General relativity is describing the gravitational field and the equations it obeys. The theory is often used as a prototype for other, to describe forces between elementary particles or other branches of fundamental physics. This is why general relativity is separated with the various ingredients that together give shape to this paradigm. After explaining the physical motivations, the notion of an affine connection field and later on add the metric field. One then sees clearly how space and time get more and more structure, until finally all we have to do is use Einstein’s field equations.
Being published in 1916 “Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels” (Red,2016). Meaning no matter what you do when it comes to special relativity everything is the same no matter on what you use, what you do, or how you do it. Also when it comes to the speed of light within a vacuum, no matter how fast or when you measure the speed of light it automatically stays the same. Albert Einstein’s theory explains how when he pre receive as the force gravity arises from curvature of space and time, objects like the Earth and the Sun changes this geometry. There are way in real life for you to see Einstein’s theory of relativity for yourself. For example, “The theory is deceptively simple. First, there is no “absolute” frame of reference. Every time you measure an object’s velocity, or its momentum, or how it experiences time, it’s always in relation to something else. Second, the speed of light is the same no matter who measures it or how fast the person measuring it is going. Third, nothing can go faster than light”(Emspak,2017). Therefore, if the speed of light is the same all around then the astronauts going in the speed of the earth would be slower then the observer causing the astronaut to slow. This is called time dilation. More so to see time dilation the object in a big gravity field must be accelerating. For reference “if you took a picture of the spacecraft as it flew by, it would look as though it were “squished” in the direction of motion. To the astronaut on board, however, all would seem normal. In addition, the mass of the spaceship would appear to increase from the point of view of people on Earth” (Emspak,2017). Meaning that on earth when you are taking a picture everything is going to look exactly the same based off the speed the earth is moving but, once you are in space the speed of the atmosphere is not the same, just a little quicker, causing the image that you would have took in space would be normal to you but once seeing it with the speed of the earth the image would tend to be blurry and hard to recognize. As known the general theory of relativity is determined by the distribution of matter and energy contained within it. Based off of Newton’s law of universal gravitation he noticed that all forms of energy have a effective mass that makes it seem like light can pass through and this could be found out by using measurements or equations to get an approximate answer. In the website, The Physics of the Universe states that, “The General Theory of Relativity can actually be described using a very simple equation: R = GE (although Einstein’s own formulation of his field equations are much more complex)” (Mastin,2009). Based on the equation each variable have a different representation whereas R describes the distortion of space-time, G is the gravitational constant, and E represents the energy of the object basically having the same role as R. Therefore the theory has shown that it would be very hard to figure out what general theory of relativity is without the knowledge of Einstein and Newton.
Other than knowing what is the theory of relativity you also have to know how it is postulated in order for it to make more scenes to you and others. Based off of Einstein’s knowledge he came up with two postulated; The Principle of Relativity and The Constancy of Speed of Light in a Vacuum. When knowing of the principle of relativity the laws of physics are all the same in every frame reference but the constancy of speed of light have the same value c in all references. For instance, “The speed of light in vacuum c (299792458 m/s) is so enormous that we do not notice a delay between the transmission and reception of electromagnetic waves under normal circumstances” (Nobel Media AB,2017). This tells that the speed of light is the same of the absolute and the same for all observers. These “postulated played an important part into developing the Theory of Relativity. The first postulate follows that there is no coordinate system. These motions are based upon speed which is called an inertial coordinate system or an inertial frame. For example say you have two objects and one object says that they are at rest in relation to the other object causing that object to move closer to the first object and the same in vice versa. But the most important concept of special relativity is simultaneity. Simultaneity is when two events happen at the same time and and same place. For example of two lights, it would seem like the lights were simultaneously turned on at the same time hitting one object at the same time but if an observer takes a look at it they would see that one of the lights would have been switching first and hit the object before the other light does.
By going step by step you can easily figure out how general relativity was proven. First Einstein started with curvature. “The geometrical notion of the curvature of space … saw how that geometrical notion can be extended from space to spacetime. We then found the resulting theory of curved spacetime not just to cover a curved geometry of space, but gravitational phenomena as well” (Norton, February/2001). To begin with Isaac Newton’s first law of motion: An object remains in uniform motion unless acted on by a force. Meaning that if you do not feel a force you would either stay still or glide in a straight line. But Einstein says that by falling downward there would not be any force acting on him as he approaches the ground. With that being said he came up with the thought that no force should travel at a constant speed but can sometimes accelerate. He realized that Earth revolves around a warp space time while a falling object falls in a straight line due to space time. So when we fall or anything falls is doenst look straight but there’s nothing acting on it causing gravity to be the force that is warped around space time. For example, with gravity being off you would only float in the air but with it being turned back on the earth’s warp spacetime causes us to be on the ground longer than it does in the air.
Without a doubt there is a difference between classical and modern physics. The website states that, “Classical physics is normally taken to be physics as it was understood in about 1890, as the combination of Newtonian mechanics and Maxwellian electromagnetism, but not including relativity or quantum mechanics. Sometimes it’s stretched to include relativity, but never quantum mechanics” (Barton, Sep. 16/2016). With that being said classical physics includes the traditional branches such as classical mechanics, acoustics, optics, thermodynamics, and electromagnetism. Classical mechanics is more dependable on the body of motion that are being divided into statics; study the body at rest, kinematics; study of motion, and dynamics; study or motion and forces affected with it. With modern physics it deals with how matter and energy react under extreme conditions. Dealing with modern physics it’s mainly based on theories such as quantum theory; discrete of nature of many phenomena at the atomic and subatomic level, theory of relativity; description of phenomena that is referenced by motion, special theory of relativity; one motion of a straight line, and the general theory of relativity that deals with motion connected to gravity.
Bases upon the concepts of how modern physics work it tends to be hard to make claims of nature’s findings. When making observations of events it can tend to uphold a cause and effect in modern physics. Just like Einstein, in modern physics it is best to state the problem of the aspects and then work your way through them.
Citation:
Space.com – http://www.space.com/17661-theory-general-relativity.html (Date Accessed: July/12/2016)
Live Science – https://www.google.com/amp/amp.livescience.com/58245-theory-of-relativity-in-real-life.html (Date Accessed: March/14/2017)
The Physics of the Universe – http://www.physicsoftheuniverse.com/topics_relativity_general.html (Date Accessed: 2009)
nobelprize.org – https://www.nobelprize.org/educational/physics/relativity/postulates-1.html (Date Accessed:2017)
Einstein’s Pathway to General Relativity – http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters_2017_Jan_1/general_relativity_pathway/index.html (Date Accessed: February 2001; January 2, 2007, February 15, August 23, October 16, 27, 2008; February 5, 19, 2010. Minor edits February 26, 2013. December 29, 2015.)
Quora – https://www.quora.com/What-is-difference-between-classical-physics-and-modern-physics (Date Accessed: Sep. 16/2016)