General Relavitity and Quantum Physics

# General Relavitity and Quantum Physics - Announcements...

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Announcements Homework set #9 is open now and will be due next Thursday Nov 13 at 10 AM Guest lecturers next Tuesday and Thursday

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Cockroft and Walton Ernest Rutherford Let’s hear it directly from Einstein. http://www.youtube.com/watch?v=tpbGuuGosAY
What’s wrong with the derivation If the light that is emitted has mass/energy, then the mass of the box after the radiation has been emitted is reduced, something Einstein forgot to take into account. A correct derivation comes to the same conclusion, but with much more complicated algebra.

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Spacetime Introduced by Einstein in special relativity Extended in general relativity gravity is actually the curvature of space- time due to the presence of mass We identify an event with space-time coordinates (x,y,z,t) The same event will have different coordinates in different reference frames
Escape velocity

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Escape velocity for a very dense object What is the escape velocity for an object with the mass of the Sun and a radius of 1 km? M sun =1.99X10 30 kg G=6.67X10 -11 Nm 2 / kg 2 If you could shrink the Sun down to a radius of 10 km, nothing could escape from it, not even light. v = 2 GM R = 2(6.67 X 10 11 Nm 2 / kg )(1.99 X 10 30 kg ) 1000 m v = 5.2 X 10 8 m / s
i.e. a black hole

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Clicker question What would happen to the Earth if the Sun were replaced by a black hole of the same mass? A) the Earth would spiral into the Sun B) the Earth would fly away from the Sun C) nothing D) the radius of the Earth’s orbit would double E) the radius of the Earth’s orbit would decrease by a factor of 2
Where do black holes come from? They result from the supernova explosions of very massive stars

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Super-massive black holes Black holes with a mass of 1E6 to 1E10 solar masses Essentially all galaxies, including our own, contain super-massive black holes
Active galaxies Have super-massive black holes at the center, and are in the process of having lunch (accreting nearby stars, gas, dust)

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The real thing

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Are black holes permanent? Hawking radiation More when we discuss quantum mechanics
What about mini-black holes? May have been created right after the Big Bang, but have now all

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## This note was uploaded on 10/17/2011 for the course ECON 101 taught by Professor Thompson during the Spring '11 term at Michigan State University.

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General Relavitity and Quantum Physics - Announcements...

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