Ion trap enables one minute in the nanocos­mos

The storage of helium nanodroplets in an ion trap enables a detailed investigation of the processes inside the droplets. The picture shows Matthias Veternik, PhD student and first author of the study, with the experimental setup.
Photo Credit: Universität Innsbruck

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers successfully stored electrically charged helium nanodroplets in an ion trap for durations up to one minute, creating stable conditions similar to those found in space.
• Methodology: The team utilized a specialized ion trap device to capture and hold the nanodroplets, replacing previous methods that restricted observation to the brief flight time between the droplet source and a detector.
• Key Data: This new storage capability extends the experimental time window by a factor of 10,000 compared to prior millisecond-scale limits.
• Significance: The extended observation time allows for high-precision spectroscopic analyses of interstellar particle simulations and the identification of lifetime-limiting factors, such as collisions with residual gas or infrared-absorbing water molecules.
• Future Application: Upcoming developments involve incorporating detection cylinders to measure the mass-to-charge ratio of individual droplets, facilitating new forms of nanocalorimetry and time-resolved studies of chemical reactions.
• Branch of Science: Ion Physics and Applied Physics.

Physicists employ AI labmates to supercharge LED light control

Sandia National Laboratories scientists Saaketh Desai, left, and Prasad Iyer, modernized an optics lab with a team of artificial intelligences that learn data, design and run experiments, and interpret results.
 Photo: Credit: Craig Fritz

Scientific Frontline: "At a Glance" Summary

• Main Discovery: A team of artificial intelligence agents successfully optimized the steering of LED light fourfold in approximately five hours, a task researchers previously estimated would require years of manual experimentation.
• Methodology: Researchers established a "self-driving lab" utilizing three distinct AI agents: a generative AI to simplify complex data, an active learning agent to autonomously design and execute experiments on optical equipment, and a third "equation learner" AI to derive mathematical formulas validating the results and ensuring interpretability.
• Key Data: The AI system executed 300 experiments to achieve an average 2.2-times improvement in light steering efficiency across a 74-degree angle, with specific angles showing a fourfold increase in performance compared to previous human-led efforts.
• Significance: This study demonstrates that AI can transcend mere automation to become a collaborative engine for scientific discovery, solving the "black box" problem by generating verifiable equations that explain the underlying physics of the optimized results.
• Future Application: Refined control of spontaneous light emission could allow cheaper, smaller, and more efficient LEDs to replace lasers in technologies such as holographic projectors, self-driving cars, and UPC scanners.
• Branch of Science: Nanophotonics, Optics, and Artificial Intelligence.
• Additional Detail: The AI agents identified a solution based on a fundamentally new conceptual approach to nanoscale light-material interactions that the human research team had not previously considered.

New quantum boundary discovered: Spin size determines how the Kondo effect behaves

Quantum spin size determines whether the Kondo effect suppresses or preserves magnetism   
The size of the spin crucially affects how the system behaves. At spin-1/2, fully quantum spins pair up and cancel each other, so no magnetism appears. At spin > 1/2, larger spins can’t fully cancel, leaving leftover spins that can interact and create magnetic order.   
Image Credit: Osaka Metropolitan University

Scientific Frontline: "At a Glance" Summary

• Main Discovery: The Kondo effect fundamentally changes function based on spin size; while it suppresses magnetism in spin-1/2 systems by forming singlets, it conversely promotes and stabilizes long-range magnetic order in systems with spin greater than 1/2.
• Methodology: Researchers synthesized a precise organic-inorganic hybrid "Kondo necklace" material containing organic radicals and nickel ions using the RaX-D molecular design framework, then utilized thermodynamic measurements and quantum analysis to compare spin-1/2 and spin-1 behaviors.
• Key Data: Increasing the localized spin from 1/2 to 1 triggered a clear phase transition to a magnetically ordered state, challenging the established view where Kondo interactions typically bind free spins into non-magnetic singlets.
• Significance: This finding overturns the traditional understanding that the Kondo effect primarily suppresses magnetism, establishing a new quantum boundary where spin magnitude acts as a determinative switch between non-magnetic and magnetic regimes.
• Future Application: Development of next-generation quantum materials with tunable magnetic properties, specifically for managing entanglement and magnetic noise in quantum computing and information devices.
• Branch of Science: Condensed-Matter Physics / Quantum Materials Science
• Additional Detail: The study provides a rare experimental realization of the "Kondo necklace model," a theoretical platform proposed by Sebastian Doniach in 1977 to isolate spin degrees of freedom.

A new way to decipher quantum systems

Image Credit: Scientific Frontline / stock image

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers at the University of Geneva have developed a novel protocol to determine the state of a quantum system by utilizing its interaction with the environment rather than minimizing it.
• Methodology: The team employed transport measurements to analyze particle flows and their correlations through a quantum system coupled to multiple environments with potential or temperature imbalances.
• Key Data: The study, published as an "Editor's Suggestion" in Physical Review Letters, demonstrates that monitoring currents induced by environmental differences provides sufficient data to reconstruct the quantum state without direct projective measurements.
• Significance: This approach transforms environmental disturbance—typically considered a hindrance—into a critical informational resource, allowing for the characterization of "open" quantum systems where strict isolation is impractical.
• Future Application: The method allows for the certification of high-sensitivity quantum sensors used in medical imaging and geophysics, as well as the advancement of quantum neuromorphic computing.
• Branch of Science: Quantum Physics and Applied Physics.
• Additional Detail: Unlike standard Quantum State Tomography (QST) which requires weak environmental coupling, this technique is specifically tailored for devices that function through continuous environmental interaction.

Polar weather on Jupiter and Saturn hints at the planets’ interior details

This infrared 3D image of Jupiter's north pole shows a ring of 8 vortices surrounding a central cyclone. MIT researchers have now identified a mechanism that determines whether a gas giant evolves one versus multiple polar vortices.
Image Credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
(CC BY-NC-ND 4.0)

Scientific Frontline: "At a Glance" Summary

• Main Discovery: MIT researchers determined that the divergence in polar vortex patterns between Jupiter and Saturn—multiple smaller vortices versus a single massive one—is governed by the "softness" of the vortex's base, a property directly linked to the planet's interior composition.
• Methodology: The team utilized a two-dimensional model of surface fluid dynamics, adapting equations used for Earth's midlatitude cyclones to gas giant polar regions; they simulated vortex evolution from random fluid noise under varying parameters of size, rotation, heating, and fluid softness.
• Key Data: Simulations indicate that "softer" bases limit vortex growth, resulting in Jupiter's cluster of 3,000-mile-wide vortices, whereas "harder" bases allow expansion into a single, planetary-scale system like Saturn's 18,000-mile-wide hexagonal vortex.
• Significance: This study establishes a novel theoretical link between observable surface atmospheric patterns and hidden interior properties, suggesting Saturn possesses a denser, more metal-enriched interior compared to Jupiter's lighter, less stratified composition.
• Future Application: These findings provide a non-invasive framework for astrophysicists to infer the internal stratification and composition of gas giants solely by analyzing their surface fluid dynamics.
• Branch of Science: Planetary Science and Atmospheric Physics.
• Additional Detail: The researchers successfully reduced a complex 3D dynamical problem to a 2D model because the rapid rotation of gas giants enforces uniform fluid motion along the rotating axis.

New method for predicting high-temperature superconducting materials

Focusing on cerium superhydride (CeH9)
Image Credit: Scientific Frontline / AI generated

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers identified electron-electron scattering as the missing key to accurately predicting high-temperature superconductivity in cerium superhydride, solving a long-standing theoretical discrepancy.
• Methodology: The study utilized a novel computational approach that accounts for complex many-body quantum problems, specifically integrating the effects of electronic friction and repulsion into existing phonon-mediated superconductivity models.
• Key Data: The new model eliminated a 50% error margin seen in state-of-the-art theories, successfully reproducing the experimental transition temperature of CeH9 within 1%.
• Significance: This work proves that strong electron correlations can actually enhance rather than suppress superconductivity by screening nuclear charges and softening atomic lattice vibrations.
• Future Application: Scientists can now apply this framework to screen vast combinations of crystal structures and chemical compositions, potentially guiding the synthesis of superconductors that function at room temperature and lower pressures.
• Branch of Science: Condensed Matter Physics.
• Additional Detail: The team compared the electron behavior in cerium to "viscous honey" to illustrate the substantial drag and interaction distinct from the water-like flow in standard metals.

Energy flow in semiconductors: new insights thanks to ultrafast spectroscopy

It took three years for researchers Grazia Raciti, Begoña Abad Mayor, and Ilaria Zardo (from left to right) to develop and characterize the complex setup – only then were the now-published measurements possible.
Photo Credit: C. Möller, Swiss Nanoscience Institute, University of Basel

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers achieved unprecedented accuracy in observing energy flow mechanisms within the semiconductor germanium, detailing step-by-step energy transfer from the electronic system to the atomic lattice following ultrafast excitation.
• Methodology: The team utilized a novel combination of time-resolved Raman spectroscopy to measure lattice vibration changes and transient reflection spectroscopy to record light behavior, stimulating the material with 30-femtosecond laser pulses and validating results with computer simulations.
• Key Data: The experimental setup detected intensity changes of less than 1 percent and frequency shifts under 0.2 cm⁻¹ with a temporal resolution capable of distinguishing picosecond-scale responses from microsecond-interval pulses.
• Significance: This study provides a comprehensive understanding of how energy dissipates and converts to heat in semiconductors, addressing critical challenges regarding overheating and efficiency in modern electronics.
• Future Application: Findings will directly inform the design of next-generation computer chips, sensors, and phononic components that offer faster recovery times and reduced thermal accumulation.
• Branch of Science: Condensed Matter Physics and Nanoscience.
• Additional Detail: The specific combination of spectroscopic methods allowed for the simultaneous observation of frequency, intensity, and duration of lattice vibrations (phonons) as they evolved over time.

Honeycomb lattice sweetens quantum materials development

In a honeycomb lattice of potassium cobalt arsenate, cobalt spins (red and blue arrows) couple and align. Potassium, arsenic and oxygen are removed to highlight the magnetic cobalt atoms.
Image Credit: Adam Malin/ORNL, U.S. Dept. of Energy

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Scientists synthesized potassium cobalt arsenate, a new magnetic honeycomb lattice material where structural distortions cause cobalt spins to strongly couple and align, serving as a stepping stone toward quantum spin liquids.
• Methodology: The team crystallized the compound from a solution of potassium, arsenic, oxygen, and cobalt at low temperatures, subsequently characterizing it via neutron scattering, electron microscopy, heat capacity measurements, and computational modeling.
• Key Data: Theoretical calculations indicated that the material's "Kitaev" interaction is currently weaker than other magnetic forces, causing the spins to freeze into an ordered state rather than forming the desired fluid quantum state.
• Significance: This study establishes a critical experimental platform for generating Majorana fermions, exotic collective excitations theorized to be essential building blocks for stable, error-resistant quantum computing.
• Future Application: Researchers plan to tune the material's magnetic interactions by altering its chemical composition or applying high pressure, aiming to develop robust components for next-generation quantum sensors and computing architectures.
• Branch of Science: Condensed Matter Physics, Materials Science, and Inorganic Chemistry.
• Additional Detail: The research supports the global search for "Kitaev materials"—substances with electrically insulating interiors but highly conductive edges—that can resist the loss of quantum properties during environmental interaction.

Hidden magma oceans could shield rocky exoplanets from harmful radiation

UNDER ARMOR?
Deep layers of molten rock inside some super-earths could generate powerful magnetic fields—potentially stronger than Earth’s—and help shield these exoplanets from harmful radiation.
Illustration Credit: University of Rochester Laboratory for Laser Energetics  / Michael Franchot

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Deep layers of molten rock known as basal magma oceans (BMOs) within super-earths become electrically conductive under extreme pressure, creating a dynamo capable of generating magnetic fields.
• Methodology: Researchers utilized laser shock compression experiments to replicate high-pressure planetary interiors, integrated with quantum mechanical calculations and planetary thermal evolution models.
• Key Data: Super-earths exceeding three to six times Earth's size can sustain these silicate-based dynamos for billions of years, potentially producing magnetic fields stronger than Earth's.
• Significance: This finding challenges the assumption that planetary magnetic fields require liquid metal cores, thereby expanding the definition of habitable zones to include massive rocky worlds previously thought to be unshielded from cosmic radiation.
• Future Application: Astronomers can apply these models to interpret future observations of exoplanet magnetic fields and atmospheric retention, refining the selection of targets for biosignature searches.
• Branch of Science: Planetary Science and High-Energy Density Physics

Fermilab researchers supercharge neural networks, boosting potential of AI to revolutionize particle physics

Nhan Tran, head of Fermilab’s AI Coordination Office, holds a circuit board used for particle tracker data analysis.
Photo Credit: JJ Starr, Fermilab

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Fermilab researchers led the development of hls4ml, an open-source framework capable of embedding neural networks directly into customized digital hardware.
• Methodology: The software automatically translates machine learning code from libraries such as PyTorch and TensorFlow into logic gates compatible with field-programmable gate arrays (FPGAs) and application-specific integrated circuits (ASICs).
• Key Data: Specialized hardware utilizing this framework can execute more than 10 million decisions per second, a necessity for managing the six-fold data increase projected for the High-Luminosity Large Hadron Collider.
• Significance: By processing algorithms in real time with reduced latency and power usage, the system ensures that critical scientific data is identified and stored rather than discarded during high-volume experiments.
• Future Application: Primary deployment targets the CMS experiment trigger system, with broader utility in fusion energy research, neuroscience, and materials science.
• Branch of Science: Particle Physics, Artificial Intelligence, and Microelectronics.

Swiss X-ray laser reveals the hidden dance of electrons

Artistic impression of X-ray four-wave mixing – a technique that reveals how electrons interact with each other or with their surroundings. The ability to access this information is important for many fields: from understanding how quantum information is stored and lost to designing better materials for solar cells and batteries.
Image Credit: © Noah Wach

Scientific Frontline: Extended "At a Glance" Summary

The Core Concept: X-ray four-wave mixing is an advanced experimental technique that allows scientists to observe the direct interactions—or "dance"—between electrons within atoms and molecules. By using ultrashort X-ray pulses, the method reveals how energy and quantum information flow at the atomic scale, offering a view into previously hidden electronic behaviors.

Key Distinction/Mechanism: Conceptually similar to Nuclear Magnetic Resonance (NMR) used in MRI scans, this technique utilizes X-rays instead of radio waves to achieve significantly higher spatial resolution. The process involves three incoming X-ray beams interacting with matter to generate a fourth wave; this signal isolates and visualizes "electronic coherences," the fleeting patterns of interaction between electrons, which other methods cannot easily detect.

Origin/History: The successful realization of this long-theorized experiment was reported in Nature on January 14, 2026. It was achieved at the Swiss X-ray Free-Electron Laser (SwissFEL) by a collaborative team led by the Paul Scherrer Institute (PSI) and EPFL, fulfilling a goal physicists had pursued for decades.

What Is: Nuclear Winter

A Planetary System Collapse
Image Credit: Scientific Frontline

Scientific Frontline: Extended"At a Glance" Summary

The Core Concept: A severe, prolonged, and global climatic cooling effect hypothesized to occur following widespread urban firestorms ignited by a large-scale nuclear exchange. It represents a fundamental decoupling of the Earth’s climate from its current stable equilibrium, resulting in sub-freezing terrestrial temperatures and precipitation collapse.

Key Distinction/Mechanism: Unlike the immediate, localized destruction of blast waves and radiation, nuclear winter is a planetary-scale environmental catastrophe. The primary mechanism is the injection of millions of tons of black carbon soot into the stratosphere via "pyrocumulonimbus" (fire-driven storm) clouds; this soot intercepts solar radiation, heating the upper atmosphere while plunging the surface into darkness and cold.

Origin/History: The term was coined in the early 1980s (notably associated with the TTAPS studies) and has been rigorously re-examined in the 2020s, culminating in a landmark 2025 consensus study by the National Academies of Sciences, Engineering, and Medicine (NASEM).

Major Frameworks/Components:

• Urban Fuel Loading: Modern cities act as dense reservoirs of combustible mass (plastics, hydrocarbons), capable of fueling firestorms with higher soot yields than mid-20th-century targets.
• Self-Lofting Microphysics: Black carbon particles absorb sunlight and heat the surrounding air, causing the soot plume to rise deeper into the stratosphere (40–50 km) where it persists for years.
• The "Nuclear Niño": A feedback loop where unequal cooling between land and oceans disrupts the Walker Circulation, triggering a seven-year El Niño-like state that collapses marine ecosystems.
• Hydrological Collapse: The stabilization of the atmosphere and reduction in surface evaporation could reduce global precipitation by 40% to 50%, causing a "cold drought."
• "UV Spring": As the soot clears, a severely depleted ozone layer (destroyed by stratospheric heating and nitrogen oxides) exposes the surface to dangerous levels of UV-B radiation.

Why It Matters: Nuclear winter is identified as the primary mechanism of destruction in a nuclear conflict, potentially killing up to 5 billion people through starvation rather than blast effects. It triggers a "system of systems" failure—collapsing agriculture, energy grids, and global trade—that creates an "energy trap" from which civilization may not be able to recover.

This exotic form of ice just got weirder

Researchers paired ultrafast X-rays with specialized instruments to study the atomic stacking structures of superionic water – a hot, black and strangely conductive form of ice that is believed to exist in the center of giant ice planets like Neptune and Uranus.
Illustration Credit: Greg Stewart/SLAC National Accelerator Laboratory

Researchers hoped to clarify the boundaries between different types of superionic water – the hot, black ice believed to exist at the core of giant ice planets. Instead, they found multiple atomic stacking patterns coexisting in overlapping configurations never seen before in this phase of water. 

Superionic water – the hot, black and strangely conductive form of ice that exists in the center of distant planets – was predicted in the 1980s and first recreated in a laboratory in 2018. With each closer look, it continues to surprise researchers.

In a recent study published in Nature Communications, a team including researchers at the Department of Energy’s SLAC National Accelerator Laboratory made a surprising discovery: Multiple atomic packing structures can coexist under identical conditions in superionic water.

Natural physical networks are continuous, three-dimensional objects, like the small mathematical model displayed here. Researchers have found that physical networks in living systems follow rules borrowed from string theory, a theoretical physics framework.
Illustration Credit: Xiangyi Meng/RPI

For more than a century, scientists have wondered why physical structures like blood vessels, neurons, tree branches, and other biological networks look the way they do. The prevailing theory held that nature simply builds these systems as efficiently as possible, minimizing the amount of material needed. But in the past, when researchers tested these networks against traditional mathematical optimization theories, the predictions consistently fell short. 

The problem, it turns out, was that scientists were thinking in one dimension when they should have been thinking in three. "We were treating these structures like wire diagrams," Rensselaer Polytechnic Institute (RPI) physicist Xiangyi Meng, Ph.D., explains. "But they're not thin wires, they're three-dimensional physical objects with surfaces that must connect smoothly." 

Synchronising ultrashort X-ray pulses

At the ATHOS beamline of SwissFEL, PSI researchers demonstrated a technique known as mode-locking, which allows fully coherent, ultrashort X-ray pulses to be produced. In the photo, several undulator modules are visible (blue); between each pair are magnetic chicanes used to delay the electrons.
Photo Credit: © Paul Scherrer Institute PSI/Markus Fischer

Scientists at the Paul Scherrer Institute PSI have, for the first time, demonstrated a technique that synchronises ultrashort X-ray pulses at the X-ray free-electron laser SwissFEL. This achievement opens new possibilities for observing ultrafast atomic and molecular processes with attosecond precision.

Scrutinising fast atomic and molecular processes in action requires bright and short X-ray pulses – a task in which free-electron lasers such as SwissFEL excel. However, within these X-ray pulses the light is internally disordered: its temporal structure is randomly distributed and varies from shot to shot. This limits the accuracy of certain experiments.

To tame this inherent randomness, a team of PSI researchers has succeeded in implementing a technique known as mode-locking to generate trains of pulses that are coherent in time. “We can now obtain fully ordered pulses in time and frequency in a very controlled manner,” says accelerator physicist Eduard Prat, who led the study, published in Physical Review Letters. Selected by the journal as Editor’s Suggestion, the study, funded by the EU/ERC project “HERO”, represents a significant step towards the generation of tailored attosecond X-ray pulses and a range of new experiments that are only possible with precisely timed, synchronized light pulses.

A Clear Signal Emerging from Quantum Noise

Surprising signals can arise from the coupling of light particles.
Image Credit: © Oliver Diekmann

Researchers at TU Wien and the Okinawa Institute of Science and Technology (OIST) have demonstrated an unexpected effect: in a quantum system that is highly disordered, coherent microwave radiation can suddenly emerge. 

Two candles emit twice as much light as one. And ten candles have ten times the intensity. This rule seems completely trivial—but in the quantum world it can be broken. When quantum particles are excited to a higher-energy state, they can emit light as they relax back to a lower-energy state. However, when many such quantum particles are coupled together, they can collectively generate a light pulse that is far stronger than the sum of individual contributions. The pulse intensity scales with the square of the number of particles—this phenomenon is known as superradiance. It is a form of collective emission in which all quantum particles in the system release energy almost instantaneously and, so to speak, “in lockstep.” 

TU Wien and the Okinawa Institute of Science and Technology (Japan) have now discovered a different, completely unexpected manifestation of this phenomenon. They observed superradiance in irregular diamonds and found that after the initial superradiant pulse, a series of additional pulses follows, emitting further radiation in a coherent and perfectly regular manner. This is about as surprising as if the uncoordinated chirping of many crickets were suddenly to merge into a single, synchronized bang. 

MicroBooNE finds no evidence for a sterile neutrino

Members of the MicroBooNE collaboration pose in front of Wilson Hall with a 3D-printed model of the MicroBooNE detector. The collaboration consists of 193 scientists from 40 institutions.
Photo Credit: Dan Svoboda, Fermilab

Scientists on the MicroBooNE experiment further ruled out the possibility of one sterile neutrino as an explanation for results from previous experiments. In the latest MicroBooNE result, the collaboration used one detector and two beams to study neutrino behavior, ruling out the single sterile neutrino model with 95% certainty.

Scientists are closing the door on one explanation for a neutrino mystery that has plagued them for decades.

An international collaboration of scientists working on the MicroBooNE experiment at the U.S. Department of Energy’s Fermi National Accelerator Laboratory announced that they have found no evidence for a fourth type of neutrino. The paper was published today in Nature.

Physics: In-Depth Description

Image Credit: Scientific Frontline / AI generated

Physics is the fundamental natural science dealing with the study of matter, energy, space, and time, and the interactions between them. Its primary goal is to understand how the universe behaves at every scale, from the subatomic particles that constitute matter to the vast structure of the cosmos.

Anything-goes “anyons” may be at the root of surprising quantum experiments

MIT physicists propose that under certain conditions, a magnetic material’s electrons could splinter into fractions of themselves to form quasiparticles known as “anyons.”

In the past year, two separate experiments in two different materials captured the same confounding scenario: the coexistence of superconductivity and magnetism. Scientists had assumed that these two quantum states are mutually exclusive; the presence of one should inherently destroy the other.

Now, theoretical physicists at MIT have an explanation for how this Jekyll-and-Hyde duality could emerge. In a paper appearing today in the Proceedings of the National Academy of Sciences, the team proposes that under certain conditions, a magnetic material’s electrons could splinter into fractions of themselves to form quasiparticles known as “anyons.” In certain fractions, the quasiparticles should flow together without friction, similar to how regular electrons can pair up to flow in conventional superconductors.

Surfing on the waves of the microcosm

A particle (red sphere) is guided from left to its destination (right) using a laser trap (double-cone) by means of a protocol developed in the study, which is described by the parameter λ. A known time-dependent external force field F (t) acts on this environment. The optimised protocol exploits this force field in a way that extracts the maximum amount of work. This can be applied to various external fields, to active particles and to micro-robot transport problems. 
Image Credit: HHU/Kristian S. Olsen

Conditions can get rough in the micro- and nanoworld. To ensure that e.g. nutrients can still be optimally transported within cells, the minuscule transporters involved need to respond to the fluctuating environment. Physicists at Heinrich Heine University Düsseldorf (HHU) and Tel Aviv University in Israel have used model calculations to examine how this can succeed. They have now published their results – which could also be relevant for future microscopic machines – in the scientific journal Nature Communications. 

When planning an ocean crossing, sailors seek a course, which makes optimum use of favorable wind and ocean currents, and maneuver to save time and energy. They also react to random fluctuations in wind and currents and take advantage of fair winds and waves. Such considerations regarding energy costs are also important for transport processes at the micro- and nanoscale. For example, molecular motors should use as little energy as possible when transporting nutrients from A to B between and within biological cells.