The General Theory of Relativity 149
unified field theory and the detection of gravity waves. After Einstein
published his General Theory of Relativity, he pursued the problem of
finding an underlying structure of the gravitational field and the
electromagnetic field, which would unite them. In the Special Theory of
Relativity, he was able to find the underlying structure, which united the
electric and magnetic fields. In the General Theory of Relativity, he
showed that gravity may be regarded as a property of the space-time
continuum. He tried to show that the electromagnetic field could also be
explained as a property of the space-time continuum so he could unite
the gravitational and the electromagnetic fields. He never succeeded
during his lifetime to solve this problem.
The idea of gravity waves was proposed in analogy to electro-
magnetic waves. If the electromagnetic field has waves in the form of
light, it would seem that the gravitational waves should also exist.
Electromagnetic waves are generated through the acceleration of charge,
so, perhaps, the acceleration of matter would produce gravity waves.
Theoreticians estimated that gravity waves would be very weak. The
experimental detection of gravity waves has not been established.
Experimental work in this area continues.
General Relativity also plays a role in the study of cosmology and
dark matter and energy, which we will study in Chapter 25.