direct evidence: evidence (usually the testimony of a witness) directly related to the fact in dispute
evidence: (law) all the means by which any alleged matter of fact whose truth is investigated at judicial trial is established or disproved
hubble's constant: (cosmology) the ratio of the speed of recession of a galaxy (due to the expansion of the universe) to its distance from the observer; the Hubble constant is not actually a constant, but is regarded as measuring the expansion rate today