DP Physics (last assessment 2024)
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A.5 – General relativity (HL only)

Description

Nature of science:

Creative and critical thinking: Einstein’s great achievement, the general theory of relativity, is based on intuition, creative thinking and imagination, namely to connect the geometry of spacetime (through its curvature) to the mass and energy content of spacetime. For years it was thought that nothing could escape a black hole and this is true but only for classical black holes. When quantum theory is taken into account a black hole radiates like a black body. This unexpected result revealed other equally unexpected connections between black holes and thermodynamics. (1.4)

Understandings:

  • The equivalence principle
  • The bending of light
  • Gravitational redshift and the Pound–Rebka–Snider experiment
  • Schwarzschild black holes
  • Event horizons
  • Time dilation near a black hole
  • Applications of general relativity to the universe as a whole

Applications and skills:

  • Using the equivalence principle to deduce and explain light bending near massive objects
  • Using the equivalence principle to deduce and explain gravitational time dilation
  • Calculating gravitational frequency shifts
  • Describing an experiment in which gravitational redshift is observed and measured
  • Calculating the Schwarzschild radius of a black hole
  • Applying the formula for gravitational time dilation near the event horizon of a black hole

Guidance:

  • Students should recognize the equivalence principle in terms of accelerating reference frames and freely falling frames

Data booklet reference:

 

Theory of knowledge:

  • Although Einstein self-described the cosmological constant as his “greatest blunder”, the 2011 Nobel Prize was won by scientists who had proved it to be valid through their studies on dark energy. What other examples are there of initially doubted claims being proven correct later in history?

Utilization:

  • For the global positioning system to be so accurate, general relativity must be taken into account in calculating the details of the satellite’s orbit
  • The development of the general theory of relativity has been used to explain the very large-scale behaviour of the universe as a whole with far-reaching implications about the future development and fate of the universe

Aims:

  • Aim 2: the general theory of relativity is a great synthesis of ideas that are required to describe the large-scale structure of the universe
  • Aim 9: it must be appreciated that the magnificent Newtonian structure had serious limitations when it came to the description of very detailed aspects of planetary motion

 

Directly related questions

Sub sections and their related questions

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