What causes weightlessness in a free fall?

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SUMMARY

The discussion centers on the concept of weightlessness during free fall, highlighting Einstein's realization that a person in free fall experiences no weight due to the cancellation of forces. While Newtonian physics acknowledges gravity as the sole force acting on a free-falling object, it does not account for the sensation of weightlessness. In contrast, general relativity posits that gravitation is not a force, and thus, an object in free fall is indeed weightless. This distinction is crucial for understanding the principles of general relativity.

PREREQUISITES
  • Understanding of Newtonian physics and gravitational forces
  • Familiarity with Einstein's theories of special and general relativity
  • Knowledge of the concept of free fall and its implications
  • Basic comprehension of force and acceleration in physics
NEXT STEPS
  • Study Einstein's general relativity and its implications on gravity
  • Explore the differences between Newtonian physics and general relativity
  • Investigate the concept of weightlessness in various gravitational contexts
  • Learn about the mathematical formulations of free fall in both Newtonian and relativistic frameworks
USEFUL FOR

Students of physics, educators teaching gravitational concepts, and anyone interested in the principles of relativity and the nature of weightlessness in free fall.

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Einstein said one his happiest realizations was that a person in free fall would feel no weight. Unless I am mistaken he said this. But didn't Newton realize this?
 
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I don't think Newton did realize this. Einstein was given a huge hint by a guy fell 60ft and lived to tell the tale. He is reported to have said he felt 'weightless' whilst falling.
 
It depends on the definition of 'weight', 'weightless', and 'felt'.
 
You wouldn't actually be weightless in a freefall, but you would feel like it because the forces are canceled out.

Einstein did realize that an observer accelerating due to a rocket or other force is analogous to an observer accelerating due to gravity: http://www.astronomynotes.com/relativity/s3.htm he used this to formulate general relativity from special relativity
 
Viracocha said:
You wouldn't actually be weightless in a freefall, but you would feel like it because the forces are canceled out.
What forces are canceled out? In Newtonian physics there is no cancelation of forces for an object in free fall. There is only one force acting on such an object, and that force is gravity.

There is no cancelation of forces in general relativity, either. There is no force acting on an object in free fall in general relativity. Gravitation is not a force in general relativity. There is no local experiment that can distinguish free fall conditions from force-free conditions far removed from any gravitational source. The two situations are identical as far as general relativity is concerned.

Bottom line: You actually are weightless in a free fall in general relativity.
 

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