It is quite clear that some people are just giving Abrams a free pass why that is? Beats me but there is NO alternate universe. Spock and Nero changed the time line by going back in time. That is the WHOLE premise of the movie. Again, the VCR tape which has been recording has now been rewound and started to record again, thus erasing everything as it moves forward. References to "time travel" not parallel worlds is mentioned. Nimoy Spock clearly says "129 years from NOW" not "from another universe."
So is there anything you need to know that you clearly don't understand?
So people need to realize that all Trek (except for ENT) has now been erased. The movie clearly tells you this. Spock on the bridge says alternate reality which does NOT mean alternate universe. He merely points out that the events have been altered because of the time travel. It IS that clear. Making up excuses to say that it is not just being in denial.
"Forget all that you know"...Remember this slogan? This was their way of telling the world and the fans that Trek has been ERASED and they are starting everything again.
To quote Denny Crane..."It is just that simple".