ok, this is gonna sound lame since I dont know some of this stuff... does sperm immediately die when its exposed to air? also, is there a time of the month in the female cycle that my girlfriend and i could have "safe" or "almost 100% safe" sex, unprotected?
No, it does not immediately die. If this becomes an argued topic I'd be happy to do a little research and prove the point, but from my past research, as long as the fluid (semen) is wet, the sperm can live. And there is a time during her cycle that she's virtually guaranteed safety. Sadly, there is no way that you or she can know exactly when that is. Women ovulate at different time, meaning I may ovulate ten days after the first day of my menstrual cycle, another woman may ovulate 14. That is why it's a myth that a woman cannot get pregnant during her cycle; some women ovulate nearing the end of their cycle. There's just not a way to concretely know when she ovulates. Utilizing an ovulation kit in an experimental way, keeping a log, can give you/her clues, but it is still not something one would bet safety from pregnancy based on. If you don't want to become parents, don't have sex without protection, even once..... testing fate is NOT wise!
nope, it doesn't die. a vagina isn't a vacuum, there is air in it : ) And don't have sex unprotected, she could get pregnant at all times of the month. In theory there are days where she won't get pregnant, but in practice it's silly to rely on unless you're not that bothered about getting her pregnant. Edit: hehe, melicious : ) posting on the same posts with the same answers!
About the sperm dying, it doesn't just DIE once it hits air. I'm pretty sure that sperm can live upwards of 6 hours outside of the human body as long as it's in a moist environment.