When NASA astronaut Scott Kelly completes his yearlong mission on the International Space Station next year, he'll come back just a little bit younger than his twin, Mark, than he was before. This is because time travels more slowly in space, a phenomenon first described by Albert Einstein's 1915 theory of general relativity. 

This December, universities and academies around the world are celebrating the 100th anniversary of the theory's publication. 

Even 60 years after his death, Einstein is still the most important scientist of the modern era. Looking back as far as 2,400 years ago, only Newton, Galileo and Aristotle were his equals. 

Born in the era of horse-drawn carriages, his ideas started a technological revolution that brought about more change in one century than in the 2,000 years before. 

In 1905, Einstein published four important scientific papers. These completely changed people's ideas about space, time, light and matter. In one of these papers Einstein. introduced his theory of special relativity. Two groundbreaking parts of the theory were about the relationship between mass and energy and the speed of light. Einstein was able to show that mass and energy were connected through the formula E=MC2. The theory also says that no object can travel faster than the speed of light. 

About 10 years later came his theory of general relativity, the theory that modern physics is really based on. In Einstein's mathematics, space has three dimensions, and the fourth dimension is time. Space and time are part of one continuum, called space-time. The presence of mass changes space-time, which explains where gravity comes from. 

Computers, satellites, telecommunication, lasers, television and nuclear power, many of the biggest developments in the modern world, can be linked to Einstein's work. 

"We are a different people than we were a century ago," said astrophysicist Michael Shara of the American Museum of Natural. History, "completely different, because of Einstein." 

However, there's more to him beyond the image of a science mastermind. Einstein, as a person, has also become a grandfatherly icon in our culture. 

He liked playing Mozart on his Violin and keeping fit by hiking and walking. Power was not his goal. In 1952, the young nation of Israel asked Einstein to be its president, but he refused. 

And, yes, he was eccentric. With hair like that, how could he not be? QUESTIONS:

Q1:
1. What is Scott Kelly known as?
2. What is the profession of Scott Kelly?
3. 
Q2:
1. Is time known to travel faster in space?
2. Is space known as a medium in which time travels faster?
3. 
Q3:
1. What was the year when Albert Einstein theory of relativity was introduced?
2. Albert Einstein's theory of relativity was introduced in what year?
3. 
Q4:
1. What is Albert Einstein known as even after his death?
2. What do people consider Albert Einstein as even after his death?
3. 
Q5:
1. What are the names of the people that are considered to be Albert Einstein's equals?
2. Albert Einstein is considered to be equal to which people in the article?
3. 
Q6:
1. In which era was Albert Einstein born?
2. Albert Einstein was born in which era?
3. 
Q7:
1. People's idea in which areas were completely changed thanks to Albert Einstein's papers?
2. Albert Einstein's papers changed people's ideas in which areas?
3. 
Q8:
1. Albert Einstein came up with what formula?
2. What is the formula that Albert Einstein came up with?
3. 
Q9:
1. What can no object travel faster than?
2. What is the fastest that an object can travel?
3. 
Q10:
1. Most of the developments in the modern world can be linked to what?
2. Modern world developments can be linked to what?
3. 
