PHYSICS 222
Introduction to Classical Physics II
Prof. Ruslan Prozorov
Iowa State University
Fall 2011
LECTURES 34
Relativity

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relativity theories
•
Special relativity
- formulated by Albert Einstein in
1905 based on works of Henri Poincaré and
Hendrik Lorentz
o
is the physical theory of measurement in an inertial
frame of reference
•
General relativity
- Einstein's theory of gravitation
o
the geometric theory of gravitation published by
Albert Einstein in 1916.
14 November 2011
PHYS222 - Lecture 34 - Prof. Ruslan Prozorov - Iowa State University
2

The Twin Paradox
14 November 2011
PHYS222 - Lecture 34 - Prof. Ruslan Prozorov - Iowa State University
3
One of the twin sisters travels 3 light years from Earth at a speed of
0.6c and returns back home to see her twin sister.
On Earth, 1o years have passed, whereas the travelling twin calendar
only showed 8 years. How can this be?

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The Ladder Paradox
14 November 2011
PHYS222 - Lecture 34 - Prof. Ruslan Prozorov - Iowa State University
4
let a long ladder fly lengthwise at great
velocity past a normal garage. The proper
length of the ladder is more than the length
of the garage. Due to the length contraction
of special relativity, the passing ladder can
for an instant (or two) fit into the garage, as
observed by the garage owner.
However, for an observer riding on the
ladder, it is the garage that moves at high
speed and is length contracted. For the
ladder observer there is no way that the
ladder can fit into the garage, even for the
briefest of moments. Hence, the whole
idea seems paradoxical.
http://en.wikipedia.org/wiki/Ladder_paradox