Tuesday, April 5, 2011

Physics Relativity short chapter

Post-1- 1).  I define frames of reference as... where a person is looking at a moving object.  It is how a stationary or moving person each look at a certain velocity of a moving object and how they perceive it.  
2)  The reason the Michelson-Morley experiment did not fit the Galilean/Newtonian understanding of the day was... that the speed of light was proved to be always the SAME.  Back then, the velocities would have been expected to change if the angle of the light was changed or reversed.

Post-2- Simultaneity can be better under stood by watching as one of two objects is hit on two ends and watching as the waves move while one object moves.  This moment by moment diagram reveals why simultaneity is relative to the viewer by showing when the moving object realizes that each end has been hit and when the stationary object does. This diagram helped me by clearing up why the rule works.
 diagram found on : http://conduit9sr.tripod.com/SR3.html

I received a 100% on the special relativity quiz on the first try  :)
Post-3-
1.  Respond to the reading - what are some of the quotes from Penrose that resonated with you, and why?
"...it was the general theory was Einstein's most uniquely original contribution." because I was under the impression that Einstein had come up with all of the theories of relativity on his own.   
"...has Einstein not been there, the theory might well still not have been found by anyone, a century or more later."  We would know much less about relativity had Einstein not used his God given mind and discovered some of the theories of relativity.
2.  From a historical perspective, what particular person or event did you find especially interesting?
Hermann Minkowski- Einstein's teacher who provided a mathematical connection in 1908 known as space time that helped Einstein's theory
3.  What physical evidence did Penrose provide to substantiate Einstein's relativity theories?
binary pulsar PSR1913+16
gravitational lensing
tidal distortions
time slowed down in a gravitational field
sun's gravitational field would deflect light
orbital processing of the orbit of Mercury
GPS devices

 Post -4-
substantiate general relativity-
            Gravitational lensing, redshift in light and blackholes are a major part of Einstein's general relativity theory.  Gravitational lensing is the warp  or ripple in space that causes light to bend.  This was seen when a total eclipse occurred in 1919 and light from stars behind the sun was visible.  
The bending caused by the gravity of the obstructing object in the fabric of space and time causes light of other objects to be redirected and curved around the object itself creating almost duplicates of the original light giving object that is being obstructed.  This type of redirection only makes sense in a gravitational theory based on a fabric streched and relaxed by the objects on/in it.  One can use geometry based on where the duplicate image is, the position of the object and the viewer to calculate the position of the real light giving object. 
The red shift in light shows how distant other galaxies are from the earth based on the Doppler effect.  The expansion of the universe explains the redshift and how it accurately describes the furthering of other galaxies from our position. This also proves relativity in that it shows that although the object is emitting photons at one rate, they're wave lengths are actually lengthened by the time they reach an object.  This shows the time delay related to relativity. 
Black holes are specifically detailed in the theory of relativity. 
"The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole"- wikipedia  This is like a heavy object weighing a hole into a faberic and then causing everything including light from that hole to be emptied into an abyss through that hole.  Once light enters the event horizon of a black hole there is no going back literally.  The light is not reflected because the figurative fabric of space and time has been damaged and cannot allow gravitational lensing to occur due to the damage.  The light is instead "swallowed" by the black hole or more realistically just not reflected or deflected it is simply absorbed (I wonder if star light rays are attracted to black... black shirts absorb the sun's heat and attract the UV rays).  Einstein's theory of general relativity allows for  a gravity field that is strong enough not to let light escape from it.  This is also known as a black hole.  A black hole can also cause gravitational lensing around it this is seen at times when galaxies views are obstructed by a black hole NOT when a black hole is receiving light from the galaxy. 

http://www.electricalfun.com/ElectronCafe/gravity_magnetism_dimensions.aspx
http://physics.stackexchange.com/questions/7179/gravitation-as-the-source-of-redshift-of-light-beams
http://en.wikipedia.org/wiki/Black_hole

Summery:
1.  What did you learn through this short course?  Do you feel you've gained an appreciation and understanding of relativity?
I have learned everything I know about relativity while studying in this course.  I especially liked the general relativity idea and simultaneity.  I have gained a greater interest and understanding of relativity.
2.  How long did it take you to complete this course?
I have worked on this course for 8 hours, but that was spread over a total of five days due to my insanely busy schedule.  
3.  Would you enjoy taking another similar short course?  What improvements would you make?
I enjoyed taking this course and would not mind another like it.  It relieves pressure while allowing me to learn interesting objects.  I would add more visuals, but that is just me... :) I loved the visuals of the general relativity theory.