The year the Universe expanded

Steve Connor reviews Science journal's top 10 research breakthroughs of 1998, which have increased our understanding of life, the Universe, and everything
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Breakthrough of the Year - the expanding Universe

This has been the year when Albert Einstein was proved right - again. Two independent teams of astronomers were studying far-off exploding stars, known as supernovae, when they witnessed a phenomenon that they found difficult to believe. Einstein had made a theoretical prediction of something similar 80 years before and he, too, had dismissed it as being impossible.

The astronomers found that the supernovae were further away than expected, indicating that the Universe in general was expanding at a faster rate than it should be as a result of the Big Bang explosion some 10 to 15 billion years ago. The simplest explanation for this was that there is some hitherto unexplained energy that is repelling objects on a cosmic scale, effectively counteracting and overriding the tendency of stars and galaxies to attract one another under the force of gravity.

In 1917 Einstein completed his general theory of relativity. He found that one consequence of his calculations was that the Universe must be expanding. At that time, 12 years before Edwin P Hubble, the great American astronomer, demonstrated that stars really were moving apart, scientists believed the Universe was neither expanding nor contracting, but was in a steady state. As a consequence, Einstein inserted a "fudge factor" into his equations, which he called the cosmological constant, to make his theory conform to the "reality" of a Universe that was not expanding. When Hubble showed he need not have bothered, Einstein said it was "the greatest blunder of my life".

However, even the followers of modern cosmology had assumed that gravity must still have an influence on the explosive forces repelling the stars and galaxies. They thought the expansion would slow down; there is even a school of cosmology who believes that one day the expansion will end and the Universe will begin to contract in what some have dubbed the Big Crunch.

This year's new observations of distant supernovae have dispelled this idea totally. "These implications are so profound and unsettling that astronomers around the world are still trying to disprove the finding, to uncover anything that could create a false impression of cosmic acceleration," Science says.

The two international teams of astronomers found that the supernovae they observed were between 10 and 15 per cent further away than expected, indicating that the expansion of the Universe has accelerated over billions of years. Data from the research suggests that about 70 per cent of the total energy in the Universe is made up of this mysterious element. The remaining 30 per cent is the matter making up stars and galaxies.

As Science says: "Einstein is proved right, albeit for reasons he could not have foreseen."

Runner-up: the ultimate clock of life

This was the Year of the Clock. A series of experiments from several independent groups of scientists shed some much-needed light on the clockwork mechanisms governing the the daily biorhythms of life. Perhaps the most amazing find of all is that the body clocks of fruit flies and mice - which have been separated by 700 million years of evolutionary history - share a similar timekeeping system.

Many different kinds of animals, including humans, have a circadian rhythm, meaning they exhibit periods of rest and activity that run on a roughly 24-hour cycle. A number of genes are known to be involved in the biorhythms of mammals. In fruit flies the "clock" gene becomes active during the morning and switches on two other genes, called "per" and "tim".

When these two genes become active and produce their own proteins, they eventually switch themselves off, and the cycle is complete. But to keep themselves tuned in to the 24-hour cycle, this turn-off must not happen too soon after the genes are turned on.

This year scientists found that the delay in flies is caused by another gene, called "doubletime". The protein made by the "doubletime" gene destabilises the "per" gene's protein. Eventually, enough of the "tim" protein accumulates to bind with the "per" protein and so shield it from "doubletime's" destabilising influence. Precisely the same delay tactics occur in bacteria and mice, suggesting that the mechanism, or a derivative of it, may even operate in human beings.

Keeping the timing mechanism accurate, like a daily adjustment of a clock that runs slightly fast or slow, was known to involve light. This year also saw how this might work. Scientists found that light causes the rapid destruction of "tim" proteins in flies. In humans, light is also known to be critical in determining the bio-clock's accuracy, but scientists have found, most surprisingly, that instead of working through the eyes, light shone on to the back of the knees seems to be able to reset the clock.

How to transmit a brainwave

Every simple activity, such as reading a book or driving a car, requires billions of tiny electrical signals to pass along millions of nerve cells running to and from the brain. How precisely the nerve cells control these signals rests with molecular "gates" that determine which charged particles, or ions, can enter or leave the cell. This year, for the first time, the detailed three-dimensional structure of one of these gates was determined.

Science has called it a landmark discovery because it shows at the molecular level how the gate traps its target ion - in this case potassium - and swings it through the gate at top speed, while blocking the way to any other particles with the same electric charge, such as sodium. "After decades of wondering, electrophysiologists can now understand such riddles as how the potassium channel manages to keep out wrong ions, such as sodium, while shuttling an amazing 100 million potassium ions per second across the membrane," Science says.

The secret of the gate is that potassium ions must pass through a narrow filter that is just snug enough for them to cross; this is impossible for the slightly larger sodium ions.

The mass of a neutrino

Neutrinos are mysterious sub-atomic particles that are contenders for being the least interactive matter in the Universe. They are so ghostly that millions of them are thought to pass straight through the Earth on their travels through space. Not surprisingly they have been difficult to detect - until this year.

Japanese physicists deployed their Super-Kamiokande, a 50,000-ton tank of water packed with 11,200 light sensors, to detect the faint glow caused when a neutrino hits a water molecule. Ever since the existence of neutrinos was suggested as a theoretical possibility in the Thirties, scientists have thought they were devoid of mass and electric charge. But in an announcement in June, the Japanese team said that they had detected neutrinos, and that they do indeed have a "wisp of mass", says Science.

The findings raised the possibility that neutrinos, if they have mass, may be at least partly responsible for the missing mass of the Universe - the dark matter that astronomers cannot see with telescopes but which they know must be there because of the gravitational influence that it exerts. "1998 marked a new understanding of the neutrino, but this wily particle is still a few steps ahead of the scientists pursuing it," Science says.

Genetic blueprint of the first many-celled animal

It took more than 15 years, and pounds 30m. A joint effort by two teams from Britain and America has resulted in the genetic blueprint being published of the first multicellular animal - a 1mm-long worm called Caenorhabditis elegans. The book contains the complete instructions for building the worm - 97 million letters of the genetic alphabet that spell out the 19,000 genes of the animal.

The full sequence would, if printed on paper, be longer than two dozen copies of War and Peace. Yet the worm consists of fewer than 1,000 cells and is one of the simplest multicellular animals there is.

About 40 per cent of the worm's genes are closely related to those of humans, says John Sulston, who is director of the Sanger Centre in Cambridge and the leader of the British team. "Now we have a better understanding of how an animal is built, we can get some way closer to knowing how the human body works in health and disease."

Beam me up, Scotty

Teleportation, the transmission of matter from one point to another without physically passing through the intervening medium, is the stuff of science fiction. Most people would never have thought that the teleporter in Star Trek would ever gain any sort of scientific credibility. But it has done so in 1998.

"This year, physicists boldly went where no one has gone before," Science says. The scientists reconstructed the quantum state of a particle of light and transmitted it across their laboratory. "The key to teleportation is the odd phenomenon known as quantum entanglement, in which the fates of two or more particles are entwined without physical contact," reports Science.

Not many people can understand the intricacies of the experiment, involving as it does the esoteric science of quantum physics, but Science believes that this is a major breakthrough. "That technology will be worthy of inclusion in a Star Trek episode; It's teleportation, Jim, but not as we know it."

A chip off the block

Nineteen ninety-eight has been the year of a marriage between the silicon- based technology of microelectronics and the carbon-based science of genetics. The result has been the birth of biochips, silicon wafers that can be used to carry out a range of tasks, from sequencing the structure of DNA to genetic diagnosis of inherited diseases.

One biochip just a few centimetres wide looks as though it may soon be used to sequence DNA, scientists having already mastered the art of chopping up the molecule, amplifying it to usable amounts and then separating out the fragments in order of size.

"Also this year, researchers at a California biotech firm developed a biochip that can screen a blood sample for cancer cells, bacteria or other cell types and remove their DNA for analysis," Science says.

Another class of DNA chips can be used for diagnosing genetic faults. "Such chips could one day screen for genetic disease. Their foundations may be in electronics, but microchips have a bright biomedical future."

A chemical cocktail

Combination chemistry - a way of looking quickly at the result of mingling more than one chemical - became a vogue term in laboratories this year. Science calls it a "high-speed discovery engine" which "allows researchers to assemble a handful of chemical building blocks into all possible combinations thousands of times faster than before".

Nearly all pharmaceutical companies have adopted the approach as a fast- track way of finding new drugs. At least two potential drugs, including one to treat inflammations, are now in clinical trials as a result of combination chemistry.

One team has used the technique to generate a "library" of more than 2.1 million complex organic molecules that resemble natural products such as antibiotics.

Instead of testing each of these, the scientists can scan the "library" to find the candidates that look as though they may be best suited to activating or deactivating a target protein in the body that is involved in a particular illness. "When the goal is to create new compounds, chemists seem to have hit on a winning combination," says Science.

The war on cancer continues

The war on cancer is not a single fight but many far-flung skirmishes, and no superweapon has yet emerged to rout the enemy from all its hideouts." Yet, says Science, some battles were won this year, although the war on cancer is not over.

Several types of cancer prevention gained respectability in 1998. "Researchers can proudly point to a new use for the drug tamoxifen."

This oestrogen-like drug has already proven to be a success in the treatment of breast cancer and this year was approved in America for the prevention of the disease in women who are thought to be at high risk.

Cancer rates have also been dropping as a result of changes in lifestyle, notably a fall in the numbers of people smoking in some age groups since the early Nineties.

Meanwhile, several new approaches to therapy have been tested with some success, such as the antibodies Herceptin, to slow breast cancer, and Panorex, to combat cancer of the colon.

"The war on cancer goes on but physicians now have a few new weapons to fight with," Science says.

Molecular mimicry

Some infections appear to have the power to cause long-term effects, but no one has really understood why. Lyme disease, for instance, starts with short-lived effects such as flu-like symptoms but can end up causing chronic arthritis, even after antibiotics have wiped out the microbes. What is going on?

One theory that has gained some support in 1998 is that the infection somehow triggers the immune system to attack the body's own molecules - an auto-immune response. People literally become allergic to themselves. But the idea has been hard to prove. "This year, two teams convincingly linked infections and auto-immune disorders, paving the way to better understanding of diseases such as diabetes and MS," Science says.

In the first experiment, scientists showed that mice infected with the herpes virus had the corneas of their eyes destroyed by their own T-cells. The second piece of research found that patients who developed chronic arthritis as an effect of Lyme disease possessed immune cells that attacked both a protein of the Lyme disease bacterium, and a closely related human protein. Science said these experiments set the scene for a flood of research to demonstrate further the links between auto-immunity and infection.

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