What is the theorem of leggetts

Physical debate about the direction of time: time vector and time travel

No matter how many clocks you look at: time only runs in one direction. (© SerrNovik / fotolia.com)

We can remember the past and influence the future - but not the other way around. Physicists around the world disagree about why this is so. Leggett's answer is based on what is known as the second law of thermodynamics. By definition, this main theorem deals primarily with the states of equilibrium of systems and with the processes that result in changes of a state between systems. To what extent this statement can be applied to the question of the fixed direction of time, Leggett explains in the video interview.

The print version of this text (pdf) can be found here.

Portrait of the researcher

Anthony Leggett is Professor of Physics at the University of Illinois at Urbana, USA. In 2003 he received the Nobel Prize in Physics for his findings in the field of superfluidity. Leggett was a guest at the Freiburg Institute for Advanced Studies (FRIAS) at the University of Freiburg in November 2010. In the 7th Hermann Staudinger Lecture he gave a lecture on the physical view of the phenomenon “time”. As part of the public Hermann Staudinger Lectures, Nobel Prize winners from all over the world are invited to a guest lecture in Freiburg.


to the top