PHYSICS 221 TOPICS: TIME DILATION
PHYSICS 221 TOPICS: TIME DILATIONCreated by Dwayne MacLeod
According to the theory of Special Relativity, as an object approaches the speed of light, the time for that object will appear to slow down by an observer who is not moving with the object. That is because the time interval between two events depends on how far apart they are; that is, their spatial and temporal separations are entangled. If we were able to monitor a clock in a spaceship as it went by at near the speed of light it would seem to us that the clock is moving very slow. But to the astronaut who was monitoring our clocks they would say that our clocks are moving slowly also. This phenomenom is called Time Dilation. When two events occur at the same location in an inertial reference frame, the time interval between them, measured in that frame, is called the proper time. Measurements of the same time interval from any other inertial reference frame are always greater. The standard equation for time dilation is given by: T = To/(1-(v/c)^2)^0.5 where T stands for the time in the observer's reference frame, To stands for the time in the proper reference frame, v = speed of the moving object, and c stands for the speed of light. From this equation, it obvious to note that the closer v gets to c, the greater the time dilation will be. For example, if v reaches 90% of the speed of light for the spaceship in the earlier example, for each day on board, two and a quarter days pass for an observer stationary with the respect to Earth.
| Introduction
to Time Dilation |
Creator: The Timeline Group
Audience: High school level (some knowledge of physics) Presentation: This is a very good site. It is very simple and to the point. It has a very good introduction and good illustrations. Also, it is kept pretty low level to allow for a greater range of audience. Content: This site explains a lot about time dilation and it covers a lot of aspects of time dilation in general. It provides good examples of time dilation and interesting facts. Could use more links to other sites on time dilation Questions: At what percent of the speed of light would a space ship have to travel from earth, so that for every second that passes on a clock in the space ship, 2 seconds pass for a clock on earth? answer: 86.6% |
| Interview with Einstein: Time dilation | Creator: GeoCities
Audience: Univeristy level but may apply to some levels of high school Presentation: The presentation is very original because it brings about much debate over Einsteins work in time dilation. Content: The focus is basically the author creating what he would believe an interview between him and Einstein. He raises issues about Einsteins work in time dilation that some people would argue against. The site seems a little biased in the fact that Einstien work may not be correct. Questions: If an experiment was conducted to test time dilation by putting a clock on an airplane and comparing it's recorded time after flying at high speeds (however fast an airplane can fly) with a clock that remained at rest, would the results hold true for Einsteins equation for time dilation? answer: Not always due to the factors of acceleration and gravitaion. |
| C-ship: The Dilation of Time | Creator: Fourmilab
Audience: Univeristy level but may apply to some levels of high school Presentation: This is also a very good site. It has good visual aid that allows you to get a good feel of how the velocity of an objects relates to it's time dilation. Content: The site gives a brief discussion of time dilation and equations dealing with time dilation. It provides a graph representing the effect of time dilation for velocities which are factors of the speed of light. It also provides a table showing the time dilation in years and days for different velocities (factor of the speed of light). The site could use a better introduction to time dilation so the site could easily make more sence to a wider range of people. Questions: A space station is orbitting around the earth with a velocity of 7700 m/s. How many seconds does the space station age by for every second that passes on earth? answer: 3 nanoseconds (3.8 seconds behind earth's time after 1 year) |