natsci1report (2007version)


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natsci1report (2007version)

  1. 1. Einstein’s Theories of Relativity<br />Dizon, Samantah Louise<br />Lacanilao, Alezandria Nicole<br />Membrere, Ingrid Mae<br />Hipolito, YzaLennor<br />
  2. 2. Special Theory of Relativity<br />It was published in 1905.<br />It deals with problems involving inertial frames of reference (frames moving at constant velocity) with respect to each other.<br />General Theory of Relativity<br />It was published in 1915.<br />It deals with problems involving accelerated reference frames.<br />
  3. 3. The Search for the Ether: The Michelson-Morley Experiment<br />
  4. 4. What is Ether?<br />It was believed to occupy all cosmos.<br />It is undetectable by ordinary means.<br />It was supposed to permeate all matter and space.<br />It was supposedly a medium to act as a carrier of waves, including light.<br />
  5. 5. The Michelson Interferometer<br />(c)RiA<br />
  6. 6. Results of the Experiment<br />The results were negative, even after repeating it six years later.<br />
  7. 7. Hypotheses for the Results<br />The ether was not stationary but was dragged along with the earth.<br />The earth was fixed in the ether and everything else in the universe moved with respect to the earth and the ether.<br />The velocity of light was always at constant with respect to the source which emitted it.<br />Ether did not exist at all.<br />
  8. 8. Postulates of Special Theory of Relativity<br />
  9. 9. Postulate 1: The speed of light is independent of the motion of the Light of source or receiver.<br />This postulate concerns the constancy of the speed of light to all observers.<br />All measurements, whether stationary or moving observers relative to a moving or stationary source always give the same value for the speed of light, c=3x10 m/s.<br />This postulated is supported by the results of the Michelson-Morley Experiments.<br />8<br />
  10. 10. Postulate 2: All inertial frames are equivalent with respect to all laws of physics<br />This postulate concerns “relativeness” of reference frames (principle of relativity).<br />It follows directly from the absence of a universal frame of reference.<br />A place moving with constant velocity are the same as those in a stationary place.<br />
  11. 11. Herman Bondi labelled the 2 postulates respectively:<br />Uniqueness of light –the speed of light is the same for all observers whether moving or not. The speed of light is an invariant.<br />Irrelevance of Velocity –there is no absolute reference frame. All frames are equivalent with respect to the laws of physics.<br />
  12. 12. Space, Time, Mass and Energy according to Einstein <br />
  13. 13. Length/Space Contraction<br />The length of an object is maximum when measured in a frame which is at rest; the length is minimum when measured in a moving reference frame.<br /> L = L √1 – v / c <br />_______<br />2<br />2<br />0<br />
  14. 14. Time Dilation<br />Time is affected by relative motion.<br />Time runs slower in a moving reference frame than in a stationary frame.<br /> t’ = t<br /> √ 1 – v / c <br />_______<br />_______<br />2<br />2<br />
  15. 15. Relativity of Mass<br />Classical physics regard mass as constant, but mass according to relativity is also dependent on motion. Therefore, the mass of a body changes as the body is set into motion.<br />m = m<br /> √ 1 – v / c<br />*Nothing can exceed the speed of light; it is the limit to which moving objects can approach.<br />_______<br />_______<br />0<br />2<br />2<br />
  16. 16. Equivalence of Mass and Energy<br />Mass is a form of energy. E = mc shows that 1kg of mass = 9 X 10 J <br />Significance of the Special Theory of Relativity:<br /> 1.) Effect of Newtonian Mechanics<br /> 2.) The practical use of relativity is in atomic and nuclear physics.<br /> 3.) Philosophical impact on the course of physical theory.<br /> 4.) The idea of ether had to be discarded.<br />2<br />16<br />
  17. 17. Experimental results that support the Special theory of Relativity:<br /> 1.) Radioactive Particle Experiments<br /> 2.) Elementary Particle Experiments<br /> 3.) The Cockroft and Walton Experiment<br />
  18. 18. The General Theory of Relativity<br />
  19. 19. Einstein published the General Theory of Relativity which was an attempt to account for the properties of motion in accelerated and noninertial frames of reference.<br />The basis of this theory is the Principle of Equivalence:<br />A homogeneous gravitational field is completely equivalent to a uniformly accelerated reference frame.<br />
  20. 20. Four-Dimensional Space Time; Consequences of The General Theory of Relativity<br />
  21. 21. Space and are dynamic quantities.<br />Space-time is flat in free space. Space-time is curved or warped near gravitational fields.<br />Objects that follow the shortest path between two points in a curved space (Geodesics).<br />Gravity is a consequence of the fact that space-time is curved.<br />Light rays also follow geodesics. Light is bent by gravitational fields.<br />Outstanding Consequences of the General Theory of Relativity<br />
  22. 22. The principle of equivalence is the deflection of a light beam in a gravitational field.<br />Light will accelerate (hence, it is deflected) in a gravitational field.<br />Other consequences<br />