According to John of Patmos, these are the words of God himself.
Alpha is the first letter of the Greek alphabet and Omega is the last.
Now we are going to discuss nothing less than the beginning and ending of the universe. Cosmology is a huge and wonderful subject, and we can only touch on some of the high points here. There are also several excellent books on the subject. There are many good web sites on cosmology. I list the best ones I could find here, starting with relatively simple ones and proceeding to higher level.