The phrase "first microseconds" refers to a very short period of time, specifically the initial millionth part of a second.
Sentences with «first microseconds»
To sum up in lay terminology, after the first microseconds of the big bang, there was an amorphous energy field. (religion.blogs.cnn.com)
The best current astrophysics understanding of the first microseconds of the big bang event agree completely with the Genesis account. (religion.blogs.cnn.com)
As I understand it, Alan Guth's work, and that of others exploring the first microseconds of what people of biblical faith know as Creation, builds on Lemaître's insights. (firstthings.com)