Pure subtype system type safety
A type system can let programs and their types share the same language. Can the remaining proof show that the proposed pure-subtype rules stay valid as a program evaluates?
Explore all problems.
Rabin–Mostowski index problem
A finite automaton can check an infinite branching tree using a hierarchy of recurring priorities. Can an algorithm tell whether the same trees can be recognized with a smaller priority hierarchy?
Gallium anomaly
Gallium detectors exposed to intense laboratory neutrino sources make fewer germanium atoms than standard capture calculations predict. Is the missing yield a nuclear-calculation problem, a measurement effect or new neutrino physics?
Bilayer nickelate pairing mechanism
Nickel-oxide bilayers superconduct under high pressure and in suitably prepared ambient-pressure films. What interaction binds the electron pairs, and can one quantitative account explain the measured gaps and material dependence?
Saturn’s tidal dissipation
Saturn transfers spin to its moons, moving them outward. The strength and frequency pattern of this transfer point to unusually effective internal energy loss. Which interior processes set those rates and their evolution?
Magnetotail reconnection energy partition
When Earth’s stretched magnetic field reconnects, released energy heats particles and creates fast-moving tails in their energy distributions. What determines the ion/electron and thermal/nonthermal shares under measured magnetotail conditions?
Roughness-induced hypersonic transition
A rough patch on a hypersonic heat shield can change a smooth boundary layer into turbulent flow and increase heating. How can engineers predict the onset and heat load from the actual roughness geometry and flight conditions?
Solid-state nuclear clock accuracy
Laser-controlled clocks can already use thorium-229 nuclei inside crystals. Can their environmental shifts be measured and controlled well enough to establish a complete fractional-frequency uncertainty near 10^-18?
Air-breathing electric propulsion
A very low satellite could scoop up the thin atmosphere and use it as electric-thruster propellant. Can the complete intake and thruster provide sustained thrust exceeding their own drag with available onboard power and no steady stored propellant supply?
Gamma-ray burst prompt emission
The first flash of a long gamma-ray burst reveals an ultra-relativistic jet releasing energy. Which radiation processes produce the photons, and how do their contributions change during the burst?
Psychological refractory period
Two quick tasks can make the second response wait. What controls that queue when response demands and task priorities change?
Visual stability across saccades
Each glance sweeps an image across the retina. How do prediction, masking and learned omission hide that sweep while leaving external motion visible?
Visual serial dependence
A judgment can lean toward what was seen or reported a moment ago. Which lingering process produces attraction rather than repulsion?
Learned distractor suppression
A bright irrelevant item first attracts the eyes, then becomes easier to ignore. Must attention visit it before suppression can be learned?
Spacing effect
Repeating a word later can help more than repeating it immediately. Which changes across the gap determine lasting verbal memory?
Retrieval-induced forgetting
Practicing some items can make related unpracticed items harder to recall. Is their access inhibited, or does the new retrieval context favor competitors?
Tip-of-the-tongue states
A known word feels close but will not come out. When does another retrieval attempt clear the block, and when does the same block return?
McGurk effect
Hearing “ba” while seeing lips form “ga” can sound like “da.” Does the brain average possible speech causes or select among them?
Mental rotation
Comparing turned objects often takes longer at larger angles. Do people rotate continuously, use discrete view changes, or recognize shape more directly?
Pure-water AEM electrolysis
An electrolyzer can make hydrogen without circulating caustic solution. Can its catalyst layers keep conducting ions and releasing gas as their polymer binder ages?
Implantable bioartificial pancreas
An implant can shelter insulin-producing cells and even generate oxygen for them. Can one retrievable device deliver a useful endocrine response at human scale while keeping its cells contained?
Organic flow-battery lifetime prediction
A charged flow battery can lose capacity while merely waiting. Can a model forecast how much active organic material will remain when its temperature and charging schedule change?
Self-healing concrete chloride protection
A bridge crack can appear to seal while salt still reaches the steel inside. How much reliable corrosion delay does healing provide when the crack and exposure keep changing?
Process-based fatigue qualification of printed metals
Two printed metal brackets can look alike and fail after different numbers of load cycles. Can manufacturing information predict that scatter before every process change requires a new fatigue campaign?