Why doesn't light get absorbed?

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Discussion Overview

The discussion revolves around the question of why light emitted by the Sun does not get absorbed back into it due to gravitational effects. Participants explore concepts related to gravity, light behavior, and orbital mechanics, touching on theoretical and conceptual aspects of physics.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why light does not fall back into the Sun, suggesting a connection to gravitational effects.
  • Another participant explains that the gravitational pull of the Sun is insufficient to attract photons back, comparing it to a powerful rocket escaping Earth's gravity.
  • There is a clarification that while the Sun can bend light, it cannot capture it, and that a much more massive object, like a black hole, would be needed for that.
  • Participants discuss how the Earth is attracted to the Sun, noting that objects need to be moving slowly or be very close to be captured in orbit, contrasting this with the speed of light.
  • It is emphasized that light travels too quickly to be pulled in by the Sun's gravity.

Areas of Agreement / Disagreement

Participants generally agree on the idea that the speed of light prevents it from being absorbed by the Sun, but there are varying levels of understanding regarding the mechanics of gravity and light interaction.

Contextual Notes

The discussion includes assumptions about gravitational effects and the nature of light that are not fully explored, such as the specifics of spacetime curvature and the conditions under which objects can be captured by gravity.

Gravitonion
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If light can give off gravity, why doesn't the gravity exerted by the sun kind of. Absorb it before it can go off to Earth and other planets?
 
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If you're asking why doesn't the light emitted by the Sun simply fall back into the Sun, it's for the same reason I can build a rocket ship so powerful that it can fly out of the solar system and away from the pull of the Earth. The gravitational pull (or really, the curvature of spacetime) isn't enough to bring a photon back into it. You need something far more massive and compact like a black hole. What the Sun can do is only really bend light passing by slightly.
 
Last edited:
But then how does the sun attract the earth?
 
Gravitonion said:
But then how does the sun attract the earth?

Through the same process. Something needs to be going rather slowly or be very close to an object like the Sun to be caught in an orbit. The Earth is moving very slow compared to something like light.

Light, even if emitted directly off the surface of the Sun, is just going way too fast to be pulled in by the Sun.
 

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