Relativity - Albert Einstein

Appreciation before understanding

If you think you get it you don’t

If it makes no sense, makes your head hurt, you get it

Wednesday, December 28, 11

Albert Einstein

• one of the most recognized faces of Science

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Albert Einstein - Quotes

• “I want to know the thoughts of God, the rest are details”

• I have not particular talent. I am merely inquisitive.”

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Albert Einstein

• “Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That’s relativity.”

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Albert Einstein

• born 1879, died 1955

• “the father of modern physics”

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E = mc2

• one of the most recognized equations of Science

• tells us that energy and mass are one and the same

• this idea lead to the birth of the atom bomb

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Einstein’s accomplishments

• wrote four ground breaking papers in 1905 while working as a Patent Clerk in the Bern Patent Office in Switzerland

• Basically wrote these papers in his spare time

• was not employed as a professor or researcher

• any one of these papers would have got him in the history books

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Einstein’s accomplishments

• First Paper

• Photoelectric effect, 1905

• proved that light is a particle (photon)

• award Nobel prize in 1921

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Einstein’s accomplishments

• Second Paper

• Brownian Motion, 1905

• proved beyond a doubt that atoms exist

• the term is used in Hitch Hikers Guide to Galaxy

• based on a botanists observation of jostling pollen grains

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Einstein’s accomplishments

• Third Paper

• Special Theory of Relativity, 1905

• stated that nothing can travel faster than “c”, the speed of light

• discussed what happens at speeds near the speed of light

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Einstein’s accomplishments

• Third Paper

• Special Theory of Relativity, 1905

• Mass Energy Equivalence

• introduced E=mc2

• this equation led to the atomic bomb

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Einstein’s accomplishments

• Fourth Paper

• 1915, General Theory of Relativity

• says that gravity will bend light or that space time is bent

• confirmed by observing and eclipse in 1919

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Special Theory of Relativity

• tells us that we will observe three effects when speeds approach the speed of light

• these things do not happen at regular speeds

• states that the speed limit for the universe is c

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Special Theory of Relativity

• three effects

• time dilation,time slows down

• length contraction, things get shorter

• mass increase

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Special Relativity

• three effects

• these effects seem bizarre to us because we never see them

• we never travel fast enough

• they have been confirmed by experiment

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Evidence for Relativity - Mass increase

• by tracking collisions among particles physicists can work backwards and determine that the mass must have increased

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Evidence for Relativity - time dilation

• the clocks, and time itself, on moving object will run slower

• scientists have placed one clock on a jet and left one on the runway, the one on the plane was slow by a small amount after a single flight

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Special Relativity - @ normal speeds

time and distance are absolute

(will be the same for all observers)

speed is relative

(depends on the motion of the observers)

Wednesday, December 28, 11

Special Relativity - @ normal speeds

speed is relative

(depends on the motion of the observers)

if you throw a ball at 5 m/s and the catcher is running towards you at 2 m/s, the catcher will measure the speed

to be 7 m/s

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Special Relativity - @ speeds close to C

speed is absolute

(will be the same for all observers)

time and distance are relative

(depends on the motion of the observers)

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Special relativitytime dilation

• V = D/T

• rearranges to

• C = D/T , remember C is constant

• if D gets larger, T must get larger

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Special relativitytime dilation

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Special relativitytime travel

• Special Relativity tells us that time can slow down

• General Relativity goes even further, it suggests that we can actually travel back wards in time or perhaps appear to travel faster that the speed of light

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Special relativity

• although special relativity may seem really weird, it is true

• if we did not take relativistic effects into account none of our satellite technology would work

Wednesday, December 28, 11