Open Questions

Open Physics

Why It Is Open Superconductivity above the boiling point of liquid nitrogen was discovered in copper-oxide ceramics in 1986, but unlike low-temperature superconductivity, no accepted theory explains why electrons pair and flow without resistance at such comparatively high temperatures. The mechanism remains, in the field's own words, an important unsolved theoretical problem in condensed matter physics.

What Would Settle It A microscopic theory of high-temperature superconductivity that predicts, rather than merely fits after the fact, which materials will superconduct and at what temperature, tested against the growing family of known high-temperature superconductors.

Expertise Needed Condensed matter physics

Question posed in Physics (Wikipedia).

Open Mathematics

Why It Is Open The P versus NP problem asks whether every problem whose solution can be quickly checked can also be quickly solved. It has resisted proof or disproof since it was formalized in the early 1970s and is one of the seven Millennium Prize Problems; a solution in either direction would reshape cryptography, optimization and much of theoretical computer science.

What Would Settle It A rigorous proof that P equals NP, exhibiting a general fast algorithm for an NP-complete problem, or a proof that P does not equal NP, most likely by establishing a genuine computational barrier no such algorithm can cross.

Expertise Needed Theoretical computer science and mathematical logic

Question posed in Mathematics (Wikipedia).

Open Neuroscience

Why It Is Open Neuroscientist and Nobel laureate Eric Kandel described understanding the biological basis of learning, memory, behavior, perception and consciousness as the epic challenge of the biological sciences. Decades of work mapping neurons and circuits have not yet produced an accepted account of how subjective experience arises from physical brain activity.

What Would Settle It A theory of consciousness that makes testable predictions linking specific patterns of neural activity to the presence or absence of subjective experience, confirmed across independent experimental paradigms rather than argued from a single framework alone.

Expertise Needed Cognitive and computational neuroscience

Question posed in Neuroscience (Wikipedia).

Open Cosmology

Why It Is Open Observations of distant supernovae in the late 1990s showed the expansion of the universe is accelerating rather than slowing under gravity, implying roughly 68 percent of the universe's total energy content is an unseen component dubbed dark energy. No experiment has yet detected it directly or explained its physical nature, whether a constant property of space itself or a dynamic field.

What Would Settle It Direct physical detection or a theoretical account of dark energy that makes testable predictions distinguishing it from a simple cosmological constant, confirmed by independent observational surveys of cosmic expansion.

Expertise Needed Physical cosmology and theoretical physics

Question posed in Cosmology (Wikipedia).

Open Particle Physics

Why It Is Open The Big Bang should have produced equal amounts of matter and antimatter, which would have annihilated each other completely, leaving no universe of matter at all. The known laws of particle physics do not explain the small asymmetry, thought to be about one extra matter particle per billion matter-antimatter pairs, that let the observable universe of stars, planets and everything else exist.

What Would Settle It Discovery of a new source of charge-parity violation, beyond the small amount already observed in known particle interactions, sufficient to account for the measured cosmic matter-antimatter imbalance.

Expertise Needed Particle physics and physical cosmology

Question posed in Particle Physics (Wikipedia).

Open Seismology

Why It Is Open Decades of seismological research have established longer-run probabilistic hazard estimates for a given region, but no method has reliably forecast the precise time, location and magnitude of an individual future earthquake, and some researchers argue short-term prediction may be fundamentally impossible given how earthquakes nucleate.

What Would Settle It A precursor signal, whether seismic, geochemical or geodetic, shown across many independent earthquakes to reliably precede rupture with enough lead time and specificity to issue an actionable short-term warning.

Expertise Needed Seismology and geophysics

Question posed in Seismology (Wikipedia).

Open Photometer

Why It Is Open Wikipedia's Photometer article states three photometer types (Rumford's, Ritchie's, and shadow-extinction types) were already in common use by 1861, but names no invention year or event for the instrument itself. The existing invented edge already credits Benjamin Thompson (Count Rumford), but neither his own Wikipedia biography nor the Photometer or Photometry (optics) articles state a year. A web search found a plausible date, Rumford's 1794 paper in Philosophical Transactions vol. 84, but the corroborating page (Citizendium) returned HTTP 403 and was not visited, so it is not citable under the quote-capture duty.

What Would Settle It A fetchable, quotable page (not blocked) that states the year Rumford, Ritchie or an earlier figure such as Bouguer or Lambert first built or described a working photometer, ideally naming the specific publication (Rumford's 1794 Philosophical Transactions paper is the leading candidate).

Expertise Needed History of science

Question posed in Photometer (Wikipedia), History section.

Open Panini

Why It Is Open Panini's own text carries no date and almost nothing external is known about his life, so his working century has to be inferred rather than read off a record, and the lines of evidence point in different directions. His grammar uses the words rupya and nishka for coined money, and numismatists date those coin types in India to the fourth century BCE; Johannes Houben has argued this places Panini at around 350 BCE on unrefuted concrete grounds. Hartmut Scharfe has argued instead that the language Panini's own grammar describes sits close enough to the language of the Upanishads and the Vedic sutras to suggest a fifth or sixth century BCE date, a linguistic argument that does not touch the coinage evidence directly. George Cardona, weighing both, holds that the evidence taken together supports a date no earlier than 400 BCE and that the case for anything earlier depends on interpretation rather than proof. MacTutor's own independent review of the question calls the proposed dates pure guesses and finds proposals spanning the fourth through the seventh century BCE. No consensus exists among these positions, and none has become the settled view.

What Would Settle It A securely dated external reference to Panini himself, or to the Ashtadhyayi by name, from an inscription, a coin, or a text whose own date is independently fixed, would resolve it. Short of that, resolution would need either an agreed dating of the coin terminology Panini's grammar assumes that displaces or confirms the current fourth century BCE numismatic reading, or a linguistic dating method for Vedic-adjacent Sanskrit precise enough to be preferred over both the coinage evidence and rival linguistic readings. Absent new evidence of either kind, the dispute stays where the current scholarship leaves it: a disagreement over how to weigh evidence that is itself not in dispute.

Expertise Needed Historical linguistics, Sanskrit philology and Indology, numismatics

Question posed in Panini (MacTutor), Biography, dating discussion.

Open Joule's Mechanical Equivalent of Heat Experiment

Why It Is Open Wikipedia's Mechanical equivalent of heat article documents Joule's method and result in detail but names no location. Two candidate sources naming a location (a small laboratory at Pendlebury near Manchester, later moved to his Manchester home after the family brewery was sold) could not be fetched: aps.org returned HTTP 403 and a PMC/NCBI commentary article returned a captcha wall.

What Would Settle It A fetchable biography or history-of-science source (not aps.org or PMC/NCBI, both currently blocked) confirming Joule's experimental site by name.

Expertise Needed History of Science

Question posed in Mechanical Equivalent of Heat (Wikipedia), History and priority dispute section (absence of location noted).