8 The Most Accurate Theory in Physics
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one reason why it has proved so difficult to unify Quantum Mechanics and
the Theory of Relativity into a theory of everything (TOE), describing all the
fundamental natural forces.
8.3 Fields and Relativistic QM
Action at a distance was never a concept embraced readily by physicists.
Newton’s theory of gravity was criticised by Descartes and Leibnitz on the
grounds that he had not explained the nature of gravity, which appeared in
his writings as almost supernatural. A quarter of a century after the initial
publication of his ideas in Principia Mathematica, Newton addressed these
criticisms. He admitted he did not understand how gravity exerted its pull
on objects across empty space.
Similar conceptual difficulties arise when considering the mutual interaction of magnets and of static electric charges. Gradually, in the nineteenth
century, these non-local influences were attributed to fields which surround
the particles. For instance, an electric field emanating from a charged particle
is capable of influencing another charged particle some distance removed.
Conversely, the field produced by the second particle can influence the first,
resulting in a chicken-and-egg dilemma.
Now let us suppose that the first electrically charged particle is moved.
How does the electric field in the vicinity of the second particle behave? Does
it change instantaneously as the first particle moves, or is there a time lag?
These questions were addressed by Gauss and Faraday, before being resolved
by James Clerk Maxwell, as we have seen in Chap. 5, in a seminal paper in
the second half of the 19th Century.
Maxwell found that not only did the electric field propagate out from a
moving electric charge with a definite speed, but the moving electric charge
generated a magnetic field, which also propagated. These propagating intertwined fields became known as electromagnetic radiation and the study of their
properties was called Electromagnetism.
Maxwell went even further: he was able to predict the speed of propagation
of the electromagnetic radiation from two independent physical constants
which could be measured in the laboratory. The value he obtained for this
speed was close to another well-known physical constant, the speed of light.
Not believing this to be just a coincidence, he then made the bold assertion
that light was actually a form of electromagnetic radiation. His work united
the three separate disciplines of electricity, magnetism and optics under the
149
one reason why it has proved so difficult to unify Quantum Mechanics and
the Theory of Relativity into a theory of everything (TOE), describing all the
fundamental natural forces.
8.3 Fields and Relativistic QM
Action at a distance was never a concept embraced readily by physicists.
Newton’s theory of gravity was criticised by Descartes and Leibnitz on the
grounds that he had not explained the nature of gravity, which appeared in
his writings as almost supernatural. A quarter of a century after the initial
publication of his ideas in Principia Mathematica, Newton addressed these
criticisms. He admitted he did not understand how gravity exerted its pull
on objects across empty space.
Similar conceptual difficulties arise when considering the mutual interaction of magnets and of static electric charges. Gradually, in the nineteenth
century, these non-local influences were attributed to fields which surround
the particles. For instance, an electric field emanating from a charged particle
is capable of influencing another charged particle some distance removed.
Conversely, the field produced by the second particle can influence the first,
resulting in a chicken-and-egg dilemma.
Now let us suppose that the first electrically charged particle is moved.
How does the electric field in the vicinity of the second particle behave? Does
it change instantaneously as the first particle moves, or is there a time lag?
These questions were addressed by Gauss and Faraday, before being resolved
by James Clerk Maxwell, as we have seen in Chap. 5, in a seminal paper in
the second half of the 19th Century.
Maxwell found that not only did the electric field propagate out from a
moving electric charge with a definite speed, but the moving electric charge
generated a magnetic field, which also propagated. These propagating intertwined fields became known as electromagnetic radiation and the study of their
properties was called Electromagnetism.
Maxwell went even further: he was able to predict the speed of propagation
of the electromagnetic radiation from two independent physical constants
which could be measured in the laboratory. The value he obtained for this
speed was close to another well-known physical constant, the speed of light.
Not believing this to be just a coincidence, he then made the bold assertion
that light was actually a form of electromagnetic radiation. His work united
the three separate disciplines of electricity, magnetism and optics under the