A phenomenon (Greek: φαινόμενον, romanized: phainómenon, lit. 'thing appearing to view'; plural phenomena) is an observable fact or event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which cannot be directly observed. Kant was heavily influenced by Gottfried Wilhelm Leibniz in this part of his philosophy, in which phenomenon and noumenon serve as interrelated technical terms. Far predating this, the ancient Greek Pyrrhonist philosopher Sextus Empiricus also used phenomenon and noumenon as interrelated technical terms.
See also: Phenomenology (philosophy)
In modern philosophical use, the term phenomena has come to mean 'that which is experienced in the basis of reality.' In his inaugural dissertation, titled On the Form and Principles of the Sensible and Intelligible World, Immanuel Kant (1770) theorizes that the human mind is restricted to the logical world and thus can only interpret and understand occurrences according to their physical appearances. He wrote that humans could infer only as much as their senses allowed, but not experience the actual object itself. This may make sense in terms of a communications-channel (epistemology) feeding from an ensemble of reality-inputs (ontology) yet not in the sense of applying wise imagination (a-la Albert Einstein, to partial success). Thus, the term phenomenon refers to any incident deserving of inquiry and investigation, especially processes and events which are particularly unusual or of distinctive importance.
A comparison between a candle flame on Earth (left) and in a microgravity environment, such as that found on the International Space Station (right).
The same burning phenomenon is observed, but different flame shape and colouring phenomena are also observed.
Cloud chamber phenomena. Scientists use phenomena to refine some hypotheses and sometimes to disprove a theory. See also animated version.
See also: Phenomenalism
In scientific usage, a phenomenon is any event that is observable, including the use of instrumentation to observe, record, or compile data. Especially in physics, the study of a phenomenon may be described as measurements related to matter, energy, or time, such as Isaac Newton's observations of the moon's orbit and of gravity; or Galileo Galilei's observations of the motion of a pendulum.
In natural sciences, a phenomenon is an observable happening or event. Often, this term is used without considering the causes of a particular event. Example of a physical phenomenon is an observable phenomenon of the lunar orbit or the phenomenon of oscillations of a pendulum.
A mechanical phenomenon is a physical phenomenon associated with the equilibrium or motion of objects. Some examples are Newton's cradle, engines, and double pendulums.