What is an optical illusion?
An optical illusion is a trick played by our eyes on us. When we see an object, the actual image detection is done by our brain. The cells in the brain are the real decision-makers about what the eyes are seeing. In the case of an optical illusion, the brain sees things that may or may not be the way they are. It perceives things that may not match the true image. An optical illusion is a psychological phenomenon. Some of the common types are colour blind images, colour illusions, horizontal lines, shape illusions, etc.
What is thought?
Thoughts are impulses that originate from our brain. The speed of these impulses cannot be measured accurately; however, it has been calculated that thoughts travel at a speed of 241 km per hour. This speed is lower than the speed of messages conveyed through television, email, etc. The speed of thought varies according to the situation. For example, we react at a faster speed to sound than to light. The speed of thought varies from person to person. Some people react quickly to a situation while some are slow in reacting.
What is light?
We cannot imagine a world without light. Light lets us see. Light was first studied by Sir Isaac Newton. He said that light consisted of minute particles which are shot out from the source of light. Another theory was suggested by Huygens. He said that light is in a form of ‘wave’ or ‘pulse’. Light is a form of energy whose speed can be measured. We are familiar with many properties of light, for example, white light is a mixture of all colours. Theories also suggest that the colour of an object is due to the colour it reflects from the spectrum of white light. A green leaf is green because it absorbs all the colours except green.