Isaac Newton proposed a particle theory of light known as the corpuscular theory. According to this theory, light was thought to consist of tiny particles, or corpuscles, emitted by a light source. Newton believed that these corpuscles traveled in straight lines and could be reflected, refracted, and absorbed by matter.
However, Albert Einstein's work in the early 20th century revolutionized our understanding of light. In his theory of special relativity, Einstein proposed that light behaves as both particles (photons) and waves, depending on the experiment or observation. This duality is known as wave-particle duality.
Einstein's theory of relativity also introduced the concept that the speed of light is constant in a vacuum and is the maximum attainable speed in the universe. This was a departure from Newton's corpuscular theory, which did not consider the speed of light as a fundamental constant.
In terms of agreeing or disagreeing, it is important to note that Einstein's theories built upon and extended Newtonian physics, rather than directly contradicting it. While Einstein's theory of relativity expanded our understanding of light, it did not entirely invalidate Newton's corpuscular theory. Instead, it provided a more comprehensive framework that accounted for various phenomena associated with light, such as the behavior of light in gravitational fields and its interaction with matter.
In summary, Newton explained the nature of light through the corpuscular theory, whereas Einstein's theories of special and general relativity introduced a more comprehensive understanding of light as both particles and waves, and established the constancy of the speed of light.