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by smallnix 906 days ago
How can visible light pass from a core of a star or planet to the outside, but some routers light not? I guess it's just super duper faint?
3 comments

Visible light does not pass from the core of a star to the outside.

The sun has a radius of about 700,000 km. Only a few hundred km is transparent enough for light to pass through and has a density of about 300 mg per cubic meter. Roughly the density of air at the altitude where airliners cruise.

The photons you see originate from a layer that’s just 0.5% of the radius of the sun. That layer is heated with other photons from inside. The core temp is 15 million K while the photosphere is around 5800 K. The spectrum of the core were the rest of the sun transparent would be much different and … unsafe. (Not that this really makes sense, if the rest of the star was transparent it would go nova)

Using light to heat up the walls of a home enough to start emitting significant black body radiation poses some additional engineering challenges.
The house's thermal mass would also limit the data rate.
I think that yes, compared to the core of a star, a LiFi AP is aptly described as "super duper faint".