Our past, which is rendered non - existent, imho, reaches only to the Big Beginning #4. Even you go beyond that past, into that past, or passed time, (one of my favoured pasttimes), you are in the Pre- Big Bang time, which is a realm of matter-less energy. The subject of this thread. Un - created energy , because un created energy has always existed.
Going into the past, the life time of the Universe is ok, catching the photons that are still on the way. but
going past eternal energy could end you in theology, often a deadly subject, often no intelligent discussion there.
Chronology, & the discussion of energy , beats Theology.