Fires can devastate HOT forests.
© Getty Images
New theory shows that high performance needn’t mean high risk.
For man-made systems such as machines and markets, catastrophe lurks somewhere between high risk and high performance. US physicists may have found a way to strike the optimal balance1.
This trade-off is familiar to the financial world. Brokers develop investment portfolios to provide the best returns within a specified level of risk. Mark Newman and co-workers at the Santa Fe Institute in New Mexico have borrowed some ideas from the economic theories of risk aversion to create a general prescription for avoiding ruin.
But a HOT system has an Achilles’ heel. It is typically fragile under perturbations for which it was not designed. For example, if the distribution of fire breaks or sparks alters slightly, a forest can become highly susceptible to fires and give a poor yield.
Newman’s team now points out that HOT designs have another drawback. The cost of an optimal performance is a high chance of a ruinous collapse. Catastrophic fires that burn nearly all the trees are rare, but not as rare as one would expect if fire size were random. The optimal state is a high-risk state: it gives good returns at the price of possible ruin.
Most engineers don’t want to run this risk. So Newman’s group has calculated how to design a system to optimize performance and almost eliminate the probability of ruinous events. They call this design principle ’constrained optimization with limited deviations’, or COLD.
Surprisingly, a COLD state can completely remove the danger of total ruin while sacrificing only a few per cent of the average yield relative to a HOT state. Newman and colleagues say that, as we are generally risk-averse, we are more likely to prefer COLD designs than HOT ones.
Nature, apparently, is more short-sighted. Ecosystems, for example, are often in HOT states They are catastrophically susceptible to rare disturbances not accounted for by natural selection - such as meteorite impacts.
PHILIP BALL | © Nature News Service
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences