Physicist

From Free net encyclopedia

The word physicist should not be confused with physician, which means medical doctor.

A physicist is a scientist trained in physics. Physicists study a wide range of physical phenomena spanning all length scales: from the sub-atomic particles from which all ordinary matter is made (particle physics) to the behavior of the material Universe as a whole (cosmology). There are numerous different branches of physics and each has its corresponding specialists, such as astrophysicists, geophysicists, or biophysicists.

Employment as a professional physicist generally requires a doctoral degree. Physicists are employed by universities as professors, lecturers, and researchers, and by laboratories in industry. Many people who are trained as physicists, however, use their skills in other parts of the economy, in particular in engineering, computing, and finance.

1 Astrophysicists and physical cosmologists
2 Particle and quantum physicists
3 See also
4 External links

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Astrophysicists and physical cosmologists

At the largest scale, astrophysicists and astronomers study the structure and motion of the universe. This branch of physics is one of the oldest, with its foundations in the ancient study of astronomy. Modern astronomic observation dates from the early 17th century, when Galileo Galilei made the first telescopic observations of the sky. Around the same time period, Tycho Brahe and Johannes Kepler made their careful study of the motion of the planets and comets, laying the groundwork for the first principles of planetary motion.

Traditional tools of the astronomer include the telescope, and a device such as the quadrant or sextant to measure elevation. In the 20th century, the radio telescope extended the range of astronomical observation. This expanded range of observation led to the development of physical cosmology, the study of the structure, beginnings, and fate of the cosmos. Two of the more celebrated physicists of the modern age are Edwin Hubble and Stephen Hawking.

Despite enormous advances in the technology used to make observations of the universe, the majority of astrophysical observation is still a slow and painstaking job.

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Particle and quantum physicists

Physicists who deal with the smallest end of the physical universe study particle physics. This is the branch of physics that deals with the structure and ultimate nature of matter. These physicists study particles and phenomena that cannot be seen with the naked eye. To conduct their research, these physicists use particle accelerators and sensitive detecting equipment. Modern particle physics was born when the Danish physicist Niels Bohr first proposed a model for the atom, which consisted of a cloud electrons surrounding a very small nucleus, in which most of the atomic mass is concentrated, that would explain certain behavior of photon emission.

It was found that the atomic nucleus could can decay by particle emission (Alpha decay, Beta decay or Gamma decay), be split (fission) or combined (fusion). Each process resulted in behavior that could not be explained by Bohr's model of the atom. In the atomic age, Werner Heisenberg and Erwin Schrödinger developed a theory of quantum mechanics to explain the behavior of matter at the smallest scale. Modern physicists are still trying to cope with difficulties introduced by this theory. In particular, it does not fit well with our view of gravity and the universe at the large scale, although it explains the small scale very well. Some of today's particle physicists hope to reconcile the two views of the universe some day, and are presently trying to do so with modern string theory.

Other physicists continue to study nature at intermediate size (and energy) scales in the fields of atomic physics, nuclear physics, and solid state physics. Each of these branches of physics are subdivided into a variety of different sub-disciplines.

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