I already realized the anti-intuition conclusion that when we do free fall, we do not have any force and is a free moving object, while when we land on the earth, we subject to a feeling of force, equivalent to staying on a rocket moving in an acceleration of g.

According to Newton’s law, object without force will be moving at even speed or stay still. But when we are rid of any force – free falling, that’s the scenario same as in outer space drifting. But we think we are moving fast toward the earth! So the actual truth is that we staying on earth are constantly subject to a force and are accelerating. It’s very mind-twisting. But this video -What is General Relativity-verified the odd conclusion is true.

The experiment that proved the existence of gravitational waves was called the Laser Interferometer Gravitational-Wave Observatory (LIGO). It used a pair of large, L-shaped interferometers to detect the very faint ripples in space-time caused by passing gravitational waves. In September 2015, LIGO detected gravitational waves for the first time, generated by the collision of two black holes about 1.3 billion light-years away. This discovery was announced to the public on February 11, 2016 and was a major breakthrough in the field of physics.

LIGO scientists were able to confirm that the detected gravitational waves were caused by the collision of two black holes by analyzing the “waveform” of the signal. The waveform is a detailed pattern of the gravitational waves that is unique to the specific event that caused them, such as the collision of two black holes. By comparing the LIGO data to numerical simulations of black hole collisions, scientists were able to confirm that the detected signal matched the predicted waveform for such an event. They also looked for other sources of noise and interference, such as earthquakes or human-made vibrations, and found that the signal could not have been caused by these other sources. Additionally, the LIGO detectors were located thousands of miles apart, so any local disturbances would not have caused the same signal at both detectors, and that was not the case. It was a confirmation of the general relativity theory’s prediction about gravitational waves.

There is A new way to visualize General Relativity! If we take two dimensions and leave the third dimension to time, then we can visualize gravity on earth as

As a creature only can perceive three dimensional space, and experience time instant by instant. It’s very hard to take the perspective of genius Einstein’s lens and realize the phenomena of gravity is simple when we can have four-dimensional view.

Quantum Electrodynamics