Discussion Overview
The discussion centers around the behavior of photons emitted from a laser pointer when directed into the sky, particularly regarding their ability to travel through the atmosphere and into space. Participants explore theoretical and practical aspects of light propagation, including interactions with matter and the implications of atmospheric conditions.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
Main Points Raised
- Some participants propose that photons from a laser pointer could theoretically travel indefinitely through space once they escape the atmosphere.
- Others argue that in reality, photons will lose energy through interactions with matter, particularly in the atmosphere, which is dense enough to cause scattering.
- It is suggested that if the photons make it out of the atmosphere, they would encounter very little matter in space, allowing them to travel further.
- One participant mentions that astronauts have observed city lights from space, implying that light can travel significant distances.
- Some participants express certainty that laser light can exit the atmosphere in a coherent form, but acknowledge that even in space, there is some gas that could eventually interact with the light.
- A later reply references the Lunar Laser Ranging Experiment, noting that lasers have been successfully used to measure distances to the moon, which demonstrates the ability of laser light to travel long distances.
- Another participant reiterates the success of the Lunar Laser Ranging Experiment, mentioning the placement of mirrors on the moon by astronauts to facilitate these measurements.
Areas of Agreement / Disagreement
Participants generally agree that photons can escape the atmosphere and travel through space, but there is disagreement regarding the extent to which they will interact with matter and the implications of atmospheric scattering. The discussion remains unresolved regarding the practical limits of laser light travel in space.
Contextual Notes
Participants note the dependence on atmospheric conditions and the presence of gas in space, which may affect the travel of laser light. There are also references to specific experiments that illustrate the concepts discussed, but the details of these experiments are not fully explored.