Reading a book in the infrared

[Deep_Spacing]

If you walked into a cave that led several stories underground, completely cut off by light, would you be able to read a standard textbook you'd carried with you using a set of infrared goggles? Along with a spectrometer? After several days? My guesses are no, in all cases, unless the ink print contained something metallic; in which case you might be able to, until it had cooled to the same stable temperature of the pages.

This is a long-standing argument with friends, when as kids we were playing D&D with an Elf who came across a tome in a pitch-black dungeon. :)

 

[torquil]

Maybe the ink would reflect the infrared body-heat radiation differently from the rest of the page?

Btw, for different types of objects that are in thermal equilibrium, isn't the thermal radiation spectrum still different from material to material?

Torquil

 

[Jim1138]

Light amplification goggles typically use wavelengths 900 nm and shorter. There is little emission from "room temperature" objects at these wavelengths. Without a light source such as an infrared LED (which are available on some light amplification devices), you would not see anything. You would need a thermal imager and the ink would need to have a different emissivity than the paper. You might want to warm up the paper maybe by holding your hand on it for better viewing.

 

[Deep_Spacing]

Thanks - good points.

 

[PJC01]

I would say that it is highly unlikely that you would be able to read a standard textbook using infrared goggles and a spectrometer in a completely dark cave after several days. Infrared light is a form of electromagnetic radiation that is emitted by objects with a temperature above absolute zero. In a dark cave several stories underground, there would likely be no sources of infrared light, so the goggles would not be able to detect any useful information.

Additionally, even if there were some small sources of infrared light, they would not be enough to provide sufficient illumination for reading a book. The spectrometer would also not be helpful in this scenario, as it is used for analyzing the properties of light, not for enhancing visibility.

In terms of the ink print containing something metallic, it is possible that this could reflect some infrared light and make the text slightly visible. However, as you mentioned, this effect would likely only last until the ink and pages reached the same stable temperature, and it would not be enough to read comfortably for an extended period of time.

In conclusion, while it may make for an interesting thought experiment, the reality is that reading a standard textbook in a completely dark cave using infrared goggles and a spectrometer is not a feasible option.