In the Dark

When I was in Bath on Friday evening I made a point of visiting the Herschel Museum, which is located in the house in which Sir William Herschel lived for a time, before moving to Slough.

Unfortunately I got there too late to go inside. It did remind me however of an interesting connection between astronomy and forensic science, through a certain William Herschel..

When I give popular talks about Cosmology,  I sometimes look for appropriate analogies or metaphors in detective fiction or television programmes about forensic science. I think cosmology is methodologically similar to forensic science because it is generally necessary in both these fields to proceed by observation and inference, rather than experiment and deduction: cosmologists have only one Universe;  forensic scientists have only one scene of the crime. They can collect trace evidence, look for fingerprints, establish or falsify alibis, and so on. But they can’t do what a laboratory physicist or chemist would typically try to do: perform a series of similar experimental crimes under slightly different physical conditions. What we have to do in cosmology is the same as what detectives do when pursuing an investigation: make inferences and deductions within the framework of a hypothesis that we continually subject to empirical test. This process carries on until reasonable doubt is exhausted, if that ever happens.

Of course there is much more pressure on detectives to prove guilt than there is on cosmologists to establish the truth about our Cosmos. That’s just as well, because there is still a very great deal we do not know about how the Universe works. I have a feeling that I’ve stretched this analogy to breaking point but at least it provides some kind of excuse for mentioning the Herschel connection.

In fact the Herschel connection comes through William James Herschel, the grandson of William Herschel and the eldest son of John Herschel, both of whom were eminent astronomers. William James Herschel was not an astronomer, but an important figure in the colonial establishment in India. In the context relevant to this post, however, his claim to fame is that he is credited with being the first European to have recognized the importance of fingerprints for the purposes of identifying individuals. William James Herschel started using fingerprints in this way in India in 1858; some examples are shown below (taken from the wikipedia page).

Later,  in 1877 at Hooghly (near Calcutta) he instituted the use of fingerprints on contracts and deeds to prevent the then-rampant repudiation of signatures and he registered government pensioners’ fingerprints to prevent the collection of money by relatives after a pensioner’s death^. Herschel also fingerprinted prisoners upon sentencing to prevent various frauds that were attempted in order to avoid serving a prison sentence.

The use of fingerprints in solving crimes was to come much later, but there’s no doubt that Herschel’s work on this was an important step.