Here’s my question explained with a little more detail….
Room #1: Blackout curtains/blinds/shades have been drawn for one day. No sunlight whatsoever has entered the room that entire day.
Room #2: All curtains/blinds/shades have been kept open the entire time. However, the blackout curtains/blinds/shades have now been drawn, at the end of the day.
A scientist enters each now-darkened room. Can the scientist accurately detect or measure which room was the “sunnier” room during that day?
Putting aside long-term sun bleaching, which I understand can lighten fabrics when they are exposed to sunlight over a long period of time, my question is whether the photons of sunlight from a single day could be detectable, objectively, at the end of that day. Does sunlight “change” anything that can be measured, after the light is gone?
In: Physics
> Putting aside long-term sun bleaching
Why should we? We know that over long periods of time substances can be changed by exposure to sunlight. Therefore we should expect that even short term exposure does change the materials to some degree as the long term impacts are simply the accumulation of the shorter term effects.
It should then be possible to determine which room has been exposed to more sunlight overall. It may also be possible to determine if the sunlight exposure was recent by considering other chemical reactions which may release volatile chemicals which would break down over time.
Surfaces in the sunlit room will have a higher temperature that will take some time to reach equilibrium with the darkened room again.
Yes.
Some of the photons were absorbed by the things in the room. Those absorbed photons have raised the temperature of the things they interacted with, so the warmer room is the one that you filled with sunlight for a while.
I think the only thing that would be measurable would be the residual energy. A black wall would absorb the sunlight throughout the day, and then slowly emit that back through the night. So someone could come in and measure like the temperature of the room, or the infrared radiation being emitted from the walls
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