Nav: Home

Physics shows that imperfections make perfect

January 20, 2020

EVANSTON, Ill. --- Northwestern University researchers have added a new dimension to the importance of diversity.

For the first time, physicists have experimentally demonstrated that certain systems with interacting entities can synchronize only if the entities within the system are different from one another.

This finding offers a new twist to the previous understanding of how collective behavior found in nature -- such as fireflies flashing in unison or pacemaker cells working together to generate a heartbeat -- can arise even when the individual insects or cells are different.

Northwestern's Adilson Motter, who led the research, explained that identical entities naturally behave identically -- until they start interacting.

"When identical entities interact, they often behave differently from each other," said Motter, who is a professor of physics in Northwestern's Weinberg College of Arts and Sciences. "But we identified scenarios in which the entities behave identically again if you make them suitably different from each other."

This discovery could help researchers optimize human-made systems, such as the power grid, in which many parts have to remain synchronized while interacting with one another. It also could potentially inform how groups of humans, such as juries, can coordinate to reach a consensus.

The research will publish on Monday, Jan. 20 in the journal Nature Physics. Motter coauthored the paper with Northwestern's Takashi Nishikawa and Ferenc Molnar, a former postdoctoral researcher at Northwestern who is now at Notre Dame University.

This work expands upon Nishikawa's and Motter's 2016 paper, which theoretically predicted the phenomenon.

"It is interesting that systems need to be asymmetric to exhibit behavioral symmetry," said Nishikawa, a research professor of physics in Weinberg. "This is remarkable mathematically, let alone physically. So, many colleagues thought that experimentally demonstrating this effect was impossible."

Motter and his collaborators made the seemingly impossible possible by using three identical electric generators. Each generator oscillated at a frequency of exactly 100 cycles per second. When separated, the identical generators behaved identically.

When connected to form a triangle, their frequencies diverged -- but only until the generators were properly mismatched to have different energy dissipations. At that point, they synchronized again.

"This can be visualized by putting a small lamp between each pair of generators," Molnar explained. "When the generators are identical, the lamp flickers, meaning that the generators are not synchronized. But when the generators' dissipation is tweaked to different levels, the flickering stop, indicating that the generator voltages are oscillating in sync."

The researchers dubbed this phenomenon "converse symmetry breaking" because it represents the opposite of the previously known phenomenon of symmetry breaking, which underlies superconductivity, the Higgs mechanism and even the appearance of zebra stripes.

In symmetry breaking, the dynamical equations have a symmetry that is not observed in the behavior of the system, while converse symmetry breaking concerns situations in which the behavior of the system has a given symmetry only when that symmetry is avoided in the dynamical equations.

"It might seem counterintuitive," Motter said. "But our theory predicts that this is true across many systems, not just electromechanical ones."

Motter's team plans to explore the implications of their findings across social, technological and biological systems. In particular, the team is actively working on the design of a power grid that is more stable while allowing incorporation of an increasing share of energy from renewable sources.
-end-
The study, "Network experiment demonstrates converse symmetry breaking," was supported by Northwestern University's Finite Earth Initiative and the Army Research Office (grant number W911NF-15-1-0272). Motter also is a member of the Northwestern Institute on Complex Systems.

Northwestern University

Related Behavior Articles:

Fishing for a theory of emergent behavior
Researchers at the University of Tsukuba quantified the collective action of small schools of fish using information theory.
How synaptic changes translate to behavior changes
Learning changes behavior by altering many connections between brain cells in a variety of ways all at the same time, according to a study of sea slugs recently published in JNeurosci.
I won't have what he's having: The brain and socially motivated behavior
Monkeys devalue rewards when they anticipate that another monkey will get them instead.
Unlocking animal behavior through motion
Using physics to study different types of animal motion, such as burrowing worms or flying flocks, can reveal how animals behave in different settings.
AI to help monitor behavior
Algorithms based on artificial intelligence do better at supporting educational and clinical decision-making, according to a new study.
Increasing opportunities for sustainable behavior
To mitigate climate change and safeguard ecosystems, we need to make drastic changes in our consumption and transport behaviors.
Predicting a protein's behavior from its appearance
Researchers at EPFL have developed a new way to predict a protein's interactions with other proteins and biomolecules, and its biochemical activity, merely by observing its surface.
Spirituality affects the behavior of mortgagers
According to Olga Miroshnichenko, a Sc.D in Economics, and a Professor at the Department of Economics and Finance, Tyumen State University, morals affect the thinking of mortgage payers and help them avoid past due payments.
Asking if behavior can be changed on climate crisis
One of the more complex problems facing social psychologists today is whether any intervention can move people to change their behavior about climate change and protecting the environment for the sake of future generations.
Is Instagram behavior motivated by a desire to belong?
Does a desire to belong and perceived social support drive a person's frequency of Instagram use?
More Behavior News and Behavior Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.