Atmosphere in the cave. What was it for?

Almost exactly as you said. It is there so that humans can breathe in the tunnel complex. It's a very important point actually.

Because they had no clue on what they were writing about. Making up nonsense along the way. I know it is science fiction but let us use some common sense about space, space travel and other worlds. Alien was perfection.

There was not supposed to be an atmosphere in the temple. That is why the Engineers were all in their space suits inside. Why not? Because the canisters are in all in stasis, ie, stable until the ampule room door is opened by David and the atmosphere changes. David and the Prometheus crew bring an Earth-like atmosphere with them when they come inside. The canisters (weapon) were designed to "come alive" when it comes into contact with a human friendly atmosphere. The Engineers were smart enough to build in a fail safe to their weapon. The canisters would only become active when they were in Earth's atmosphere, or one like it. I believe that the human-friendly atmosphere was an accident, a result of the temple sitting idle for 2000 years. Why else would the Engineers all be in their suits?

It was outright stupid to make them take their helmets off in first place (obvious presence of unidentified organic material nearby, high possibility of toxic dust particles floating around, etc), but even this logical inconsistency could have been salvaged and made somewhat logical by making their use of helmets outside to be an issue of atmospheric pressure, temperature or maybe lethal UV radiation on the surface. The problem is that they don't even ask about the atmospheric pressure or temperature inside the cave, nor is there ever any mention of any surface radiation. Heck, they don't even have the patience to double-check the atmospheric data before ripping their helmets off. Scientific accuracy aside, the movie lacks even basic scientific believability!

Exactly, the decisions made throughout the movie were idiotic. The crew acted as though they had been on a million alien expeditions and had some form of insight on [i]this[/i] world and with [i]those[/i] aliens and they didn't! They are explorers and scientist...archeologist and they go into uncharted areas and make discoveries, get their hands dirty with a minimal look at the consequences but you don't do that on an alien terrain. If they went there looking for something, what did they expect to happen if they found it. The setting looked like an ancient alien military base. The aliens seemed primitive in the way Egyptians or Greeks were primitive but with space travel capabilities. They literally had cave drawings aside digital space navigation. Yet, if a group of upright standing dogs started walking around a military base found a soldier in hibernation and awoke him, barking out to him and showing animosity toward one another it would be safe to say those dogs would have to die. There is no way that this situation could have played out differently. Why they thought they were meeting a friendly set of aliens was ridiculous. Would it be that easy to coheres a human being to go on a space ship and tell you all the secrets of life. Above that they can't just pick any alien and say tell us why we are here. Why do you think he would know or was a part of it. If someone asked me the meaning of life and where they came from and they were an alien to this world and just came across me, sorry I would not be able to answer....how the hell would I know. The only thing that is difficult to me is that the aliens laugh in the face of death, they didn't seem to have the fear. That is why when the black goo really did serious harm to the alien in the opening scene he was literally shocked which probably prompted the aliens who didn't know what happened to figure out why and they put their all into it creating a earth atmosphere and recreating the goo, just trying to figure out what happened and why. They then decided to go back and recover from their loss or do something about it. I don't get the feeling it was simply about the aliens wanting to kill humans, it was something bigger than that but that is unanswered. My main concern was why the DNA matched perfectly but yet we looked different from the aliens? Why did David say he knew there was nothing, how did he know? Where are Elizabeth and David going and what exactly is she planning on doing when she gets there? Her ambitions are like saying she is an alien and is going to a president or king demanding answers. Why would they not just discard you or run test on you. It is not realistic to think you will find answers by going to a planet where you are the alien and expect them to bow to their knees and offer up all their secrets.

Colonial Soldier, stop hating on the film and THINK. You may not like the film, even if you get it, but don't just start and end at "I don't like it" The whole POINT of that scene was to show that humans can breathe there. We ASSUME that means that the Space Jockeys need the same atmosphere. But they don't. Scene 1... Space Jockey in primordial atmosphere. Very unlikely to have more than 1% oxygen (on Earth the primordial atmosphere contained less than 1% oxygen, and had lots of ammonia and methane) Scene where he is chasing Shaw.... if he needed an earth like atmosphere... He'd be dead. CO at 3% ... remember. Dr. Forde said it was fatal in two minutes. What she forgot to say is you lose consciousness in SECONDS, and die in minutes. This guy looks fit to run a marathon. And by the way, does he actually hurt Shaw? You might want to re-evalute your thinking on this whole film. It's worth watching again, and this time, do not put ANY trust in the theories put out by any of the characters. Work it out for yourself. Shaw is a highly educated well meaning fool.

@ N Diezl, I thought this too at first but remember the last engineer is w/o a chair suit and is breathing air in the star map room along with the humans breathing the air....

dup post sorry