How Romer determined the speed of light will surprise you | Science

in StemSocial2 years ago (edited)

Ole Christensen Romer was a Danish astronomer born in 1644. This famous man, in 1676, made the first quantitative measurement of the speed of light that still amazes people today and his work was truly admirable. Instead of his real name, Christen Pedersen, he uses the pseudonym Romer to distinguish himself from others. He invented the modern thermometer that we use today. Romer took every opportunity to learn mathematics and astronomy using Tycho Brahe's astronomical observations. Although he was born in a wealthy family, there is evidence of his hard work in science.


Ole Christensen Rømer( 1644 – 1710)source

The Paris Observatory is a research institute of the Paris Sciences et Letters University, one of the largest astronomical centers in the world, founded in 1667. This institution contributed significantly to the development of astronomy and the acceleration of science.Giovanni Cassini was appointed director of the Royal Observatory because of his expertise in using the Galilean moons to establish longitude standards. He sent Jean Picard, a French astronomer and priest to the Danish astronomical observatory at Brahe in Uraniburg. Romer began to work there efficiently as Picard's assistant, and Picard was so impressed with his skills that he arranged for Romer to come to work at the Royal Observatory as well, giving him the opportunity to do more serious work.

Romer was at the observatory compiling extensive observations of the orbit of Jupiter's moon Io, discovered by Galileo in 1610. Io is the largest of Jupiter's four major moons. Romer was trying to determine the exact period of the IO Moon's orbit by determining the time of its eclipse. According to Galileo, tables of the orbital motions of Jupiter's satellites would work like a clock.At this time Romar noticed something strange. Some numbers didn't seem right to him. So he was observing for some more years and timing the eclipses of IO. During this time he observed that as the distance of Jupiter from Earth decreases, the time interval between two successive eclipses becomes shorter. Similarly, when the Earth moves away from Jupiter, the time interval between two eclipses becomes longer.

Romer knew that the actual orbital period of Io was not related to the relative positions of Earth and Jupiter that would affect the duration of the eclipse. He had no problem understanding the reason. He hypothesized that the time difference between the two eclipses could be due to the finite speed of light. This means he knew then that there is a limit to the speed of light. He assumed that light takes twenty-two minutes to travel the diameter of Earth's orbit. So he calculated the speed of light by dividing the diameter of the earth's orbit by the time difference.


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He assumed that light takes twenty-two minutes to travel the diameter of Earth's orbit. So he calculated the speed of light by dividing the diameter of the earth's orbit by the time difference. His calculated speed of light was 135,000 km/sec. It is much less than the actual speed of light

In 1678, Christian Huygens determined the speed of light to be 131,000 miles per second, which was much lower than the correct value (186,000 miles per second). None of them could figure out the true speed of light because it takes 16.7 minutes for light to travel the diameter of Earth's orbit, not 22 minutes. Romer's calculation was wrong, so Christian Huygens' calculation was also wrong. This suggests that Rome had miscalculated the diameter of the Earth. However, if he had modern equipment, he could have determined the speed of light more accurately with this method. What Romer did at that time was of utmost importance. At that time it was very famous among its people, although it is not less famous even now.

Later, Isaac Newton wrote about Romer's calculation of the finite speed of light in his 1704 book Opticks and estimated the time it takes for light to travel from the Sun to Earth at seven or eight minutes. Today we know that it takes 8 minutes and 19 seconds for light to reach Earth from the Sun. So it is clear how right Isaac Newton was. Newton asked if Roemer's eclipses were colored. He got the answer that the eclipse was the same color so he also concluded that different colors travel at the same speed. Really amazing. In 1729, after James Bradley discovered stellar aberrations from the effect he determined that light must travel 10,210 times faster than Earth in its orbit. It is currently 10,066 times faster. Isn't that amazing? He also said that it would take 8 minutes and 12 seconds for light to travel from the Sun to Earth, which is currently 8 minutes and 19 seconds. Think how perfectly James Bradley said it.

The 17th meeting of the General Conference of Weights and Measures (CGPM) was held in 1983. In this meeting, it is said that by measuring the frequency, wavelength and speed of light values ​​can be determined which will give more accurate values. Thus, using advanced experimental techniques, the value of the speed of light in vacuum is determined to be exactly 299792458 m/s. Here meter and second were used as units of measurement. Thus we now know the exact speed of light.

The speed of light is of utmost importance to scientists. GPS receivers measure the distance to GPS satellites based on the time it takes for radio signals from each satellite to arrive. This method indicates the positional distance of the GPS and the receiver. Lunar laser ranging experiments can be used to determine distances to the moon, planets and spacecraft. However, the speed of light is considered the cosmic constant. It has deep connections with various theories such as Albert Einstein's theory of relativity. The importance of speed of light in today's science is much that ancient scientists may have understood earlier. So they became desperate to determine the speed of light. It is because of their efforts that modern science is so advanced today


References :

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!1UP It is very interesting to see how the efforts of researchers many years ago were extremely relevant to the way science is today, and how much it has evolved from that. Thanks for sharing!


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