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GENERAL RELATIVITY II CURVED SPACE-TIME. Intrinsic Curvature. Airlines follow the shortest path This is not a straight line because the Earth’s surface is intrinsically * curved. *Cannot be made flat without stretching or tearing. Intrinsic curvature measured by triangulation.
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GENERAL RELATIVITY II CURVED SPACE-TIME
Intrinsic Curvature Airlines follow the shortest path This is not a straight line because the Earth’s surface is intrinsically* curved *Cannot be made flat without stretching or tearing
Intrinsic curvature measured by triangulation Draw any triangle = 3 points joined by geodesics* *Geodesic – line of shortest distance in curved space (in flat space this is a straight line) Σ angles > 180o Σ angles < 180oΣ angles = 180o The first 2 shapes cannot be made from a flat piece of paper without tearing or stretching
General Relativity’s BIG IDEA Generalization of curved space to more than 2 dimensions Mathematician -> Riemann, Einstein used this work for GR. Space & Time are intrinsically curved by mass. This alters motion `as if’ there is a force of gravity (there isn’t).
Worldine t t Spacetime y At rest TABLE x Worldine t • Minkowskispacetime • has 3 space and 1 time • = 4 dimensions • Spacetime is intrinsically • curved by mass Constant velocity
In free fall, objects are following geodesics in 4-dimensional spacetime General Relativity’s Law of Motion E.g. planetary orbit t y y x x Note: Path in space only is not geodesic Spacetime curved by Sun’s mass. Planet’s geodesic is not `straight’.
What general mathematical name is given to the shortest path between two points? a) Line b) Geometric c) Worldline d) Geodesic
What general mathematical name is given to the shortest path between two points? a) Line b) Geometric c) Worldline d) Geodesic
How many dimensions does our spacetimehave? a) 2 b) 3 c) 4 d) 5
How many dimensions does our spacetimehave? a) 2 b) 3 c) 4 d) 5
Which of the following is not part of Einstein’s General Relativity model • Gravity is due to the curvature of the Earth’s surface • Spacetimeis curved by the presence of mass • Free fall due to gravity is equivalent to being in an inertial frame • Objects in free fall follow geodesics in spacetime
Which of the following is not part of Einstein’s General Relativity model • Gravity is due to the curvature of the Earth’s surface • Spacetimeis curved by the presence of mass • Free fall due to gravity is equivalent to being in an inertial frame • Objects in free fall follow geodesics in spacetime
Which of the following is evidence that General Relativity is better than Newton’s models? a) The measured advance of the perihelion of Mercury b) The phase of Venus c) That the Earth orbits the Sun, not vice versa d) The existence of Jupiter’s moons
Which of the following is evidence that General Relativity is better than Newton’s models? a) The measured advance of the perihelion of Mercury b) The phase of Venus c) That the Earth orbits the Sun, not vice versa d) The existence of Jupiter’s moons