I will come clean if it helps, DOC. I did know that science says the universe came from something smaller than an atom: and I found this quite interesting but not very exciting. This is because I am not a scientist and I trust those who are to go on researching and learning and disseminating what they learn for the rest of us, at whatever level we would like to know about it. For me that is just about the level called "general knowledge". I cannot follow mathematical arguments and I do not have enough knowledge about physics to read text books. I had trouble when I read A Brief History of Time so maybe I am a lot like you, if you resist reading recommended books because they are too hard for you. I do like to have things outlined for me in this forum because I can ask my daft questions and people are patient in explaining.
I don't ask about things I don't want to know about (well not very often and usually only in social situations where it is polite to do so). I assume this is also true of you, because otherwise you would be wasting other people's time and that would not be polite, IMO.
People here have tried to engage honestly in discussion with you in this thread and in the other one about evolution. I can only conclude that you are not getting the kind of answers you are looking for, therefore.
Since you ask whether most atheists know this, and that has been answered in the affirmative, the second question does not arise, does it? So what is it you now wish to know? Obviously it is not the detail of what is known by scientists, because that has been offered and you have ignored the offer. While reading science books might be hard, if you took up the generous offer made then asked questions where you got lost, I think the people here would be more than willing to help you: so I have found, anyway.
On the basis of your question I am inclined to think you find it hard to accept that people can be aware of the fact you raised at the outset and you are not willing to take the answer "yes" you have been given. Mashuna has very cleverly shown you what to do about that, so if that is the problem you have a strategy. We will all be interested in the results, I imagine.
If you do accept the answer you have been given then perhaps your problem lies elsewhere. Maybe you just find it really difficult to believe that the fact does not cause an atheist any problem. If that is so then, speaking only for myself, I can tell you honestly that I do not find this fact affects my outlook. You asked if atheists do not care about the origin of the universe: well surprising as it may be to you that is exactly where I find myself. I couldn't give a toss, frankly. What science is telling us is interesting but it does not impinge on my life at all and my interests (as in what I really pay attention to) are elsewhere.
I wonder if that is a problem for you. I have seen many people insist that everybody is interested in the "big questions of life" like why we are here and what happens after death. If that is what you believe then I am here for to tell you that it is not universally true. I do not care because I concluded long ago that these things are not knowable. Once I reached that conclusion I never troubled my light-minded little head about it again. I quite like hearing what scientists and theologists are doing about it, but then I quite like reading fiction too. And it has just as much practical importance to me.
Does that help at all ?