There HAS to be an experiment that PROVES the earth is a sphere.
I haven't been able to find em.
How can we have air pressure without a container?
I have an experiment for the first. Start 2 people at the equator 1000 km apart. When they reach the north pole, measure the distance between them.
For the second: how does an air bubble travel through water? As a sphere, as this is the most efficient shape. The pressure is contained within by the pressure from the water. Same as a soap bubble in air. One could compare the Earths atmosphere to a bubble. This is the container. A bubble in water. Now, could the bubbles temperature inside differ the that outside? Yes. Will it eventually equalize? Yes. However, this is due to the low matter within. Add substance inside the bubble that can be radiantly warmed. The outside would not be heated, but the matter within would.
Then there is geodesics. Consider an aeroplane. The most efficient method of travel from point A to point B is a straight line. However, when this straight line of travel is transposed upon a sphere, it is not straight at all. It is geodesic. This is the explanation for the proposed experiment. If the Earth is flat, the two individuals will never meet. If the Earth is a sphere, they with converge at the apex.
Now, if we want to get into gravity, then gravity is technically not a force from an inertial frame of reference. To go full Einstein, one should really consider space-time. For a second, let us mutually agree that the Internation Space Station is in space (for this thought experiment). To them, an inertial observer, they are traveling in a straight line orbiting Earth. Now, include time. The Earth, if it is moving through space at x speed, would cause the actual path of the ISS to be a helix and not a circular orbit. This is a rudimentary explanation of General Relativity (as I understand it, anyway), which considers gravity as no force at all, but that massive objects curve space-time. "Matter tells spacetime how to curve and space-time tells matter how to move"- John Wheeler
Since I am rambling, I may as well keep going. Consider this (as another thought experiment): an inertial observer, such as a person that unfortunately stepped off a building. They are an inertial observer as they are considered weightless. To see a person on the ground, the ground is moving upwards. You, the inertial observer have no acceleration. It is the Earth's rotation through space and time that is moving....at 9.81 seconds/metre squared....upwards.
Another way: Inside an aeroplane, everything relative to you is stationary, but to an observer on the ground, the aeroplane and its contents are accelerating. This is the difference in observations.
Now, there is the whole question of "if the Earth is moving up and everything in the Earth is moving up, then why is the Earth not expanding?" since up in a sphere it outward and outward is expansion....well, General Relativity has put forth an equation that (simply) states one needs to accelerate in curved space-time, just to stay still. LoL.
Consider why 2 objects of differing mass descend to the ground at the same speed.
Well, Fg= GMm/r2 = ma and a=GM/r2, but why can m=m ? m being gravitational mass =
inertial mass. Two fundamentally differing properties. Simply put: they are the same. So, the 2 dropped objects are not accelerating, they are following a "straight line" trajectory until something (the ground) stops them as it is the Earth that is accelerating through space-time.
....I think I rambled on quite enough and did not do Einstein justice, but regardless. Let's meet at the equator and go for a walk. You owe me a beer if we meet at the top. Cheers.
