How Does Light Travel?

How does light travel? The simple answer is that it travels very fast and always in a straight line. 

Light is a formed by a stream of small packets of energy called photons. These travel very fast and will not stop until they run into a barrier. So for example if you shine a flashlight on a person or a wall, the light will illuminate the area but it will not be able to bend or get through a solid object.

How does light travel is a common question. The simple answer is that it can only travel in straight lines in a constant beam from the source. You can not cause light to bend or make it deviate from this projection. 

School children learning science can take part in a simple experiment to demonstrate this. A torch is shone on a line of three cards suspended in a milky water solution. The first card has three pinholes, the second card has two pinholes and the last one just has one pinhole. All these are aligned with each other. 

When the light is shone on the first card, the pinholes enable three beams of light to shine through to the second card where the pinholes then send two beams of light through to the last card which has only one pinhole. Students can clearly see the light beams against the milky water solution and notice how the light beams are straight and are easily stopped by a physical barrier. 

Einstein discovered that the speed of light is constant and that light from a fast moving object such as a car moves no faster than light emitted from a stationary object. In short, you cannot speed up the speed of light.  

How does light travel and how fast is it

So light only ever travels in a straight line and it moves very fast. It travels 186, 000 miles (300,000Km) per second making it an effective way to calculate distances in space. The distant planets and stars are so far away that they are measured in light years. This means the distance that a beam of light travels over a course of a year. 

According to NASA, one light year is equal to 5.8 trillion miles (9.4 trillion kms). Our nearest galaxy is the Andromeda galaxy and is around 220 million light years away. Our nearest neighbouring star is Proximi Centauri and if we travelled at the speed of light it would take 4.25 years to get there. 

The Sun is about 8 light minutes from the earth. This means that when we look at the sun we are seeing it as it was 8 minutes previously. It would take 1.87 light years to reach the furthest edge of our own Solar System (the Oort Cloud which is made up of dormant comets) 

How does light travel is the fundamental principle of Albert Einstein’s Law of Relativity, which he discovered in 1905. This not only shone a light on our own natural world, it enabled scientists to better understand the cosmos and the vast distances of space.