scale, and their huge density cannot arise within a context of quarks and leptons alone. Their eventual observation would therefore be a direct vindication of physics beyond the standard model of particle physics, possibly far beyond the reach of the Large Hadron Collider (LHC), in a relatively simple and inexpensive manner. If relic objects of this type exist, they can possibly be detected by present and future x-ray observatories, high-frequency gravitational wave detectors, and seismological detectors. To have a realistic detection rate, i.e., to be observable, they must necessarily constitute a significant fraction of cold dark matter.

    Download full text (pdf)
    FULLTEXT01
12 51 - 92 of 92
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