KOMPAS.com – The universe has a speed limit and that is the speed of light.
Nothing can travel faster than light, not even today’s best space probes.
So what is the speed of light?
It was quoted in Live Science, Wednesday (31/5/2023) light travels at an extraordinary speed, which is 300,000 km per second, or the equivalent of more than 1 billion km / hour.
That’s fast enough to circle the Earth 7.5 times in a second.
Just compare it to an ordinary passenger plane that takes more than two days to circle the Earth once. This does not include stops for refueling or layovers.
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Measure the speed of light
In the early 1600s, scientist Ole Roemer was able to measure the speed of light (commonly called c) using observations from Jupiter’s satellites.
At the turn of the 19th century, physicist James Clerk Maxwell created his theory of electromagnetics.
Light itself consists of electric and magnetic fields, so electromagnetics can describe the behavior and movement of light.
This value is 299,788 km per second, with a margin of error plus or minus 30.
nonetheless, the calculation was refined again in the 1970s by using a laser to measure the speed of light with higher precision, leaving only an error of 0.001.
The result is a fixed value and is used to determine the length unit. People also agreed that the speed of light is exactly 299,792,458 km per second.
The speed of light changes
But the speed of light can change depending on what it is traveling through, such as air, water or something else. This causes the speed of light to slow down.
Interestingly, the speed of light is not proportional to the vast distances in space, which is a vacuum.
It takes 8 minutes for light from the Sun to reach Earth and several years for light from other nearby stars (such as Proxima Centauri) to reach our planet.
That’s why astronomers use light years, or the distance light can travel in one year, to measure vast distances in outer space.
Because of this universal speed limit, telescopes are essentially time machines.
When astronomers look at a star 500 light years away, they see light from 500 years ago.
Light from about 13 billion light years away (equivalent to 13 billion years ago) appears in the cosmic microwave background, which is the leftover radiation from the Big Bang in the early universe.
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