8It’s an object of high enough mass and small enough radius What is a Black Hole?It’s an object of high enough massand small enough radiussuch thatthe escape velocity isfaster than light.Nothing can escape.
12Black holes are really massive, Forcing the IssueThe force of gravity from an object depends on1) the mass of the object2) your distance from itGm1m2F=r2So if it’s really massive, or you’re really close, the force is high.Black holes are really massive,And you can getreally, really closeBut this means….
13Forcing the Issue (2) The force you feel CHANGES as you get closer. Something closer to the black hole feels MORE force.STRETTTTTCH!If you fall in feet first, you have a problem.
14There is a Tide BLACK HOLE TIDES The change in force is called a TIDE Tides on surface of Earth (distance = 6400 km): 1/1,000,000th of a g(for a 3 solar mass black hole)6400 kmFupFdownDISTANCEFORCE (g)6400 km0.52000181000144100150,00010150,000,000BLACK HOLE TIDES
15The Second Way A Black Hole Can Kill You 188.8.131.52.5.6.7.Falling inSpaghettification
17The Third Way A Black Hole Can Kill You 184.108.40.206.5.6.7.Falling inSpaghettificationBe near one when it’s bornBe near one when it’s born
18Cold War, Hot Topic NOT ONE WAS OF THIS EARTH Vela Satellites flown to detectnuclear explosions on Earthin 1960s and 1970sby looking for gamma raysOver their lifetime, they detected 73 events.NOT ONE WAS OF THIS EARTH
19Gamma Ray BurstsGRBs happen every day,somewhere in the Universe
20The Birth of a Black Hole Hypernova!Coalescingneutron stars
21over its entire lifetime. Birth PangsEnergy generated in a GRB = 1052 ergsThis is 10x theSun’s total energyover its entire lifetime.Enough energy to vaporize the Earth100 billion times over.
23NASA’s Swift Response Swift detects >100 GRBs per year Launched November 20, 2004
24The Fourth Way A Black Hole Can Kill You 220.127.116.11.5.6.7.Falling inSpaghettificationBe near one when it’s bornBe near one when it dies
25Black holes radiate away energy Pare ProductionParticles created hereFree at last!Buh bye!Hawking Radiation:2 particles created,one particle leavesBlack holeNet Effect:Black holes radiate away energy
26radiation faster as size shrinks. Size Does MatterHawking radiation depends on size/mass of the black hole:smaller holes radiate faster!In fact, radiation emitted goes as 1/mass3Stellar black hole lives for 1067 yearsA mini black hole(mass =1012 kg)would be exploding nowEmits higher energyradiation faster as size shrinks.KABOOM!
27The Fifth Way A Black Hole Can Kill You 18.104.22.168.5.6.7.Falling inSpaghettificationBe near one when it’s bornBe near one when it diesJust passing through