What's slowing down disruptive science

Discoveries that push science in new directions are happening less often than they did in the last century, according to a new finding that will help to frame debates about how (and how much) to try to spur this type of research.

Why it matters: Scientific advances fuel economies and contribute to improving human health and life — and they are increasingly at the center of geopolitics. Countries are strengthening their scientific institutions to compete for top talent and scientific and technological dominance.

• "What we understand about those institutions and how to make them better really has the potential of making a big impact over the long run on who we are as a society and on human welfare," says Pierre Azoulay, an economist at MIT who studies technological innovation.

What's new: A study of 25 million scientific papers published between 1945 and 2010 and 3.9 million patents (from 1976 - 2010) found the proportion of "disruptive" papers being published fell.

• Previous analyses have found patents, papers, Nobel Prizes and grant applications have become less novel than earlier work and less likely to bring together existing knowledge in new ways, both of which support innovation, the study authors write in the journal Nature.
• But the new study takes a broader look at the question.

How it works: The researchers gauged a paper's "disruptiveness" using the consolidation-disruption (CD) index that captures how a paper is cited.

• Citations of a paper that builds on earlier work (consolidates knowledge) typically also cite that earlier work. But a paper is considered disruptive if the papers that later cite it don't reference the same papers in the original paper — the new finding replaces the old in the network of knowledge.
• The researchers also analyzed the words in papers and found older papers were more likely to be written in terms of discovery ("form," "measure" and "determine") whereas newer ones contained language of improvement.
• They found a decline in disruptiveness across fields but it was greatest in the social sciences and least in the life sciences.

Yes, but: The number of disruptive papers held steady over the decades. That helps to reconcile the findings with headline-making discoveries about advancing AI, blackhole photographs and the rapid development of COVID vaccines, says Russell Funk, a sociologist at the University of Minnesota and a co-author of the new study.

• The optimistic take: "We're still asking new questions at a remarkably consistent rate and solving problems at a much higher rate," says Dashun Wang, who directs the Center for Science of Science and Innovation at Northwestern University's Kellogg School of Management.
• The more pessimistic view: "The fact that the absolute number is not falling can be taken as a positive ... but the fall in proportion is pretty drastic and opens a lot of questions," Azoulay says.

The big question: "We have more knowledge to build on than ever so why isn't innovation accelerating?" Funk says.

What's happening: It's likely several factors are contributing to the apparent slowdown in scientific progress — even though the number of scientists, the papers they publish and the funding for their work have all increased.

• Funk and his colleagues found scientists are using narrower slices of knowledge — across many fields, they are citing the same work over and over again. "So a lot of science gets produced that doesn't get used," he says.
• A 2021 study similarly pointed to an "ossification of canon" due paradoxically to a deluge in new publications. And as knowledge accumulates in ever greater amounts, researchers may face a higher burden to learn about a field.

• Others have suggested scientists have picked their fields' low-hanging fruits and more research (and money) is needed to make the same amount of headway. But Funk says the findings aren't consistent with that view because the rates of declines happen around the same time in different fields and at more or less the same rate.
• Some researchers point to the incentives that drive science: Research confirming earlier work is often more attractive to funding agencies that "want to make investments in research that's likely to pay off not just for science, but for the public," Funk says. And there is immense pressure to publish papers in order to be funded. But funding may not be a strong driver of the trend in some fields.

The big picture: For many, disruption — coveted and promoted in the culture of Silicon Valley — carries a positive connotation and is increasingly synonymous with progress.

• But it can't be all there is to science, Wang says. "There needs to be people who ask questions and people who solve problems. Problem solvers are probably viewed as less disruptive but it doesn’t mean they are not as valuable."
• He points to Einstein's theory of general relativity and the Nobel Prize-winning LIGO experiments that test it.
• "There are super important discoveries that aren’t disruptive but advance a field or make a technology viable. You really need both," Funk says, noting the index's original name was consolidation-destablization. "If I had my way, I wouldn't call it disruption."

What's next: Funk is interested in looking at whether the disruptiveness of a paper is influenced by a range of different factors: which agency or foundation funds it, the type of peer-review process it undergoes or the age of the researchers.

• Countries also have different — and shifting — R&D goals and different policies to incentivize certain types of science over others.
• One question is whether that national diversity could actually be "good for scientific progress, rather than everybody trying to do the disruptive thing," Funk says.