The Wikipedia page on gravitational time dilation (https://en.wikipedia.org/wiki/Gravitational_time_dilation) states:
"Relative to Earth's age in billions of years, Earth's core is effectively 2.5 years younger than its surface."
A clock subjected to less acceleration (gravitational or...
Isn't Alpha Centauri 4.37 light-years from Earth? I don't see any "trick," unless you meant to ask how far Alpha Centauri is from the ship. An observer on the ship will measure a contracted distance, correct?