As long as my food lasts. Almost none of my social drive is satisfied face-to-face.
Take away the internet and it depends on whether I have other stimulation. If not, then not long. I haven't tried going without all contact (well, I have tried, but I don't live alone, and my family doesn't seem to be able to do without me for very long no matter how much I wish they would), but I've gone without all meaningful and positive contact for days on end, which doesn't bother me at all, so I don't see why not being annoyed by certain people's mere presence should make me any happier.
I estimate that if I had stimulation of some sort (anything interesting is fine, but it always needs to be varied because my attention span is finite), and if my physical needs were met (not likely), and if I had my Bible, I could go indefinitely. I would definitely miss my friends after a couple of weeks, but in my experience, missing my friends is the same kind of thing as wanting to play a videogame I haven't played in a while or reread an old book I liked as a child.
The only exception to this is that if anything bad happened, I would want to talk to my best friend about it. We don't really share the good times with each other. Our pictures of success and happiness are very different. But our failures, our setbacks, our losses are similar. We're there for each other, and although I can get through anything without help from another human being (God is a different matter), I wouldn't necessarily want to.
But what would there be to get upset about anyway? No school (requires contact with teachers), no fights with anyone... there's PMS, illness, boredom and something getting broken. The first goes away on its own, the second is too vague a category to make blanket statements about, the third invalidates the experiment (if I have no stimulation, I will seek it, and people are a form of stimulation) and the fourth... well, yecch. I hate it when things break.
In sum, I could go indefinitely without people, almost without missing them at all if I had internet, but I like to have a small amount of interaction in my life. It's like chocolate. A lot is bad and will make you sick. And it comes in different varieties, some of which are better than others. And just the right amount will greatly enrich your life.
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I'm using a non-verbal right now. I wish you could see it. --dyingofpoetry
NOT A DOCTOR