The distinction between the past and the future has long been a puzzle. The world around us displays a huge asymmetry between the two directions of time, with eggs that easily break but never reassemble. However, according to the known laws of physics, for every system that evolves in time, there exists in principle a time-reversed (i.e., CPT conjugate) state that evolves in exactly the same way, but backwards in time. The time asymmetry is often attributed to the assumption that the universe began in a very low entropy state. This explanation is satisfactory, but leaves open the question of why the universe started in a low entropy state. In this talk I will describe a new picture of spacetime, proposed in 2004 by Carroll and Chen, in which the arrow of time can be explained by using only time-symmetric laws of physics and time-symmetric initial conditions as well.
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