(physics) A relativistic paradox concerning the concept of Born rigidity within special relativity, where an ideally rigid cylinder that is made to rotate about its axis of symmetry. The radius R as seen in the laboratory frame is always perpendicular to its motion and should therefore be equal to its value R₀ when stationary. However, the circumference should appear Lorentz-contracted to a smaller value than at rest. This leads to the contradiction that R = R₀ and R < R₀.

The observation that, because of the very large number of degrees of freedom in an unfolded polypeptide chain, the molecule has an astronomically large number of possible conformations, and therefore sequentially sampling all the possible conformations is not practical, yet most small proteins fold spontaneously on a millisecond or even microsecond timescale.

(logic) A paradox arising from vague predicates and repeatedly applying a small difference. For example, removing one grain from a heap of sand still leaves a heap, yet removing enough grains will eventually not leave a heap.

plural of sorites paradox

The situation in which a phenomenon being observed for study is unwittingly influenced by the presence of the observer.

(economics) The apparently paradoxical observation that people's reported happiness varies directly with income both among and within nations, but over time happiness does not trend upward as income continues to grow.

(set theory) The paradox that supposing the existence of a set of all ordinal numbers leads to a contradiction; construed as meaning that it is not a properly defined set.

The paradox whereby aid agencies report the success of most of their programs, yet it is impossible to establish any significant correlation between aid and GDP growth in developing countries.

A semantic paradox of self-reference, where, supposing that "autological" means "self-describing" and "heterological" means "not self-describing", then "heterological" itself cannot be meaningfully classified as either of the two.

The apparent contradiction that, although water is generally more useful than diamonds, diamonds command a higher price in the market.