Problems by archive

Can a protein's three-dimensional folded structure be reliably predicted from its amino acid sequence alone, without needing slow, expensive experimental methods like X-ray crystallography?

Can nuclear fusion reactions be harnessed in a reactor that produces more usable energy than it consumes, for practical power generation?

Can a dilute gas of atoms be cooled and compressed into a single, coherent quantum state (a Bose-Einstein condensate), and how well does phase-transition theory describe such ultracold systems?

How do rod- or disk-shaped molecules self-organize into the partially ordered liquid-crystal phases, and what microscopic physics produces ferroelectric materials with a switchable spontaneous electric polarization?

Can carbon atoms self-assemble into closed cage molecules (fullerenes) and rolled-up cylindrical sheets (nanotubes), and can these exotic carbon forms be produced, understood, and put to practical use?

Is there a general theory that predicts the statistical behavior of turbulent fluid flow directly from the Navier-Stokes equations, and can fully chaotic dynamical systems be understood from first principles?

Does Einstein's general theory of relativity correctly describe gravity in every regime tested so far, including the strongest fields near black holes and at cosmological scales?

Can ripples in spacetime itself, predicted by general relativity and generated by events like merging black holes, be directly measured on Earth?

Do black holes really exist exactly as general relativity predicts, with event horizons as described, and do hypothetical thread-like 'cosmic strings' left over from the early universe exist?

What is the invisible 'dark matter' that makes up most of the gravitating mass in galaxies and the universe, and can it be directly detected in a laboratory?

What cataclysmic events power gamma-ray bursts, the most luminous explosions in the universe, and are long and short bursts produced by different mechanisms?

Do neutrinos have mass and change ('oscillate') between flavor types as they travel, explaining why fewer solar and atmospheric neutrinos than expected reach detectors on Earth?

Why do physical processes in our universe overwhelmingly run in one time direction (entropy increasing), even though the fundamental microscopic laws of physics are very nearly symmetric under time reversal?

What does quantum mechanics actually tell us about physical reality — is the wavefunction real, does measurement cause genuine collapse, and could hidden variables restore classical determinism?

By alternately standing/squatting or rocking your body on a swing with no one pushing, you can increase the swing's amplitude: what is the physical mechanism, and is it a driven or a parametric oscillator?

In a partially evacuated glass bulb, a four-vaned wheel with one blackened and one silvered face per vane spins when light shines on it, but it spins with the black faces trailing, not leading as simple radiation-pressure reasoning predicts: why?

Given the air temperature and a pond's depth, roughly how long will it take for the pond to freeze solid from the surface down, and what physical law governs how the ice thickness grows with time?

A pinhole camera with too large a hole gives a blurry, doubled image from simple geometry, but too small a hole also blurs the image from diffraction: is there an optimal pinhole diameter, and if so, what determines it?

Sound waves from an elevated bell reach the ground, but the loudest point on the floor is not necessarily directly below the bell: where is it, and why?

The 1908 Tunguska event released energy equivalent to a very large meteorite impact: could an object of that scale have measurably changed the length of Earth's day or its axis of rotation?