What is...
What is Theoretical Physics?
Physics is the study of matter and energy. The subject was first so described by Aristotle, over 2300 yrs ago, although earlier Greek philosophers (notably the atomists Leucippus and Democritus) had given elaborate theories of matter. Since the Ancient Greeks, theoretical physics has tried to explain an ever-increasing range of phenomena. Notable advances were made by Galileo (who was also one of the first to use experimental tests in physics), Newton (who gave us the first mathematical 'laws of physics'), and Maxwell (who explained electrical and magnetic phenomena with his theory of the electromagnetic field). Hand in hand with these developments went the development of technology, the industrial revolution, and the rise of Europe in the 18-19th centuries as the dominant world power.
In the 20th century an extraordinary
revolution took place, with the discovery of 2 new
theories of physics- quantum
mechanics and general
relativity. These suddenly extended the purview of
physics to cover all known phenomena in the universe.
They also correctly predicted a vast range of new
objects, ranging from an expanding universe and black
holes to a host of hidden sub-nuclear particles. The
extraordinary technological developments of the 20th
century, in physics, chemistry, and biology, are almost
entirely due to quantum mechanics. This has led to a
curious (and historically unprecedented) dependence of
modern society on the ruminations of theoretical
physicists- themselves armed with no more than pen,
paper, and the occasional computer. The success of
quantum mechanics and relativity has been so stunning
that many now believe that physics describes is all
there is- that there is nothing else in the universe,
and that everything can ultimately be explained by
physics.
This belief is certainly premature, even if one does believe that 'emergent collective phenomena' like life, or mental processes, will ultimately be reduced to the laws of physics. The main reasons for caution are (i) that we have yet to unify quantum mechanics and gravity, and (ii) that quantum mechanics itself poses fundamental problems. Nevertheless the ideas of theoretical physics will certainly continue to guide the evolution of science and technology, in the 21st century.
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