Albert Einstein believe that neither Newton’s First Law of Motion nor existing Relativity Theory could explain how light travels through space so he proposed a new modified theory of relativity. Einstein developed the general relativity to explain why objects are drawn toward each other. .
During the 20th century, Einstein’s theory of relativity replaced Newton’s law of mechanics. Einstein’s relativity theory refers specifically to his two theories, which is general relativity and special relativity. According to Einstein’s Principle of Equivalence, the gravitational mass and inertia mass are the same. In 1922, Einstein believes that when a man falls freely, he would not feel the weight. This belief led to the theory of gravity Maartens). According to Newton‘s law, no matter what the mass of an object, it will fall toward Earth with the same acceleration of 9.8 meters per second squared. Newton explained the two types of mass, inertia mass and gravitational mass. Inertia mass resists motion and enters into his laws of motion and gravitational mass, which enters into his equation of the force of gravity. Newton wants to explain that if the two masses were equal, then all the objects would fall with the same gravational acceleration.
Einstein realized something more profound from Newton‘s law of mechanics. For instance, when a person is standing in an elevator with a broken cable will not feel the weight as that person falls freely toward the Earth. He discovered that he and the elevator accelerated downward at the same rate and will fall at exactly the same speed. According to Einstein‘s general theory of relativity, it is impossible to distinguish between the effects of gravitation and acceleration. In fact, he believes that there is no experiment he can do with a falling elevator to determine he is in Newtonian gravitational field. Both Einstein and Newton have a different view of gravity. Einstein’s view of gravity is its geometric nature, whereas Newton thought that gravity was a force. According to Einstein’s space-time, space and time warps under gravity. Einstein assumed that gravitational force arises from the shape of space-time.
Albert Einstein
By tvbpug - Posted on October 3rd, 2009
First, let me give a short paean on the usefulness of short paragraphs separated by spaces. They make the material much more readable.
Albert Einstein believe that neither Newton’s First Law of Motion nor existing Relativity Theory could explain how light travels through space so he proposed a new modified theory of relativity. Einstein developed the general relativity to explain why objects are drawn toward each other. .
Your phraseology makes me think you are unclear on a few concepts:
(1) Newton's First Law of Motion -- A body at rest remains at rest and a body in motion remains in motion unless acted upon by an outside force. This is commonly known as inertia.
(2) There are two "theories of relativity", both were proposed by Einstein. The first was the SPECIAL THEORY OF RELATIVITY. It deals with objects in an INERTIAL REFERENCE PLANE. An inertial reference plane is one that is either at rest or in motion at a constant velocity.
The second theory of relativity that Einstein proposed was the GENERAL THEORY OF RELATIVITY. It deals with objects in an ACCELERATED REFERENCE PLANE. An accelerated reference plane is one whose motion is not constant. The velocity is changing.
(3) I suspect that when you say "existing Relativity theory" you are referring to Einstein's special theory of relativity. It came first and along with Newton's first law of motion it deals with inertia. However, it is not intuitively obvious what either one of these theories has to do with light traveling through space.
Here's the deal with Einstein. He knew that his special theory of relativity applied only to inertial reference planes. But inertial reference planes are a SPECIAL case of accelerated reference planes. In other words an inertial reference plane is an accelerated reference plane in which the acceleration is zero. That is why his theory is called the SPECIAL THEORY OF RELATIVITY.
Einstein wanted a more GENERAL theory, one that deals with all accelerated reference planes. That is why his second theory of relativity is called the GENERAL THEORY OF RELATIVITY. In developing that theory, he proposed that the gravity around massive objects (equivalent to an accelerated reference plane) would bend light. This was an unexpected prediction from his theory since at that time it was thought that light would travel in a straight line no matter what.
The confirmation of Einstein's general theory of relativity came when it was observed that light from distant stars were indeed bent when it passed close to our sun. This experiment was only able to be done during a complete solar eclipse, and was dramatic confirmation of Einstein's prediction. That is where light traveling in space comes into account during the development of Einstein's general theory of relativity.
During the 20th century, Einstein’s theory of relativity replaced Newton’s law of mechanics. Einstein’s relativity theory refers specifically to his two theories, which is general relativity and special relativity. According to Einstein’s Principle of Equivalence, the gravitational mass and inertia mass are the same. In 1922, Einstein believes that when a man falls freely, he would not feel the weight. This belief led to the theory of gravity Maartens). According to Newton‘s law, no matter what the mass of an object, it will fall toward Earth with the same acceleration of 9.8 meters per second squared. Newton explained the two types of mass, inertia mass and gravitational mass. Inertia mass resists motion and enters into his laws of motion and gravitational mass, which enters into his equation of the force of gravity. Newton wants to explain that if the two masses were equal, then all the objects would fall with the same gravational acceleration.
Again you have some correct and interesting facts, but you haven't quite put them together right.
Yes, Einstein's principle of equivalence does state that gravitational and inertial mass are the same things. But that was known way back with Galileo. Galileo showed that the acceleration due to gravity was the same regardless of the mass of the object. Newton agreed. His improvement over Galileo was to show that force depended upon both the mass and the acceleration (ie F=ma).
The importance of Einstein's principle of equivalence is that he used it to liken gravity to an accelerated reference plane. Indeed the 9.81 m/sec2 is the accelerated reference plane associated with Earth's gravity.
Einstein realized something more profound from Newton‘s law of mechanics. For instance, when a person is standing in an elevator with a broken cable will not feel the weight as that person falls freely toward the Earth. He discovered that he and the elevator accelerated downward at the same rate and will fall at exactly the same speed. According to Einstein‘s general theory of relativity, it is impossible to distinguish between the effects of gravitation and acceleration. In fact, he believes that there is no experiment he can do with a falling elevator to determine he is in Newtonian gravitational field. Both Einstein and Newton have a different view of gravity. Einstein’s view of gravity is its geometric nature, whereas Newton thought that gravity was a force. According to Einstein’s space-time, space and time warps under gravity. Einstein assumed that gravitational force arises from the shape of space-time.
Again you have an interesting mix of off-kilter and exactly-right statements here.
The point Einstein was making with his elevator analogy was this:
Suppose you are in an elevator whose cable is cut. As you and the elevator fall you do not feel the force of gravity within the elevator. You are essentially weightless. The same thing you would feel if you were in a space ship.
Now suppose you were in an enclosed space the same size as the elevator. Only you weren't sure if you were in a falling elevator or if you were in a space ship. Einstein said that there was no experiment you could do to determine which was the true situation. You would feel exactly the same and all potential measuring devices would measure exactly the same.
Finally suppose you felt a pull downward. Gradually you gained weight until you felt until scales under your feet measured the same weight you feel on earth. Perhaps, the elevator came to a gradual stop. Alternatively, the space ship accelerated to 1 g. Again there is no way for you to tell which had happened. You would feel the same thing either way.
THIS IS EINSTEIN'S EQUIVALENCE PRINCIPLE. Acceleration due to gravity is exactly the same as acceleration due to acceleration from a space ship. The importance of this insight was that it allowed Einstein to model gravity with equations dealing with uniform acceleration. By doing relativistic transforms on those equations he was able to show that space-time is warped in intense gravitational fields.
Perhaps you already knew this ... I don't know. But if you didn't I hope this further clarifies a few things for you.
Cheers,
DB
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If a million people say a foolish thing, it is still a foolish thing. - Anatole France