Information conservation

There is another very subtle law of physics that may be even more fundamental than energy conservation.

It’s sometimes called reversibility, but let’s just call it information conservation.

Information conservation implies that if you know the present with perfect precision, you can predict the future for all time.

But that’s only half of it. It also says that if you know the present, you can be absolutely sure of the past. It goes in both directions.

— The Black Hole War, p.87

— Leonard Susskind

2012.06.12 Tuesday ACHK