Physical Sciences and Mathematics Commons^™

Light Scattering From Periodic, Conducting Nanostructures, Wesley Kenneth Mills

Undergraduate Honors Capstone Projects

A material with broadband light absorbing capabilities has the potential for much usefulness in devices such as photovoltaics and thermoelectrics. By energy conservation, a non-transparent material with low reflectance will be highly absorbing. Thus, much research has been devoted to understanding what makes material having low reflectance across a wide wavelength spectrum.

The importance of a material’s electronic structure in determining reflectance is well-established. Current research is revealing the additional importance of surface architecture in the reflective properties of a material. A metasurface is a two-dimentional material with physical features at or smaller than the wavelength of light considered. These …

Embedded Charge Distributions In Electron Irradiated Polymers – Pulsed Electroacoustic Method Reproducibility And Calibration, Zachary Gibson, Jr Dennison, Ryan Hoffmann

Physics Student Research

The pulsed electroacoustic (PEA) method has been used to measure the embedded charge distributions in electron irradiated polymers. The PEA method allows for non-destructive direct measurements of embedded charge distributions in dielectric materials. Samples of polyether-etherketone (PEEK) and polytetrafluoroethylene (PTFE) of 125 μm or 250 μm thickness were tested after irradiation with either a 50 keV or 80 keV electron beam. The reproducibility of the PEA method and the experimental conditions were studied by: (i) measuring each sample multiple times in a given mounting configuration, (ii) re-measuring each sample after repositioning them in the PEA test fixture, and (iii) measuring …

Fundamental Aspects Of Black Holes, Jacob Fisher Ciafre

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The literature study here seeks to present the foundations of black hole physics in General Relativity. The report includes a discussion of the Kerr black hole metric, black hole entropy, particle creation, the laws of black hole mechanics, and a bilinear mass formula for the Kerr-Newman black hole solution.

Physics 4900, David Maughan

Physics Capstone Projects

More than a century has passed since Albert Einstein published his general theory of relativity. The theory has been tested many times experimentally, primarily in the relatively weak gravitational fields of the solar system [1,2]. More recently the first experimental results from the strong gravitational fields of two black holes have been measured in the form of gravitational waves, which are another prediction of general relativity. The 2017 Nobel prize in physics was awarded to Kip Thorne, Rainer Weiss, and Barry Barish for their role in the detection of gravitational waves. This year we have seen the first image of …

Collaborative Research: Fundamental Mechanisms Of Microfluidic Traveling-Wave Electrophoresis, Boyd F. Edwards

Funded Research Records

No abstract provided.

Special Relativity, 7, David Peak

Special Relativity

Relativistic electromagnetism

Let’s return to the problem posed at the end of BK2.

Special Relativity, 2, David Peak

Special Relativity

Events not connected by light propagation

Previously, we considered two events (A, with s-t coordinates (x_A, y_A,z_A ,T_A ) = (x^′_A, y_^′A,z^′_A,T ^′_A ) = (0,0,0,0) according to both O and Oʹ [moving relative to O with constant velocity β along the mutual x, x^′ -axes], and B, with coordinates (x_B,0,0,T_B) and (x^′_B,0,0,T^′_B)) connected by a light pulse.

Special Relativity, 5, David Peak

Special Relativity

No abstract provided.

Physics 3710 – Problem Set #4, David Peak

Problems

Physics 3710 – Problem Set #4 Relativistic kinematics, II

Physics 3710 – Problem Set #11, David Peak

Problems

Physics 3710 – Problem Set #11 QED Feynman diagrams

The solid arrows are electrons or positrons, the wavy lines are photons. Describe the “in” and “out” states shown below and describe what happens at each vertex. What is an overall name for each of the diagrams shown? (e.g., “electron-photon scattering”)

Physics 3710 – Problem Set #6, David Peak

Problems

Physics 3710 – Problem Set #6 Relativistic dynamics, II

Problems 1-5 refer to: The mass of the neutron is 1.008664 u and that of the proton is 1.007276 u, where 1 u = 931.5 MeV.

Physics 3710 – Problem Set #9, David Peak

Problems

Physics 3710 – Problem Set #9 Relativistic gravity, II

Rudiments Of Quantum Mechanics (Qm), David Peak

Structure of Matter

Rudiments of Quantum Mechanics (QM)

Structure Of Matter, 8, David Peak

Structure of Matter

Neutrino mass and family mixing

Neutrinos are products of radioactive decay in many stellar fusion processes, primarily starting with the reaction p + p → ²He*→ ²H + e⁺ +ν_e . The nucleus ²He* is a highly unstable (that’s what the * represents) isotope of helium consisting of four primary u quarks and two primary d quarks. For years (since 1962 or so), various groups have been measuring the solar electron-neutrino flux, invariably observing it to be lower than theoretical predictions. Moreover, neutrinos are generated in the upper atmosphere, via collisions of cosmic ray particles …

Structure Of Matter, 2, David Peak

Structure of Matter

Quantum electrodynamics

Quantum electrodynamics (QED) is the quantitatively best physical theory yet developed. Where it has been tested, it agrees with experiment to at least a few parts in 10¹¹! It is a theory of how charged particles and photons interact. It starts with electrons, for example, described by the Dirac Equation, interacting with photons described by a suitable electromagnetic potential energy.

Structure Of Matter, 5, David Peak

Structure of Matter

The quark-gluon plasma

At the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory on Long Island in New York (the only major research accelerator functioning in the US) and the Large Hadron Collider (LHC) at CERN in Switzerland, heavy atoms, stripped of most or all of their electrons, are collided with energies approaching 100-1000 GeV per nucleon. Traveling at nearly the speed of light, these heavy ions are Lorentz contracted into pancake shapes in the laboratory frame of reference and, consequently, have very large quark and gluon densities within the constituent protons and neutrons. The energy density in the …

General Relativity, 1, David Peak

General Relativity

In special relativity, events occur in the arena of space-time which may be coordinatized differently by different observers, but which is otherwise immutable. Adding gravity to relativity provides an amazing result: space-time becomes “organic,” taking its form from the matter and energy it contains. This is Einstein’s general theory of relativity and it has the capacity to tell us about the past and future of the universe. Embedded in the history book of the cosmos are several chapters on the origins of matter. As a result, relativity + gravity unites the structures of matter on the largest and smallest scales.

Inflation (Excel), David Peak

General Relativity

No abstract provided.

General Relativity, 7, David Peak

General Relativity

The expanding universe

The fact that the vast majority of galaxies have a spectral redshift can be interpreted as implying that the universe is expanding. This interpretation stems from the Doppler effect in which the relative motion of an emitter and a detector produces a frequency shift of the detected light with respect to the emitted light.

General Relativity, 8, David Peak

General Relativity

The Cosmic Microwave Background (CMB)

As previously noted, the universe is filled with microwave radiation. The frequency spectrum of this ubiquitous radiation follows a blackbody curve, as shown to the right. (http://map.gsfc.nasa.gov/media/ContentMedia/990015b.jpg) Note that photon energy (proportional to 1/wavelength) increases to the right. You might think the curve shown is the plot of a theoretical equation, but what is shown is actual measured data taken during the flight of the COBE (Cosmic Microwave Explorer) satellite/microwave observatory in 1990. The uncertainties in the measurements are about the thickness of the curve plotted. When compared with a theoretical blackbody curve the disagreement …

General Relativity, 4, David Peak

General Relativity

Orbital motion of small test masses

The starting point for analyzing free fall trajectories in the (2-space, 1-time) Schwarzschild spacetime is Equation (3) from GR 3:

General Relativity, 3, David Peak

General Relativity

Gravity as geometry: part II

Even in a region of space-time that is so small that tidal effects cannot be detected, gravity still seems to produce curvature. The argument for this point of view starts with the recognition that, for mechanical systems, it is impossible to distinguish a frame of reference with a uniform gravitational field from a uniformly accelerating frame that has no gravity. Thus, for example, in a (small) rocket ship with no windows it is not possible to determine whether the weight one reads standing on a scale at the tail of the rocket is due to …

General Relativity, 5, David Peak

General Relativity

No abstract provided.

Background, 2, David Peak

Background

Ordinary, everyday, Galilean/Newtonian relativity

An “event” is something that happens at a point in space, at an instant in time. In physics, relativity means the rules by which two observers can compare and make sense of measurements each makes of the positions and times of the same events. In physics, an observer is not a person or an individual measuring device. Such isolated “detectors” are plagued by experimental issues of parallax, delay times, and so forth. For our purposes, an observer will always mean an infinite collection of rigidly attached, perfect sensors and microprocessors whose internal clocks are perfectly synchronized. …

General Relativity, 6, David Peak

General Relativity

Modern cosmography

The “normal” matter in the universe—i.e., stuff made of protons, neutrons, and electrons— consists, approximately, of lumps floating in a dilute fog. The lumps are galaxies, clusters of 10⁷ to 10¹¹ stars bound together by gravity. In the currently observable universe, it is estimated that there are roughly 10¹¹ galaxies. The dilute fog is primarily neutral atomic hydrogen gas with some helium-4 mixed in (making up a total of 98% or more of the fog); there are also very small fractions of ²H (deuterium), ³He , and ⁷Li . The ratio …

Structure Of Matter, 4, David Peak

Structure of Matter

Antiscreening: The triumph of lattice QCD

QED is a phenomenally accurate theory of the interactions of electrically charged particles with photons. The way interactions are described in QED—by adding electromagnetic potential fields to the energy and momentum operators in the charged particle field equations— is essentially exactly correct given that the detailed calculations that can be made in QED agree so well with observation. These calculations are possible because simple processes (involving small numbers of interaction vertices) are significantly more important than complicated processes. That is, QED is a “perturbative” theory. Higher order QED effects, therefore, invariably consist of small …

History Graph, David Peak

Background

History graph image.

Late History Graph, David Peak

Background

Late History graph image.

Structure Of Matter, 1, David Peak

Structure of Matter

In the hot early universe, prior to the epoch of nucleosynthesis, even the most primitive nuclear material—i.e., protons and neutrons—could not have existed. Earlier than 10–5 s or so after t = 0 , the universe would have been a hot soup consisting of the most elementary of particles—photons, electrons, positrons, neutrinos, quarks, and gluons. We now turn to the,” “Standard Model of Particle Physics,” our current understanding of these elementary building blocks and their interactions. The Standard Model of Particle Physics (SMPP), developed in fits and starts over the past 50 years, is a quantitatively predictive theory of subatomic …

Structure Of Matter, 9, David Peak

Structure of Matter

Beyond the Standard Models

As noted in SM 8 there are problems with the standard model of particle physics that beg for resolution. Indeed, there are significant unknowns concerning the standard model of cosmology as well—for example, what really is “inflation” and what preceded it? The latter suggests the need for the unification of gravity and quantum mechanics. In addition, both models involve bizarre empirical parameters. Why are the elementary particle masses so wildly different? Why are the strengths of the interactions so different? What is dark matter? What is dark energy and why is its density so small? Why …