Why is gravity a fictitious force?

[Dale]

As Einstein said, it is theory which determines what is measurable.

Where did Einstein say this? Since many things were measured prior to the development of the corresponding theory, that seems like a pretty difficult claim to justify. Even if Einstein did say it.

According to the Newtonian theory of gravity, the gravitational force can be measured.

How?

 

[Demystifier]

How?

E.g. by weighing scale.

 

[Dale]

E.g. by weighing scale.

That doesn’t measure the gravitational force, even in Newtonian physics. In the ISS the Newtonian gravitational force is almost the same as it is on the ground, but a weighing scale reads 0.

In Newtonian theory there is no way to measure the gravitational force. All you can do is infer it from the motion. Just like a fictitious force.