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probability

prob-uh-BIL-ih-tee /ˌprɒbəˈbɪlɪti/

nounB1SATACTTOEFLIELTS

generalformal

The extent to which something is likely to happen or be the case, expressed numerically between 0 and 1.

In quantum mechanics, the outcomes of measurements are inherently probabilistic. The wave function describes the probability distribution of finding a particle in a certain state or location, rather than its definite position.

The story behind the word. The word 'probability' comes from the Latin probabilitas, meaning 'credibility, likelihood.' It derives from probabilis ('provable, credible'), which itself comes from probare ('to test, to prove'). In science, it refers to the mathematical measure of how likely an event is, a concept that became central to quantum mechanics' description of reality.

Word relationships

likelihood: Often used interchangeably, but 'probability' usually implies a numerical measure.
chance: More informal; 'probability' is the formal term.

certainty: The state of being absolutely sure, without doubt.
impossibility: The state of being unable to happen.

Word family

probable (adjective): likely to happen or be true
probably (adverb): most likely

Collocations

high probability
low probability
probability distribution
calculate probability

Idioms & expressions

in all probability

Example sentences

"The probability of rolling a six on a fair die is one-sixth." General mathematical context.
"According to quantum theory, we can only calculate the probability of finding an electron at a particular point in space, not its exact location." In quantum mechanics.
"The collapse of the wave function yields a definite outcome, but the specific outcome is governed by probability." Discussing quantum outcomes.

Memory hook

To figure out the 'PROBABILITY', you have to 'PROBE' the situation and see how likely something is to happen. Likely outcome

When not to use

While 'probability' is a general term, in quantum contexts, it refers to the fundamental, irreducible probabilistic nature of reality, not just our lack of information.

Fun facts

The Copenhagen interpretation of quantum mechanics, one of the most widely accepted, posits that quantum probability is fundamental and not due to hidden variables.
Quantum mechanics replaced the deterministic predictions of classical physics with probabilistic ones, leading to Einstein's famous quote, 'God does not play dice with the universe.'

Related words

uncertainty principle, wave function

Explore more words

stochastic, prospect, contingent, Risk, contingency, aleatory

Also appears in

Technology → Mathematics & Statistics