Saturday 21 December 2013

...there are some things we can predict and others that we can only measure.

For my birthday I got a copy of Seeing Further: The Story of Science and the Royal Society. Edited by Bill Bryson and published by HarperPress

All round it is a good read.

The Chapter that stands out for me is by John D Barrow, SIMPLE, REALLY: FROM SIMPLICITY TO COMPLEXITY - AND BACK AGAIN.  In it Barrow explains where we are at on the development of Grand Unified Theories (GUT's) & Theories Of Everything (TOE's) and how ordinary physical laws based on symmetries relate to Chaos. 

The following passage introduces a great distinction that on reflection is straightforward, but nevertheless very well expressed;
The simplicity and economy of the laws and symmetries that govern Nature's fundamental forces are not the end of the story. When we look around us we do not observe the laws of Nature; rather we see the outcomes of those laws. The distinction is crucial. Outcomes are much more complicated than the laws that govern them because they do not have to respect the symmetries displayed by the laws. By this subtle interplay, it is possible to have a world which displays an unlimited number of complicated asymmetrical structures yet is governed by a few, very simple, symmetrical laws. This is one of the secrets of the universe.  
He also goes on to explain that "it would be a strange (non-Copernican) universe that allowed us to determine everything that we want about it. We may just have to get used to the fact that there are some things we can predict and others that we can only measure".  

Barrow's piece also references the work of Mitchell Feigenbaum on the universal behaviour of non-linear systems (latterly often referred to as Chaos). The image above is from the front cover of the first issue of Los Alamos Science from 1980, showing a visualisation of some of Feigenbaum's work (HERE).