I have been thinking about jet packs a lot these days. This may be because it's been a hot, boring summer and I have time on my hands and lots of empty space in my brain once I finished rereading Harry Potter prior to seeing the final movie. In any event, Harry Potter can fly on a broomstick or thestral or hippogriff. He might choose to Apparate/Disapparate, take a Portkey or use the Floo Network. Evidently certain really advanced wizards can also fly without broomsticks.
All this has made me pretty envious in a wistful, slacker sort of way. Thus the problem of jet packs. Are they supposed to be the broomsticks of our time or something else? In any event, we don't have them yet.
If we did have them--my spouse and I were discussing this today--there might be insurmountable problems:
1) How far could you go before having to come back and refuel?
2) Could you achieve airplane-like speed and height? Probably not unless you were wearing a spacesuit and what would be the fun of that?
3) What about the traffic problems? If you and your neighbors all had jet packs, it could make flying as time consuming as driving in some places. Could you cut across some open space to make time, only to bump into someone headed in the opposite direction? In other words, how regulated would jet pack travel have to be?
4) What would be the aim? Would you want to be able to travel at low heights (above the average suburban treeline, say) just to get around without a car or bike?
5) Would you want to be able to use your jet pack to lift you to say, a mountain top without having had to climb it? Some would say what's the fun of that--but what if you were on a rescue mission? I think jet packs would be great for rescue missions in the mountains. But you'd have to carry oxygen, supplies and more oxygen for whoever you are rescuing.
Back to the drawing board...