We have thought about the universe since ancient time. And we have had lots of question. Like why did the universe begin, since when did the universe begin, the progress of star’s creation, How big is the universe, why does the planets orbit the stars, how old is the universe, the identity of dark energy and dark matter etc… Also there are many ideas, theories of these question. Some of these mysteries were solved by brilliant scientist. But others are not solved until now.
This interesting book, From Ptolemy’s Spheres to Dark Energy by John Farndon is all about history of astrophysics. The reason why I chose this book is that science is my favorite. And among the science, I like astrophysics most. Also, nowadays I am interesting in dark energy. So I searched the book about astrophysics and dark energy. And finally I found this book. This book is composed with 19 different contents. Also these contents are explained in chronological sequence.
Name of first content is The Many Mysteries of Space. This content explain how many mystries is in the universe, how big is the universe and the Big Bang.
According to From Ptolemy’s Spheres to Dark Energy express “People have been asking this question [the size of universe] for thousands of years, but still nobody knows” (John Farndon 4), nobody knows how big is the universe so, this question is big mystery of universe.
Also, he claimed that the universe is very very huge throughout his narration:
The universe is the whole of space and everything in it. The universe contains over 100 billion galaxies (vast groups of stars) , each containing as many as 100 billion stars like the Sun. Many of these stars have planets circling them, just as Earth circles the Sun. (John Farndon 4).
According to From Ptolemy’s Spheres to Dark Energy express ” Scientists now think the universe began from virtually noting about 13.7 billion years ago and has been swelling out at a incredible rate ever since (John Farndon 5), he said the Big Bang is incredible swelling out when the universe created.
According to From Ptolemy’s Spheres to Dark Energy express “the more we learn, the more mysterious we find it” (John Farndon 5), there are unlimited mysteries in the universe.
There are two ancient country that first studied the universe scientifically. One is Egypt. Egyptians made precise observations of the stars. Other is Greeks. They thought Earth is round. According to John Farndon’s research, From Ptolemy’s Spheres to Dark Energy may explain “They [Greeks] figured out that Earth is round, from clues such as the way ships dip below the horizon” (6).
Ancient people thought the Earth is the centre of universe. So, based on their thought, two brilliant astronomers, the Greeks Hipparchus and the Roman Ptolemy built up a Ptolemaic system.
The Ptolemaic system is a model that Earth is center of the universe and it was a great mathematical machine for predicting the exact movements of celestial bodies for over 1,500 years throughout his narration:
In the Ptolemaic system, Earth is the fixed centre of the universe.
It was a mathematical machine for predicting the exact movements of the Sun, the Moon, the planets, and stars. Although it turned out to be wrong, it provided a good basic for astronomical calculations for more than 1,500 years. (John Farndon 6~7)
This system seemed to work well for 1400 years. But around 1500, a polish priest, Nicolaus Copernicus(1473-1543), suggested some other ideas because he found some problems. His idea was the sun is centre of the universe and other planets orbit the Sun.
According to From Ptolemy’s Spheres to Dark Energy express “Earth is part of the solar system. The solar system is made up of the Sun, along with the planets and various smaller objects, such as asteroids, that continually orbit it” (John Fardon 9), it show the Copernicus explained solar system as the Sun is centre of our solar system and other celestial object orbit the Sun.
After this big two happened, Kepler found few problem of Copernicus’s theory and he figured out the planets orbit the Sun in ellipse. And Galileo made his own telescope and found Jupiter and four satellites of Jupiter.
In mid-1600s, Isaac Newton figured out the reason why planets orbit the Sun and moons orbit the planets. His answer was the balance between gravity and inertia throughout his narration:
Inertia is the tendency for things to stay still or keep moving at the same speed in a straight line, The planets’ inertia keeps them flying on through space. The gravitational pull between each planets and the Sun holds them in orbit. Gravity and inertia are in perfect balance. If the inertia were too great or the gravity too weak, the planets would fly off into space, away from the Sun. If inertia were too weak and the gravity too strong, the planets would spiral into the Sun.
Most of classic astronomical events finished. Now I supposed to talk about modern astrophysics. The first event/person is one of the most important turning point events in the history and he is my role model. The Albert Einstein. He had made remarkable achievements.
Einstein published one of the best theories in the world. This theory concluded relation between time, place and light and suggest our life are relative. And finally he realised the speed of light is absolute throughout his narration:
In 1905, Einstein had stunned the scientific world with his Special Relativity theory. In this, he built onGalileo’s theory that all movement is relative. In other words, you can only tell that you are moving by comparison to something.
Einstein is said to have wondered what would happen to your reflection in a mirror if the ship sailed as fast as light. However, Einstein realized that this is not what happens, because you can never catch up with light, no matter how fast you go. Light is the one speed that is absolute, not relative. Einstein called his theory Special Relativity. Then he realised that if the speed of light is fixed, something else has to be changeable, and that must be time and space. In other words, time and space vary instead of the speed of light. (John Farnbon 24~25)
Also he predicted when the spaceship traveling as fast as light. He thought there are 3 strange things happen. In “From Ptolemy’s Spheres to Dark Energy” John Fardon argues:
Einstein’s theory showed that some strange things must go on when objects are traveling very fast. Imagine watching a spaceship accelerating to near the speed of light. Everything in the ship would seem completely normal to the astronauts. But, from Earth, you would notice three things.
- The spaceship would get shorter.
- Clocks on the spaceship would run slower as time stretched. This is called time dilation.
- If you could measure it, you would find that the spaceship would grow heavier. (John Fardon 25)
Also he published General Relativity theory in 1915. According to From Ptolemy’s Spheres to Dark Energy express ” In this theory [General Relativity theory], he explored what happens to objects that change speed or direction. As he did so, he came up with an entirely new idea of gravity (John Farnbon 26), the General Relativity theory is related with gravity.
Finally he found the space is bended by gravity throughout his narration:
According to Einstein, gravity is not a force. It is a distortion in spacetime that is created by the presence of mass and energy. Scientists often visualize spacetime as a sheet go stretchy fabric. Imagine putting a large mass, such as the Sun, on the “fabric” of spacetime. It will warp to from a hollow, just as a trampoline might if you put a heavy bowling ball on it. If you then add a smaller, lighter mass, such as Earth, it will run down into the hollow created by the Sun. Only Bath’s momentum keeps it from falling altogether. (John Farndon 27)
Before Einstein’s great work, there were remarkable works by Hubble and Georges Lemaître. Edwin Hubble discovered the galaxies and Georges Lemaître realized the universe is expanding. After Einstein’s great study, lots of remarkable things happened too. Many scientists tried to figure out the beginning of universe with great technology and discovered the Big Bang eventually. In 1916, German astronomer Karl Schwarzschild claimed that there should be a thing which absorbs everything even the light in the universe called Black Hole. And then, scientists discovered the Black Hole. They succeeded to find the black hole which is created by supernova and it pulls everything in the universe.
And now scientists are trying to make sure what is dark matter and dark energy. According to From Ptolemy’s Spheres to Dark Energy express “Scientists used the WMAP data to figure out that the universe is made of 4 percent ordinary matter, 23 percent dark matter, and 73 percent dark energy (John Farndon 52), there are only 4 percent of materials that we discovered already and we don’t know what things are composed of other 96% and we called these things dark matter and dark energy.
We have talked about astrophysics’ history. And this book teach us from Ptolemy’s Spheres to Dark Energy. Today, scientists are still researching about lots of mysteries in universe. I hope that they solve mysteries in universe and I want to help about solving these mysteries. It because my dream job is astrophysicist. Anyway we were talking about astrophysics today. I wish that some of reader become interesting in astrophysics.
Hyperlinks link: http://www.astronomy.com