The scientific magazine Science traditionally publishes a list of what it considers to be the Top Ten Scientific Breakthroughs of the year. In its December 19, 2003 issue, Science published the top ten scientific breakthroughs of 2003. The following is an account of this year's breakthroughs, retold in condensed form.

#1. The WMAP map of the earliest universe. The satellite WMAP has been registering and mapping the background radiation of the Universe. This has now made it possible to give a precise age of the universe -- 13.7 billion years. The results also indicate that the Universe mainly consists of strange, unknown stuff: only 4% of the Universe is the normal matter, that the stars, planets and we ourselves are made of. In contrast, as much as 23% is dark matter, and a whooping 73% is dark energy, two components of the Universe with properties that are to date completely unknown to science. Dark matter is thought to consist of unknown particles. What dark energy is, is anybody’s guess. But physicists are working on it.

#2 Genes behind depression. In July an international group of researchers presented a gene that affects the risk for becoming victim of depression. This gene controls how the signal substance serotonin is transported in the brain. People who have a longer form of the gene are protected from depressions, while bearers of the shorter form are more vulnerable.

#3 Global warming. Climate researchers have a century of temperature measurements to show that the globe has been warming. New work shows that the planet has been affected by the change. A number of studies suggest that global warming's impact on Earth increased significantly in 2003, with reports on melting ice, droughts, decreased plant productivity, and altered plant and animal behavior.

#4 RNA’s role in the cell.. The role played by miniature RNA molecules in modulating gene expression has been investigated more in detail in 2003, by exploring how RNAs coordinate a cell's behavior and how this knowledge could be used to combat disease. The most interesting subject is RNAi, or RNA-interference.

#5 Working with single molecules. Biologists and physicists are detailing the behavior of single molecules, in real time, in the cell. Single molecules can be marked with “glowing” markers, revealing basic properties of a single enzyme bound to DNA.

#6 Source of gamma ray bursts identified. In March, astronomers confirmed the connection between gamma ray bursts and supernovas -- the death throes of massive stars -- when they identified a supernova as the source of a burst of gamma rays. Astrophysicists now believe that the burst's jets of energy spewed into space when a star's core imploded, forming a black hole or -- in a minority view -- a rapidly spinning neutron star with a crushing magnetic field.

#7 Sperm and eggs from stem cells. Mouse embryonic stem (ES) cells can develop into both sperm and egg cells in culture dishes. The discoveries should help reveal how germ cells develop. If this can be reproduced in human cells, it could provide a renewable source of human eggs and/or sperm for research. But it also opens ethical questions: Could a child be born whose genetic parent is merely a cell line?

#8 Materials with negative refractive index. After 2 years of debate, work this year confirmed that certain oddball materials are capable of bending light and other electromagnetic waves in the wrong direction. In natural materials, light always bends at a positive angle with respect to the angle at which it entered. Two years ago, researchers beamed microwaves at a composite of copper rings and wires, which refracted microwaves at a negative instead of a positive angle. Last year other teams challenged those results, but this year definitive proof came from several groups. Physicists are already finding ways to make use of such “left-handed” materials. Last month, researchers reported that a set of electronic devices wired together to make a left-handed material produced an inverse Doppler effect. Another team made the first-ever image with a flat lens made from a “left-handed” material. Such lenses could generate far less distortion than standard optics.

#9 The structure of the male Y chromosome. Sequencing has revealed the genetic code of the Y chromosome, the piece of DNA that makes a man a man. Half of the 59 million bases in this chromosome are jumbled, possibly useless, and virtually impossible to decipher. This suggests that the Y is slowly fading as a chromosome. But the new sequence of the other half of Y's DNA, which contains the genes, shows that it has evolved an unusual, but effective, way to take care of itself.

#10 Starving cancer. As a cancerous tumor grows, it must induce the growth of new blood vessels to supply it with nutrients. Antiangiogenic agents try to starve tumors by preventing this blood vessel growth (= angiogenesis), which seems to be the most rational approach to cancer therapy. Unfortunately, in the past such therapies have not been successful. Now at last some encouraging results with antiangiogenic therapy have been reported: In June, researchers announced that an antiangiogenesis drug, given with conventional chemotherapy drugs in a large clinical trial, prolonged the lives of patients with advanced colon cancer.


Science, December 19, 2003

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