Time and space bend: The earth's heart is 2 and a half years younger than the surface.

There is an uncognitive side to the Earth: the center of the Earth is two and a half years younger than the Earth's surface, but this has nothing to do with the way the Earth was formed, but rather because of the gravitational effects described in general relativity.
Einstein's general theory of relativity, the rate at which time passes in the gravitational field changes, an effect known as gravitational time expansion.
, the stronger the gravitational force, the slower the passage of time, because gravity bends time and space.
fact, the gravitational time expansion effect has been rigorously tested to have an impact on satellites of navigation and positioning systems.
GPS satellite, which is located about 20,000 kilometers above the Earth's surface, is slightly away from earth's gravitational field, so it will go through a little faster.
In fact, the clocks on these satellites are about 45 microseconds faster than those on the Earth's surface, so scientists have to correct the clocks of satellites to make sure that the GPS data sent back to Earth has a matching time.
Otherwise, the positioning error will accumulate up to 45 microseconds per day x the speed of light x 13.5 km (the actual positioning error also needs to take into account the special relativity - the satellite clock is about 7 microseconds slower than the ground clock), such positioning is equivalent to invalid.
back in the 1960s, physics guru Richard Feynman estimated that the age difference between the earth's heart and the surface was about a day or two -- a number that has been repeated and cited many times in many physicists' papers.
, however, the team, led by physicist Dr. Ulrik Uggerh of Aohus University, realized that the effects of gravitational time expansion should be more pronounced on Earth, and decided to revisit Feynman's claims.
To calculate this age difference, the team first calculated the difference in gravitational potential at the center and surface of the Earth -- measuring the work of gravity when a mass object moves from one position to another.
then, physicists brought this gravitational difference into the equation of general relativity and got a time-expansion factor of about 0.00000000003, which means that the center of the earth is 0.00 million seconds slower per second than on the Earth's surface.
seems to be a very small time difference, but the cumulative effects of time expansion add up to about a year and a half, knowing that the Earth is 4.5 billion years old.
However, this calculation uses an idealized model in which physicists assume that the Earth has a uniform density, but this is not the case, and the density of the core is much greater than the density of the mantle (the core accounts for 16% of the Earth's volume and 31% of the mass).
, physicists used more realistic models of Earth density and found that the age difference between the earth's heart and surface was actually two and a half years.
the gravitational field equation of general relativity, of course, this number cannot be proved by experiments.
, however, general relativity has stood all the tests, so it is probably right.
physicists said it was unclear whether Feynman had initially made a mistake, or whether his lecture had been recorded incorrectly -- misreading the unit from year to year.
, the center of the Earth must be younger than the Earth's surface, because the space-time bends deep in the earth's heart are more intense.
, the team calculated that the center of the sun is about 40,000 years younger than its surface.
these results give the "young heart" a whole new meaning.
source: Weird Rokop.