The Cat in the Box and a Real Eureka Moment

October 2012 the announcements of the Nobel Prizes in physics and chemistry, both of which were for work centring on transfers of information. While the prize-winning physics predictably involved brain bending quantum mechanics, the chemistry prize focused not on test tube reactions, but on cellular biology.

            The Nobel Prize in Physics was jointly awarded to Serge Haroche, of
Collège de France and Ecole Normale Supérieure, France, and David Wineland, of National Institute of Standards and Technology (NIST) and University of Colorado Boulder, USA, "for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems.”

            These experiments involve the sort of quantum weirdness described by physicist Erwin Schrodinger in 1935. By extrapolating quantum mechanics to the everyday world, he described a “ridiculous” situation in which a cat was placed in a box with a flask of poison and some radioactive material whose decay could shatter the flask. According to quantum mechanics, the cat would be both alive and dead at the same time; but of course, if anyone opened the box, they could only find a living or a dead cat.

            Until recently, it had been thought difficult or impossible to observe individual atoms and sub-atomic particles that might be in two quantum states at the same time: physicists usually studied many particles at once. But sophisticated new techniques, with pioneering work by teams led by Haroche and Wineland, are helping us peer into the quantum world.

            Both teams have succeeded by finding ways to trap particles.

Haroche traps light particles – photons – in a cavity between mirrors of superconducting material so reflective that a photo can remain trapped for a tenth of a second – enough time for it to travel 40,000km bouncing about in the roughly 3cm wide space. He then fires through individually prepared atoms, each of which interacts with the photon, resulting in a tiny shift in the wave motion of the atom.

Using this phase shift, Haroche can detect photons without destroying them – unlike normal detectors that convert photon energy to electrical energy. He has also monitored photons in their “cat state”, essentially oscillating both up and down at the same time, until they oscillated one way or the other.

Wineland, by contrast, keeps electrically charged atoms – ions – trapped within a vacuum in an electric field. Using a laser to encourage energy emission, his group members lower their temperatures to almost absolute zero, so they are near motionless. Here, too, he can create states like Schrodinger’s cat, with laser pulses nudging an ion into two states simultaneously.

Wineland has used the ion traps to create the world’s most accurate clocks, albeit they are so far short lived and hardly the sort of timepieces you can buy in a store. These may help with applications such as navigation. The Nobel Foundation also envisages work by Haroche and Wineland can pave the way towards creating quantum computers that could transform lives as radically as have the computers we use today.

The chemistry prize is for work that’s more readily understood, but can also have far reaching consequences. It was awarded to Robert Lefkowitz, of Howard Hughes Medical Institute and Duke University Medical Center, USA, and Brian Kobilka, of
Stanford University School of Medicine, USA, “for studies of G-protein–coupled receptors."

The origins of their work can be traced to the late 19th century, when scientists found adrenaline raised the blood pressure and heart rate, but could not discover how it worked. Adrenalin did not enter cells, so how did information get through? A mechanism involving nerves was ruled out. When a student, Lefkowitz was tasked with finding a receptor in cells producing adrenalin.

This led to a position as head of a research team in new laboratories, and Lefkowitz chose to focus on receptors for adrenalin and closely related noradrenalin. Using radioactive tagging, the team extracted receptors from living tissue. Other researchers had found what were called G-proteins within cells, and a signal from a receptor can trigger these to cause a series of reactions altering a cell’s metabolism.

Kobilka joined the team, and helped find the gene for the adrenaline receptor protein – which suggested it probably winds through the cell wall seven times. In what he later described as a “real eureka moment”, Lefkowitz realised this was the same number of spiral strings as in the light receptors others had found, and concluded there must be a family of receptors that look alike and function in the same manner.

In a new position at Stanford, Kobilka set himself the tough task of creating an image of the receptor. He needed to use X-ray crystallography, which had been successfully used for water soluble proteins. Yet the receptors are not water soluble, and Kobilka took two decades before at last obtaining an image. This was published last year, and shows a receptor at the moment it is passing a signal to a G-protein. “This image is a molecular masterpiece – the result of decades of research,” notes the Nobel Foundation.

Lefkowitz has likewise stayed at the forefront of the field, which has revealed almost a thousand genes that code for receptors, roughly half of which receive odours, a third are for hormones and other signalling substances like adrenaline, histamine, and dopamine. Some capture light; and the functions of more than a hundred are unknown.

As about half of all medications act through these receptors, they are of immense importance in medicine, and research on them can help with creating more effective drugs.

  “That’s all very well,” you’re probably thinking now. “But how can I get myself a Nobel Prize?” Perhaps surprisingly, an outstanding school performance is not essential: a school report on John Gurdon, joint winner of this year’s Nobel Prize for Medicine, said his ideas about becoming a scientist were “quite ridiculous”. It might be good if you’re a man: only four women have ever won the chemistry prize. Plus: eat plenty of chocolate.

Yes, chocolate. For in more science news this week, the New England Journal of Medicine published findings that the higher a nation’s per capita chocolate consumption, the more Nobel laureates it spawns. Author Franz Messerli acknowledges this might be coincidence, but advises, “if you want a physics Nobel Prize it pretty much has got to be dark chocolate."

Martin Williams