arXiv subjects

J. R. Mureika

Publications and source records attributed to J. R. Mureika.

At least 19 recordsLinked to original sources

arXiv2018

Extended Uncertainty Principle Black Holes

An Extended Uncertainty Principle inspired Schwarzschild metric that allows for large scale modifications to gravitation is presented. At a new fundamental length scale $\Ls$, the usual black hole characteristics (horizon radius, ISCO, and photosphere) deviate from their general relativistic counterparts by an additional term proportional to $\frac{G^3M^3}{\Ls^2}$ for $\hbar=c=1$. If the scale is $\Ls\sim10^{13}$m, EUP modifications become relevant for black holes of mass $M \geq 10^{6}~M_\odot$. This would affect the characteristics of most known supermassive black holes, and thus presents a unique set of experimental signatures that could be tested by the Event Horizon Telescope and similar future collaborations. The Newtonian potential is similarly modified, and it is shown that for values of $\Ls$ in the range considered, the effect will emerge at about 1~kpc from the galactic center, coincident with the flattening of the Milky Way's rotation curve. This suggests that the EUP could contribute to dark matter effects.

gr-qc↗

arXiv2012

Primordial Black Hole Evaporation and Spontaneous Dimensional Reduction

Several different approaches to quantum gravity suggest the effective dimension of spacetime reduces from four to two near the Planck scale. In light of such evidence, this letter re-examines the thermodynamics of primordial black holes (PBHs) in specific lower-dimensional gravitational models. Unlike in four dimensions, $\done$-D black holes radiate with power $P \sim \Mbh^2$, while it is known no $(2+1)-$D (BTZ) black holes can exist in a non-anti-deSitter universe. This has important relevance to the PBH population size and distribution, and consequently on cosmological evolution scenarios. The number of PBHs that have evaporated to present day is estimated, assuming they account for all dark matter. Entropy conservation during dimensional transition imposes additional constraints. If the cosmological constant is non-negative, no black holes can exist in the $(2+1)$-dimensional epoch, and consequently a $(1+1)$-dimensional black hole will evolve to become a new type of remnant. Although these results are conjectural and likely model-dependent, they open new questions about the viability of PBHs as dark matter candidates.

gr-qc↗

arXiv2011

Constraints on vector unparticle physics from cosmic censorship

Vector unparticle couplings to standard model fields produce repulsive corrections to gravity. From a general relativistic perspective, this leads to an effective Reissner-Nordström-like metric whose "charge" is a function of the unparticle coupling constant $λ$, and therefore can admit naked singularities. Requiring the system to respect cosmic censorship provides a new method of constraining the value of $λ$. These limits are extremely loose for stellar-mass black holes, but commensurate with existing bounds for primordial black holes. In the case of theoretical low-mass black holes, the bounds on $λ$ are much stricter than those derived from astrophysical and accelerator phenomenology. Additional constraints on the lower limit of $λ$ are used to estimate the mass of the smallest possible black hole $\Mbh^{\rm min}$ that can be formed in the unparticle framework, as a function of the unparticle parameters ($Λ_\unp,M_\unp,\du,\dbz$).

hep-ph↗

arXiv2011

(1+1)-Dimensional Entropic Gravity

We consider the formulation of entropic gravity in two spacetime dimensions. The usual gravitational force law is derived even in the absence of area, as normally required by the holographic principle. A special feature of this perspective concerns the nature of temperature and entropy defined at a point. We argue that the constancy of the gravitational force in one spatial dimension implies the information contained at each point in space is an internal degree of freedom on the manifold, and furthermore is a universal constant, contrary to previous assertions that entropic gravity in one spatial dimension is ill-defined. We give some heuristic arguments for gravitation and information transfer constraints within this framework, thus adding weight to the contention that spacetime and gravitation might be emergent phenomena.

hep-th↗

arXiv2010

Does Entropic Gravity Bound the Masses of the Photon and Graviton?

If the information transfer between test particle and holographic screen in entropic gravity respects both the uncertainty principle and causality, a lower limit on the number of bits in the universe relative to its mass may be derived. Furthermore, these limits indicate particles that putatively travel at the speed of light -- the photon and/or graviton -- have a non-zero mass $m \geq 10^{-68}~$kg. This result is found to be in excellent agreement with current experimental mass bounds on the graviton and photon, suggesting that entropic gravity may be the result of a (recent) softly-broken local symmetry. Stronger bounds emerge from consideration of ultradense matter such as neutron stars, yielding limits of $m \geq 10^{-48}-10^{-50}~$kg, barely within the experimental photon range and outside that of the graviton. We find that for black holes these criteria cannot be satisfied, and suggest some possible implications of this result.

gr-qc↗

arXiv2010

Vector unparticle enhanced black holes: exact solutions and thermodynamics

Tensor and scalar unparticle couplings to matter have been shown to enhance gravitational interactions and provide corrections to the Schwarzschild metric and associated black hole structure. We derive an exact solution to the Einstein equations for vector unparticles, and conclusively demonstrate that these induce Riessner-Nordström (RN)-like solutions where the role of the "charge" is defined by a composite of unparticle phase space parameters. These black holes admit double-horizon structure, although unlike the RN metric these solutions have a minimum inner horizon value. In the extremal limit, the Hawking temperature is shown to vanish. As with the scalar/tensor case, the (outer) horizon is shown via entropy considerations to behave like a fractal surface of spectral dimension $d_H = 2\du$.

hep-ph↗

arXiv2009

Differentiating unparticles from extra dimensions via mini black hole thermodynamics

A simple method for differentiating two similar accelerator-based black hole creation mechanisms -- compactified extra dimensions and unparticle-enhanced gravity -- is discussed, in light of several properties of black hole thermodynamics. The real-valued scaling dimension $\du$ will induce interactions that mimic those in a universe with $(2\du-2)$-extra spatial dimensions, and thus provides an alternative mechanism for black hole creation at the LHC within the confines of standard 4D general relativity. This results in mass-dependent Hawking temperature profiles that depend primarily on $\du$, yielding an evaporation signature unique to the framework. Specifically, a precision reconstruction of the Hawking temperature spectrum morphology for black holes of mass $\Mbh$ yields conclusive evidence of one mechanism over the other, due to the presence of additional adjustable parameters in the unparticle sector.

hep-ph↗

arXiv2008

Unparticle-Enhanced Black Holes at the LHC

Based on the idea that tensor unparticles can enhance the gravitational interactions between standard model particles, potential black hole formation in high energy collisions is examined. Modifications to the horizon radius $r_H$ are derived, and the corresponding geometric cross-sections of such objects are calculated. It is shown that $r_H$ increases dramatically to the electroweak scale for masses $M_{BH} \sim 1-10 $TeV, yielding a geometric cross-section $σ_{BH}=πr_H^2$ on the order of $leq 50$ pb. This suggests that unparticle physics provides a mechanism for black hole formation in future accelerators, without the requirement of extra spatial dimensions.

hep-ph↗

arXiv2007

Fractal Holography: a geometric re-interpretation of cosmological large scale structure

The fractal dimension of large-scale galaxy clustering has been demonstrated to be roughly $D_F \sim 2$ from a wide range of redshift surveys. If correct, this statistic is of interest for two main reasons: fractal scaling is an implicit representation of information content, and also the value itself is a geometric signature of area. It is proposed that the fractal distribution of galaxies may thus be interpreted as a signature of holography (``fractal holography''), providing more support for current theories of holographic cosmologies. Implications for entropy bounds are addressed. In particular, because of spatial scale invariance in the matter distribution, it is shown that violations of the spherical entropy bound can be removed. This holographic condition instead becomes a rigid constraint on the nature of the matter density and distribution in the Universe. Inclusion of a dark matter distribution is also discussed, based on theoretical considerations of possible universal CDM density profiles.

gr-qc↗

arXiv2006

Predicting Baseball Home Run Records Using Exponential Frequency Distributions

A new model, which uses the frequency of individuals' annual home run totals, is employed to predict future home run totals and records in Major League Baseball. Complete home run frequency data from 1903--2005 is analyzed, resulting in annual exponential distributions whose changes can be a used as a measure of progression in the sport and serve as a basis against which record-setting performances can be compared. We show that there is an 80% chance that Barry Bonds' current 73 home run record will be broken in the next 10 years, despite the longevity of previous records held by baseball legends Babe Ruth and Roger Marris.

physics.pop-ph↗

arXiv2006

Implications for cognitive quantum computation and decoherence limits in the presence of large extra dimensions

An interdisciplinary physical theory of emergent consciousness has previously been proposed, stemming from quantum computation-like behavior between 10^9 or more entangled molecular qubit states (microtubulin). This model relies on the Penrose-Diosi gravity-driven wavefunction collapse framework, and thus is subject to any secondary classical and quantum gravity effects. Specifically, if large extra spatial dimensions exist in the Universe, then the resulting corrections to Newtonian gravity cause this model to suffer serious difficulties. It is shown that if the extra dimensions are larger than 100 fm in size, then this model of consciousness is unphysical. If the dimensions are on the order of 10 fm in size, then a significantly smaller number of microtubulin than originally predicted are required to satisfy experimental constraints. Some speculation on evolution of consciousness is also offered, based on the possibility that the size of these extra dimensions may have been changing over the history of the Universe.

physics.gen-ph↗

arXiv2006

Gravitationally-Induced Quantum Superpopsition Reduction with Large Extra Dimensions

A gravity-driven mechanism (``objective reduction'') proposed to explain quantum state reduction is analyzed in light of the possible existence of large extra dimensions in the ADD scenario. By calculating order-of-magnitude estimates for nucleon superpositions, it is shown that if the mechanism at question is correct, constraints may be placed on the number and size of extra dimensions. Hence, measurement of superposition collapse times ({\it e.g.} through diffraction or reflection experiments) could represent a new probe of extra dimensions. The influence of a time-dependent gravitational constant on the gravity-driven collapse scheme with and without the presence of extra dimensions is also discussed.

gr-qc↗

arXiv2005

Fractal Dimensions in Perceptual Color Space: A Comparison Study Using Jackson Pollock's Art

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process which models perceptual response to color differences ($\Lab$ color space). The advantage of the $\Lab$ space filtering method over traditional RGB spaces is that the former is a perceptually-uniform (metric) space, leading to a more consistent definition of ``perceptually different'' colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to Fechner's 'Principle of the Aesthetic Middle' and Berlyne's work on perception of complexity are discussed.

physics.soc-ph↗

arXiv2005

The Effects of Temperature, Humidity and Barometric Pressure on Short Sprint Race Times

A numerical model of 100 m and 200 m world class sprinting performances is modified using standard hydrodynamic principles to include effects of air temperature, pressure, and humidity levels on aerodynamic drag. The magnitude of the effects are found to be dependent on wind speed. This implies that differing atmospheric conditions can yield slightly different corrections for the same wind gauge reading. In the absence of wind, temperature is found to induce the largest variation in times (0.01 s per $10\dc$ increment in the 100 m), while relative humidity contributes the least (under 0.01 s for all realistic conditions for 100 m). Barometric pressure variations at a particular venue can also introduce fluctuations in performance times on the order of a 0.01 s for this race. The combination of all three variables is essentially additive, and is more important for head-wind conditions that for tail-winds. As expected, calculated corrections in the 200 m are magnified due to the longer duration of the race. The overall effects of these factors on sprint times can be considered a ``second order'' adjustment to previous methods which rely strictly on a venue's physical elevation, but can become important in extreme conditions.

physics.pop-ph↗

arXiv2005

On Multifractal Structure in Non-Representational Art

Multifractal analysis techniques are applied to patterns in several abstract expressionist artworks, paintined by various artists. The analysis is carried out on two distinct types of structures: the physical patterns formed by a specific color (``blobs''), as well as patterns formed by the luminance gradient between adjacent colors (``edges''). It is found that the analysis method applied to ``blobs'' cannot distinguish between artists of the same movement, yielding a multifractal spectrum of dimensions between about 1.5-1.8. The method can distinguish between different types of images, however, as demonstrated by studying a radically different type of art. The data suggests that the ``edge'' method can distinguish between artists in the same movement, and is proposed to represent a toy model of visual discrimination. A ``fractal reconstruction'' analysis technique is also applied to the images, in order to determine whether or not a specific signature can be extracted which might serve as a type of fingerprint for the movement. However, these results are vague and no direct conclusions may be drawn.

physics.pop-ph↗

arXiv2005

Multifractal Fingerprints in the Visual Arts

The similarity in fractal dimensions of paint ``blobs'' in samples of gestural expressionist art implies that these pigment structures are statistically indistinguishable from one another. This result suggests that such dimensions cannot be used as a ``fingerprint'' for identifying the work of a single artist. To overcome this limitation, the multifractal spectrum is adopted as an alternative tool for artwork analysis. For the pigment blobs, it is demonstrated that this spectrum can be used to isolate a construction paradigm or art style. Additionally, the fractal dimensions of edge structures created by luminance gradients on the canvas are analyzed, yielding a potential method for visual discrimination of fractally-similar paintings.

physics.pop-ph↗

arXiv2005

The Effects of Temperature, Pressure, and Humidity Variations on 100 Meter Sprint Performances

It is well known that ``equivalent'' sprint race times run with different accompanying wind speeds or at different altitudes are anything but equivalent races. The drag force acting on a sprinter is a function of air density and the relative wind speed, where the former has traditionally been calculated using the race venue's elevation above sea level. However, air density variation is dependent on more than just altitude. This work will quantify how changes in air temperature, barometric pressure, and humidity levels influence 100 m sprint performances. When these effects are considered in combination, the corrections to performances can be very large. The results suggest that a non-negligible difference in race times can be expected for ``equivalent'' performances run with the same wind speed at the same venue or physical altitude, but under different atmospheric conditions.

physics.pop-ph↗

arXiv2005

Multifractal Analysis of Packed Swiss Cheese Cosmologies

The multifractal spectrum of various three-dimensional representations of Packed Swiss Cheese cosmologies in open, closed, and flat spaces are measured, and it is determined that the curvature of the space does not alter the associated fractal structure. These results are compared to observational data and simulated models of large scale galaxy clustering, to assess the viability of the PSC as a candidate for such structure formation. It is found that the PSC dimension spectra do not match those of observation, and possible solutions to this discrepancy are offered, including accounting for potential luminosity biasing effects. Various random and uniform sets are also analyzed to provide insight into the meaning of the multifractal spectrum as it relates to the observed scaling behaviors.

gr-qc↗