14 DAY TRIAL // Rensselaer researchers concluded that if there are too many delays in communication between two or more parts of a system, the performance of the whole system will eventually collapse.
Scientists analyzed the failures in coordination in complex networks, going from flocking birds to the Web.
Any individuals that are part of a network, communicate information to each other in order to synchronize their activities.
What researchers found out is that the principle of “more communication increases harmony and efficiency within a network” is only valid if the communication and its actions are immediate.
If coordination and synchronization are not respected, then large delays in communication will appear, even between only two or three parts of a system, and the entire system will collapse.
The researchers came to this conclusion by using statistical physics and network science on network systems where the fact that individuals interact with each other results in a better outcome.
Their previous studies have concluded that even the smallest interactions between close individuals (called nodes) are responsible for the whole performance of the structure.
They got to this conclusion by using stochastic differential equations - mathematical equations that model the evolution of complex systems in time, with random variables – to see what happens when delays appear within the system.
Corresponding author for the paper and Associate Professor of Physics, Applied Physics, and Astronomy, Gyorgy Korniss said that “when there are no delays, the more you communicate with your neighbor, the better global performance becomes.
“If there are delays, for a while performance will increase, but even if you work harder to better communicate with your neighbors, eventually performance will decrease until it reaches zero.
“Understanding the impact of delays can enable network operators to know when less communication effort can actually be more efficient for overall performance.”
These calculations show that the longer the delays are, the faster the system breaks down; and also even if a system has delays, there is a small lapse of time when increasing communication can improve performance.
But, as Korniss explained, after a while you simply have to know when to “shut up”, because you will get to a point where all communication is useless and counterproductive.
Study co-author Boleslaw Szymanski, Rensselaer’s Claire & Roland Schmitt Distinguished Professor of Computer Science, said that the “conclusion that coordination can sometimes be restored by decreasing node connectivity offers an important perspective on today’s world with its abundance of connectivity in social and technological systems, raising the question of their stability.”
This research could be extended to real-life situations in economic or social networks, and it might help predict global markets' response to the trading of certain stocks.
The work is part of the Social Cognitive Network Academic Research Center (SCNARC) at Rensselaer, and was funded by the Defense Threat Reduction Agency (DTRA) and by the Army Research Laboratory (ARL) through SCNARC, part of the Network Science Collaborative Technology Alliance (NS-CTA).
The results were published last month, in Physical Review Letters in a paper titled “Network Synchronization in a Noisy Environment with Times Delays: Fundamental Limits and Trade-Offs.”