Physics is the branch of natural science that is concerned with understanding and explaining the properties of nature at a more abstract or fundamental level than generally that of the other branches of science. Physics is thus a very broad subject since it is not concerned with knowledge in any one particular area, but instead asks questions about the fundamental causes or behaviours of things over a very wide range of topics. For example, some of the things that fall under the topic of physics include: how particles interact with one another; what interactions or forces exist in nature; the geometry and age of the Universe; how stars form, produce light and how they might they die; the creation of superconducting materials; the behaviour of substances at very cold temperatures; and the behavior of substances on the microscopic scale or in extreme conditions, to give a few examples. Some of the concepts that one might typically encounter in physics include: particles and fields, space and time, energy and momentum, and forces and charges, as well as the various laws and principles that relate these concepts to one another.
Since physics, thus, has no very specific definition[note 1] sometimes the boundaries between physics and the other branches are blurred and not well defined. For example, whilst the question of the age of the Universe is regarded as absolutely a topic of interest only to physics, the question of how a molecule behaves might well be seen to be of interest to both physics and chemistry. In such cases, the branch of science that the topic belongs to is therefore referred to as physical chemistry. Similarly, where the topics of physics and biology overlap the topic is said to belong to the science called biophysics.
The modern science of physics has no definite point of origin, although might reasonably be argued to have been substantially formed during the scientific revolutions of the 16th and 17th centuries CE, having derived from earlier disciplines and having evolved during the past four hundred years. Today physics is an active subject and many countries around the world conduct physical research in both the private and public sectors. Indeed some topics of physics are conducted at an international level, where multiple governments collaborate on a particular subject. Most physics research today is done via collaboration with other physicists, or with the physical community in general, and the subject continues to evolve as new discoveries are made and technology progresses.
Physics is one of the core sciences, and thus adheres to the Scientific Method, which states that ultimately knowledge is gained only via the observation of nature. Thus, physics, both conducted today and over time, has conducted experiments in order to observe and test nature and derive laws about how objects behave.
Relation to other Sciences
Relation to other Subjects
Areas of Research
- Feynman opens his Lectures on Physics thus:
The things with which we concern ourselves in science appear in myriad forms, and with a multitude of attributes. For example, if we stand on the shore and look at the sea, we see the water, the waves breaking, the foam, the sloshing motion of the water, the sound, the air, the winds and the clouds, the sun and the blue sky, and light; there is sand and there are rocks of various hardness and permanence, color and texture. There are animals and seaweed, hunger and disease, and the observer on the beach; there may be even happiness and thought. Any other spot in nature has a similar variety of things and influences. It is always as complicated as that, no matter where it is. Curiosity demands that we ask questions, that we try to put things together and try to understand this multitude of aspects as perhaps resulting from the action of a relatively small number of elemental things and forces acting in an infinite variety of combinations.
For example: Is the sand other than the rocks? That is, is the sand perhaps nothing but a great number of very tiny stones? Is the moon a great rock? If we understood rocks, would we also understand the sand and the moon? Is the wind a sloshing of the air analogous to the sloshing motion of the water in the sea? What common features do different movements have? What is common to different kinds of sound? How many different colors are there? And so on. In this way we try gradually to analyze all things, to put together things which at first sight look different, with the hope that we may be able to reduce the number of different things and thereby understand them better.— The Feynman Lectures on Physics, vol. I, p. 2-1
- Feynman, Richard P.; Leighton, Robert B.; Sands, Matthew (1963), The Feynman Lectures on Physics, Reading, Massachusetts: Addison-Wesley Publishing Company