# Physics

Physics explores the natural world and applies the findings to improve human life. Advances in physics lead to new technologies. Students in physics at Yeshiva College acquire mathematical skills and ways of thinking that support success in many careers. Many of our physics graduates have gone on to earn graduate degrees in physics and engineering. Many others have succeeded in jobs such as law, medicine, engineering, business and finance. The Department of Physics has state-of-the-art laboratory equipment for introductory and advanced experiments in mechanics, electromagnetism, optics, lasers, electronics, quantum and nuclear physics. In addition, the department has an engineering laboratory with 3D printers, lased cutters and tools for machining. A weekly colloquium brings physicists from all over the world to present and discuss their research.

## Mission Statement

The mission of the Yeshiva College Physics Major is to prepare students with a solid foundation of physics and engineering knowledge and skills through their course work and experiences working directly with faculty through scholarly research. Physics Majors acquire expert knowledge on physical principles and scientific, mathematical and critical reasoning skills, which prepare them for success in a diversity of careers including science, law, medicine, engineering, business and finance. In addition, many graduates go on to earn graduate degrees in the field in top graduate departments.

#### Careers in Physics

#### Who is hiring Physics Bachelors?

#### Latest Employment Data for Physicists

## Student Learning Goals

- Understand physical principles behind natural phenomena and their applications.
- Analyze scientific and engineering problems, generate logical hypotheses, evaluate evidence, and tolerate ambiguity.
- Effectively communicate scientific knowledge using their own informed perspectives both orally and in writing.
- Develop the ability to produce computer algorithms and code based on physics principles.

For more information about the Physics Department at Yeshiva College, please contact Professor Zypman at zypman@yu.edu or 212.960.3332.

## Program Information

Please see the Schedule of Classes for the current semester’s offerings.

**PHY 1051R, 1052R, General Physics—Lectures**

4 credits

Introduction to Newtonian mechanics for particles, systems of particles (in particular rigid bodies). Notions of fluid mechanics and elasticity. The physics of waves and geometrical and physical optics. Gravitation. Electricity and magnetism. Circuits of resistors, capacitors, and inductors. Transformers. Maxwell’s equations. Elements of Thermodynamics. Optics and Waves. Relativity Theory. Elements of Quantum Mechanics

Lecture: 4 hours; Recitation: 1 hour.

Prerequisite for PHY 1051R: MAT 1412- Corequisite for PHY 1051R: PHY 1051L

Prerequisite for PHY 1052R: PHY 1051R.

Corequisites for PHY 1052R: MAT 1413 and PHY 2061L

Prerequisite for PHY 2051R: PHY 1052R

Prerequisite for PHY 2052R: PHY 2051R **PHY 1051, 1052 General Physics—Laboratories**

1 credit

Laboratory experiments designed to complement the principles covered in PHY 1041R–1042R. Covers mechanics, heat, optics, elasticity, electricity, circuits, and magnetism. (2 hours)

Laboratory fee: $40.

Corequisite: PHY 1051R, PHY 1052R.**PHY 2051R General Physics—Lectures**

4 credits

Introduction to normal modes in discrete and continuous systems, linearization, basic Fourier analysis, and applications. Traveling waves on strings, sound waves, introduction to electromagnetic waves. Wave reflection, refraction, and partial transmission. Doppler effect. Waves on transmission lines and characteristic impedance. Group velocity, pulses, wave packets, Fourier integral, bandwidth theorem. Elements of geometrical optics. Fermat’s principle. Physical optics: interference, diffraction, limit of resolution, applications.

Prerequisites: PHY 1051, PHY 1052.

Corequisite: MAT 1510.**PHY 2052 General Physics—Lectures**

4 credits

Einstein’s theory of relativity. Time dilation and length contraction. E=MC2. The great experiments that shaped last-century physics. Blackbody radiation. The basis of kinetic theory. Quantum theory and Bohr’s model of the atom. Waves of matter, wave-particle duality, and the uncertainty principle. Schrödinger’s equation.

Prerequisites: PHY 1051, PHY 1052.

**Physics 1031 and 1032 not for Physics and Engineering:****PHY 1031R, 1032R Introductory Physics—Lectures**

4 credits

Algebra-based, two-semester introduction to mechanics, electromagnetism, waves, optics, and thermodynamics.

Lecture: 4 hours; Recitation: 1 hour.

Corequisite: PHY 1031L, PHY 1032L.**PHY 1031L, 1032L Introductory Physics—Laboratory**

1 credit

Algebra-based version of PHY 1041L–1042L. (2 hours)

Laboratory fee: $40.

Corequisite: PHY 1031R, PHY 1032R.**PHY 1036 Physics Problems for Pre-Health**

1 credit

Complement to PHY 1031–1032. Topics include optics, fluid mechanics as related to the health sciences.

Prerequisites: PHY 1031, PHY 1032.

**PHY 5221 Classical Mechanics**

3 credits

Particle motion in space, time, or velocity-dependent potentials. Damped and driven oscillations, resonances. Elements of nonlinearity and chaos. Noninertial reference systems. Motion relative to the Earth. Central forces. Planetary motion. Stability of orbits.

Prerequisites: PHY 1041, PHY 1042.

Corequisite: MAT 1510.**PHY 5222 Advanced Mechanics**

3 credits

Systems of particles. Variable mass. Collision theory. Lagrangian mechanics. Constraints. Variational calculus and Hamilton’s equations. Rotations of rigid bodies in two and three dimensions. Euler’s equations. Tensor analysis. Small coupled oscillations and normal coordinates. Fluid mechanics. Viscosity. Relativistic mechanics.

Prerequisites: PHY 1041, PHY 1042, MAT 1510

Recommended: MAT 2105, PHY 1221.**PHY 5321 Electromagnetic Theory**

3 credits

Review of vector calculus. Electro- and magnetostatics, multipole expansions, time-dependent fields. Development of Maxwell’s equations. Laplace and Poisson equations, boundary value problems. Electromagnetic wave equation, plane waves in a vacuum. Poynting vector, “blue sky law.” Microscopic and phenomenological theories of dielectric and magnetic materials. Resistors, capacitors, inductors, and their uses in circuits, transformers; generalized forces on charges in electro-magnetic fields.

Prerequisite: PHY 1042 (or PHY 1032 with permission of the instructor).

Corequisite: MAT 1510.**PHY 5322 Electromagnetic Theory II**

3 credits

Relativistic transformation of fields and covariance of Maxwell’s equations. Polarizability tensor, electrodynamics in matter. Electromagnetic radiation by accelerating charges; Lienard-Wiechert potentials, multipole radiation, bremsstrahlung, synchrotron radiation, applications to astrophysical sources. Antennas. Electromagnetic wave propagation in matter. Electromagnetic basis of physical optics. Fresnel equations, Kirchoff diffraction theory. Wave-guides and cavity resonators.

Prerequisite: PHY 1321.**PHY 5401 Introduction to Solid State Physics**

3 credits

A survey of the properties of condensed matter. Classification of crystalline lattices. Elements of crystallography. Cohesive forces in solids. Vibrations of crystals phonons. Debye and Einstein theories of phonons and thermal conductivity. Free electron theory of metals. Bloch states and band theory. The Fermi surface. Semiconductors.Survey of advanced topics: excitations in lattices (plasmons and polarons), superconductivity, magnetic materials and models, theory of crystalline defects and alloys.

Prerequisite: PHY 1120.**PHY 5510 Elements of Thermodynamics and Statistical Mechanics**

3 credits

The laws of thermodynamics. Entropy. Equations of state. Phase transitions. Thermodynamic potentials. The Third Law. Distribution functions. Theory of ensembles. Statistical formulation of temperature. Quantum and classical ideal gasses. Electronic conductance. Bose-Einstein statistics: phonons, Planck’s Law, Bose condensation.

Prerequisites: PHY 1041, PHY 1042.**PHY 5520 Advanced Statistical Mechanics**

4 credits

Gibbs theory of ensembles. Quantum statistics. Superfluidity. Quantum transport. Virial expansions. Magnetic systems and the Ising model. Theory of phase transitions. Ideas of the renormalization group. Random walks, accretion and percolation phenomena. Complexity and self-organization. Nonequilibrium statistical mechanics. Boltzmann’s equation.

Prerequisite: PHY 1510.**PHY 5621 Quantum Mechanics**

3 credits

Wave-particle duality. Operators. Commutation relations. Solutions of Schrödinger’s equation in one dimension for square well and barrier potential, harmonic oscillator, and rigid rotator with fixed axis; dynamics of non-monochromatic free particles. Observables, expectation values, uncertainty relations; wave packets. Applications to quantum wells and superlattices, molecular beam epitaxy and scanning probe microscopy.

Prerequisite: PHY 1120.**PHY 5622 Advanced Quantum Mechanics**

3 credits

Perturbation theory, approximations; solution of Schrödinger’s equation for the hydrogen atom; Angular momentum. Addition of angular momentum. Clebsch-Gordon coefficients. Pauli exclusion principle, electron spin; atomic spectroscopy and second quantization. Elements of quantum field theory.

Prerequisite: PHY 1621.**PHY 5724 Electronics**

3 credits

Electronic devices and their use in power supplies, audio and radio frequency amplifiers, operational amplifiers, and instrumentation circuits. Electrochemical and biomedical applications; generation, processing, and analysis of signal waveforms related to speech, music, optical, and biophysical phenomena, and radio and television broadcasting.

Prerequisite: PHY 1032 or PHY 1042R&L.**PHY 5810 Advanced Experimental Physics I**

3 Credits

Experimental projects relevant to modern experimental physics and engineering. Covers the fields of mechanics, analog communication electronics, transmission lines and wave-guides, physical and fiber optics, atomic spectroscopy, nuclear statistics, nuclear spectroscopy, interferometer, and laser physics. Recent examples: impedance divider, gravitational acceleration, thermocouple junction, microwave optics, mechanical phonons, Millikan’s experiment, dielectric constant of water, Stephan-Boltzmann law, radioactivity and Poisson statistics, Michelson interferometer.

Lecture: 1 hour; Lab: 3 hours.

Laboratory fee: $50.

Prerequisites: PHY 1041, PHY 1042 or (PHY 1031, PHY 1032 and permission of the instructor).**PHY 5830 Advanced Experimental Physics II**

A selection of independent projects designed to prepare students for contemporary research in physics. Recent examples: statistics of discharges, temperature dependence of conductivity, Einstein temperature, and the Hall effect. (Lab: 4 hours) Laboratory fee: $50 per semester.

Prerequisites: PHY 1810**3 Credits****PHY 5255R, 5256R + PHY 5255L, 52256L Biophysics—Lectures & Laboratory**- Thermodynamics of the body, pressure, hemodynamics, nerve cells, transmission of signals, electrocardiography, transport phenomena, diffusion, osmosis, radiation, production and use of X-rays, nuclear medicine, physics of the eye and ear, exponential growth and decay, measurement, instrumentation.

Experiments to accompany Biophysics—Lecture. (2 hours)

Laboratory fee: $50.

Prerequisites: PHY 1041, PHY 1042, BIO 1011R, BIO 1012R.

**Note: You MUST sign up for both classes to be allowed in these courses.** **2 + 1 credits****PHY 5601, 5602 Special and General Relativity**

3 credits

Einstein’s special and general theories of relativity; underlying physical and mathematical concepts; formulation of Einstein’s theory of gravitation; mathematical structure, observational tests, exact and approximate methods of solution; problem of gravitational radiation; theory of motion of ponderable bodies.

Prerequisites: PHY 1120, PHY 1221.**PHY 5301 Computational Methods in the Physical Sciences**

3 credits

Basic use of symbolic logic software and exploration of different areas of physics through numerical and computational techniques, including random-walk models, accretion phenomena, Monte Carlo methods in statistical physics, cellular automata, complexity, chaos, and planetary motion. Methods of interpolation, rates of convergence, projection methods, boundary problems and singular perturbation methods.

Prerequisites: PHY 1041, PHY 1042.

Recommended: COM 1300.**PHY 4911 Research in Physics**

Variable credits

Independent individual research projects done under the guidance of a physics faculty member.**PHY 4933 Topics in Physics**

2 credits

Analysis of biological phenomena from a physical perspective. Topics include diffusion of macromolecules, self-assembly of amphiphiles, molecular machines and protein crystallization.

Basic techniques underlying the foundations of medical imaging. Reconstruction imaging by absorption (X-rays) and transmission (MRI). Radon transform. Complementarity between CAT scan and magnetic resonance imaging. Positron emission tomography. Side effects of imaging fields: artifacts and heating. Description of model building: phantoms.

Prerequisites: PHY 1041, PHY 1042 or permission of the instructor.

**PHY 1021R The Physical Universe**

2 credits

Interdisciplinary course for non-science majors, emphasizing the main ideas in astronomy and the physics of motion, light, heat, and electricity. Not open to students who have completed any college course in physics.

Corequisite: PHY 1021L.**PHY 1021L The Physical Universe Lab**

1 credit

Laboratory experiments designed to help students master the principles covered in PHY 1021. (2 hours)

Laboratory fee: $40.

Corequisite: PHY 1021R.**PHY 1024C Great Ideas and Experiments in Modern Physics**

3 credits

Oriented toward non-science students, explores the great ideas that shaped physics during the early part of the 20th century: the theory of relativity and the quantum revolution. Hands-on experiments investigate the ideas of particle creation and destruction, nuclear reactions, magnetic resonance, atomic structure, and crystallography.**PHY 1026R Introduction to Astronomy: Planets**

2 credits

History of astronomy; early models of the universe. The Copernican Revolution and the Newtonian Universe. The solar system, from terrestrial and Jovian planets to comets and asteroids. Possibility of organic life elsewhere in the solar system and beyond. Future evolution of our planetary system. Recently discovered planetary systems around other stars.

Corequisite: PHY 1026L.**PHY 1026L Introduction to Astronomy: Planets—Laboratory**

1 credit

Hands-on experiments and computer simulations illustrating concepts introduced in the course. Observations of planets, stars, galaxies, and nebulae with the university’s 12-inch telescope.

Laboratory fee: $50.

Corequisite: PHY 1026R.**PHY 1027R Introduction to Astronomy: Stars**

2 credits

Birth, life, and death of stars: from proto-stars, main sequence, red giant stages to white dwarfs, neutron stars, and black holes. The Milky Way galaxy. Evolution of galaxies and their types. Hubble law and expansion of the universe. Big bang and inflation theory.

Corequisite: PHY 1027L.**PHY 1027L Introduction to Astronomy: Stars—Laboratory**

1 credit

Hands-on experiments and computer simulations illustrating concepts introduced in the course. Observations of planets, stars, galaxies, and nebulae with the university’s 12-inch telescope.

Laboratory fee: $50.

Corequisite: PHY 1027R.**PHY 1028R Environmental Physics**

2 credits

Discusses how relatively cheap energy shapes modern life—and causes many problems. Fossil fuels (power plants, cars), nuclear energy, solar energy, eolic and hydroelectric plants. Related environmental issues in the world, our homes, and workplaces.

Corequisite: PHY 1028L.**PHY 1028L Environmental Physics—Laboratory**

1 credit

Experiments involving making measurements and analyzing data that are relevant to the different topics of the course.

Laboratory fee: $40.

Corequisite: PHY 1028R.**PHY 4991 or 4991H The New Physics and Astronomy**

3 credits

Review of the new problems and areas that have reshaped physics in the last 30 years: theory of chaos, the quark and the Standard Model, the new cosmology, and the inflationary universe. Physics of scales and the renormalization group. The quantum fluids and superconductivity and superfluidity. The new theory of complexity, quantum transport.

Prerequisites: PHY 1041, PHY 1042, PHY 1120 or permission of the instructor.

### Physics Major: 53 Credits

#### Required Physics Courses (32 credits)

- PHY 1051R, General Physics 1 Lecture,
*Fall* - PHY 1052R, General Physics 2 Lecture,
*Spring* - PHY 1051L, General Physics 1 Lab,
*Fall* - PHY 1052L, General Physics 2 Lab,
*Spring*- 1 Credit - General Physics 1 and 2 Laboratory and Lecture are bundled (4 credits each). The courses also include each a mandatory recitation (0 credits).
- PHY 2051R, General Physics 3 Lecture,
*Fall*- 4 credits - PHY 2052R, General Physics 4 Lecture,
*Spring*- 4 Credits - PHY 5321, Electromagnetic Theory - 3 Credits
- PHY 5221, Classical Mechanics - 3 Credits
- PHY 5810, Advanced Physics Lab - 3 Credits
- PHY 5510, Statistical Thermodynamics - 3 Credits
- PHY 5621, Quantum Mechanics - 3 Credits
- PHY 4935, Physics Colloquium - 1 Credit
- PHY 2550, Physics Computer Programming, 3 Credits (Can be replaced by the elective Computational Physics/Engineering ENGR/PHY 5301)

#### Required Math Courses (12 credits)

- MAT 1412, Calculus 1 - 4 Credits
- MAT 1413, Calculus 2 - 4 Credits
- MAT 1510, Multivariable Calculus - 4 Credits

#### Physics Electives (6 credits)*

*Up to 12 credits can be used towards an MA in physics at YU. Students interested in this option need to make an appointment with an academic advisor as soon as possible and make sure to register for classes with the 5000 code.

NOTE: Courses within any given major or minor require a grade of a “C-“ or better to fulfill its requirement

### Physics Minor (22 Credits)

#### Required Physics Courses (16 credits)

- PHY 1051R, General Physics 1 Lecture,
*Fall* - PHY 1052R, General Physics 2 Lecture,
*Spring* - PHY 1051L, General Physics 1 Lab,
*Fall* - PHY 1052L, General Physics 2 Lab,
*Spring*- 1 Credit - General Physics 1 and 2 Laboratory and Lecture are bundled (4 credits each). The courses also include each a mandatory recitation (0 credits).
- PHY 2051R, General Physics 3 Lecture,
*Fall*- 4 credits - PHY 2052R, General Physics 4 Lecture,
*Spring*- 4 credits - Two electives - 6 credits

**Pre-Engineering/Physics Requirements Major: 53 Credits**

#### Required Physics and Engineering Courses (32 credits)

- PHY 1051R, General Physics 1 Lecture,
*Fall* - PHY 1052R, General Physics 2 Lecture,
*Spring* - PHY 1051L, General Physics 1 Lab,
*Fall* - PHY 1052L, General Physics 2 Lab,
*Spring*- 1 Credit - General Physics 1 and 2 Laboratory and Lecture are bundled (4 credits each). The courses also include each a mandatory recitation (0 credits).
- PHY 2051R, General Physics 3 Lecture,
*Fall*- 4 Credits - PHY 2052R, General Physics 4 Lecture,
*Spring*- 4 Credits - ENGR 5321, Electromagnetic Theory - 3 Credits
- ENGR 5221, Classical Mechanics - 3 Credits
- ENGR 5810, Advanced Physics and Engineering Lab - 3 Credits
- ENGR 5510, Statistical Thermodynamics - 3 Credits
- ENGR 5621, Quantum Engineering - 3 Credits
- PHY 4935, Physics Colloquium - 1 Credit
- ENGR 2550, Physics Computer Programming, 3 Credits (Can be replaced by the elective Computational Physics/Engineering ENGR/PHY 5301)

**Required Math Courses (12 credits)**

- MAT 1412, Calculus 1 - 4 Credits
- MAT 1413, Calculus 2 - 4 Credits
- MAT 1510, Multivariable Calculus - 4 Credits

#### Physics/Pre-Engineering Electives (6 credits)*

*Up to 12 credits can be used towards an MA in physics at YU. Students interested in this option need to make an appointment with an academic advisor as soon as possible and make sure to register for classes with the 5000 code.

NOTE: Courses within any given major or minor require a grade of a “C-“ or better to fulfill its requirement

The following list includes faculty who teach at the Beren (B) and/or Wilf (W) campus.

- Neer Asherie

Professor of Physics and Biology (Wilf) - Sergey Buldyrev
- Professor of Physics Emeritus
- August Krueger
- Instructor in Physics (Wilf)
- Gabriel Cwilich

Professor of Physics (Wilf)

Mark Edelman - Clinical Associate Professor of Physics (Beren and Wilf)
- Emil Prodan
- Professor of Physics (Beren)
- Chair, Department of Physics, Stern College
- Fredy Zypman

Professor of Physics (Wilf)

Chair, Department of Physics, Yeshiva College

Please note: Links to external sites are offered as a convenience to visitors, as a starting point for exploration. Such sites are neither endorsed nor regulated by Yeshiva University, which accepts no responsibility for their content.

### Research

- Physics World
- Physical Review Focus

Selections from*Physical Review*and*Physical Review Letters*explained for students and researchers in all fields of physics. - Physics Central

From the American Physical Society.

### Internships

- National Science Foundation Research Experience for Undergraduates
- Association for the Exchange of Students for Technical Experience
- Oak Ridge Institute for Science and Education

Fellowships, scholarships, and research experiences for students at various stages of their academic careers. - DAAD Exchange Program for American Students

Provides stipends for US students to spend a summer conducting research at a German university or research institute.

### Graduate Study

- Physics GRE (PDF)
- Practice booklet and detailed information from ETS.

### Careers

### News and Organizations

- PhysOrg.com

Science and technology news. - American Institute of Physics
- American Association of Physics Teachers (AAPT)
- American Physical Society (APS)
- National Science Foundation (NSF)
- Society of Physics Students

## Colloquia

### Percolation and Epidemiology

**Dr. Robert Ziff**

Center for the Study of Complex Systems and

Department of Chemical Engineering

University of Michigan

In this talk, I review the percolation model, which goes back to the 1950’s but is closely connected to polymerization theory and branching theory that goes back further. Percolation is the process of long-range connectivity or cluster formation through multiple links, generally in randomly connected systems or networks. When there is a sufficient number of connections, the connectivity becomes infinite in size and the percolation threshold is reached. Finding that percolation threshold has been a longstanding challenge both theoretically and numerically. The behavior near the percolation transition satisfies scaling behavior similar to other models such as the Ising model near the critical point, with universal critical point exponents and functions. These will be discussed. There is a close connection between percolation and epidemiology, and some epidemiological models, such as the SIR (susceptible-infected-recovered) model, maps exactly. In this talk we will discuss how having long-range percolation affects the spread of a disease and the basic reproduction number R in an epidemic.

### Additional Colloquia: Spring 2024

- Alexander Khanikaev, Physics Department, Queens College
- Pouyan Ghaemi
- Ignacio Pascual
- Lev Ostrovsky

### Systems with Power-law Memory and Fractional Attractors

**Mark Edelman (Yeshiva University / New York University)**

Abstract: Systems with power-law memory appear in many areas of science (physics, biology, psychology, …), engineering applications (material with memory),and they are used in control. We investigated a relatively simple but still general model of such systems. In the case of discrete systems this model is equivalent to a difference equation with coefficients which are fractional/integer Eulerian numbers. In the continuous limit this equivalence leads to the equivalence of differential equations with Grunvald-Lentnikov fractional derivatives and integral Volterra equations of the second kind. This analysis allows to derive new properties of fractional Eulerian numbers.

We investigated behavior of nonlinear discrete systems with power-law memory in the case of harmonic (standard map) and quadratic (logistic map)nonlinearities. In addition to sinks and chaotic attractors which appear in regular dynamics systems with memory demonstrate new type of attractors– cascade of bifurcations type trajectories (CBTT). In CBTT a trajectory first converges to a fixed point, then this fixed point abruptly turns into a period-2 sink, then to period-4, and so on without any changes in map parameters. Bifurcation diagrams of systems with power-low memory depend on two parameters: the nonlinearity parameter and the memory parameter (exponent in a power-law). This may allow additional control of the corresponding biological, psychological, social systems, in which bifurcations can be caused by manipulating a memory parameter.

### Simulations of liquid bridge trapped in different geometries

**Alexandre Almedia (Universidade de São Paulo)**

A small amount of liquid trapped between two solid surfaces due to capillary forces is called a liquid bridge. Liquid bridges can be found in different situations, for example, in the liquid phase sintering process, in atomic force microscopy in an environment with humidity, and also in the course of certain lung diseases. We are studying liquid bridges in these three situations using Monte Carlo or molecular dynamic simulations. We explore the effect of the solid-liquid contact angle and the distance between of the solid surfaces on the stability of the bridge. We compare the profile the of the bridge and in the force applied from the bridge on the solid surfaces, with the prediction of the classical theory based on the minimization of the surface energy. We find that the classical theory gives a good approximation even at nanoscales when the bridge consists of a few thousand molecules.

### Coherent propagation of waves: Theory and some applications

**Gabriel Cwilich (Yeshiva University)**

Abstract: When a wave propagates in an environment interacting with randomly placed scatterers in such a way that the collisions are elastic and the phase of the wave is preserved, new phenomena appear due to the interference between the different paths through which the wave moves through the medium, and deviations from the classical diffusion of waves can be expected. In this talk I will review the origin and consequences of these coherence effects, and we I discuss in detail these effects in the case of the fluctuations and correlations of the intensity of the wave. I will also propose, based on these effects, a new microscopy tool to image objects in a turbid medium, at distances below the wavelength of the signal: “speckle contrast microscopy"

### Force Reconstruction and Applications of Atomic Force Microscopy

**Fredy Zypman (Yeshiva University)**

Abstract: Force reconstruction algorithms for Atomic Force Microscopy need to pay more attention to the spurious forces than to the desired ones. Since most current applications of Atomic Force Microscopy happen in liquid environment, notably salty water, a good understanding of the effects of liquid on the dynamics of the AFM sensor is critical. This involves hydrodynamics, but also electrostatics effects peculiar to the liquid state. Once those effects are understood and removed, one can convert experimental signal into desired forces, for example charge-charge and or charge-dipole interactions which ultimately are related with the behavior of the system under study. For example one may be interested in understanding self-assembly of molecular chains. Work supported in part by NASA GRC-RXN0.

- P.B. Abel, S.J. Eppell, A.M. Walker, F.R. Zypman, Viscosity of liquids from the transfer function of microcantilevers, Measurement 61, (2015) Pages 67-74
- J. Mehlman and F.R. Zypman, Scanning Probe Microscope Force Reconstruction Algorithm via Time-Domain Analysis of Cantilever Bending Motion, J. Adv. Microsc. Res. 9, 268-274 (2014)
- Paul Creeger, Fredy Zypman, Entropy Content During Nanometric Stick-Slip Motion, Entropy 16 (2014) 3062-3073
- F.R. Zypman, S.J. Eppell, Electrostatic Force Curves in Finite-Size-Ion Electrolytes, Langmuir, 29 (2013) 11908–11914

### Photonic topological insulators: from theory to practical realization

The past three decades have witnessed the discovery of the Quantum Hall Effect (QHE), Quantum Spin Hall Effect (QSHE) and Topological Insulators (TIs) and transformed our views on the quantum states of matter. These exotic states are characterized by insulating behavior in the bulk and the presence of the edge states contributing to charge or spin currents which persist even when the edge is distorted or contains impurities. In the last few years, a number of research groups have realized that the same "robust" conducting edge states can be implemented in photonic systems. An early theoretical prediction [1, 2] and experimental demonstration [3] of the topologically protected light transport opened a new direction in photonics. In this talk I will review development of this field with focus on photonic topological insulators with preserved time-reversal symmetry that we have recently proposed to implement with the use of bianisotropic metamaterials [4]. I will present new designs of photonic topological insulators based on waveguide geometries that can be readily implemented at microwave frequencies and will discuss perspectives for applications. I will show that photonic topological insulators offer an unprecedented platform for controlling light: deliberately created distribution of the bianisotropy, playing the role of the effective magnetic field, allows routing of photons along arbitrary pathways without significant loss or backscattering [5].

[1] F. Haldane and S. Raghu, Phys. Rev. Lett. **100**, 13904 (2008).

[2] Z. Wang, Y. D. Chong, J. D. Joannopoulos, and M. Soljačić, Phys. Rev. Lett. 100, 013905 (2008).

[3] Z. Wang, Y. Chong, J. D. Joannopoulos, and M. Soljacic, Nature **461**, 772 (2009).

[4] A. B. Khanikaev, S. H. Mousavi, W.-K. Tse, *et al.*,Nature Mater. **12**, 233 (2013).

[5] A. B. Khanikaev, Nature Photon. **7**, 941 (2013).

### Structure of Singularities in Black Holes and the Big Bang

**Edward Belbruno, Princeton University / Innovative Orbital Design**

A new approach is described on studying the dynamical structure of the gravitational singularity in the big bang. This is accomplished, in part, by a McGehee regularization map. Current work by the speaker and BingKan Xue is discussed which addresses realistic physical modeling. A surprising condition is derived, necessary for resolution, the big bang and extending solutions through it. This methodology, in part, was applied in an earlier work with Frans Pretorius for Schwarzschild black holes.

### Dynamical Cell Complexes: Evolution, Universality, and Statistics

**Emanuel Lazar, University of Pennsylvania**

Many natural structures are cellular in nature -- soap foams, biological tissue, and polycrystalline metals are but a few examples that we frequently encounter in everyday life. In many of these systems, energetic factors force the geometry and topology of these structures to evolve in a continuous manner that drives the system towards more stable configurations. We use computer simulations to study how mean curvature flow shapes cell structures in two and three dimensions and consider how this can be measured in a statistical manner. This research lightly touches on discrete geometric flows, combinatorial polyhedra and their symmetries, and the quantification of topological features of large cellular systems.

### Can one melt a crystal by cooling at constant pressure?

**Ivan Saika-Voivod, Memorial University of Newfoundland**

### A metallic glass that grows from the melt like a crystal

**Gabrielle Long, X-ray Science Division, Argonne National Laboratory**

When a molten material is cooled, it typically grows into orderly crystls. But if the cooling rate is too fast for the entire melt to crystallize, the remaining material ends up in a non-crystalline state known as a glass. This talk is about the discovery and characterization of a unique metallic glass that, during rapid cooling, forms a solid by means of nucleation followed by growth normal to a moving interface between the solid and melt, with partitioning of the chemical elements. We were able to show experimentally that this is not a polycrystalline composite with nanometer-sized grains, and conclude that this may be a new kind of structure: an atomically ordered, isotropic, non-crystalline solid, possessing no long-range translational symmetry. This novel structure-isotropic with infinite rotational symmetry and no translational symmetry-is considered theoretically possible, but has never before been observed.

### Non-equilibrium statistical physics, population genetics and evolution

**Marija Vucelja, Rockefeller (Mark)**

I will present a glimpse into the fascinating world of biological complexity from the perspective of theoretical physics. Currently the fields of evolution and population genetics are undergoing a renaissance, with the abundance of accessible sequencing data. In many cases the existing theories are unable to explain the experimental findings. The least understood aspects of evolution are intrinsically quantitative and statistical and we are missing a suitable theoretical description. It is not clear what sets the time scales of evolution, whether for antibiotic resistance, emergence of new animal species, or the diversification of life. I will try to convey that physicists are invaluable in framing such pertinent questions. The emerging picture of genetic evolution is that of a strongly interacting stochastic system with large numbers of components far from equilibrium. In this colloquium I plan to focus on the dynamics of evolution. I will discuss evolutionary dynamics on several levels. First on the microscopic level - an evolving population over its history explores a small part of the whole genomics sequence space. Next I will coarse-grain and review evolutionary dynamics on the phenotype level. I will also discuss the importance of spatial structures and temporal fluctuations. Along the way I will point out similarities with physical phenomena in condensed matter physics, polymer physics, spin-glasses and turbulence.

### The Search for Higher Symmetries in Nature

**Sultan Catto, Baruch College (Amish)**

Symmetry is a wide-reaching concept that has been used in a variety of ways in physics. Originally it was used mainly to describe the arrangement of atoms in molecules and crystals (geometric symmetries). Over the course of the past century it has been considerably extended, covering some of the most fundamental ideas in physics. This talk will center on the role played by the new symmetry principles and their consequences.

**Dr. Philip Kim, Dept. of Physics, Columbia University **

### Transformations in supercooled liquids

**Austen Angel, Arizona State University
With participation of Martin Goldstein, Yeshiva University**

### What dimensionality does to crystals: The new 2D crystals

**Dr. Osgood, Dept. of Applied Physics and Electrical Engineering, Columbia University**

Two-dimensional crystals present new physical phenomena and materials properties. These ideas have excited a wide range of pure and applied physicists. In our talk we will illustrate these intriguing properties by examples from our research in graphene and the metal dichalcogenides, as well as others in the field and show how dimensionality affects both the structural and electronics properties of these materials. Typically these crystals are prepared by either exfoliation or CVD growth. Our analysis is based on either high-energy/momentum resolution probes or via ultrafast time-resolved photoemission. In one example, for MoS_{2} there is an evolution in band structure with layer number; that is, there is an indirect-to-direct bandgap transition in going from few-layer to monolayer MoS_{2} crystals due to changes in quantum confinement as the number of layer decreases. In addition it has strong strong spin-orbit-coupling-induced split valence bands due to broken inversion symmetry, which makes it interesting for spin-physics exploration. One of the consequences of this evolution is a decrease in dispersion of the valence band at in monolayer MoS_{2}, thus leading to a dramatic increase in the hole effective mass.

### Self-regularisation in systems with long-range interactions.

**Xavier Leoncini, Centre de Physique Théorique, Aix-Marseille University**

Dynamics of many-body long-range interacting systems is investigated, using the XY-Hamiltonian mean-field model as a case study. We show that regular trajectories, associated with invariant tori of the single-particle dynamics emerge as the number of particles is increased. Moreover, the construction of stationary solutions as well as studies of the maximal Lyapunov exponent of the systems show the same trend towards integrability. This feature provides a dynamical interpretation of the emergence of long-lasting out-of-equilibrium regimes observed generically in long-range systems. Extension beyond the mean-field system is considered and display similar features. At the end of the talk I will consider the influence of the topology, and show that some state with infinite susceptibility can emerge.

### Coherence, Decoherence, and Incoherence in Natural Light Harvesting Systems

**Paul Brumer, Department of Chemistry, University of Toronto**

Abstract: A number of 2D Photon Echo experiments have shown the presence of long-lived coherences in light harvesting systems, such as FMO and PC645. Such studies have led to conjectures about the role of quantum coherences in biology, leading to arguments in favor of "quantum biology." However, experiments of this kind involve excitation with coherent laser sources, whereas nature irradiates with essentially incoherent sunlight/moonlight. We discuss the differing responses of molecular systems to coherent vs. incoherent excitation in both open and closed quantum systems, demonstrating that the experimentally observed coherences, although revealing features of the system Hamiltonian and of the system-bath interactions, do not argue for quantum coherent evolution in nature.

### Demonstrations of Photo-induced Magnetism in Metallic Nanocolloids Uusing Sunlight and Fridge Magnets

**Luat Vuong, Queens College, CUNY**

Abstract:The focus of this talk is on nonlinear plasmonic vortex dynamics, which are far from understood and lead to appreciable photo-induced magnetic fields in metallic nanostructures. We have recently experimentally, analytically and numerically demonstrated the nonlinear photo-induced plasmon-assisted magnetic response that occurs with 80-nm gold particles in aqueous solution. The anomalously large magnetic response-theoretically considered too small to observe at room temperature- was observed using light from a solar simulator and small (micro-to-milli-Tesla) magnetic fields. I will explain why the effect is observable using disperse nanocolloidal liquids and present our theoretical model of an increased and anisotropic electrical conductivity, which yields modified absorption spectra in agreement with our experimental results.

This work, which is the first nano-demonstration of old physics, improves our fundamental understanding of surface charges in nanostructures and aids the development of broad-band photonics metamaterials, new polarization-encoded imaging methods, photocatalytic materials, photovoltaic devices, and sensors.

### Structural and Dynamical Aspects of Networks: Some New Results

**Bala Sundaram, University of Massachusetts, Boston**

Abstract: The talk addresses two aspects of our work where I will first discuss a new mechanism for generating networks with a wide variety of degree distributions. The idea is variation of the well-studied preferential attachment scheme in which the degree of each node is used to determine its evolving connectivity. Though modifications to this base protocol, involving features other than connectivity have been considered, schemes based on preferential attachment in any form require substantial information about the network. We propose instead a parsimonious protocol based only on a single statistical feature which results from the reasonable assumption that the effect of various attributes, which determine the affinity of each node to other nodes, is multiplicative. This composite attribute or fitness is then used in forming the complex network. It is shown that, by varying a single statistical parameter, we can recover all known degree distributions. In the case of power-law networks, the exponents exhibit a range consistent with that seen in real-world networks and the network exhibits other attributes seen in data. In the last part of the talk, a variety of applications will be discussed including the issue of robustness and centrality, as well as pattern formation and dynamics on complex networks. Read about our past colloquia (PDF).