The General Theory of Relativity for us Non-Scientists
Albert Einstein’s General Theory of Relativity gave us an astonishingly new understanding of the interplay of space, time, matter, energy, and gravity. It is considered the most important breakthrough in modern physics. The impact of his theory was so all-embracing that it’s not surprising Time magazine name Einstein “the person of the century” on 31 December 1999.
In 1905, an unknown 26-year-old technician working in a Swiss patent office submitted four papers to a scientific journal. They led to young Albert Einstein being hailed as a genius. One of them revealed his Special Theory of Relativity, which ripped apart accepted notions of space and time as separate and absolute.
On the contrary, proclaimed Einstein, for the laws of physics to remain the same for all observers, then both lengths and times vary depending on where you’re looking from. He came to this stunning conclusion with the help of what he called “thought experiments” — taking real-life scenarios to explain the laws of science. For example, he imagined one person on a fast moving train and another on a station platform. Lightning hits both ends of the train as its middle passes the person on the platform. That person must see the lightning strikes happen at the same time. However, the person on the train must see the front struck before the back, because the train is moving forwards, so the flash has less far to travel. The same events — lightning striking the train’s ends — are viewed simultaneous from the platform but not from the train. Therefore things happening at the same time is a relative concept!
This suggested to Einstein that time and space are intertwined into a single continuum known as “spacetime”.
He also postulated that nothing can travel faster than the speed of light (186k miles a second). He invented what became the world’s most famous equation,
E=MC2 (E is energy, m is mass and c is the speed of light).
Demonstrating that there is a deep equivalence between mass and energy. Because the speed of light is such a big number, even a small mass can be converted to a huge amount of energy.
But something was missing from this theory: gravity. Sir Isaac Newton’s Law of Gravitation in 1697 states that gravity is an invisible force that attracts two objects together, decreasing in strength as they get further apart. Einstein shattered that view yet made his discovery sound simple: “I was sitting on a chair in my patent office in Bern. Suddenly a thought struck me: if a man falls freely, he would not feel his weight. I was taken aback. This led me to the theory of gravity.” The image of a falling man traveling inside an elevator falling at the same speed, weightless and unable to tell if he was falling or in deep space, convinced Einstein that acceleration and gravity are equivalent. He later called it “the happiest thought in my life”.
Einstein published these further findings in 1916 as the General Theory of Relativity. Among many other things, it recognized that all massive objects cause a distortion — a curving — in spacetime, which is felt as gravity. An example commonly used to explain this complex idea is to take a rubber sheet and place a heavy ball on it. The weight of the ball causes a dip in the sheet, so when a lighter marble is rolled across the sheet it doesn’t roll in a straight line but curves around the ball. The marble traveling along a surface warped by the ball looks as if it is attracted by a gravitational force, just as the Earth looks as if it is attracted to the sun. Einstein argued that beams of light from distant stars must also travel along curved trajectories as they pass around the warped spacetime near the sun. After his calculations were confirmed by scientists observing a solar eclipse in 1919, he was asked what would have happened if he’d been proved wrong. “ I would have been sorry for the Dear Lord because the theory is correct”, was his no-nonsense reply.
Another of Einstein’s counterintuitive realizations was that time is also affected by the influence of huge masses. The nearer you are to a massive object like the Earth, the slower time passes. So clocks on mountaintops tick ever so slightly quicker than those at sea level, meaning that people effectively live a tiny fraction less long the higher place they live.
Einstein’s theory was quickly hailed as brilliant and he became a scientific hero. When his young son asked why he was so famous, Einstein used a thought experiment to explain how he discovered that gravity was the curving of the fabric of spacetime. He said a blind beetle does not notice the curve when it walks over a curved branch; “I was lucky enough to notice what the beetle didn’t.”
The General Theory of Relativity has given us a new, large-scale understanding of the universe. It explains phenomena from the origin of stars to black holes. It has been used in the creation of nuclear weapons and power plants and to identify the mass of distant galaxies. Our cars and phones guide us to locations because, thanks to Einstein, GPS takes account o earth’s gravitational field in order to work out our destination with pinpoint accuracy.
There is so much more to Einstein’s finding’s than non-scientists like us have either the time or ability to explain but we believe it is less important to understand his theory than to marvel at what makes it possible.
Images and excerpt taken from Treasures of World History
Tyler Wall is the founder of Cyber NOW Education by night and works full time in the cybersecurity industry as his day job. He creates cybersecurity training material in his free time, often after feeling the need to shout what he’s just learned and also because a little bit of passive income never hurt anyone.
He holds bills for a Master of Science from Purdue University, and also CISSP, CCSK, CFSR, CEH, Sec+, Net+, A+ certifications
You can connect with him on LinkedIn.
