Black HoleBlack Hole

Vacuum Cleaner of the UniverseVacuum Cleaner of the Universe

Formation of Black HoleFormation of Black Hole

nuclear fusionnuclear fusion - tends to blow the star's - tends to blow the star's hydrogen outward from the star's centerhydrogen outward from the star's center

gravitationgravitation - tends to pull all hydrogen - tends to pull all hydrogen back in the direction it had comeback in the direction it had come

Mass of StarMass of Star OutcomeOutcome

< 1.4 solar mass< 1.4 solar mass White DwarfWhite Dwarf

> 1.4 solar mass &> 1.4 solar mass &

< 3.0 solar mass< 3.0 solar mass

Neutron StarNeutron Star

> 3.0 solar mass> 3.0 solar mass Black HoleBlack Hole

Formation of Black HoleFormation of Black Hole

primordial black holeprimordial black hole is formed upon extreme is formed upon extreme compression of matter by external forcescompression of matter by external forces

One possibility of the existence of such black One possibility of the existence of such black holes are during the early stages of the universe holes are during the early stages of the universe where high temperatures and pressures existedwhere high temperatures and pressures existed

Formation of Black HoleFormation of Black Hole

Structure of Black Hole (1)Structure of Black Hole (1)

Schwarzschild singularitySchwarzschild singularity: : a point of infinite densitya point of infinite density

Event horizonEvent horizon: boundary of : boundary of the region inside which light the region inside which light cannot escapecannot escape

Schwarzschild radiusSchwarzschild radius: : radius of the event horizonradius of the event horizon

Schwarzschild black hole (史瓦西黑洞 ) – a non-rotating black hole

Photon sphere

Outer event horizonOuter event horizon: Boun: Boundary inside of which nothing dary inside of which nothing can resist being can resist being dragged arodragged aroundund with the rotating mass with the rotating massInner event horizonInner event horizon: Bound: Boundary inside of which nothing cary inside of which nothing can escapean escapeErgosphereErgosphere: A particle ente: A particle entering it will be split into two: oring it will be split into two: one falls into the black hole, ane falls into the black hole, and the other ejected with mond the other ejected with more energyre energy

Structure of Black Hole (2)Structure of Black Hole (2)

Kerr black hole – a rotating black hole

Structure of Black Hole (2)Structure of Black Hole (2)

EvaporationEvaporation

energy is "borrowed" energy is "borrowed" from the vacuum, from the vacuum, creating a particle - creating a particle - antiparticle pairantiparticle pairOne particle of the pair is One particle of the pair is pulled into the black hole, pulled into the black hole, and the other escapes, and the other escapes, carrying with it some carrying with it some energyenergyA black hole of 1 solar A black hole of 1 solar mass would take ~ 10^66 mass would take ~ 10^66 years to evaporate years to evaporate completely completely

Curvature of space-timeCurvature of space-time

A A smallsmall celestial body celestial body with with large masslarge mass

Severe curvature of Severe curvature of space-timespace-time

Not even light can get Not even light can get out (light loses all energy out (light loses all energy in climbing out of such in climbing out of such holes)holes)

Detection of Black holeDetection of Black hole

If light is not given off If light is not given off by black holes, how do by black holes, how do

we detect them? we detect them?

Orbiting around nothing Orbiting around nothing

When a star changes into a black hole, the When a star changes into a black hole, the strength of its gravitational field remains strength of its gravitational field remains the samethe same

The planets in orbit would continue in their The planets in orbit would continue in their orbits as usual orbits as usual

The planets would appear to be orbiting The planets would appear to be orbiting around nothingaround nothing

X-ray telescopeX-ray telescope

The dust particles near the black hole The dust particles near the black hole speed and heat up, emitting x-raysspeed and heat up, emitting x-rays

Objects that emit x-rays can be detected Objects that emit x-rays can be detected by x-ray telescopes outside of the Earth's by x-ray telescopes outside of the Earth's atmosphere atmosphere

Gravity-lensingGravity-lensing

Gravity lensingGravity lensing occurs when a massive object occurs when a massive object passes between a star and the Earth. passes between a star and the Earth.

From an observer's point of view on the Earth, thFrom an observer's point of view on the Earth, the star would appear to brightene star would appear to brighten

Measuring massMeasuring mass

If a region has large amounts of dark If a region has large amounts of dark mass, one can suspect the presence of a mass, one can suspect the presence of a black holeblack hole

Falling into the black holeFalling into the black hole

Time dilationTime dilation

Gravitational redshiftGravitational redshift

(Observing outside event horizon)

Falling into the black holeFalling into the black hole(Observing inside event horizon)

WormholeWormhole

Developed by Albert EDeveloped by Albert Einstein and Nathan Roinstein and Nathan Rosen in 1935sen in 1935

Einstein-Rosen bridge Einstein-Rosen bridge

A shortcut between twA shortcut between two points in spaceo points in space

Connecting a black hoConnecting a black hole and a white holele and a white hole

E=mc^2E=mc^2

WormholeWormhole

Exotic matterExotic matter is requi is required to keep a wormholred to keep a wormhole openede opened

Exotic matter has –ve Exotic matter has –ve mass and energymass and energy

Gravitationally repulsivGravitationally repulsivee

Light rays passed through a Light rays passed through a wormhole are defocusedwormhole are defocused

Faster-than-light travelFaster-than-light travel

Special relativitySpecial relativity says that one cannot says that one cannot outrun a light signal in a fair raceoutrun a light signal in a fair race

It might be possible to beat a light signal It might be possible to beat a light signal by taking a different routeby taking a different route

The Twin ParadoxThe Twin Paradox

A person who leaves Earth in a spaceship, A person who leaves Earth in a spaceship, travels at near light speed and returns will travels at near light speed and returns will have aged less than someone who have aged less than someone who remains on Earthremains on Earth

http://webphysics.davidson.edu/physletprohttp://webphysics.davidson.edu/physletprob/ch10_modern/twin.htmlb/ch10_modern/twin.html

Time travelTime travel

If the traveler manages to outrun a light If the traveler manages to outrun a light ray, perhaps by taking a shortcut through ray, perhaps by taking a shortcut through a wormhole or a warp bubble, he may a wormhole or a warp bubble, he may return before he left return before he left

Grandfather ParadoxGrandfather Paradox

What happens if I go back in time and What happens if I go back in time and kill my grandfather, thus preventing my kill my grandfather, thus preventing my future existence? future existence? 

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