Erwin Schroedinger, born in Vienna, Austria in 1887 was awarded the Nobel Prize in Physics in 1933, fled Austria in 1938 and established the Dublin Institute for Advanced Studies on invitation from the Irish Dictator de Valera where he remained until 1955.
Quantum mechanics states that an object in a physical system can simultaneously exist in all possible configurations, but observing the system forces the system to collapse and forces the object into just one of those possible states. Schroedinger disagreed with this interpretation.
So what does this have to do with cats? Schroedinger wanted people to imagine that a cat, poison, a geiger counter, radioactive material, and a hammer were placed inside a sealed container. The amount of radioactive material was minuscule enough so that it only had a 50/50 chance of being detected within one hour. If the geiger counter detected radiation, the hammer would then smash the poison, killing the cat. Until someone opened the container and observed the system, it was impossible to predict the cat’s fate. Thus, until the system collapsed into one configuration, the cat would exist in some superposition zombie state of being both alive and dead. Schroedinger maintained this scenario was not only impossible it was also nonsense and challenged quantum mechanics. No scenario, no cat!
If we can understand how life assembled complex life forms from simpler components then we may be able to resolve Schroedinger’s paradox. In What is Life? Schroedinger’s intriguing lectures and little book of 1943, he remarked that a defining feature of a living thing is that it avoids decay, which is the reason why living things appear ‘so enigmatic.’
The second law of thermodynamics states that the entropy of an isolated system always stays the same or increases – it never decreases. Life is a notable exception it appears to be second law defying; it avoids decay, as Schroedinger wrote. Life avoids decay and it actively assembles itself into extremely complex structures, which ensures life is often attributed to some supernatural power/designer.
Schroedinger’s programme of accounting for life using the laws of physics and chemistry would easily be discounted. So, how does life assemble itself in seeming contradiction of the second law of thermodynamics? This is Schroedinger’s paradox.
In answer: Simple living things were able to assemble that most spectacular monument to emergent complexity - our current 4-billion-year-old ecosystem which is presently under threat due to unprecedented global warming. This complex order was built up from year to year and millennium to millennium. How was this complex order achieved? Schroedinger answered that there is inherent memory in the system and once emerged it did not require continual reinvention. Schroedinger did not know the memory mechanism however he deduced much of its properties and named it as an ‘aperiodic crystal’ a stable molecule capable of passing information onto generations throughout the history of life on Earth.
Inspired partly by Schroedinger’s little book What is Life, Watson, Crick, Wilkins and Franklin discovered the precise structure of that aperiodic crystal a decade later in 1953 – the double helix of DNA which encodes complex order from one generation to the next.