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The Speed of Light | Why Does it Matter?

HOW FAST DOES LIGHT TRAVEL?

If you could travel at the speed of light, you could go around the Earth 7.5 times in one second.

This is because the speed of light is as fast as 300,000 kilometres per second or 300,000,000 metres per second.

The speed of light in a vacuum is 186,282 miles per second or 299,792 kilometers per second , and in theory nothing can travel faster than light. 

This is the cosmic speed limit, and the constant that stands for the speed of light in vacuum is known as 'c' or 'celeritas'.


BUT CAN ANYTHING ELSE TRAVEL AT THE SPEED OF LIGHT?

Quarks, leptons, neutrinos, and even dark matter all have masses as a property inherent to them.

Objects made out of these particles, such as protons, atoms, and even human beings all have masses as well.

As a result, they can approach, but never reach the speed of light in a vacuum.

No matter how much energy you put into them, the speed of light, even in a vacuum, will forever be unattainable, and nothing else other than light itself can really travel at the speed of light. 


REFRACTION DUE TO CHANGE IN THE SPEED OF LIGHT

The speed of light changes depending on the medium, this is what leads to refraction in lenses.

When light travels from a rarer medium(air for example) to a denser medium(glass slab for example) then it bends towards the normal because the speed of light is different in the two media.

And when it travels from the denser medium to the rarer medium, the light ray bends away from the normal for the same reason.

IMPORTANCE OF THE SPEED OF LIGHT

The speed of light is very important in physics. 

It tells us that what we are seeing right now has actually already happened.

For example, it takes about 8 minutes for  light from the sun to reach us. Which means that if anything was to happen on the sun we could only see it 8 minutes later.

So if the sun was to disappear suddenly, we would see it dissapear 8 minutes after it actually did.

And for objects which are very far away, this is very significant. If there is a solar system 5 million light years away from us, we would only be able to see it from earth the way it was 5 million years ago.

Even for his special theory of relativity, Einstein had used the concept that nothing can travel faster than the speed of light.

So the speed of light is a significant concept in physics.



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