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# Is Speed of Light a Lie?

Ever heard about the speed of light? Obviously! everyone has!

It is exactly 299,792,458 meters per second. But if said that the speed of light is never actually measured, no one will believe it. We are so sure of it that since 1983, we have used the speed of light to define how long a meter is. It’s just the distance light travels in a vacuum in 1/299,792,458ths of a second. It ensures that the speed of light is exactly 299,792,458 m/s. But here in this article we will ,prove you that light might never actually travel at this speed and it can be said as no one ever had measured it.

The speed of light can’t be measured as speed of the other things.

Whenever we talk about the speed of light we first need to know whether it is on e-way speed or two-way speed. The one-way speed of light, from a source to a detector, cannot be measured independently as it is not possible to synchronize the clocks at the source and detector. However experimentally it is only possible to measure the round-trip speed( two-way speed) from the source to detector and back again. Albert Einstein chose a synchronization convention that made the one-way speed equal to the two-way speed.

The constancy of the one-way speed in any given inertial frame is the basis of his special theory of relativity. Speed of light was first experimentally measured by Hippolyte Fizeau in 1849 and it was about 313000 km/s which is also the two-way speed of light. So, no one has ever measured the one-way speed of light. It can also be true that the speed of light going from source and coming back can also be different as the value of speed going can be instantaneous and coming back can be ’c’.

It is just a convention that light is travelling at the same speed in all directions rather than an experimentally verified fact. As physicist have discovered in internally consistent theories of physics that speed of light can be different in forward and reverse. Einstein said” is neither a supposition nor a hypothesis about the physical nature of light, but a stipulation that I can make of my own free will to arrive at a definition of simultaneity.” This is the only reason why GPS synchronized clocks won’t work as this whole system is based on assumptions but the speed of light is different in different directions so we won’t be ever able to measure the one-way speed of light.

So, in reality we are stuck as we need synchronized clocks to measure the one-way speed of light but we need to know the one-way speed of light to synchronize our clocks. Physics work the same whether it is c or twice and instantaneous. As long as the round-trip speed is c none of the physics break. So if we can never measure the one-way speed of light and it makes no difference to any of the laws. But we just need to keep in mind that it is just a convention that light travels at same speed in every directions and not a experimentally proved fact. So ,maybe when physics takes the next paradigmatic leap we will be able to measure the one-way speed of light by general relativity, quantum mechanics, space and time are all connected.

An Article for JarWiz

By Niharika Arora