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Nobel Prize in physics and in medicine explained

The Nobel Prize announcements for 2024 are rolling out this week with awards in physiology or medicine to two Americans who discovered microRNA and honors in physics for an American and a Canadian who were key to development of the machine learning that’s underpinning artificial intelligence.
Most of the Nobel prizes, which include several categories — some coming later this week — are presented in Stockholm, Sweden, while the Nobel Peace Prize is presented in Oslo, Norway. The ceremonies take place on December 10, the day that Swedish inventor Alfred Nobel, the award’s founder and funder, died. His will created what are widely seen as the premier awards in science, humanism and peace.
John Hopfield, of Princeton, and Geoffrey Hinton, of University of Toronto in Canada, share the prestigious physics prize “for foundational discoveries and inventions that enable machine learning with artificial neural networks,” per the Nobel Prize Foundation. That allows AI to find patterns in large batches of data.
“Machine learning has long been important for research, including the sorting and analysis of vast amounts of data. John Hopfield and Geoffrey Hinton used tools from physics to construct methods that helped lay the foundation for today’s powerful machine learning. Machine learning based on artificial neural networks is currently revolutionizing science, engineering and daily life,” the foundation announcement said.
The Nobel Prize in Physiology or Medicine will be shared by Victor Ambros, now a professor at the University of Massachusetts Medical School, and Gary Ruvkun, now professor of genetics at Harvard Medical School, “for the discovery of microRNA and its role in post-transcriptional gene regulation.” The announcement explained microRNA as a “new class of tiny RNA molecules that play a crucial role in gene regulation. Their groundbreaking discovery in the small worm C. elegans revealed a completely new principle of gene regulation. This turned out to be essential for multicellular organisms, including humans. MicroRNAs are proving to be fundamentally important for how organisms develop and function.”
In other words, microRNA are little on-off switches within cells that help direct their function.
Nobel, who made a fortune from the invention of dynamite, died in 1895 and left instructions for the awards in his will, saying his estate should fund “prizes to those who, during the preceding year, have conferred the greatest benefit to humankind.” The prizes were first awarded in 1901.
According to Reuters, “Nobel named the Royal Swedish Academy of Sciences to award the prizes for chemistry and physics, the Swedish Academy for literature, Sweden’s Karolinska Institute medical university for physiology or medicine, and the Norwegian parliament for peace. It is not known why Nobel chose Norway, which at the time was in a union with Sweden, to hand out the peace prize.”
A separate award for economics is not technically a Nobel Prize. Instead, since the late 1960s Sweden’s central bank has funded the “Prize in Economic Sciences in Memory of Alfred Nobel,” presented through the Nobel Foundation. It’s awarded by the Royal Swedish Academy of Sciences.
According to Reuters, “Five individuals — Linus Pauling, John Bardeen, Marie Curie, Barry Sharpless and Frederick Sanger — and one organization, the International Committee of the Red Cross, have won multiple Nobel Prizes.” The article said two laureates, the title borne by the winners, declined the award: Jean-Paul Sartre in 1964 for literature and Le Duc Tho in 1973 for the Peace Prize.
The award includes a medal, a personal citation and a cash award that is 11 million Swedish crowns, about $1.1 million in U.S. dollars. When there are multiple honorees, they share the award.
As the Deseret News reported in 2007 when University of Utah professor and geneticist Mario Capecchi won the Nobel Prize in Medicine, “Alfred Nobel was reportedly an unpretentious man, but the party thrown to honor the Nobel Prize recipients is straight out of a fairy tale: A royal family, thousands of flowers from Italy, music by a renowned orchestra and a noted soprano, all watched by an international cast of bit players, the men wearing tuxedos and the ladies in evening gowns.”
The festivities in Stockholm include lectures by the laureates, formal presentation of the awards at Sweden’s Concert Hall and a very formal banquet at Stockholm City Hall presided over by the Swedish royal family.
Hopfield created the Hopfield network, which describes the characteristics of a material “due to its atomic spin — a property that makes each atom a tiny magnet,” per the foundation’s press release. Ultimately, when the Hopfield network is given a distorted image or one that is missing something, it is able to work “stepwise to find the saved image that is most like the imperfect one it was fed with.”
Hinton built on Hopfield’s network to create a different method called the Boltzmann machine that “can learn to recognize characteristic elements in a given type of data,” per the release. He employed a number of tools from statistical physics. The foundation noted that “the machine is trained by feeding it examples that are very likely to arise when the machine is run.”
Hinton, the foundation said, built on earlier work, helping “initiate the current explosive development of machine learning.”
An illustration from the foundation showed that Hopfield’s “associative memory” connects all the nodes together and information is fed into and read out from every node. Hinton’s Boltzmann machine is created in two layers with information fed in and read out using visible nodes connected to hidden nodes. In a restricted Boltzmann machine, nodes are not connected on the same layer. “The machines are frequently used in a chain one after the other. After training the first restricted Boltzmann machine, the content of the hidden nodes is used to train the next machine and so on.”
Ambros and Ruvkun were postdoctoral fellows studying cell development in the C. elegans roundworm in the 1980s at MIT. Their work eventually took them to separate labs and projects, but as they compared notes, their findings would eventually help them discover microRNA, leading to “a completely new principle of gene regulation that turned out to be essential for multicellular organisms, including humans.”
Ambros did the relevant research at Harvard University, while Ruvkun’s work took place at Massachusetts General Hospital and Harvard Medical School.
They published their findings in two journal articles in 1993. Per the foundation’s news release, the results “were initially met with almost deafening silence from the scientific community. Although the results were interesting, the unusual mechanism of gene regularity was considered a peculiarity of C. elegans, likely irrelevant to humans and other more complex animals.”
That changed in 2000 when Ruvkun’s research group found another microRNA that coded for a very prevalent gene in the animal kingdom. Over time, hundreds of microRNAs have been identified and it’s been shown that microRNA as a gene regulator “is universal among multicellular organisms.”
The Nobel Prize in chemistry will be announced Wednesday, the literature honor on Thursday. The Nobel Peace Prize announcement is Friday, while the economics award will be announced separately Oct. 14.

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