# What is the value of the Avogadro number

## These inventions would be unthinkable without Albert Einstein

Albert Einstein is known to us as an inventor and productive thinker. Einstein's theories influence us to this day, because many everyday techniques would probably not work without him. Whether the theory of relativity or photoelectric effects: We summarize Albert Einstein's most important inventions.

Albert Einstein works on a math problem on the blackboard in front of American scientists. Einstein was born on March 14, 1879 in Ulm and died on April 18, 1955 in Princeton, New Jersey.

Photo: dpa

Dates of life: March 14, 1879 to April 18, 1955

Nationality: Swiss

Albert Einstein was born in Ulm in 1879 to Jewish parents. He spent the first years of his life moving to Munich. But his father's business that opened there was not going well, so the Einsteins emigrated to Milan. But Albert Einstein didn't want to go along and dropped out of high school without a degree. He switched to a school in Switzerland. He graduated from the Polytechnic of the Zurich Technical University with a diploma as a teacher of mathematics and physics. However, he mainly worked as a technical expert at the Swiss Patent Office. So he was mainly responsible for the inventions and decisions of third parties. Since he felt underutilized, he continued to research theoretical physics in his free time. When he was 26 he published his major scientific works. His proof that space and time are interrelated was the breakthrough for his fame. Since then, Albert Einstein has worked as a director, including at what is now the Max Planck Institute.

The year is 1915: Albert Einstein formulates the general theory of relativity and thus turns our understanding of space and time upside down. The theory says that times should always be viewed relative to their reference system, since time depends on the moving body. The fact is: nuclear physics or astronomy would be inconceivable without Einstein's theory of relativity. Below you will find Inventions that would not be possible without Albert Einstein.

### Albert Einstein: The most famous equation in history

E = mc² is probably the best-known equation in physics. The principle of relativity says that mass and energy are equivalent quantities that are related. In other words: mass and energy can be converted into one another. The high value c (speed of light) already ensures large amounts of energy when converting small masses. The formula has become the basis for nuclear power plants. Einstein published the equation for mass-energy equivalence as an addendum to his special theory of relativity published in 1905. Many more geniuses were to follow.

### The quantum theory of light

Einstein discovered that all light consists of tiny packages of energy - the so-called photons. He assumed that these photons are particles that also have wave-like properties. A completely new idea at the time.

He also spent time sketching the emission of electrons from metals. He was particularly fascinated by the effects of enormous electrical impulses such as lightning. We will come to the photoelectric effect later.

With this keyword memories of the chemistry class are awakened. While Einstein was working to explain Brownian motion, that is, the irregular movement of particles in a liquid, he also determined an expression for the amount of Avogadro's number in the form of measurable quantities.

All of this meant that scientists now had the ability to determine the mass of an atom, or the molar mass for each element on the periodic table.

Amadeo Avogadro was one of the most important natural scientists of the 19th century. Between 1776 and 1856 he developed chemical formulas and dealt with physical questions. One of his most important achievements is the option of being able to calculate the molecular mass of gaseous substances. To this end, he gave his name to a constant: the Avogadro constant. This applies to all substances. The Avogadro constant N A means the number of particles that are contained in one mole of a substance.

### The Bose-Einstein condensate

In 1924, Einstein was sent a paper from a physicist named Satyendra Nath Bose. This article detailed how 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.

A Bose-Einstein condensate is essentially a group of atoms that have cooled down very close to absolute zero. When they reach this temperature, they hardly move relative to each other. They start to clump together and enter exactly the same energy states. This means that from a physical point of view, the atomic group behaves as if it were a single atom.

### The photoelectric effect

Einstein's theory of the photoelectric effect discusses the emission of electrons from metal when light shines on them. Scientists had observed this phenomenon and could not reconcile the finding with Maxwell's wave theory of light.

Albert Einstein's discovery of photons contributed to the understanding of this phenomenon. He suspected that when light hit an object, electrons were emitted, which he called photoelectrons.

This model formed the basis for how solar cells work - light causes atoms to release electrons, which then generate electricity and then generate electricity.

### Wave-particle duality

Einstein's research on the development of quantum theory was the most powerful he has ever done. During his early career, Einstein insisted that light should be treated as both a wave and a particle. In other words, photons can behave as particles and waves at the same time. This became known as wave-particle duality.

Einstein himself said: “We are facing a new kind of difficulty. We have two conflicting images of reality; separately neither fully explains the phenomena of light, but together they do. "

Albert Einstein's work advanced modern quantum mechanics, the model of physical time, the understanding of light, solar panels, and even modern chemistry. The natural scientist clearly influenced our understanding of physics as we know it today.

### Special theory of relativity

In his studies, the great thinker noted that there are inconsistencies in Newtonian mechanics in its relationship to the understanding of electromagnetism. In an essay published in September 1905, he proposed a new way of thinking about the mechanics of objects approaching the speed of light. This concept came to be known as Einstein's special theory of relativity. It changed the understanding of physics at the time.

The special theory of relativity is not exactly catchy. Here is a simple example to explain:

Einstein understood that light always travels at a constant speed of 300,000 km / s and wondered what would happen to our ideas of space and time if this were the case. When a laser is fired with a movement at half the speed of light, the laser beam keeps it constant and does not move at one and a half times the speed of light. So Einstein realized that either our measurement of the distance between objects must be wrong or the time it took to travel that distance was greater than expected.

Einstein found that both answers were correct. Contrasts of space and time expand as objects move. He found that movement through space can also be thought of as movement through time. Essentially, space and time influence each other.

### general theory of relativity

On November 25, 1915, Albert Einstein caused a sensation at the Prussian Academy of Science in Berlin. He presented his general theory of relativity. Among other things, it says that the speed of light is a constant - independent of the movement of the observer and the direction of propagation.

Sound banal? But it is not. Because it means renouncing the idea that there is a universal quantity called time. The faster an observer moves, the more slowly it passes. The observer also becomes heavier and heavier at high speeds. These relationships are not just gray theory, but play a key role in the everyday life of modern people with the following inventions:

World famous picture of the physicist Albert Einstein with his tongue out. Incidentally, Einstein was also an engineer in disguise: in 1926 he filed a patent for a refrigerator that does not use toxic coolants.

Source: Arthur Sasse / dpa

### 1. TVs would not have worked without Einstein

Even if the tube TVs have long since disappeared from the living room: It is thanks to the findings of the theory of relativity that we used to see a sharp picture on TV. Why? Because a television set accelerates electrons at over 20,000 volts. And according to Einstein, their mass increases measurably. An effect that engineers have to compensate for. Otherwise the electrons on the screen would show deviations in the millimeter range and the image would be blurred.

### 2. Relativity theory helps GPS to be more accurate

The theory of relativity also plays a role in the Global Positioning System (GPS). Since the atomic clocks on board the satellites move at 140,000 kilometers per hour, they would theoretically run seven microseconds slower per day than clocks on Earth.

Albert Einstein's calculations on the theory of relativity (E = mc2) can be seen under a magnifying glass on the manuscript.

Source: Jon Levy / dpa

But it doesn't stop there: Since the time indicators at an altitude of 20,000 kilometers feel the force of gravity only a quarter as strongly as clocks on the earth's surface, they would theoretically run 45 microseconds faster every day. Taking these two effects into account, there is a 38 microsecond difference that GPS systems have to compensate for. Otherwise they would show a misstatement of 11 kilometers every day.

And it's only been two years since scientists started to prove these deviations in reality. They evaluate the data from two Galileo satellites, which are in the wrong orbit compared to their sister satellites. Accordingly, the time information of these satellites must differ minimally.

### 3. Without Einstein, nuclear power would be unthinkable

In the special theory of relativity Einstein proved that the mass of the atoms and their energy are equivalent: With the famous formula E = mc2 he laid the theoretical framework for all of atomic physics.

The German physicist Albert Einstein smoking a pipe: The founder of the theory of relativity received the Nobel Prize for Physics in 1921 for his contributions to quantum theory, especially for his interpretation of the photo effect.

Source: dpa

### 4. Solar cells are also based on Einstein's findings

Not only the theory of relativity has significantly influenced modern inventions. The so-called photoelectric effect, for whose discovery Einstein received the Nobel Prize in 1922, is also important. It says that light knocks electrons out of the surfaces of certain materials, which can generate electricity. This principle is followed by solar cells that have become indispensable nowadays - for example on the roofs of houses and in pocket calculators.

Albert Einstein spoke in a famous speech in February 1950 on the question of the nuclear arms race. At the end of December 1999, the unconventional scientist was voted "Person of the Century" by the American Time magazine. In addition to his scientific work, Einstein advocated the pacifist idea and pleaded for a supranational world government.

Source: dpa

### 5. On the side: the Einstein refrigerator

This point is a bit out of line, but it is still worth mentioning: Einstein did not only deal with theory, but was also an engineer at heart. In 1926 the physicist had read in the newspaper that sulfur dioxide escaping from a refrigerator had suffocated an entire family in their sleep. He then filed a patent for a device that works without toxic coolants and relies on the evaporation of highly concentrated alcohol. At that time, AEG secured the license rights to the Einstein refrigerator, but never brought the device onto the market.

### Ulm dedicates a museum to Albert Einstein

Albert Einstein was born in Ulm. His hometown is dedicating a permanent exhibition to him and his family, which is to open in November 2022 in the "Engländer".

In fact, Albert Einstein only lived in Ulm for 15 months before his parents moved with him to Munich. However, the extensive family of Einstein lived temporarily in the city. These included 18 cousins ​​of Einstein's. The 2022 exhibition will focus on Albert Einstein's relationship with his second wife Elsa, his cousins ​​and the Ulm family ties.

The best quotes from Albert Einstein

Where Einstein was half wrong

A contribution by:

• Patrick Schroeder

Patrick Schroeder works as a freelance journalist for magazines and online magazines such as VDI Nachrichten and Ingenieur.de.

• Sarah Janczura

Sarah Janczura is content manager and responsible editor for ingenieur.de. After an internship with a focus on social media, she worked as an online editor in a digital agency. She writes about technology, research and career topics.