Albert Einstein is thought to have been a genius, and he is considered one of the world's greatest thinkers. Although he isn't known for inventions, as with Thomas Edison or Nikola Tesla, Einstein's theories and ideas related to physics continue to exert influence today. He spent much of his life researching his theories of relativity, investigating space, time, matter, and energy.
As we think back on this innovative thinker, here are some of Albert Einstein's most significant achievements and inventions.
Quantum Theory of Light
Einstein proposed his theory of light, stating that all light is composed of tiny packets of energy, called photons. He suggested these photons were particles but also had wave-like properties, a totally new idea at the time.
He also spent some time outlining the emission of electrons from metals as they were hit with large electric pulses, like lightning. He expanded on this concept of the photoelectric effect, which we'll discuss later in this article.
Special Theory of Relativity
In Einstein's studies, he began to notice inconsistencies of Newtonian mechanics in their relation to the understanding of electromagnetism, specifically Maxwell's equations. In a paper published in September 1905, he proposed a new way of thinking about the mechanics of objects approaching the speed of light.
This concept became known as Einstein's Special Theory of Relativity. It changed the understanding of physics at the time.
Understanding the Special Theory of Relativity can be a little difficult, but we'll boil it down to a simple situation.
He began with the understanding that light always travels at a constant 300,000 km/s, and asked what would happen to our ideas of space and time if that was the case? If you fire a laser at something moving half the speed of light, the laser beam still keeps this constant, and it doesn't travel at one and a half times the speed of light.
So, he realized that either our measurement of the distance between objects must be wrong or the time taken to travel that distance was greater than expected.
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Einstein realized the answer was both. Space contracts and time dilates as objects move. He determined that motion through space can also be thought of as motion through time. In essence, space and time affect each other, both being relative concepts in relation to the speed of light.
For anyone that has made it through a chemistry class, you likely remember Avogadro's number or it, at least, rings a bell.
While Einstein was working to explain Brownian motion, the erratic movement of particles in a fluid, he also determined an expression for the quantity of Avogadro's number in terms of measurable quantities.
All of this meant that scientists now had a way to determine the mass of an atom, or the molar mass for each element on the periodic table.
The Bose-Einstein Condensate
In 1924, Einstein was sent a paper from a physicist by the name of Satyendra Nath Bose. This paper discussed detailed a way to think of light as a gas, filled with indistinguishable particles.
Einstein worked with Bose to extend this idea to atoms, which led to a prediction for a new state of matter: the Bose-Einstein Condensate. The first example of this state was produced in 1995.
A Bose-Einstein condensate is essentially a group of atoms that are cooled very close to absolute zero. When they reach that temperature, they hardly move in relation to one another. They begin to clump together and enter into exactly the same energy states. This means that, from a physical point of view, the group of atoms behaves as if they were a single atom.
General Theory of Relativity
In 1916, Einstein published his General Theory of Relativity. This paper generalizes the concepts of Special Relativity and Newton's Law of Universal Gravitation, describing gravity as a property of space and time. This theory has aided our understanding of how the large-scale structure of the universe is set up.
The Theory of General Relativity can be explained like this:
Newton helped quantify gravity between two objects as a tugging of two bodies, independent of how massive each one is or how far apart they are.
Einstein determined that the laws of physics hold constant for all non-accelerating observers, that the speed of light is constant no matter how fast the observer travels. He found that space and time were interwoven and that events that occur at one time for one observer could occur at a different time for the next.
This led to his theory that massive objects in space could distort spacetime.
Einstein's predictions have helped modern physicists study and understand black holes and gravitational lensing.
The Photoelectric Effect
Einstein's theory of the Photoelectric Effect discusses the emissions of electrons from metal when light shines on it, as we alluded to before. Scientists had observed this phenomenon and had been unable to reconcile the finding with Maxwell's wave theory of light.
His discovery of photons aided the understanding of this phenomenon. He theorized that, as light hits an object, there is an emission of electrons, which he deemed photoelectrons.
This model formed the basis of how solar cells work - light causes atoms to release electrons, which generate a current, and then creating electricity.
Einstein's research into the development of the quantum theory was some of the most impactful he ever accomplished. During his early career, Einstein persisted in asserting that light should be treated as both a wave and a particle. In other words, photons can behave as particles and as waves at the same time. This became known as wave-particle duality.
He is quoted as saying this on the subject, "We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together they do."
As we think about all of Einstein's "inventions," we have to think of them in the light of his influence. His work advanced modern quantum mechanics, the model of physical time, the understanding of light, solar panels, and even modern chemistry.
Einstein's has unequivocally influenced our understanding of physics as we know it today.