"I knew it"


How Albert Einstein created a “fiat lux” moment for humankind.

When I was 14 years old, in the midst of the cold war, I was impressed by the talks about the destruction power of atomic bombs and could not stop reading any word published about the A and H bombs. How they work, how they were built, and all the surrounding questions young curiosity could bring up, were food to feed my days. It was then that I first learned about Einstein and the Relativity Theory. What a blast! That was a transformational subject to me and ever since, the Science of Physics became one of my passions. At 16, I got hand of a translation from the Einstein Relativity 1905 original paper published at the “Annalen der Physik” journal, and dedicated hours trying to understand each one of the passages and mathematical formulas in the article.  My very early exposure to Einstein papers and theories were the foundations of my adulthood but at that the time that passion caused me many harsh moments in High School. Bullying was constant from my classmates because of my incomprehensible narratives about the space-time fabric distortions or my explanations about time travel possibilities. Now, that everybody is talking about the finding of gravitational waves, the last missing proof to Einstein’s Relativity theory, I have a big smile on my face.

It is indeed an amazing achievement, but to the ones that once studied Einstein’s Relativity Theory in depth, this finding will sound like an “I told you”.  That simple. Indeed, I am quite sure Einstein himself would have said that. During a total eclipse in 1922, when the first proof of Relativity was produce by measuring the distortion caused by sun’s gravity in light beams coming from stars, confirming earlier Einstein’s predictions, someone rushed into Einstein’s house to tell him that his theory was confirmed and he was asked if the news excited him. Is said that he gave then a very frugal answer:  

– No… I knew it.

But the thing nobody is talking about is really the amazing similarity between the two experiments that led to the creation of relativity and its ultimate proof.  The Michelson-Morley experiment in 1887, contrary to all scientific knowledge and beliefs at that time, proved that the all mighty Newton’s Theory of Mechanics didn’t work for Light. Scientists were puzzled and astonished. That experiment demonstrated that the speed of light was the same, no matter the speed of its source. That discovery was the corner stone for the genesis of Relativity, and Einstein was the one who tackle the mystery about the constant value for the light speed and solved it brilliantly giving us, among many other things, the most famous equation of all times: E=mc2

Now, the LIGO experiment bring us the last missing proof of Einstein’s relativity theory by confirming the existence of gravitational waves, exactly as Einstein predicted. After one hundred years since the “Annalen der Physik” relativity article was released, G-waves were finally detected!  So, what is the deal? The Michelson-Morley experiment divided a light beam into two beams at 90 degrees each. They used mirrors to reflect the beams back to the source so they can measure if there was any speed difference between the beams, as this was expected according to Newton’s theory.  Since they found no difference in the light speed between the two beams, the conclusion was that the speed of light was always the same and it was independent of the speed of the light source.  The LIGO experiment used in essence the same idea. Off course technology improved since 1887, but the concept was the same: One light beam, split 90 degrees apart and mirrors to reflect the light back to the source. However, all the hardware for the Michelson-Morley experiment fitted within a small lab room, while the size of the LIGO device is humongous: 4 kilometers each side!

Since we now know that speed of light is always 299,792,458 meters per second (or aprox. 185,000 miles/sec), any time difference it takes to the light beam to travel from its source to the mirrors and back to the source, would have been caused by a contraction in the size of one of the pipes and the culprit would be a passing gravitational wave.  

In summary, the main difference between the Michelson-Morley experiment and the LIGO experiment is the size of the device. Both were built to measure differences in the travel time of two light beams placed at 90 degrees from each other. The first experiment was the Genesis of Relativity. The later, was the ultimate proof of its magnificence.

Light was the untamed beast that hunted physicists of the earlier XX century.  Einstein was the master genius who brilliantly explained it all, creating a “Fiat Lux” moment for humankind.


Lorenzo Madrid is a Brazilian engineer, writer, travel photographer and lecturer living in the Seattle area. He has published several articles about the impact of technology in social economic development and his Magic Realism short book, “The Pillow”, is available in English at Amazon.”

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