|
|
Text 1. IS LIGHT A PARTICLE OR A WAVE?
Isaac Newton and the astronomer Christiaan Huygens both pondered the true nature of light, but reached very different conclusions. They examined the problem stating that any theory about the nature of light had to explain the phenomena of reflection, refraction, diffraction, and color. Thus, refraction is the bending of light while passing from one substance to another, and is the reason why lenses can focus light. On the other hand, diffraction means the spreading out of light when it passes through a very narrow gap.
Before the experiments of Newton, it was widely accepted by natural philosophers that light obtains its quality of color by interacting with matter, meaning that the “rainbow” effect we may see when light passes through a prism is produced due to the prism has somehow stained the light. Newton by his experiments demonstrated that the “white” light seen is in reality a mixture of different light colors. Moreover, these are split up by a prism. Alongside with the majority of natural philosophers of his time, Newton claimed that light consists of a stream of particles, or “corpuscles.” This idea effectively explained the idea of light traveling in straight lines and “bounced” off reflective surfaces. It was also applied to explain refraction in terms of forces at the boundaries of different materials.
Partial reflection
Newton’s theory, however, could not explain the phenomenon that light hits many surfaces, but some reflect it and some refract it. Examining the problem, in 1678, Huygens made a proposal that space was filled with many weightless particles (the ether), and that light caused the disturbances in the ether while spreading out in spherical waves. So, Huygens’ theory helped to explain the reason why both reflection and refraction can occur at a given surface. It also helped to explain the phenomenon of diffraction. But Huygens’ ideas made almost no impact at his time, mostly due to Newton’s stature as a scientist.
Nevertheless, in 1803, Thomas Young demonstrated that light does indeed behave as a wave. Moreover, the experiments made in the 20th century have shown that it behaves both like a wave and a particle. Although there exists a great difference between Huygens’ “spherical waves” and our modern models of light. Huygens claimed that light waves were longitudinal as they passed through a substance—the ether. The modern view of light waves states that they are transverse waves behaving similar to the waves of water. So, they do not require any matter to 5 propagate, while particles vibrate at the right angles (up and down) to the direction of the wave.
Exercises
1. Find Russian equivalents to the following words and expressions:
To ponder – reflection – diffraction – to pass through – interaction – a particle – to bounce – to reflect – to occur – impact – a substance – a surface – an angle
2. Form adjectives from the following nouns:
Nature – an experiment – a quality – a mixture – a difference – a reflection - a theory
3. Give synonyms to the following words used in the text:
To ponder – different – to state – to obtain – to demonstrate – to examine – to occur – impact – indeed
4. Translate these sentences paying attention to the underlined words:
• They examined the problem stating that any theory about the nature of light had to explain the phenomena of reflection, refraction, diffraction, and color.
• Before the experiments of Newton, it was widely accepted by natural philosophers that light obtains its quality of color by interacting with matter, meaning that we may see the “rainbow” effect when light passes through a prism.
• So, Huygens’ theory helped to explain the reason why both reflection and refraction can occur at a given surface.
• The modern view of light waves states that they are transverse waves behaving similar to the waves of water.
5. Translate into English the following words and expressions:
Èñòèííàÿ ïðèðîäà ñâåòà – îáúÿñíèòü ôåíîìåí – ïðîõîäèòü ÷åðåç – âçàèìîäåéñòâîâàòü ñ ìàòåðèåé – îòðàæàþùàÿ ïîâåðõíîñòü – îêàçàòü âëèÿíèå – ñîâðåìåííàÿ òåîðèÿ
6. Translate the text orally.
7. Answer the following questions:
• What is refraction?
• What does diffraction mean?
• What was the idea accepted by natural philosophers before the experiments of Newton?
• What was the problem with the Newton’s theory? • Explain the discovery of Thomas Young
• What did Huygens’ theory help to explain? • What does the modern view of light waves state?
• How did Huygens consider light?
8. Read the text again and write the summary in English