Reflection – The nature of light

The article:

A brief history of light

We’re starting on a new topic:


So here’s a brief history of the theories throughout history on “What is Light?”

Summarized, the theories are as follows:

  1. Tactile theory (Ancient Greece) – the eyes send out invisible probes to ‘touch’ and ‘feel’ objects around it. When these probes return, the eye can see the objects. But then, how do we see in the dark?
  2. Emission theory (Later in Ancient Greece) – the eyes emit light, which travels in rays or straight lines.
  3. Emission theory 2 (around AD 990+) –  objects emit light, which travels back to the eye.
  4. Particle/ Corpuscular theory (Newton) – light is composed of tiny particles of matter that travel through an invisible medium called “aether” that fills all empty space between objects
  5. Wave theory (Huygens) – light comprises longitudinal waves that slow down when they enter optically denser media
  6. Electromagnetism (Maxwell) – Since electromagnetic waves travel at the same speed as the measured speed of light, light is an electromagnetic wave.
  7. <Quantum theory (Einstein)> This is not covered in the article, but was mentioned in class

An observation: The explanations for what light is have graduated from ‘physical explanations’ (e.g. the tactile theory – based on what people saw in daily life) to more ‘abstract explanations’ (e.g. electromagnetism – we can’t actually see these waves, can we?)

What I’ve learnt

– The history of science can teach us many things

This article shows how theories on what light actually is have changed throughout history. In this process, scientists have continuously improved on previous scientists’ works by questioning their thinking and conducting their own experiments. In doing so, they have thus inched closer towards the truth.

  • Therefore, I’ve learnt that learning is a continuous process. Who knows, maybe the current theory on what light is may be disputed in the near future!

These scientists have also made numerous errors throughout history.

  • As such, we must be open-minded to others’ ideas. Quote from the article: “Clash of ideas is very important for science to progress since it affords an opportunity for refinements to be made as erroneous beliefs give way.”
  • A case in point is the suffocating influence of ‘giants’ in the scientific world. People were afraid to challenge Newton’s particle theory because his influence was too great – “few dared to think differently from him!”
  • As a result, people believed that “aether” existed for 2 centuries!

Lastly, great ideas that go against convention are often challenged. Thus, perseverance is important!

  • Thomas Young was belittled by other scientists, but he was eventually proved right.