Albert Einstein (1879-1955), one of the most well-known scientists of all time, is almost synonymous with "genius". His eccentric personality and occasional statements on philosophy, politics, and other topics are part of his fame, but his true claim to fame is due to his contributions to modern Physics, which changed the way we see the universe and helped to shape the world that we live in today.
Here are some world-changing ideas Einstein owes us.
Space-time
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His theory of special relativity, which deals with relative motion in the case that gravitational forces are not neglected, was Einstein's first achievement at 26 years old. Although it may seem innocuous, this was one of the most important scientific revolutions in the history of physics. It completely changed the way that physicists view space and time. These were combined into one space-time continuum by Einstein. Because space and time are measured in different units such as seconds and miles, we tend to think they are completely distinct. Einstein proved that they can be linked by the speed of light at approximately 186,000 miles per hour (300,000. km per second).
The most well-known consequence of special relativity, however, is that light cannot travel faster than it can. It also means that things behave strangely when the speed of light approaches. Imagine a spaceship traveling at 80% of the speed light. It would appear 40% smaller than it did at rest. According to the HyperPhysics website at Georgia State University, it would appear that everything is moving in slow motion. It would take 100 seconds for a minute to complete one minute. This would mean that the crew of the spaceship would age slower the faster they travel.
E = mc2
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Einstein's famous equation E = mc2 was an unexpected side effect of special relativity. It is probably the only mathematical formula that has achieved the status of cultural icon. This equation expresses the equivalence between mass (m), and energy (E), which were previously thought to be totally separate. Traditional physics defines mass as the amount of matter in an object. Energy, however, is the property that the object has due to its motion and the forces that act on it. Energy can also exist in complete absence of matter such as radio waves or light. Einstein's equation states that energy and mass are basically the same thing, provided you multiply the mass by the square of speed of light. This is a large number to make sure it ends up in the exact same units as energy.
This is because an object gains mass when it moves faster simply because it's gaining more energy. This means that even a stationary, inert object can have a lot of energy stored within it. This is a brilliant idea that has practical applications in high-energy particle Physics. CERN (European Council for Nuclear Research) states that if enough energetic particles are combined, the energy from the collision can produce new matter in form of additional particles.
Lasers
The stages of stimulation in a laser cavity. (Image credit: Encyclopaedia Britannica/UIG via Getty Images
Modern technology is replete with lasers. They are used in everything, from barcode readers and laser pointers to fiber-optic communication and holograms. While lasers aren't often associated with Einstein's work, they were made possible by his efforts. According to the American Physical Society, "light amplification through stimulated emission of radio radiation" is a term Einstein invented in 1959. Einstein's 1917 paper on quantum theory of radiation described how light can pass through a substance to stimulate the emission of more photons.
Einstein discovered that new photons travel in exactly the same direction and have the same frequency as the original. As more photons become virtually identical, this creates a cascade effect. Einstein, a scientist and theoretician, didn't pursue the idea further. However, other scientists recognized the immense practical potential of stimulated emitting. The world came to terms with the idea, and today people continue to find new uses for lasers, including anti-drone weapons and super-fast computers.
Wormholes and black holes
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Einstein's theory on special relativity demonstrated that space-time can do strange things even without gravitational fields. This is just the tip of the iceberg. Einstein's theory of general relativity added gravity to the equation. He discovered that large objects such as planets and stars distort space-time's fabric, which is what produces gravity.
Einstein explained general relativity using a complex set equations that have a wide range of applications. Karl Schwarzschild's 1916 solution, a black hole, is perhaps the most well-known solution to Einstein’s equations. A solution Einstein developed in 1935 with Nathan Rosen is even more bizarre. It describes the possibility of taking shortcuts between points in space-time and time. These were originally called Einstein-Rosen Bridges. Now, science fiction fans are familiar with them as wormholes.
The expanding universe
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Einstein applied his equations for general relativity to the entire universe in 1915. This was one of the first things he did with them. The answer he got was wrong. This implied that space's fabric was expanding continuously, pulling galaxies with it, so that distances between them were growing constantly. Einstein knew that this was not true and so he created the cosmological constant in his equations to create a static universe.
Edwin Hubble's 1929 observations of galaxies revealed that the universe is actually expanding in exactly the same way Einstein's original equations predicted. It seemed like the end of the line in terms of the cosmological constant. Einstein later called it his greatest blunder. However, that was not the end of the story. We now know, based on more precise measurements of the expansion, that it is speeding up rather than slowing down, as it should in the absence a cosmological constabulary. It appears that Einstein's "blunder", as it were, wasn't so bad after all.
The atomic bomb
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Although Einstein is sometimes credited with "inventing" nuclear weapons using his equation E =MC2, according to the Max Planck Institute for Gravitational Physics's Einstein Online website the connection between the two is at best tenuous. Einstein did not directly participate in the science of nuclear fission. He played an important role in the development of the first atomic weapons. He was alerted by colleagues to the dangers of nuclear fission in 1939 and the potential horrors of Nazi Germany acquiring such weapons. According to the Atomic Heritage Foundation, Einstein was eventually persuaded by his colleagues to relay these concerns to Franklin D. Roosevelt, the President of the United States. Einstein's letter led to the creation of the Manhattan Project, which was responsible for the creation of the atomic bombs that were used against Japan at war's end.
While many prominent physicists were involved in the Manhattan Project, Einstein was not one of them. According to the American Museum of Natural History, Einstein was not granted the security clearance he needed because of his left-leaning political views. Einstein said that this was a minor loss. His only concern was to deny the Nazis monopoly of the technology. According to Time magazine, Einstein stated that in 1947, he knew that the Germans wouldn't be able to develop an atomic bomb.
Gravitational waves
(Image credit to R. Hurt/Caltech JPL)
Although Einstein passed away in 1955, his vast scientific legacy continues to be a major focus of the 21st century. In February 2016, Einstein's discovery of gravitational wave, another consequence of general relativity, was announced in a dramatic way. Gravitational waves, which are small ripples that travel through space-time's fabric, are often stated as if Einstein "predicted their existence." However, reality is more complex than that.
Einstein was never able to decide whether his theory of gravitational waves predicted them or not. Astronomers spent decades trying to resolve the matter.
They succeeded eventually, using huge facilities like the Laser Interferometer Gravitational Wave Observatories in Hanford (Washington) and Livingston (Lawrence). The discovery of gravitational wave has provided astronomers with a new tool to observe the universe, including rare events such as merging black holes.
Original publication on Live Science
