viernes, 11 de octubre de 2013

Explaining the Nobel Prizes in Science - National Geographic

Where in the world is physicist Peter Higgs? One of the winners of the 2013 Nobel Prize in physics made the scene at an Edinburgh University news conference on Friday, after he headed for the hills to hike and ducked this week's award announcement.

"Well, obviously, I'm delighted," Higgs said at the event, where he revealed he had not known of the award until a neighbor gave him the news.

That mystery solved, all that is left is understanding what the scientists actually did to win this year's prizes, which award 8 million Swedish kronor ($1.25 million) per category, which is split when there are multiple winners.

As always, the winners of Monday's medicine prize, Tuesday's physics prize, and Wednesday's chemistry prize will receive their official medals from Sweden's King Carl Gustaf XVI in a December 10 ceremony in Stockholm. (Related: Why we care about the Nobels.)

The Nobel Prizes partly owe their prominence to modern science becoming so complicated that you need experts to understand what is really important, as the late science historian Burton Feldman explained in The Nobel Prize: A History of Genius, Controversy, and Prestige.

As science has "grown increasingly remote and arcane," he wrote, "the Nobels have become the most important bridge between high intellectual achievement and the marketplace."

Drop that on your friends this weekend before explaining to them how the prize winners did their part to advance science.

Cell Post Offices and Zip Codes

"Each cell is a factory that produces and exports molecules," the Nobel award panel noted in its announcement awarding the medical prize to Yale's James Rothman, Stanford's Thomas Südhof, and Randy Schekman of the University of California, Berkeley.

Every living thing is made of cells, and the three scientists cracked the mystery of how these little factories--cells are responsible for making everything from blood to brain to bone, and much else--actually move their goods around.

Cells package the proteins and other stuff they create, such as hormones, in wrappings called "vesicles," which bud from the cell's outer covering, or membrane, and are released into the body. The outstanding question about the process, as the Nobel Prize announcement put it, was, "How do these vesicles know where and when to deliver their cargo?"

Schekman started formulating the answer in the 1970s, finding that three kinds of genes control proper shipping of vesicles. Essentially, scientists then knew what was making the rules for the body's "postal system."

Rothman picked up the story in the next decade, showing that these genes coded for a menagerie of zipperlike proteins that attached to cell surfaces and vesicles. When the zipper halves matched on cell and vesicle, they zipped together, delivering the goods. The "zip code" system for the body's cells had been discovered.

Südhof's research team completed the picture by unraveling how cells orchestrate the vesicles' delivery times.

In 1993, his team published a Nature journal paper showing that calcium-sensitive proteins inside cells responded to influxes of that element to fire up vesicle-binding proteins on their membranes. It turned out that cells "speak" to each other with these calcium signals and keep the postal system running on time.

"These discoveries have had a major impact on our understanding of how cargo is delivered with timing and precision within and outside the cell," as the prize announcement put it.

Don't Call it the "God Particle"

Physicists have spent two decades mulling over the "God particle." That's the moniker dropped on the Higgs boson subatomic particle by Nobelist Leon Lederman in his 1993 book, The God Particle: If the Universe Is the Answer, What Is the Question?

Even though the nickname was the best bit of marketing for their discipline since Einstein let his hair grow out, physicists have widely scorned this crass popularization of their noble hunt for the Higgs boson.

So, if the Higgs boson is just another physics particle, why did Peter Higgs and François Englert of Belgium's Université Libre de Bruxelles win the prize?

Well, the Higgs boson is "special," the award announcement notes, because the subatomic particle is the last one detected in the so-called Standard Model of particle physics. This is the zoo of particles, including everything from the quarks inside protons and neutrons to the ghostly neutrinos spit out by radioactive decay reactions, which together build up all matter and explain electromagnetism, radioactivity, and the nuclear forces that hold atoms together.

That's all great, but the model didn't completely explain why these interacting subatomic particles weighed something, or had mass. So in the 1960s, Higgs and Englert, together with Robert Brout, Gerald Guralnik, Dick Hagen, and Tom Kibble, conjured up the idea of the Higgs particle. The thinking basically went that if something happens in particle physics, there must be a particle to explain it.

One explanation for how the Higgs boson creates mass compares the subatomic particle to a pack of groupies surrounding a celebrity, an explanation first made by physicist David Miller of University College London. Imagine the number of groupies flocking to, say, Vanilla Ice as compared to Justin Bieber.

Just like autograph hounds beelining for the bigger celebrity, Higgs bosons flock more strongly to some subatomic particles than to others. Scientists measure this attraction as more mass for these super-celebrity subatomic particles. Other particles don't feel the attraction as strongly and thus have less mass.

Predictions about the properties of Higgs boson particles, it turns out, fell in line with experimental results from super-collider experiments at Europe's CERN laboratory near Zurich, announced last year.

"The discovery is a milestone for particle physics and a tremendous success for the Standard Model," said the prize announcement.

If you won't remember how Higgs bosons give mass to other subatomic particles, you might at least dazzle your friends with the gossip about the other particle theorists snubbed by the prize.

The Nobel can go to only three winners at most, so observers like physicist Sean Carroll of Caltech say that Kibble, Hagen, and Guralnick (Brout died in 2011) look unfairly shut out from the prize.

Chemists Go Small

Millisecond models for how leaves convert sunlight into energy, or for anything else that happens on the molecular level, garnered the chemistry prize announced on Wednesday, rounding out Nobel week for science winners.

The award went to Martin Karplus of France's Université de Strasbourg and Harvard, Michael Levitt of Stanford, and Arieh Warshel of the University of Southern California.

"Chemists used to create models of molecules using plastic balls and sticks," said the award announcement. Now, scientists use computers, and the prize winners pioneered that practice, starting when Karplus and Warshel created a computer model that described reactions in the retina of the eye in a 1972 study.

Warshel and Levitt followed up that work by creating computer programs in 1976 that modeled how biological reactions involving enzymes, the molecules that kick-start chemical reactions in the body, unfold.

The winners' real innovation was that their computers burrowed in and applied quantum mechanical effects—such as the ability of subatomic particles to essentially be in two places at once—that drove key milliseconds of chemical reactions between molecules.

"This year's Nobel Laureates in chemistry took the best from both worlds and devised methods that use both classical and quantum physics," as the award announcement said.

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