Einstein’s relativity• http://www.youtube.com/watch?v=tpbGuuGosA

Y&feature=related

• Did Newton's knew how gravity works / produced?

• What is the speed limit of the universe? Does gravity exceed that limit?

• IF the sun is to disappear right now, when will we see it? When will the earth’s orbit be altered by that event? What will we experience?

The Speed of Light Is Constant

As seen from the ground

As seen from the car

The faster an object moves, the shorter itbecomes in its direction of motion as observed by someone not moving with the object.

Time dilation:The time you experience will be different from

earthly observer. Post your answer on group discussion and verify your answer with

your group members. If you are traveling at 0.5c, then time will elapse at 15%

slower (for 1 year of travel, 1.15 year elapse on Earth). If you are traveling at 0.87c, then time will elapse at ½ rate. If you are traveling at 0.995c, then time will elapse at 1/10 rate.

• Lets say your twin has traveled away. He said he will e-mail you every day at noon ( 24 hours in his time reference) to let you know how he is doing. His ship will be traveling at 0.87c. How often will you receive his e-mail?

• Lets say in his reference frame, he has been traveling for 2 years ( 1 year each way). How much time have elapsed for you?

Watch the black holes video:

• http://www.youtube.com/watch?v=f0VOn9r4dq8&feature=related

• Explain fabric of space time. Does the sun cause curve in space time? Earth? The moon? you?

• Do you understand the kayak analogy of black hole? Explain. If you get too close, what happens to you? Can you still escape?

Curved Spacetime

In the absence of any matter in the spacetime, straight lines are straight.

In the presence of matter, spacetime curves.

This pulls the two masses toward each other.

Schwarzschild (Nonrotating) BlackHole Kerr (Rotating) Black Hole

Rsch (km) = 3M(in Msun)

Accretion Disk Around a Supermassive Black Hole

300-million solar mass black hole in the centerof galaxy NGC 7052

Evaporation of a Black Hole

Because the gravitational energy used to create the particles came from the black hole, the hole loses mass and shrinks, eventually evaporating completely.