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At least 325 records · Page 18Linked to original sources

arXiv2013

Beyond information: A bit of meaning

Is our world just information? We argue that our current notion of information has one serious shortcoming: It is quite literally meaningless. We suggest a meaningful extension of the notion of information that is dynamic, internal, approximate, contains an element of randomness, and is layered. This new notion of information derives from the interactions of material objects. Our answer to the essay question then is Bit from It or, more appropriately, Bit++ from It. We discuss how our new notion of information sheds light on the measurement problem in quantum mechanics and how it can be applied in philosophy and computer science.

quant-ph↗

arXiv2013

Reflections on the direct detection of particle dark matter

The LUX experimental group has just announced the most stringent upper limits so far obtained on the cross section of WIMP-nucleon elastic scattering [1]. This result is a factor of two to five below the previous best upper limit [2] and effectively rules out earlier suggestions of low mass WIMP detection signals. The experimental expertise exhibited by this group is extremely impressive, but the fact of continued negative results raises the more basic question of whether or not this is the right approach to solving the dark matter problem. Here I comment upon this question, using as a basis the final chapter of my book on dark matter [3], somewhat revised and extended. I muse on dark matter and its alternative, modified Newtonian dynamics, or MOND.

physics.hist-ph↗

arXiv2013

A Mixture of Ancient and Modern Understanding Concerning the Distance and Motion of the Moon

Ptolemy's model of the Moon's motion implied that its distance varies by nearly a factor of two, implying that its angular size should also vary by nearly a factor of two. We present an analysis of 100 naked eye observations of the Moon's angular size obtained over 1145 days, showing regular variations of at least 3 arc minutes. Thus, ancient astronomers could have shown that a key implication of Ptolemy's model was wrong. In modern times we attribute the variation of distance of the Moon to the combined effect of the ellipticity of the Moon's orbit and the perturbing effect of the Sun on the Earth-Moon system. We show graphically how this affects the ecliptic longitudes and radial distance of the Moon. The longitude and distance "anomalies" are correlated with the Moon's phase. This is illustrated without any complex equations or geometry.

physics.hist-ph↗

arXiv2013

A strange bridge by Leonardo

On folio 855 recto of the Codex Atlanticus, Leonardo da Vinci drew three 'easily movable' bridges, but one of them is enigmatic: all 'replicas' in Leonardo museums and exhibitions come as a surprise, to say the least, to any engineer or architect whose attention is drawn to it. This is the case for models in Amboise (France), Chicago and Portland (USA), Florence (Italy) and for the one of the traveling exhibition by the Australian company 'Grande Exhibitions' that already visited 40 major cities in the world. All 'replicas' of the bridge model attributed to Leonardo have pillars standing on the deck of the bridge, while the deck is suspended by cables attached on these pillars. At first sight this problem does not catch the attention of the observer, as the bridge seems to be a mixed form of a beam and a suspension bridge, but it was not overlooked by my colleague architect-engineer Dr. Laurens Luyten (Gent, Belgium). Yet, after a TV-interview in Brussels so much pressure was exerted by some of the museum collaborators, the architect prefers to keep the silence about the engineering by these 'scientific' exhibitions. Yet, it is the author's opinion the ridiculous models do not honor Leonardo, and so the present paper takes up the challenge to report about his observation in his name (with his permission). Something should be done, for sure: millions of people look at the bridge replicas that immediately embarrass any engineer.

math.HO↗

arXiv2013

The Superposition Principle in Quantum Mechanics - did the rock enter the foundation surreptitiously?

The superposition principle forms the very backbone of quantum theory. The resulting linear structure of quantum theory is structurally so rigid that tampering with it may have serious, seemingly unphysical, consequences. This principle has been succesful at even the highest available accelerator energies. Is this aspect of quantum theory forever then? The present work is an attempt to understand the attitude of the founding fathers, particularly of Bohr and Dirac, towards this principle. The Heisenberg matrix mechanics on the one hand, and the Schrodinger wave mechanics on the other, are critically examined to shed light as to how this principle entered the very foundations of quantum theory.

physics.hist-ph↗

arXiv2013

The reception of relativity in the Netherlands

This article reviews the early academic and public reception of Albert Einstein's theory of relativity in the Netherlands, particularly after Arthur Eddington's eclipse experiments of 1919. Initially, not much attention was given to relativity, as it did not seem an improvement over Hendrik A. Lorentz' work. This changed after the arrival in Leiden of Paul Ehrenfest. Soon relativity was much studied and lead to controversy among a number of conservative intellectuals, as elsewhere in Europe. The tone of Dutch critics was much more mild, however. This can be understood when one considers Dutch neutrality during World War I. Einstein's political positions were generally positively perceived in Holland, which Dutch academics put to use in their efforts at international reconciliation abroad, and the presentation of theoretical physics at home.

physics.hist-ph↗

arXiv2013

The quantum mechanics is a non-universal theory. The realistic Schrodinger's and positivistic Born's interpretation of the wave function

Quantum mechanics describes successfully numerous quantum phenomena both microscopic and macroscopic, such as superconductivity. But the controversies about quantum mechanics, in the old days and present day, reveal fundamental obscurity in quantum mechanics. In this work reader attention is drawn first of all to the fact that the orthodox description of superconductivity and some other quantum phenomena uses the realistic interpretation of the wave function proposed by Schrodinger whereas the controversies take place until the present about the positivistic interpretation proposed by Born. Causes and essence of the fundamental obscurity of the Born interpretation are considered in detail in the first part of the paper. The fundamental obscurities of the orthodox description of superconductivity and other quantum phenomena are considered in the end of the paper.

physics.hist-ph↗

arXiv2014

Einstein's equivalence principle in cosmology

We study physical consequences of the Einstein equivalence principle (EEP) for a Hubble observer in FLRW universe. We introduce the local inertial coordinates with the help of a special conformal transformation. The local inertial metric is Minkowski-flat and materialized by a congruence of time-like geodesics of static observers. The static observers are equipped with the ideal clocks measuring the proper time that is synchronized with the clocks of the Hubble observer. The local inertial metric is used for physical measurements of spacetime intervals with the ideal clocks and rulers. The special conformal transformation preserves null geodesics but does not keep invariant time-like geodesics. Moreover, it makes the rate of the local time coordinate dependent on velocity of the particle which makes impossible to rich the uniform parameterization of the world lines of static observers and light geodesics with a single parameter - they differ by the conformal factor of FLRW metric. It tells us that the metric on the light cone is not Minkowski-flat but depends on the scale factor of FLRW universe and it can be interpreted as a weak violation of EEP for photons. The importance of this violation for gravitational physics is that some of local experiments conducted with freely-propagating electromagnetic waves may be sensitive to the Hubble expansion. We show that the Hubble constant H can be measured within the solar system by means of high-precision spacecraft Doppler tracking as a blue shift of frequency of radio waves circulating in the Earth-spacecraft radio link. We also analyze the behavior of the standing wave in a microwave resonator and show that the standing wave is insensitive to the Hubble expansion.

gr-qc↗

arXiv2013

A Short History of Spin

The paper outlines the historical development of spin in physics from about 1920 to the present day. It aims to provide the student with an accurate chronology of important developments, both scientific and technical.

physics.hist-ph↗

arXiv2014

Against Absolute Actualization: Three "Non-Localities" and Failure of Model-External Randomness made easy with Many-Worlds Models including Stronger Bell-Violation and Correct QM Probability

Experimental violation of Bell-inequalities proves actualization of many futures (~ many-worlds); I show that this is not mere interpretation. To show this self-contained pedagogically, I resolve the EPR paradox by starting with a visually intuitive non-quantum many-worlds model that already has apparent non-locality. A modification leads to a classical-to-quantum transition model. Model-external randomness (a ghost outside the universe throwing a pebble on state-space) stays unchanged, but the modeled observers witness strong Bell-violation. I derive the quantum probability P from classical-to-quantum consistency. Model-internal probability (~ subjective Bayesianism) is derived as a measure of surprise (~ Deutsch's rational expectation). The model shows how absolute actualization, say by real hidden variables, fails. Models with P and standard Bell-violation are supplied for completeness. The transition model is the first touchable, interactive science-outreach exhibit teaching correct quantum physics. The discussion reinterprets the transition model, defends Einstein-locality, rejects "realism" etc., to the conclusion that the models teach the necessity of "many worlds/minds", rejecting probability concepts with random-randomness regress. The models teach how EPR empirically excludes certain realisms.

quant-ph↗

arXiv2013

Some lessons for us scientists (too) from the "Sokal affair"

In this little non-technical piece, I argue that some of the lessons that can be learnt from the bold action carried out in 1996 by the physicist Alan Sokal and typically known as the "Sokal affair" not only apply to some sector of the humanities (which was the original target of the hoax), but also (with much less intensity, but still) to the hardest sciences.

physics.hist-ph↗

arXiv2013

Non-standard Models and the Sociology of Cosmology

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 (the "snowball effect" or "groupthink"). 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.

physics.hist-ph↗

arXiv2013

William Sadler Franks and the Brockhurst Observatory

William Sadler Franks (1851-1935) was astronomer-in-charge at F.J. Hanbury's private observatory at Brockhurst, near East Grinstead, Sussex, from 1909 until his death in 1935. This paper reviews the observational projects Franks undertook at Brockhurst, including his work on double stars, red stars, diffuse nebulae and dark nebulae, as well as his involvement with the commissioning of a 24-inch reflector built by Thomas William Bush (1839-1928).

physics.hist-ph↗

arXiv2013

Studying Quantum Field Theory

The paper puts together some loosely connected observations, old and new, on the concept of a quantum field and on the properties of Feynman amplitudes. We recall, in particular, the role of (exceptional) elementary induced representations of the quantum mechanical conformal group SU(2,2) in the study of gauge fields and their higher spin generalization. A recent revival of the (Bogolubov-)Epstein-Glaser approach to position space renormalization is reviewed including an application to the calculation of residues of primitively divergent graphs. We end up with an optimistic outlook of current developments of analytic methods in perturbative QFT which combine the efforts of theoretical physicists, algebraic geometers and number theorists.

math-ph↗

arXiv2013

Under Augustus sign: the role of Astronomy in the foundation of Augusta Praetoria Salassorum

Augusta Praetoria Salassorum, modern Aosta, was founded around 25 BC to celebrate the victory of Augustus army on the Salassi. Aosta is a city of the founder under many respects; for instance, one of the two twin temples of the forum was devoted to Augustus, and a huge triumphal arc to the ruler still welcomes the town visitors. Recently, a sculpted block has been uncovered, still in its original position, on a corner of one of the town towers. The block carries reliefs, such as a plough and a spade, which are clearly related to the town foundation ritual. As a consequence, we carried out an archaeoastronomical analysis of the original urban plan taking into account the complex natural horizon of the Alps in which Aosta valley is nested. The results show that the town was very likely oriented in such a way as to pinpoint Augustus associations with the cosmic signs of renewal: the winter solstice and the Capricorn.

physics.hist-ph↗

arXiv2014

Solar-motion correction in early extragalactic astrophysics

Redshift observations of galaxies outside the Local Group are fairly common in extragalactic astrophysics. If redshifts are interpreted as arising from radial velocities, these must be corrected by the contamination of the solar motion. We discuss the details of such correction in the way it was performed by the American astronomer Edwin Hubble in his 1929 seminal paper. The investigations of spiral nebulae undertaken by the Swedish astronomer Knut Lundmark, in 1924, are also considered in this context.

physics.hist-ph↗

arXiv2013

Unconventional research in USSR and Russia: short overview

This work briefly surveys unconventional research in Russia from the end of the 19th until the beginning of the 21th centuries in areas related to generation and detection of a 'high-penetrating' emission of non-biological origin. The overview is based on open scientific and journalistic materials. The unique character of this research and its history, originating from governmental programs of the USSR, is shown. Relations to modern studies on biological effects of weak electromagnetic emission, several areas of bioinformatics and theories of physical vacuum are discussed.

cs.OH↗

arXiv2013

On the Possibility of an Astronomical Perspective in the Study of Human Evolution

The Sapient Paradox is the apparently unexplainable time delay of several ten thousand years following the arrival of Homo sapiens in Asia and Europe and before the introduction of impressive innovations with the agricultural revolution. Renfrew (2007) has suggested that the solution of the paradox has to do with changes in modes of thought that occurred with sedentism. According to Renfrew, this is a subject of study for cognitive archaeology where the final goal would be to understand the formation of the human mind. Several scholars, however, affirm that climatic change was crucial to such a revolution as it would have been very difficult to develop agriculture during the Palaeolithic. In other words, sedentism was not justified during the ice age, and that may be the solution to the paradox. It is widely accepted that climate variations were due to so-called orbital forcing, the slow periodic changes of orbital parameters of the Earth (known also as the Milankovitch theory). These and other astronomical effects on the climate are discussed along with the consequent impact on human evolution. The question then rises as to whether or not it is possible to adopt an astronomical perspective instead of (or complementary to) the cognitive archaeological one. Such would be possible by adopting a different point of reference (that is, from outside), and a non-anthropocentric approach.

physics.pop-ph↗