My question is fairly simple: is there light inside a bag of holding? I'm asking this because I'm trying to do a passive run and I plan on storing unconscious enemies in the bag.
I know that living creatures suffocate after 10 minutes depending on how many there are, but my plan is this: if I can grow algae, (a few kilograms per person including water) then the algae should be able to filter out CO2 and other toxins while adding oxygen to the air. This whole plan hinges on the fact that there is light (preferably sunlight) so that the algae can perform photosynthesis and stay alive.
I don't know that much but from what I've heard the bag links to a separate dimension and I wasn't sure if this dimension has light or not. I tried really hard to find out the answer before asking but I couldn't find anyone else mentioning this very specific question.
Best Answer
Light or not in the bag is not explicitly stated in any rules. With the bag otherwise behaving a lot like a normal bag, I would assume not. You could just put something glowing brightly into the bag though, if you have something appropriate (IMO would need to be bright as daylight).
It is risky to apply too much scientific analysis to items in a fantasy game. Many things in D&D do not make sense if you think about them too hard. It is best to remember that the air being breathed is fantasy air, and any plants you have are fantasy plants. Although fantasy plants no doubt grow in the sunshine, and creatures can suffocate without fresh air, there is no need to invoke scientific understanding of these things such as photosynthesis and oxygen.
One thing to do is present your plan to the DM and hope that they will go along with it. Sometimes a few nods to science and clever plans are all good for a game. Just don't get too bogged down in it. Also accept that between the whole group, your ideas probably won't be too accurate, or you will miss an important detail. For instance, do you know how much algae would sustain a person (assuming bright sunlight), and do you care to research it? (I think around 6 litres of algae-rich water is right from a quick search). How would your character know this?
Better still, find a game item that does what you want mechanically more directly.