时 间: 2011年4月19日（周二）下午4:00

地 点: 清华大学高等研究院 科学馆322报告厅

题 目: Interference of Pulses and Transient Measurements

报 告 人: Dr. Ming-Chiang LI

Formerly of U.S. Naval Research Laboratory

报告摘要: Newton mechanics is only predictable if initial conditions of position and velocity are known. These are transient physical quantities. Transient positions can be measured through fast photography. However no method exists to measure transient velocities. This has been an unsolved classical problem.

The distribution function in non-equilibrium statistical mechanics is the particle density in the six dimensional position and momentum space and varies from instant to instant. The inability to measure the transient velocity means that the distribution function can not directly observed, and the non-equilibrium statistical mechanics has been very difficult to master. Our major theoretical accomplishments become mainly confined in equilibrium thermo dynamics, low temperature and solid state physics, where we need not to deal with the distribution function in full six dimensional space.

Navier-Stokes Equations in fluid dynamics are the equations of transient velocity variation in three dimensional spatial points. The inability to measure the transient velocity means our understanding toward turbulence and thermo nuclear reaction is very limited.

The present talk will show that, at the present, an experimental means exists to measure the transient velocity in nanosecond scale directly. Hence nanosecond physics will emerge. New frontiers are waiting for us to explore. We will be able to control thermo nuclear reaction, and predict precisely the destructive power of hurricanes. Major advancements in non-equilibrium statistical mechanics and fluid dynamics are expected.