General Relativity

• Equivalent principle


  An observer cant determine by experiment weather they are in accelerating frame of reference or in a uniform gravitational field
• Using equivalent principles to explain how a system is weightless in achieved.


  The effect of gravity are exactly equivalent to the effect of acceleration. the plane accelerating downwards exactly cancels out the effect of being in a gravitational field.
• Einstein equivalent principles


  The light behaves the same way as the gravitational field as it dose in an accelerating frame of reference. This is known as gravitational leasing.
• Apparent position of star

  As the direction of light is affected by the gravitational field of large masses the apparent and true position of stars is confirmation to this effect

  
• Curved spacetime

  General relativity states that length and time will change near large masses and spacetime curves near large masses. The greater the mass the greater the distortion of spacetime. A straight line through curved space feels straight to the travelers but appears as a curve to other observes. Light or freely moving objects follow a geodesic in space time
• Meaning of geodesic

  The path with the shortest distance between two points
• Time near large masses

  time dilates (slows down) more the closer u are to large masses, time also runs slower under the influence of a greater gravity
• Distance and length near large masses

  Space contract near large masses
• Gravitational time dilation


  In an accelerating spacecraft the clock at the front of the space craft will run fast then the clock at the bottom of the space craft. Greater acceleration greater difference between the two times. this is due to the observer receiving more wave fronts per second. An accelerating clock in a centrifuge (an orbit) or a clock at a lower altitude in a gravitational field runs slower than a clock with in a small gravitational field
• Evidence of gravitational time dilation


  Doppler effect and gravitational red shift.
• Whats the name of lines drawn on spacetime diagrams

  Worldlines
• What dose it mean when the worldline is is not observed

  Means that the light is travelling faster then the speed of light
• Black holes 


  A black hole is an object with an escape velocity greater then the speed of light.
• How is a black hole formed 


  A black hole is formed when a massive star runs out of fuel for fusion and collapse in on itself
• describe a black hole

  A gravitational description of a black hole is that there is such an intense gravitational field at the surface that the escape velocity exceeds the speed of light
• general relativity on a black hole

  large mass curves spacetime infinitely
• what is the name of the mass of the black hole 


  Singularity
• What is the event horizon 


  The event horizon is the boundary between inside the black hole and the outside universe
• Radius of black hole

  Schwarzschild radius is the distance from center of singularity to event horizon. At event horizon the escape velocity is equal to the speed of light. Time appears frozen at the event horizon this is due to extreme limit of gravitational time dilation.