General relativity

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General relativity is a theory of gravity developed by Albert Einstein. It describes how massive objects like planets and stars influence the curvature of spacetime around them, causing other objects to move along curved paths. This curvature of spacetime is what we perceive as gravity.

Key concepts include:

1. Spacetime: General relativity combines space and time into a single entity called spacetime. Objects with mass or energy warp spacetime, affecting the motion of other objects.

2. Gravity as Curvature: Instead of a force, gravity is seen as the curvature of spacetime. Objects move along the straightest paths ... in this curved spacetime.

 

3. Equivalence Principle: This principle states that there's no difference between a gravitational force and an accelerated frame of reference. It's the basis for understanding how gravity affects light and time.

4. Gravitational Time Dilation: Clocks near massive objects tick more slowly due to the curvature of spacetime, creating a time dilation effect.

5. Bending of Light: Massive objects can bend the path of light as it passes by them, a phenomenon known as gravitational lensing.

6. Black Holes: These are regions where gravity is so intense that nothing, not even light, can escape their gravitational pull. They form when massive stars collapse under their own gravity.

7. Curvature and Energy-Momentum: The presence of mass and energy determines the curvature of spacetime. Einstein's field equations relate the curvature to the distribution of mass and energy.

 

People also ask

What is (sic) Einstein's equations that relates (sic) mass and energy?

E = mc2. It's the world's most famous equation, but what does it really mean? "Energy equals mass times the speed of light squared." On the most basic level, the equation says that energy and mass (matter) are interchangeable; they are different forms of the same thing.

8. Frame Dragging: Rotating masses can drag nearby spacetime along with them, a phenomenon known as frame dragging. More from same source:

 People also ask

What does frame-dragging do?

This predicted effect was called “frame- dragging” to illustrate how a rotating planet will “drag” the local frame of reference* around it. This “twisting” would alter measurements of distance, time, and direction in local spacetime. One way to visualize this effect is to place a small ball in a bowl of honey.

* Not on the page referred to.

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