Applied Physics / Physics Colloquium

Applied Physics/Physics Colloquium: Recent results on Gravitational Waves from LIGO and Virgo

Topic: 
Recent results on Gravitational Waves from LIGO and Virgo
Abstract / Description: 

Over the last two years, the Advanced LIGO and Advanced Virgo detectors have observed a handful of gravitational-wave events from the inspiral and merger of binary black holes in distant galaxies. These events have resulted in the first measurements of the fundamental properties of gravitational waves, tests of General Relativity in the strong-field, highly-dynamical regime, and the population, masses and spins of black holes in the universe. Most recently, signals were detected from the inspiral of a binary neutron star system, GW170817. That event is thus far the loudest (highest signal-to-noise ratio) and closest gravitational-wave event observed. A gamma-ray burst detected 1.7 seconds after merger confirms the long-held hypothesis that BNS mergers are associated with short gamma-ray bursts. The LIGO and Virgo data produced a three-dimensional sky localization of the source, enabling a successful electromagnetic follow-up campaign that identified an associated electromagnetic transient in a galaxy ~40 Mpc from Earth. A multi-messenger view of GW170817 from ~100 seconds before merger through weeks afterward provides evidence of a "kilonova", and of the production of heavy elements. For the first time, using gravitational waves we are able to constrain the equation of state of dense neutron stars and infer the rate of local binary neutron star mergers. When we include EM observations, we are able to directly measure the speed of gravitational waves, constrain its polarization content, independently measure the Hubble constant, probe the validity of the equivalence principle, and gain new insight into the astrophysical engine driving these events.

Date and Time: 
Tuesday, November 14, 2017 - 4:30pm
Venue: 
Hewlett 201

Making a Physicist with Jazz

Topic: 
Making a Physicist with Jazz
Abstract / Description: 

In 2005, theoretical physicist S. James Gates related a story about Abdus Salam where Salam explained that once Black people entered physics in large numbers, they would create something like jazz. Is this an essentialization of Black people or getting at the essence of how Black people have responded to the wake of slavery and colonialism? Using texts from a diverse set of disciplines -- English, ethnomusicology, and science, technology, and society studies -- I will reflect on possible answers to this question, what they tell us about how physicists are made, and whether this framework offers lessons for how physicists should be made.

Open to all interested. Limited seating. To attend this talk and discussion, please register online via this link: https://stanforduniversity.qualtrics.com/jfe/form/SV_2to6cpsyuDlqFo1

Date and Time: 
Monday, October 2, 2017 - 3:30pm
Venue: 
Black Community Services Center, Community Room

Applied Physics/Physics Colloquium: Physics in the Future

Topic: 
Physics in the Future
Abstract / Description: 

The greatest American philosopher of the 20th century and Hall of Fame Yankee baseball catcher, Yogi Berra, wisely noted, "It's hard to make predictions, especially about the future." Yogi Berra also warned, "If you don't know where you are going, you might wind up someplace else."

What excites physicists more than anything else are the unexpected discoveries that will open new horizons of the endless frontiers of science. The talk will sketch a few selected areas and offer a personal view of how physicists can position themselves to become lucky enough to stumble onto discoveries that lead us "someplace else."


 

APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore

Date and Time: 
Tuesday, November 7, 2017 - 4:15pm
Venue: 
Hewlett 201

Applied Physics/Physics Colloquium: Quantum Simulations and Tensor Networks in Condensed Matter and High Energy Physics

Topic: 
Quantum Simulations and Tensor Networks in Condensed Matter and High Energy Physics
Abstract / Description: 

 2017-10-26Many-body quantum systems are very hard to describe, since the number of parameters required to describe them grows exponentially with the number of particles, volume, etc.  This problem appears in different areas of science, and several methods have been developed in fields of quantum chemistry, condensed matter and high energy physics in order to circumvent it in certain situations. In the last years, other approaches inspired by quantum information theory have been introduced in order to address such a problem. On the one hand, quantum simulation uses a different system in order to emulate the behavior of the problem under study. On the other, tensor networks aim at the accurate description of many-body quantum states with few parameters. In this talk, I will give a basic introduction to those approaches, and explain current efforts to use them in order to attack both condensed and high-energy physics problems.


 

APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore

Date and Time: 
Tuesday, October 31, 2017 - 4:15pm
Venue: 
Hewlett 200

Increasing Accuracy and Increasing Tension in Ho [Applied Physics/Physics Colloquium]

Topic: 
Increasing Accuracy and Increasing Tension in Ho
Abstract / Description: 

 

he Hubble constant, Ho, provides a measure of the current expansion rate of the universe. In recent decades, there has been a huge increase in the accuracy with which extragalactic distances, and hence, Ho can be measured. While the historical factor-of-two uncertainty in Ho has been resolved, a new discrepancy has arisen between the values of Ho measured in the local universe, and that estimated from cosmic microwave background measurements, assuming a Lambda cold dark matter model. I will review the advances that have led to the increase in accuracy in measurements of Ho, as well as describe exciting future prospects with the James Webb Space Telescope (JWST) and Gaia, which will make it feasible to measure extragalactic distances at percent level accuracy in the next decade


APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore

Date and Time: 
Tuesday, October 24, 2017 - 4:15pm
Venue: 
Hewlett 200

Applied Physics/Physics Colloquium: The Brayton Battery

Topic: 
The Brayton Battery
Abstract / Description: 

This talk will give an overview of work I have been doing off campus for the past several years on the matter grid energy storage using reversible heat engines and molten nitrate salt. The most recent work, a secret project at X code named "Project Malta", was revealed in Bloomberg on 31 Aug 17. My own scientific writing on the matter came out about the same time as J. Renew. Sustain. Energy 9, 044103 (2917). The talk will touch on the grid storage problem itself and why I think heat beats all other ways of solving it - including in particular electrochemistry. The bulk of the talk will focus on the concept of a closed-cycle Brayton engine and the many aspects of "old time physics" associated with it: equation of state thermo-dynamics, adiabatic efficiency, metals creep, entropy creation in counterflow heat exchange, salt corrosion, high-speed bearings, hard permanent magnetism, torque limits of high-speed motor-generators imposed by Maxwell's equations and vibration physics, simulation of physical linkages with power semiconductors, and so forth. The larger idea underneath is that lowering costs to the bone is the problem, and that the physics of heat transfer facilitates this. It has no land use issues, it can be easily scaled up to the size of megacities at low cost, and it is safe - meaning that the nuclear weapon's worth of energy one most store cannot be released all at once. I will show images of the (tiny) released reprototype engine, which is about 2 m long, 0.6 m in diameter, and has the power of a diesel locomotive.This talk will give an overview of work I have been doing off campus for the past several years on the matter grid energy storage using reversible heat engines and molten nitrate salt.  The most recent work, a secret project at X code named "Project Malta", was revealed in Bloomberg on 31 Aug 17.  My own scientific writing on the matter came out about the same time as J. Renew. Sustain. Energy 9, 044103 (2917).  The talk will touch on the grid storage problem itself and why I think heat beats all other ways of solving it - including in particular electrochemistry.  The bulk of the talk will focus on the concept of a closed-cycle Brayton engine and the many aspects of "old time physics" associated with it: equation of state thermo-dynamics, adiabatic efficiency, metals creep, entropy creation in counterflow heat exchange, salt corrosion, high-speed bearings, hard permanent magnetism, torque limits of high-speed motor-generators imposed by Maxwell's equations and vibration physics, simulation of physical linkages with power semiconductors, and so forth.  The larger idea underneath is that lowering costs to the bone is the problem, and that the physics of heat transfer facilitates this. It has no land use issues, it can be easily scaled up to the size of megacities at low cost, and it is safe - meaning that the nuclear weapon's worth of energy one most store cannot be released all at once.  I will show images of the (tiny) released reprototype engine, which is about 2 m long, 0.6 m in diameter, and has the power of a diesel locomotive.


 

APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore

Date and Time: 
Tuesday, October 17, 2017 - 4:15pm
Venue: 
Hewlett 200

Quantum Matter without Quasiparticles: Strange Metals and Black Holes [Applied Physics/Physics Colloquium]

Topic: 
Quantum Matter without Quasiparticles: Strange Metals and Black Holes
Abstract / Description: 

The quasiparticle concept is the foundation of our understanding of the dynamics of quantum many-body systems. It originated in the theory of metals, which have electron-like quasiparticles, but it is also useful in more exotic states like those found in fractional quantum Hall systems. However, many modern materials exhibit a 'strange metal' phase to which the quasiparticle picture does not apply, and developing its theory remains one of the important challenges in condensed matter physics. I will describe the simplest known quantum many-body models without quasiparticle excitations. Some of these models have a dual description as black holes in a curved spacetime with an emergent spatial direction, and the black hole mapping has proved useful in understanding some experiments.


APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore

Date and Time: 
Tuesday, October 10, 2017 - 4:15pm
Venue: 
Hewlett 200

A Wandering Path to Plasma Fusion [Applied Physics/Physics Colloquium]

Topic: 
A Wandering Path to Plasma Fusion
Abstract / Description: 

 The speaker recounts an unconventional journey through academic physics and the tech industry, beginning and ending with the study of plasma fusion. Over the past three years, a team at Google has collaborated with Tri Alpha Energy in applying modern data science techniques, in particular in experiment design, to the C-2U plasma confinement machine. The collaboration continues on the much more energetic "Norman" machine, being commissioned now.


 

 

APPLIED PHYSICS/PHYSICS COLLOQUIUM is held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200 (see map). Refreshments in the lobby of Varian Physics at 4:15 pm.

Autumn 2017/2018, Committee: Roger Blandford (Chair), Aharon Kapitulnik, Bob Laughlin, Leonardo Senatore

Date and Time: 
Tuesday, October 3, 2017 - 4:15pm
Venue: 
Hewlett 200

Protecting Quantum Superpositions in Superconducting Circuits [Applied Physics/Physics Colloquium]

Topic: 
Protecting Quantum Superpositions in Superconducting Circuits
Abstract / Description: 

Can we prolong the coherence of a two-state manifold in a complex quantum system beyond the coherence of its longest-lived component? This question is the starting point in the construction of a scalable quantum computer. It translates in the search for processes that operate as some sort of Maxwell's demon, reliably correcting the errors resulting from the coupling between qubits and their environment. The presentation will review recent experiments that tested the dynamical protection, by Josephson circuits, of a logical qubit memory based on superpositions of particular coherent states of a superconducting resonator.


 

APPLIED PHYSICS/PHYSICS COLLOQUIUM

Held Tuesdays at 4:30 pm in the William R. Hewlett Teaching Center, room 200. Refreshments in the lobby of Varian Physics at 4:15 pm.

Winter 2016/2017, Committee: A. Linde (Chair), S. Kivelson, S. Zhang

Date and Time: 
Tuesday, May 30, 2017 - 4:15pm
Venue: 
Hewlett 200

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