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TWIN PARADOX
A longer life, but it
will not seem longer
Twin Paradox
Animated Movie
Experimental Verification
It really happens!!!!
Time dilation has been verified experimentally by
precise measurements of atomic clocks flown in
aircraft and satellites.
* gravitational time dilation and special relativity
together have been used to explain the Hafele–
Keating experiment.
* It was also confirmed in particle accelerators by
measuring time dilation of circulating particle beams.
Relativity
Time Dilation
• A moving clock ticks more slowly than a clock at
rest.
Analogy between Hindu and
British Calendar
Need for an equilizing factor!
Twin Paradox
FALLACY IN THE PARADOX
• Betty goes off in a rocket ship at close to the
speed of light and returns to Earth some years
later. Anna stays put. Viewed from Earth, Betty's
time is slowed, so when Betty gets back Anna
should be older than Betty.
• But viewed from the rocket ship, it is Earth that
is moving, so Anna's time is slowed, and on
return Betty should find it is she who is older.
• However both accounts cannot be right: when
the twins finally get together again, Betty might
either be younger or older than Anna, but not
both. Hence the claim of paradox.
• The resolution comes from the fact that the two
perspectives, Anna's and Betty's, are actually not
completely symmetric. To accomplish her trip,
Betty must accelerate away from Earth, cruise at
uniform speed for a while, then brake, turn
around, accelerate again, cruise some more, and
finally brake again to land on Earth. Anna
merely remains immobile.
• All Betty's maneuvers, acceleration and
deceleration, break the symmetry between the
two sets of observations. The principle of
relativity, remember, applies to uniform motion,
not to accelerations. An acceleration is not
relative; it is absolute. Taking this into account,
it is Betty who ages less. On her return, Ann
would be older.
• It has nothing to do with the effect of motion on
the aging process.
Thankyou

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Twin paradox

  • 1. TWIN PARADOX A longer life, but it will not seem longer
  • 3.
  • 4. Experimental Verification It really happens!!!! Time dilation has been verified experimentally by precise measurements of atomic clocks flown in aircraft and satellites. * gravitational time dilation and special relativity together have been used to explain the Hafele– Keating experiment. * It was also confirmed in particle accelerators by measuring time dilation of circulating particle beams.
  • 6. Time Dilation • A moving clock ticks more slowly than a clock at rest.
  • 7.
  • 8.
  • 9. Analogy between Hindu and British Calendar Need for an equilizing factor!
  • 10.
  • 11.
  • 13. FALLACY IN THE PARADOX • Betty goes off in a rocket ship at close to the speed of light and returns to Earth some years later. Anna stays put. Viewed from Earth, Betty's time is slowed, so when Betty gets back Anna should be older than Betty. • But viewed from the rocket ship, it is Earth that is moving, so Anna's time is slowed, and on return Betty should find it is she who is older.
  • 14. • However both accounts cannot be right: when the twins finally get together again, Betty might either be younger or older than Anna, but not both. Hence the claim of paradox. • The resolution comes from the fact that the two perspectives, Anna's and Betty's, are actually not completely symmetric. To accomplish her trip, Betty must accelerate away from Earth, cruise at uniform speed for a while, then brake, turn around, accelerate again, cruise some more, and finally brake again to land on Earth. Anna merely remains immobile.
  • 15. • All Betty's maneuvers, acceleration and deceleration, break the symmetry between the two sets of observations. The principle of relativity, remember, applies to uniform motion, not to accelerations. An acceleration is not relative; it is absolute. Taking this into account, it is Betty who ages less. On her return, Ann would be older. • It has nothing to do with the effect of motion on the aging process.

Editor's Notes

  1. Test of theory of relativity, Joseph c hafele a physict and Richard E. Keating, an astronomer, took 4 ceasium beam atomic clocks aboard commercial airlines. Flew twice around the world, first eastward then westward and compared the clocks against the clock that remained at naval observatory. When reunited, the three sets of clock were found to diagree with one another and their difference was consiistent with the predictions of special and general relativity.
  2. When we say something is moving, what we mean is that its position relative to something else is changing. So there is a frame of refernce. An inertial frame of reference is one which moves with a constant velocity. In such a reference frame, Newtons’s first law of motion holds tue.