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Pjpic
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Can there be an area without gravity? Are branes the only places with gravity?
It depends on what you mean by "gravity". People usually think of "gravity" in GR in terms of the Riemann tensor, the connection coefficients, or the metric. (Maybe more, that is what first comes to mind). You could have a region where the Riemann tensor was zero or the connection components ##\Gamma^{ij}_k## were all zero. There isn't any way I can think of to have no metric, or a zero metric, though you could have a flat metric. Test particles in any such region would move in straight lines. Sorry to be so technical, but I am not sure I understand the point of the question. Branes are not part of GR, I am not sure of how to relate them to your question.Pjpic said:Can there be an area without gravity? Are branes the only places with gravity?
Does that mean if space is not curved there is no gravity?pervect said:It depends on what you mean by "gravity". People usually think of "gravity" in GR in terms of the Riemann tensor, the connection coefficients, or the metric. (Maybe more, that is what first comes to mind). You could have a region where the Riemann tensor was zero or the connection components ##\Gamma^{ij}_k## were all zero. There isn't any way I can think of to have no metric, or a zero metric, though you could have a flat metric. Test particles in any such region would move in straight lines. Sorry to be so technical, but I am not sure I understand the point of the question. Branes are not part of GR, I am not sure of how to relate them to your question.
Pjpic said:Does that mean if space is not curved there is no gravity?
Pjpic said:Does that mean if space is not curved there is no gravity?
William Donald said:with space-time expansion and such; you might not ever even fall into the star.
Gravity is a natural phenomenon by which all objects with mass are brought towards one another. It is the force that keeps planets in orbit around the sun and the moon in orbit around the Earth. Gravity is a result of the curvature of space and time caused by the presence of mass and energy.
No, there cannot be an area with absolutely no gravity. Gravity is a fundamental force of nature and is present everywhere in the universe. However, the strength of gravity can vary depending on the mass and distance between objects.
No, there is no place on Earth with zero gravity. Even in outer space, where astronauts experience weightlessness, there is still some level of gravity present. This is because Earth's gravity extends far beyond its surface and affects objects in orbit around it.
Astronauts float in space because they are in a state of free-fall. This means that they are falling towards Earth due to the force of gravity, but their horizontal velocity is fast enough to keep them in orbit around the planet. This creates the illusion of weightlessness.
Yes, there are planets and locations with significantly lower or higher gravity than Earth. For example, the planet Jupiter has a much stronger gravitational pull than Earth, while the moon has a weaker gravity. Additionally, different regions on Earth, such as mountains or valleys, may have slightly different levels of gravity due to variations in the planet's mass distribution.