Category
A range of values, calculated from a sample, that is intended to capture the true population value — and it conveys both the estimate and its precision, which a single number cannot. The technical
The probability of observing results at least as extreme as yours, assuming the null hypothesis is true. It is a statement about the data given a hypothesis — not about the hypothesis given the data,
Because the shape is the underlying physics — the blocks, rows and columns are a direct picture of how electrons fill available energy states around a nucleus. The organising principle. Elements are
Two of these describe particles; two describe substances. Mixing the two categories is the source of nearly all the confusion. The particle terms: Atom — the smallest unit of an element that retains
CRISPR is a technique for making targeted changes to DNA, adapted from a bacterial immune system — and it matters because it made gene editing dramatically cheaper, faster and more accessible than
pH measures the concentration of hydrogen ions in a solution, on a logarithmic scale — and both parts of that matter for interpreting the number correctly. The definition. pH is the negative
Because soap molecules have two ends that want incompatible things, and that split personality is what lets water carry away substances water cannot normally touch. The problem soap solves. Water is
The electromagnetic spectrum is the full range of electromagnetic radiation — and the key insight is that radio waves, visible light, X-rays and everything between are the same phenomenon, differing
Because they are falling — continuously — and so is everything around them. The common phrase "zero gravity" is simply wrong about the physics. Gravity at the International Space Station is roughly
There is no single answer, and the honest position is that ageing is multi-causal — a set of interacting processes rather than one clock running down. Researchers have converged on a list of
A catalyst speeds up a chemical reaction without being consumed by it — and the mechanism is more specific and more interesting than "it helps the reaction along". The core idea: activation energy.
Because "cold" and "hot" are describing two different things, and space has almost nothing to do the transferring. Temperature is not the same as heat. Temperature measures the average kinetic energy
Tides are caused by the difference in gravitational pull across the Earth, primarily from the Moon and secondarily from the Sun. The two-a-day pattern follows from that difference rather than from
Both metals do react with oxygen. The difference is entirely in what the resulting oxide does — and it is one of the most consequential differences in materials science. Iron. Iron reacts with oxygen
Refraction, reflection and dispersion inside raindrops — and the curve is a consequence of geometry rather than of anything about the sky. What happens in a single drop: Light enters the drop and
A light year is a unit of distance, not time — the distance light travels in one year, roughly 9.46 trillion kilometres. The name misleads constantly, and it is the most common misunderstanding in
Because you feel acceleration, not speed — and the Earth's motion is almost perfectly steady. The speeds involved are enormous. At the equator, Earth's rotation carries you at roughly 1,670 km/h. Its
DNA is a molecule storing instructions for building and running an organism. A gene is a segment of it that codes for a functional product — usually a protein. The structure. DNA is a double helix of
Charged particles from the Sun colliding with gases in Earth's upper atmosphere, guided to the polar regions by the planet's magnetic field. The sequence: The Sun emits the solar wind — a continuous
More than it was long credited with. The appendix was described for most of the twentieth century as a vestigial organ with no function — Darwin himself suggested it was a remnant of a larger caecum
Two effects combine, and one of them surprises people: water is not actually colourless. Water genuinely absorbs red light. Water molecules absorb light at the red end of the visible spectrum through
In everyday speech "theory" means a guess. In science it means close to the opposite, and this single ambiguity causes a great deal of confused argument. A hypothesis is a specific, testable proposed
Entropy is a measure of how many different arrangements of a system's parts would look the same from the outside. High entropy means many arrangements produce that appearance; low entropy means very
Two reasons: heat left over from the planet's formation, and heat still being generated now by radioactive decay. Together they account for the roughly 5,000–6,000°C at the inner core — comparable to