[hep-th] Unification of Inflation and Dark Energy from Spontaneous Breaking of Scale Invariance

 By: Unknown    1:11 PM     No comments

Unification of Inflation and Dark Energy This paper proposes a method using two independent non-Riemannian volume forms (integrand of a volume integral) to derive an effective potential for the scalar matter field that is capable of describing both the early universe expansion and dark energy in our universe today. In other words, they are able to derive an effective potential that produces accurate energy densities during...

Numerical Relativity: Black Holes and Gravity - Part 3

 By: Unknown    6:47 PM  Christoffel symbols, deviation equation, Eddington-Finkelstein coordinates, general relativity, gravitational physics, metric, Minkowsky metric, Schwarzschild coordinates, spacetime, special relativity, tensors   No comments

Spacetime The definition of spacetime comes from special relativity. It tells us that different inertial frames have different notions of time. Let's take three Cartesian coordinates (x, y, z). By moving these axes parallel to themselves from some origin, we create new values of x, y, and z. In addition, by moving these coordinates we are creating a notion of time, which is different in each of these inertial frames. This...

Derivation of the Newtonian Deviation Equation

 By: Unknown    6:47 PM  deviation equation, gravitational potential, gravity, Newtonian, spacetime, tensors   No comments

In this derivation, I will use "A General Relativity Workbook" by Thomas A. Moore as a reference. Below are some basic equations that will help guide us towards the derivation. $$\textbf{F}_{grav} = m \textbf{g} = - \left( \frac{GmM}{r^2} \right) \textbf{e}_r = -m \boldsymbol{\nabla} \Phi (\textbf{x})$$ where $\textbf{e}_r$ is the unit vector pointing from the first particle to the other and $\Phi (\textbf{x})$ is the gravitational...

Derivation of the Equation of Geodesic Deviation

 By: Unknown    6:47 PM  Christoffel symbols, deviation equation, Einstein, general relativity, geodesic, gravitational physics, gravity, Riemann curvature, tensors   No comments

Because this derivation is often given as homework in classes that teach relativity, I will not show step-by-step derivations. Instead, I will only show the steps that books tend to give. If you are confident in your use of tensor notation, you shouldn't have a problem filling in the steps. However, it can get extremely messy when it calls for a change in indices. I will again reference "A General Relativity Workbook" by Thomas...

Review and application of group theory to molecular systems biology [part 1]

 By: Unknown    11:05 AM  algebra, biology, biophysics, group theory, translation   No comments

Edward A Rietman, Robert L Karp, and Jack A Tuszynski; Theor Biol Med Model. 2011; 8: 21. Link. ----- My opinion: I love it when physicists stick mathematics where it doesn't belong. This paper is a bit old I know (Elwin wanted recent papers), but I really wanted to read it, and I figured I'd summarize it too while I'm at it for this blog. I'm going to break this up into a few pieces since I want to explain concepts as we go...

Numerical Relativity: Black Holes and Gravity - Part 2

 By: Unknown    9:55 PM  astrophysics, black holes, Einstein, general relativity, gravitational collapse, gravitational physics, gravitational waves, radiation, spacetime   No comments

Einstein's Theory of General Relativity You have probably heard about Einstein's Theory of Relativity. His work on special relativity was published in 1905. This introduced a new framework in physics. He showed that the laws of physics are the same in all non-accelerating reference frame and that the speed of light is constant. This revolutionized different branches of physics and led to his 1915 Theory of General Relativity,...

[hep-ex/th][nucl-ex/th] Motivations behind today's accelerator experiments Part I (General overview)

 By: Unknown    1:27 PM  arxiv, high energy physics, nuclear physics, particle physics   No comments

http://arxiv.org/pdf/1306.5009.pdf Level-Undergraduat...

[hep-th] A Simple Introduction to Particle Physics

 By: Unknown    10:24 AM  arxiv, gauge theory, group theory, hep-th, high energy physics, particle physics, physics, standard model   No comments

A Simple Introduction to Particle Physics This is a wonderfully written paper introducing the topic of particle physics to undergraduates. It approaches the subject leisurely in Part 1 by reviewing some important classical physics concepts. These include Noether's theorem, gauge transformations, and the Classical Electrodynamics Lagrangian $$\mathcal{L_{EM}} = -\frac{1}{4} F_{\mu \nu}F^{\mu \nu} - J^{\mu}A_{\mu}$$ Following...

[math.NT] [hep-th] [math-ph] A theory for the zeros of Riemann Zeta and other L-functions. Part - 1 of 3

 By: Unknown    11:21 PM  general mathematics, general physics, mathematical physics   No comments

http://arxiv.org/abs/1407.4358 Overview: This paper gives a whopping 97 page overview of the Riemann Zeta function, its impact in physics, and how physics could potentially influence the Riemann-$\zeta$ hypothesis! (If you don't know about this, its importance, or history, you should. It is one of the millennium prize problems. See http://en.wikipedia.org/wiki/Millennium_Prize_Problems) I will certainly not be reviewing the...

Numerical Relativity: Black Holes and Gravity - Part 1

 By: Unknown    8:35 PM  gravitational physics, gravity, newton, physics   No comments

Before getting into the gr-qc publications, I would like to give you some information on this field of study. I recommend knowledge of special relativity, but it is not required. These posts will begin at a low level and become a bit more difficult as we go on. If you are already well acquainted with the concepts and the jargon, you are welcomed to skip them and start at the first gr-qc post. What is Gravity and How Do We Think...

[GR-QC] Negative Mass Bu-...Wait, What?

 By: Unknown    4:50 PM  arxiv, black holes, de Sitter space, gravity, news   No comments

Level: Possibly public, supplemented by undergraduate material So I will begin by acknowledging that I am stepping outside my proposed subfield for this blog a little bit, here, but that this is something that I feel I should address...

[q-bio.OT] An Integration of Integrated Information Theory with Fundamental Physics

 By: Unknown    11:42 AM  arxiv, biology, consciousness, psychology   No comments

Submitted to the arXiv by Adam B. Barrett on July 3rd, 2014. http://arxiv.org/abs/1407.4706 http://arxiv.org/pdf/1407.4706.pdf ----- My opinion: This paper rings strongly of a physicist entering psychologists' territory in an attempt to steer the course of consciousness research to one of more physical and fundamental origin. Although no equations nor methods of measurement are provided in this paper, the author extends a theory...

[nlin.AO] What about the birds?

 By: Jeffrey Heninger    11:13 AM  nonlinear dynamics, self-organizing systems, swarming   2 comments

The Role of Projection in the Control of Bird Flocks Pearce, Miller, Rowlands, and Turner Many animals form swarms: cohesive and coherent groups that help individuals gain protection from predators. Some of the most dramatic of these swarms are the murmurations of starlings, shown here. These swarms are usually modeled by assuming that each bird interacts only with a couple of the birds that immediately surround it. These models...

[q-bio.BM] An Introduction to Biomolecular Simulations and Docking -- Mura and McAnany

 By: Unknown    10:15 AM  arxiv, biophysics, computational, molecular dynamics, physics, simulation   No comments

http://arxiv.org/abs/1407.3752 http://arxiv.org/ftp/arxiv/papers/1407/1407.3752.pdf Any arguments with opinions in this post are welcome. I write this as (hopefully) a guide for those interested in the topic but do not want to go head first into the paper. This paper is a wonderful explanation of molecular dynamics as a tool in computational biophysics, and I highly recommend reading it if you are interested in the field. This...