Sagnac Effect

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The Sagnac effect occurs to a pair of light beams traveling in a circuit in the opposite direction. If the circuit itself is rotating, then the beams will complete the circuit in different duration. The effect was first demonstrated by Georges Sagnac in 1913.

After discovering this effect, Sagnac incorrectly used the results as proof of the aether’s existence, and today’s flat-Earthers use it as “evidence” of stationary Earth. In reality, Sagnac was not aware that the effect is consistent with Einstein’s theory of relativity. And if the effect really proved aether, then optical gyroscopes are impossible.

The Sagnac effect is used as the basis of optical gyroscopes, including fiber-optic gyroscopes and ring-laser gyroscopes. In an optical gyroscope, a pair of light beams are made to travel in a circuit in the opposite direction. Because light travels at a constant speed, irrespective of the transmitter’s speed, then if the gyroscope is rotated, a beam of light will complete the circuit sooner than the other. From the difference, we can measure the rotating motion of the gyroscope.

References

Einstein’s Thought Experiments and Daydreaming

Albert Einstein used thought experiments as a tool for formulating his theories. His theories provided predictions that can be tested in observation and experiments. He did not perform the observation and experiments himself. Others did and confirmed his theories.

Some flat-Earthers dismiss Einstein’s theories —especially those about gravity— on the basis that they are founded on thought experiments and daydreaming. They are wrong. His theories have been repeatedly confirmed by various experiments and observation performed by many others, even to this day.

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Classical vs Modern Physics

Classical physics —like Newton’s law of motion, and Newton’s law of universal gravitation— has been superseded by Special Relativity, General Relativity, and Quantum Mechanics. But it doesn’t mean classical physics is wrong. Classical physics is still applicable when the parameters approach common, terrestrial values we use every day.

Pseudoscientists —including flat-Earthers— often misunderstood this and take the fact that classical physics is still being taught in schools as ‘proof’ of deception and the failure of modern science to explain the world. They are wrong.

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