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Black Holes: physics and astronomy. Black Holes in classical physics: Given a mass M, how compact (squished) does it have to be?. Schwarzschild Radius. R s = 2GM. c 2. General Relativity and Black Holes. General Relativity: a theory of gravity
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Black Holes in classical physics: Given a mass M, how compact (squished) does it have to be? Schwarzschild Radius Rs = 2GM c2
General Relativity and Black Holes General Relativity: a theory of gravity Basic mathematical object: 4 dimensional spacetime
Basic Ingredients of General Relativity • (A) Objects move between 2 points in spacetime on the shortest path between those points (geodesics) • (B) The presence of mass warps or bends spacetime The Einstein Field Equations
General Relativistic Black Holes For sufficient concentration of mass in sufficiently small region, there is a rip or hole poked in spacetime Schwarzschild Radius DEMO with analogs
Question: Do black holes exist in nature? What would you look for? What kind of observation would reveal a black hole?
Cygnus X-1: the prototype black hole http://blackholes.stardate.org/directory/factsheet.php?id=13 Artists’s conception of Cygnus X-1 http://blackholes.stardate.org/directory/image.php?id=13&img=90
An example of a black hole system Black hole and a red dwarf
Present knowledge about black holes • 20 confirmed black hole systems • Least massive: 3.7 - 5.0 solar masses • Most massive: 10.0 - 18.0 solar masses • Remember all pulsars have 1.4 solar masses
Black holes on larger scales: the center of the Milky Way A black hole of 2.5 million solar masses, and more to come