The Shapiro Effect: Fourth Test
● The Shapiro effect is a time delay for radar signals sent from the Earth to
Mercury or Venus when they are on the far side of the Sun.
PAGE 39
● The gravitational red shift is caused by the slowing of clocks in lower gravitational
potentials, and the Haystack and Arecibo radio telescopes can be used to
observe planets close to the Sun.
● The Shapiro delay is a test of General Relativity that has continued to validate
the theory to this day.
Rotating Frames of Reference
● Einstein consigned the concept of the aether as the medium through which light
travelled to the dustbin, and left no place for the concept of absolute translational
motion. Thus, all translational motions were relative motions.
● Newton's argument utilised the laboratory-in-space which we have already
encountered, but this time the rocket motors are not in use and the laboratory is
just floating freely in space, well away from any other masses.
PAGE 40
● The scientist fires some attitude-control thrusters to set the whole laboratory
rotating at the same rate and in the same plane as the two masses. The string
joining the masses is now constantly under tension.
● The pre-Copernican view of the Universe had the non-rotating Earth surrounded
by the rotating starry sphere. We now know that the reverse is true, because of
the local effects of rotation.
● If a human colony is established on Mars, and they discover that Martians
existed until about 2,000 years ago, they will discover that the Universe rotates
around a stationary Mars once every 24 hours.
● The Shapiro effect is a time delay for radar signals sent from the Earth to
Mercury or Venus when they are on the far side of the Sun.
PAGE 39
● The gravitational red shift is caused by the slowing of clocks in lower gravitational
potentials, and the Haystack and Arecibo radio telescopes can be used to
observe planets close to the Sun.
● The Shapiro delay is a test of General Relativity that has continued to validate
the theory to this day.
Rotating Frames of Reference
● Einstein consigned the concept of the aether as the medium through which light
travelled to the dustbin, and left no place for the concept of absolute translational
motion. Thus, all translational motions were relative motions.
● Newton's argument utilised the laboratory-in-space which we have already
encountered, but this time the rocket motors are not in use and the laboratory is
just floating freely in space, well away from any other masses.
PAGE 40
● The scientist fires some attitude-control thrusters to set the whole laboratory
rotating at the same rate and in the same plane as the two masses. The string
joining the masses is now constantly under tension.
● The pre-Copernican view of the Universe had the non-rotating Earth surrounded
by the rotating starry sphere. We now know that the reverse is true, because of
the local effects of rotation.
● If a human colony is established on Mars, and they discover that Martians
existed until about 2,000 years ago, they will discover that the Universe rotates
around a stationary Mars once every 24 hours.
