Quantum minds: Why We Think Like Quarks
From the page: “….It didn’t take long for them to find they were on to something. An urgent challenge is to get computers to find meaning in data in much the same way people do, says Widdows. If you want to research a topic such as the “story of rock” with geophysics and rock formation in mind, you don’t want a search engine to give you millions of pages on rock music. One approach would be to include “-songs” in your search terms in order to remove any pages that mention “songs”. This is called negation and is based on classical logic. While it would be an improvement, you would still find lots of pages about rock music that just don’t happen to mention the word songs.
Widdows has found that a negation based on quantum logic works much better. Interpreting “not” in the quantum sense means taking “songs” as an arrow in a multidimensional Hilbert space called semantic space, where words with the same meaning are grouped together. Negation means removing from the search pages that shares any component in common with this vector, which would include pages with words like music, guitar, Hendrix and so on. As a result, the search becomes much more specific to what the user wants.
“It seems to work because it corresponds more closely to the vague reasoning people often use when searching for information,” says Widdows. “We often rely on hunches, and traditionally, computers are very bad at hunches. This is just where the quantum-inspired models give fresh insights.”
That work is now being used to create entirely new ways of retrieving information. Widdows, working with Trevor Cohen at the University of Texas in Houston, and others, has shown that quantum operations in semantic Hilbert spaces are a powerful means of finding previously unrecognised associations between concepts. This may even offer a route towards computers being truly able to discover things for themselves.
To demonstrate how it might work, the researchers started with 20 million sets of terms called “object-relation-object triplets”, which Thomas Rindflesch of the National Institutes of Health in Bethesda, Maryland, had earlier extracted from a database of biomedical journal citations. These triplets are formed from pairs of medical terms that frequently appear in scientific papers, such as “amyloid beta-protein” and “Alzheimer’s disease”, linked by any verb that means “associated with”.
The researchers then create a multi-dimensional Hilbert space with state vectors representing the triplets and applied quantum mathematics to find other state vectors that, loosely speaking, point in the same direction. These new state vectors represent potentially meaningful triplets not actually present in the original list. Their approach makes “logical leaps” or informed hypotheses about pairs of terms, which are outside the realms of classic logic but seem likely promising avenues for further study. “We’re aiming to augment scientists’ own mental associations with associations that have been learned automatically from the biomedical literature,” says Cohen.
He and his colleagues then asked medical researchers to use the approach to generate hypotheses and associations beyond what they could come up with on their own. One of them, molecular biologist Graham Kerr Whitfield of the University of Arizona in Phoenix, used it to explore the biology of the vitamin D receptor and its role in the pathogenesis of cancer. It suggested a possible link between a gene called ncor-1 and the vitamin D receptor, something totally unexpected to Kerr Whitfield, but now the focus of experiments in his lab.
Yet one big question remains: why should quantum logic fit human behaviour? Peter Bruza at Queensland University of Technology in Brisbane, Australia, suggests the reason is to do with our finite brain being overwhelmed by the complexity of the environment yet having to take action long before it can calculate its way to the certainty demanded by classical logic. Quantum logic may be more suitable to making decisions that work well enough, even if they’re not logically faultless. “The constraints we face are often the natural enemy of getting completely accurate and justified answers,” says Bruza.
This idea fits with the views of some psychologists, who argue that strict classical logic only plays a small part in the human mind. Cognitive psychologist Peter Gardenfors of Lund University in Sweden, for example, argues that much of our thinking operates on a largely unconscious level, where thought follows a less restrictive logic and forms loose associations between concepts….”