Why did Einstein and others assume that the universe had no beginning?
In my opinion, this assumption of Einstein and others is a conjecture.
When there is an event called the beginning of a process, there would be an event called the end of the process.In 1998, scientists of Case Western Reserve University, Cleveland, working on detection of Dark Energy, agreed that the end might be there. In my opinion, the end (apocalypse) is before the next beginning, in a BB - BB cycle, of period > 20 billion years. This period is for one complete 'integration - disintegration process'. As of now, I see no beginning or end, for this vicious circle. .