Great Scientists and their Inventions
Albert Einstein(1879 – 1955)
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Albert Einstein rewrote the laws of nature. He completely changed the way we understand the behaviour of things as basic as light, gravity, and time.
Although scientists today are comfortable with Einstein’s ideas, in his time, they were completely revolutionary.
Quick Guide to Albert Einstein’s Scientific Achievements
• provided powerful confirmation that atoms and molecules actually exist, through his analysis of Brownian motion.
• demonstrated the photoelectric effect, establishing that light can behave as both a wave and a particle. Light particles (he called them quanta) with the correct amount of energy can eject electrons from metals.
• proved that everyone, whatever speed we move at, measures the speed of light to be 300 million meters per second in a vacuum. This led to the strange new reality that time passes more slowly for people travelling at very high speeds compared with people moving more slowly.
• discovered the hugely important and iconic equation, E = mc2, which showed that energy and matter can be converted into one another.
• rewrote the law of gravitation, which had been unchallenged since Isaac Newton published it in 1687. In his General Theory of Relativity, Einstein:
» showed that matter causes space to curve, which produces gravity.
» showed that the path of light follows the gravitational curve of space.
» showed that time passes more slowly when gravity becomes very strong.
• became the 20th century’s most famous scientist when the strange predictions he made in his General Theory of Relativity were verified by scientific observations.
• spent his later years trying to find equations to unite quantum physics with general relativity. This was an incredibly hard task for him to set himself. To date, it has still not been achieved.
1905: The Year of Miracles
In 1905, the same year as he submitted his doctoral thesis, Albert Einstein published four immensely important scientific papers dealing with his analysis of:
• Brownian motion
• the equivalence of mass and energy
• the photoelectric effect
• special relativity
Each of these papers on their own was a huge contribution to science. To publish four such papers in one year was considered to be almost miraculous. Einstein was just 26 years old.
Mass Energy Equivalence
Einstein gave birth in 1905 to what has become the world’s most famous equation:
E = mc2
The equation says that mass (m) can be converted to energy (E). A little mass can make a lot of energy, because mass is multiplied by c2 where c is the speed of light, a very large number.
The Photoelectric Effect
If you shine light on metal, the metal may release some of its electrons. Einstein said that light is made up of individual ‘particles’ of energy, which he called quanta. When these quanta hit the metal, they give their energy to electrons, giving the electrons enough energy to escape from the metal.
Einstein showed that light can behave as a particle as well as a wave. The energy each ‘particle’ of light carries is proportional to the frequency of the light waves.
Einstein’s Special Theory of Relativity
In Einstein’s third paper of 1905 he returned to the big problem he had heard about at university – how to resolve Newton’s laws of motion with Maxwell’s equations of light. His approach was the ‘thought experiment.’ He imagined how the world would look if he could travel at the speed of light.
He realized that the laws of physics are the same everywhere, and regardless of what you did – whether you moved quickly toward a ray of light as it approached you, or quickly away from the ray of light – you would always see the light ray to be moving at the same speed – the speed of light!
If the speed of light is the same for all observers regardless of their speed, then it follows that some other strange things must be true. In fact, it turns out that time, length, and mass actually depend on the speed we are moving at. The nearer the speed of light we move, the bigger differences we seen in these quantities compared with someone moving more slowly. For example, time passes more and more slowly as we move faster and faster.
The General Theory of Relativity – Einstein Becomes Famous Worldwide
Einstein published his general theory of relativity paper in 1915, showing, for example, how gravity distorts space and time. Light is deflected by powerful gravity, not because of its mass (light has no mass) but because gravity has curved the space that light travels through.
In 1919 a British expedition travelled to the West African island of Principe to observe an eclipse of the sun. During the eclipse they could test whether light from far away stars passing close to the sun was deflected. They found that it was! Just as Einstein had said, space truly was curved.
On November 7, 1919, the London Times’ headline read:
Revolution in science – New theory of the Universe – Newtonian ideas overthrown.
Honors and More Honors
Albert Einstein was awarded the Nobel Prize in Physics in 1921. People are sometimes surprised to learn that the award was not made for his work in special or general relativity, but for his overall services to theoretical physics and one of the works from his miracle year specifically – the discovery of the law of the photoelectric effect in 1905.
The Royal Society of London awarded him its prestigious Copely Medal in 1925 for his theory of relativity and contributions to the quantum theory. The Franklin Institute awarded him with the Franklin medal in 1935 for his work on relativity and the photo-electric effect.
Einstein made his greatest discoveries when he was a relatively young man.
In his later years he continued with science, but made no further groundbreaking discoveries. He became interested in politics and the state of the world.
Einstein had been born German and a Jew. He died an American citizen in 1955.
Imagination is more important than knowledge.
Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.
The important thing is not to stop questioning. Curiosity has its own reason for existing.
Science without religion is lame, religion without science is blind.
The significant problems we have cannot be solved at the same level of thinking with which we created them.
Anyone who has never made a mistake has never tried anything new.
Try not to become a man of success, but rather try to become a man of value.
Great spirits have always encountered violent opposition from mediocre minds.
Everything should be made as simple as possible, but not simpler.
The most beautiful thing we can experience is the mysterious. It is the source of all true art and science.