 A physical law or law of physics is a statement inferred from particular facts, applicable to a defined group or class of phenomena, and expressably by the statement that a particular phenomenon always occurs if certain conditions be present. Physical laws are typically conclusions based on repeated scientific experiments and observations over many years and which have become accepted universally within the scientific community. The production of a summary description of our environment in the form of such laws is a fundamental aim of science. These terms are not used the same way by all authors. The distinction between natural law in the political legal sense and law of nature or physical law in the scientific sense is a modern one, both concepts being equally derived from thisis, the Greek word translated into Latin as natural for nature. Many scientific laws are couched in mathematical terms. While these scientific laws explain what our senses perceive, they are still empirical, and so are not mathematical laws. Physical laws can be proved purely by mathematics and not by scientific experiment.