mollyc

= **The Theory Of Relativity: ** =


 by Molly Cole   When Albert Einstein took a closer look into Sir Isaac Newton's theory of relativity, he found flaws in the theory. He then proceeded to figure out the faults in the theory. Eventually, Einstein was able to come up with the Theory of Relativity in which he found that time and distance vary at different speeds.  Albert Einstein's theory of relativity states that one cannot tell whether he is moving or not unless he has another object to compare with, and that the speed of light is always constant. Basically, the faster you travel, nearer to the speed of light, strange things start to occur to the way you perceive things. Einstein said that if you could travel at the speed of light, the way objects are seen would become distorted. Lengths would be shorter, or look shorter, than what they really were. For example, if you were to witness a car travel past extremely fast, the car would seem to have a shorter frame than what it actually is. Now, if you were in the vehicle, no physical change would have actually occurred to the car. It all lies in the eyes of the spectator. This is called a frame of reference, or the surroundings that the position and/ or motion of an object is compared to. With this idea, that everything is relative to a person's point of view, Einstein was able to conclude that there is no such thing as an absolute frame of reference. This is a basic concept to grasp in order to understand Einstein's Theory of Relativity. Two more concepts of the theory are the first and second postulates. The first states that no matter your frame of reference, the laws of physics are the same. That's a pretty easy concept to understand. The second postulate concludes that the speed of light is always the same. Now, this statement may sound bizarre, but it is true. Einstein discovered that space and time actually went hand-in-hand meaning that the speed of light depended on the ratio of distance and time, space-time. A final concept to know, in dealing with the theory of relativity is time dilation. For you to better understand this here is an example by John Zavisa.. Using the Lorentz Transform, let's put numbers to this example. Let's say the clock in Fig 5 is moving to the right at 90% of the speed of light. You, standing still, would measure the time of that clock as it rolled by to be 2.29-seconds. It is important to note that anyone in motion with the clock in Fig 5 would only measure 1-second, because it would be no different than him standing beside the clock in Fig 4. Hence, the rider aged by 1 second but you aged by 2.29 seconds. This is a very important concept. If we look closely at the clocks, we find that they do not really measure what we think they do. Clocks record the interval between two spatial events. This interval may differ depending on what coordinate system the clock is in (ie. what frame of reference). If the speed of light is held constant (has the same measured value regardless of frame of reference), time is no longer "just" a tool to measure the procession of space. It is a property that is required for the defining and existence of the event. Remember from earlier, any occurrence is an event of space and time (hence, the Space-Time Continuum)."   ||   With these concepts you can start to image things such as time travel. In theory it is possible, but for any practical use, there really is not one. When you combine all of the concepts, you come up what is essentially, Albert Einstein's Theory of Relativity.
 * [[image:http://static.howstuffworks.com/gif/relativity4-5.gif width="206" height="287" align="left" caption="Photo from John Zavisa to explain time dilation."]] " <span style="font-family: Verdana,Geneva,sans-serif;"> <span style="font-family: Verdana,Geneva,sans-serif;">In order to attempt to prove this theory of time dilation, two very accurate atomic clocks were synchronized and one was taken on a high-speed trip on an airplane. When the plane returned, the clock that took the plane ride was slower by exactly the amount Einstein's equations predicted. Thus, a moving clock runs more slowly when viewed by a frame of reference that is not in motion with it. Keep in mind that when the clock returned, it had recorded less time than the ground clock. Once re-united with the ground clock, the slow clock will again record time at the same rate as the ground clock (obviously, it will remain behind by the amount of time it slowed on the trip unless re-synchronized). It is only when the clock is in motion with respect to the other clock that the time dilation occurs. Take a look at Fig 4 and Fig 5 below. <span style="font-family: Verdana,Geneva,sans-serif;">Let's assume that the object under the sun in Fig 4 is a light clock on wheels. A light clock measures time by sending a beam of light from the bottom plate to the top plate where it is then reflected back to the bottom plate. A light clock seems to be the best measure of time since its speed remains constant regardless of motion. So in Fig 4, we walk up to the light clock and find that it takes 1 sec for the light to travel from the bottom to the top and back to the bottom again. Now look at Fig 5. In this example, the light clock is rolling to the right, but we are standing still. If we could see the light beam as the clock rolled past us, we would see the beam travel at angles to the plates. If you are confused, look at Fig 4 and you'll see that both the sent beam and received beam occur under the sun, thus the clock is not moving. Now look at fig 5, the sent beam occurs under the sun, but the reflected beam returns when the clock is under the lightning bolt, thus the clock is rolling to the right. What is this telling us? We know that the clock standing still sends and receives at 1-second intervals. We also know that the speed of light is constant. Regardless of where we are, we would measure the light beam in fig 4 and fig 5 to be the exact same speed. But Fig 5 looks like the light traveled farther because the arrows are longer. And guess what, it did. It took the light longer to make one complete send and receive cycle, but the speed of the light was unchanged. Because the light traveled farther and the speed was unchanged, this could only mean that the time it took was longer. Remember speed is distance / time, so the only way for the speed to be unchanged when the distance increases is for the time to also increase.

<span style="font-family: Georgia,serif;"><span style="font-family: Georgia,serif;">Annotation:

<span style="font-family: Georgia,serif;"> The information on this page was based of the websites found below in the works cited section. <span style="font-family: Georgia,serif;">

<span style="font-family: Georgia,serif;">Works Cited:

<span style="font-family: Georgia,serif;">Lightman, Alan. "Relativity and the Cosmos." Nova. June 2005. PBS. <span style="font-family: Georgia,serif;"> 29 Jan 2009. http://www.pbs.org/wgbh/nova/einstein/relativity/

<span style="font-family: Georgia,serif;"> Zavisa, John. "How Special Relativity Works." 01 April 2000. HowStuffWorks.com. <span style="font-family: Georgia,serif;"> 05 February 2009. < http://science.howstuffworks.com/relativity.htm<span style="font-family: Georgia,serif;">>

<span style="font-family: Georgia,serif;">Photos From:

<span style="font-family: Georgia,serif;"> <span style="font-family: Georgia,serif;"> <span style="font-family: Georgia,serif;">http://www.dailygalaxy.com/photos/uncategorized/2007/06/25/cassinigeneral_relativity1.jpg

http://4skills.com/newsletter/images/einstein.large.gif

http://www.fearofphysics.com/Relativity/house_cray.jpg