Jonas Mureika

Q&A: Prof. Jonas Mureika on the Higgs Boson

2012-07-04

On July 4, CERN scientists reported that they discovered a new particle consistent with the Higgs boson, sometimes named the "God" particle. The particle has been the subject of more than 50 years of research looking into how matter attains mass.

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3D May Have Been a New Wrinkle Eons Ago

2011-06-07

Jonas Mureika, a theoretical physicist and associate professor at LMU, and his research partner have come up with a groundbreaking suggestion that could help answer questions about the origins of the universe, and their idea is drawing widespread attention from their peers and the media.

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Sub-Planckian black holes and the generalized uncertainty principle

2015-07-10

The Black Hole Uncertainty Principle correspondence suggests that there could exist black holes with mass beneath the Planck scale but radius of order the Compton scale rather than Schwarzschild scale. We present a modified, self-dual Schwarzschild-like metric that reproduces desirable aspects of a variety of disparate models in the sub-Planckian limit, while remaining Schwarzschild in the large mass limit. The self-dual nature of this solution under M ↔ M −1 naturally implies a Generalized Uncertainty Principle with the linear form Δx∼1Δp+Δp. We also demonstrate a natural dimensional reduction feature, in that the gravitational radius and thermodynamics of sub-Planckian objects resemble that of (1 + 1)-D gravity. The temperature of sub-Planckian black holes scales as M rather than M −1 but the evaporation of those smaller than 10−36 g is suppressed by the cosmic background radiation. This suggests that relics of this mass could provide the dark matter.

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Self-completeness and the generalized uncertainty principle

2013-11-18

The generalized uncertainty principle discloses a self-complete characteristic of gravity, namely the possibility of masking any curvature singularity behind an event horizon as a result of matter compression at the Planck scale. In this paper we extend the above reasoning in order to overcome some current limitations to the framework, including the absence of a consistent metric describing such Planck-scale black holes. We implement a minimum-size black hole in terms of the extremal configuration of a neutral non-rotating metric, which we derived by mimicking the effects of the generalized uncertainty principle via a short scale modified version of Einstein gravity. In such a way, we find a self-consistent scenario that reconciles the self-complete character of gravity and the generalized uncertainty principle.

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Self-completeness and spontaneous dimensional reduction

2013-07-25

A viable quantum theory of gravity is one of the biggest challenges physicists are facing. We discuss the confluence of two highly expected features which might be instrumental in the quest of a finite and renormalizable quantum gravity —spontaneous dimensional reduction and self-completeness. The former suggests the spacetime background at the Planck scale may be effectively two-dimensional, while the latter implies a condition of maximal compression of matter by the formation of an event horizon for Planckian scattering. We generalize such a result to an arbitrary number of dimensions, and show that gravity in higher than four dimensions remains self-complete, but in lower dimensions it does not. In such a way we established an “exclusive disjunction” or “exclusive or” (XOR) between the occurrence of self-completeness and dimensional reduction, with the goal of actually reducing the unknowns for the scenario of the physics at the Planck scale. Potential phenomenological implications of this result are considered by studying the case of a two-dimensional dilaton gravity model resulting from dimensional reduction of the Einstein gravity.

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Primordial black hole evaporation and spontaneous dimensional reduction

2012-09-17

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, (1+1)-D black holes radiate with power View the MathML source, while it is known no (2+1)-D (BTZ) black holes can exist in a non-anti-de Sitter 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.

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Could Any Black Holes be Produced at the LHC?

2012-05-18

We introduce analytical quantum gravity modifications of the production cross section for terascale black holes by employing an effective ultraviolet cutoff l. We find the new cross sections approach the usual “black-disk” form at high-energy, while they differ significantly near the fundamental scale from the standard increase with respect to s. We show that the heretofore discontinuous step function used to represent the cross section threshold can realistically be modeled by two functions representing the incoming and final parton states in a high-energy collision. The growth of the cross section with collision energy is thus a unique signature of l and number of spatial dimensions d. Contrary to the classical black-disk result, our cross section is able to explain why black holes might not be observable in LHC experiments while they could be still within the reach of ultra-high-energy cosmic ray events.

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Detecting Vanishing Dimensions via Primordial Gravitational Wave Astronomy

2011-03-08

Lower dimensionality at higher energies has manifold theoretical advantages as recently pointed out by Anchordoqui et al. [arXiv:1003.5914]. Moreover, it appears that experimental evidence may already exist for it: A statistically significant planar alignment of events with energies higher than TeV has been observed in some earlier cosmic ray experiments. We propose a robust and independent test for this new paradigm. Since (2+1)-dimensional spacetimes have no gravitational degrees of freedom, gravity waves cannot be produced in that epoch. This places a universal maximum frequency at which primordial waves can propagate, marked by the transition between dimensions. We show that this cutoff frequency may be accessible to future gravitational wave detectors such as the Laser Interferometer Space Antenna.

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(1+1)-dimensional entropic gravity

2011-09-07

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.

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Vector unparticle enhanced black holes: Exact solutions and thermodynamics

2010-09-27

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 dH=2dU.

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Differentiating unparticles from extra dimensions via mini-black hole thermodynamics

2009-03-05

A thermodynamics-based method is presented for differentiating mini black hole creation mechanisms in high energy parton collisions, including scenarios with large compactified extra dimensions and unparticle-enhanced gravity with real scaling dimension dU. Tensor unparticle interactions are shown to mimic the physics of (2dU−2) noninteger extra spatial dimensions. This yields unique model-dependent production rates, Hawking temperature profiles, and decay multiplicities for black holes of mass MBH∼1–15  TeV that may be created at the LHC and other future colliders.

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Unparticle-Enhanced Black Holes at the LH

2008-03-06

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 rH are derived, and the corresponding geometric cross-sections of such objects are calculated. It is shown that rH increases dramatically to the electroweak scale for masses MBH∼1–10 TeV, yielding a geometric cross-section View the MathML source on the order of ⩽50 pb. This suggests that unparticle physics provides a mechanism for black hole formation in future accelerators, without the requirement of extra spatial dimensions.

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

2007-05-30

The fractal dimension of large scale galaxy clustering has been reported to be roughly DF~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 a 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, it is shown that because of spatial scale invariance in the matter distribution, 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, on the basis of theoretical considerations of possible universal ΛCDM density profiles.

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Lower-dimensional black hole chemistry

2015-06-12

The connection between black hole thermodynamics and chemistry is extended to the lower-dimensional regime by considering the rotating and charged Bañados, Teitelboim, and Zanelli (BTZ) metric in the (2+1)-dimensional and (1+1)-dimensional limits of Einstein gravity. The Smarr relation is naturally upheld in both BTZ cases, where those with Q≠0 violate the reverse isoperimetric inequality and are thus superentropic. The inequality can be maintained, however, with the addition of a new thermodynamic work term associated with the mass renormalization scale. The D→0 limit of a generic D+2-dimensional Einstein gravity theory is also considered to derive the Smarr and Komar relations, although the opposite sign definitions of the cosmological constant and thermodynamic pressure from the D>2 cases must be adopted in order to satisfy the relation. The requirement of positive entropy implies an upper bound on the mass of a (1+1)−D black hole. Promoting an associated constant of integration to a thermodynamic variable allows one to define a “rotation” in one spatial dimension. Neither the D=3 nor the D→2 black holes exhibit any interesting phase behavior.

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Generalized uncertainty principle and extra dimensions

Sven Köppel, Marco Knipfer, Maximiliano Isi, Jonas Mureika, Piero Nicolini

2017-03-01

The generalized uncertainty principle (GUP) is a modification of standard quantum mechanics due to Planck scale effects. The GUP has recently been used to improve the short distance behaviour of classical black hole spacetimes by invoking nonlocal modifications of the gravity action. We present the problem of extending such a GUP scenario to higher dimensional spacetimes and we critically review the existing literature on the topic.

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Black hole shadows in fourth-order conformal Weyl gravity

Jonas Mureika and Gabriele Varieschi

2016-11-01

We calculate the characteristics of the "black hole shadow" for a rotating, neutral black hole in fourth-order conformal Weyl gravity. It is shown that the morphology is not significantly affected by the underlying framework, except for very large masses. Conformal gravity black hole shadows would also significantly differ from their general relativistic counterparts if the values of the main conformal gravity parameters, γ and κ, were increased by several orders of magnitude. Such increased values for γ and κ are currently ruled out by gravitational phenomenology. Therefore, it is unlikely that these differences in black hole shadows will be detected in future observations, carried out by the Event Horizon Telescope or others such experiments.

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Horizon Wavefunction of Generalized Uncertainty Principle Black Holes

Luciano Manfredi and Jonas Mureika

2016-10-01

We study the Horizon Wavefunction (HWF) description of a generalized uncertainty principle inspired metric that admits sub-Planckian black holes, where the black hole mass m is replaced by M=m(1+β2M2Plm2). Considering the case of a wave-packet shaped by a Gaussian distribution, we compute the HWF and the probability BH that the source is a (quantum) black hole, i.e., that it lies within its horizon radius. The case β0, where a minimum in BH is encountered, thus meaning that every particle has some probability of decaying to a black hole. Furthermore, for sufficiently large β we find that every particle is a quantum black hole, in agreement with the intuitive effect of increasing β, which creates larger M and RH terms. This is likely due to a "dimensional reduction" feature of the model, where the black hole characteristics for sub-Planckian black holes mimic those in (1+1)-dimensions and the horizon size grows as RH∼M−1.

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The Good, the Bad, and the Ugly of Gravity and Information

Gerard 't Hooft, Steven Giddings, Carlo Rovelli, Piero Nicolini, Jonas Mureika, Matthias Kaminski, Marcus Bleicher

2016-09-01

Various contenders for a complete theory of quantum gravity are at odds with each other. This is in particular seen in the ways they relate to information and black holes, and how to effectively treat quantization of the background spacetime. Modern perspectives on black hole evaporation suggest that quantum gravity effects in the near-horizon region can perturb the local geometry. The approaches differ, however, in the time scale on which one can expect these effects to become important. This panel session presents three points of view on these problems, and considers the ultimate prospect of observational tests in the near future.

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Proceedings, 1st Karl Schwarzschild Meeting on Gravitational Physics (KSM 2013) : Frankfurt am Main, Germany, July 22-26, 2013

Piero Nicolini, Jonas Mureika, Matthias Kaminski, Marus Bleicher

2016-01-01

The 2013 Karl Schwarzschild Meeting on Gravitational Physics (KSM) was a top international event involving the worldwide highest qualified scientific personalities in the field of black hole physics, general relativity, and related topics. It featured the participation of 91 scientists from 15 countries over 4 continents. These attendees included undergraduate and graduate students, postdoctoral researchers, as well as junior and senior faculty. We envisioned the foundational spirit of the conference to be: “by acknowledging the past we open a route to the future.” Here “the past” refers to the pioneering black hole studies of Karl Schwarzschild, a native of Frankfurt am Main, who published his first two papers while attending the Frankfurt-Gymnasium (now the Lessing-Gymnasium) in Fürstenbergerstrabe 166 in the late 1880s.

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Horizon of quantum black holes in various dimensions

Roberto Casadio, Rogerio Cavancanti, Andrea Giugno, Jonas Mureika

2016-06-01

We adapt the horizon wave-function formalism to describe massive static spherically symmetric sources in a general (1+D)-dimensional space-time, for D>3 and including the D=1 case. We find that the probability PBH that such objects are (quantum) black holes behaves similarly to the probability in the (3+1) framework for D>3. In fact, for D≥3, the probability increases towards unity as the mass grows above the relevant D-dimensional Planck scale mD. At fixed mass, however, PBH decreases with increasing D, so that a particle with mass m≃mD has just about 10% probability to be a black hole in D=5, and smaller for larger D. This result has a potentially strong impact on estimates of black hole production in colliders. In contrast, for D=1, we find the probability is comparably larger for smaller masses, but PBH3. For D=1 we instead find the uncertainty due to the horizon fluctuations has the same form as the usual Heisenberg contribution, and therefore no fundamental scale exists.

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Black hole thermodynamics in MOdified Gravity (MOG)

Jonas Mureika, John Moffat, Mir Faizal

2016-04-01

We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and rotating black hole solutions resembles similar solutions in Einstein–Maxwell theory with the electric charge being replaced by a new mass dependent gravitational charge Q=αGNM. This new mass dependent charge modifies the effective Newtonian constant from GN to G=GN(1+α), and this in turn critically affects the thermodynamics of the black holes. We also investigate the thermodynamics of regular solutions, and explore the limiting case when no horizons forms. So, it is possible that the modified gravity can lead to the absence of black hole horizons in our universe. Finally, we analyze corrections to the thermodynamics of a non-rotating black hole and obtain the usual logarithmic correction term.

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