Time in physics

1.    Time is just another, imaginary dimension of space
2.    The question about the existence of the past depends on our definition of existence
3.    The future doesn’t exist at the present regardless of any definitions
4.    Some units of time are better than others
5.    Among conserved quantities, time has a special relationship with energy
6.    All physical systems with many degrees of freedom inevitably possess a future-time asymmetry, the so-called logical arrow of time
7.    The logical arrow of time implies the asymmetry of all macroscopic processes, i.e. the thermodynamic arrow of time and other arrows of time
8.    An exact time-reversing symmetry which holds in Nature is called CPT and only applies to the microscopic laws
9.    To properly understand the psychological perception of time, one needs to analyze the functions of the brain
10.   When times become as short as the Planck time, \(10^{-43}\) seconds, time develops some wholly unfamiliar properties

— Ten new things modern physics has learned about time

— Lubos Motl

2011.09.06 Tuesday ACHK