cargo containment

If it was a 'containment beam' it didn't do much of a job of containment! We know that it "reacts when broken" from what Kane says, and the sound that it apparently makes. For me, the most likely explanation is that it notifies the eggs that something is on its way. There are, of course, many other possibilities.

Perhaps this beam or sheet of light had; for its most important function, the purpose of preserving the eggs.

I believe it to be a form of stasis for the eggs, an incubation if u will. And it seems that it wakes the egg closest to where the stasis was broken. That's the only thing that really makes sense to me anyways

@ZZplural and aircraftfixer I think you're both right. Breaking the field is like a fly stepping on a web, it alerts the eggs to the presence of potential hosts. It might also be like a mini ozone layer that houses the conditions needed for the eggs to survive. Did the queen lay them? We have to assume she did based on existing canon however the Alien Directors Cut has challenged that somewhat by introducing the possibility that humans can be cocooned by Xeno's and turned into eggs in the absence of a queen. I get the feeling that Prometheus and it's sequels (please let there be sequels) will touch upon the idea of playing god and the unnatural results it produces. Maybe the Xeno depicted on the murial was an ancient, highly intelligent race that became extinct....the Engineers dedicated their existence to recreating them and found that mixing the DNA of various lifeforms, including humans, across the galaxy will lead to their ressurection. However, in typical fashion, the results were....unexpected. Sometimes......dead is better :)

My 2 Cents: Agree with all of the above: blue mist field shields, protects and alerts the eggs when something has broken the field, which means the eggs are being "stored" or in a cryogenic sleep, if you will (they sure use that a LOT in these films). To me, this unequivically means the queen -- if there is one aboard -- is NOT the one tending to the eggs (NB: in no other Alien film are its eggs kept neat & tidy, in columns the Romans would envy -- but we've now seen black goo canisters kept in such a fashion, sans the blue mist, by Engineers). While Carter Burke alludes in Aliens to "something we haven't seen yet" as the manufacturer of the eggs, I submit that the queen arrives after (or from, if you prefer) the terraformers sent to LV-426 by Weyland Industries after Ripley begins drifting in space for 57 years. You'll recall Burke himself sent the colonizers out into the black of night to see if Ripley's story checked out -- for selfish/greedy reasons, of course. And let's not forget that the queen is later discovered in/around the colony's nuclear reactor so it can enjoy the heat.

Now that is a fair question. I wondered what was it doing there, other than aesthetics.

Moving this one to Alien Discussions :-)

Any life form would require some type of controlled environment to sustain it through a long period of time, thus the use of the barrier layer was both a means to preserve and alert. The barrier was designed and installed by the Engineers and not the aliens, so the use of this barrier would be to alert them to an intrusion into the cargo hold, and not to alert and trigger the eggs themselves and to preserve the cargo during the long voyage that would incur. "Deadly is the unknown, for footsteps into the darkness echo thy coming."

Unless you're the REAL Jonesy (which would make you over 200 years old in "dog years," let alone a miracle cat who can write in English) I'm not sure how you write with the authority you do (not that I disagree with what you write). After looking closer at some photos of the Engineers' ship, it is clear to me that the eggs are indeed INSIDE the ship and the bridge of the craft is at center/top. Keeping scale in mind, I'd say there's MORE than enough room in the center of the ship to be the cavernous cargo hold. I agree that the Engineers stored and are caring for the eggs via the blue mist shield. HOWEVER, I recently watched Alien again and the eggs do "come to life" after Kane breaks the shield (they begin "sweating" and the sweat does move upward). So they may indeed warn Engineers, but they also alert the eggs that impregnatable prey is nearby. So, we are asked (at this point) to choose between the eggs being a product of the Deacon and subsequently ending up on LV-426 after happenings in Prometheus or the eggs being in existance since long, long ago. The "fossilization," as Dallas described it, of the SJ seems to point to the latter, which means the Deacon, thus far, may not play a further role whatsoever in this saga.