A Question to the Physics Community as a whole

When scientists say that the universe can simply come out of nothing without any divine intervention, they think of the universe in terms of its energy content only. In the book ‘The Grand Design’, page 281, scientist Stephen Hawking has written that bodies like stars or black holes cannot just appear out of nothing, but a whole universe can. The message is very clear from this: The total energy of a whole universe is zero and that is why it can come out of nothing; but stars or black holes will fail to do so, because their total energy is not zero. But universe means not only its energy, universe means its space-time as well. So if we now apply the same logic to space-time as well, then we can say that the total space-time of a whole universe must also always have to be zero, because in that case only a whole universe can appear out of nothing. Here my question is: How does the total space-time of an ever-expanding universe always remain zero?
As the universe appeared out of nothing, so initially there was no space, no time, no matter and no energy. Scientists have successfully shown how the total matter-energy content of the universe has always remained zero. But we are not satisfied with that explanation, we want something more. We also want to know how the total space-time content of the universe has always remained zero. And it should always remain zero if the universe has actually appeared out of nothing. Otherwise scientists will have to explain as to whence appeared the extra residual space-time that was not already there at the beginning.
If stars or black holes cannot appear out of nothing simply because their total energy is not zero, then can a whole universe appear out of nothing if its total space-time is not zero?
The last question here will further boil down to this one: Do the physicists think that energy cannot just appear out of nothing, but space-time can, supposing that the total space-time of the present universe is not zero?
Or, do they think that like life, mind and consciousness, space and time are also emergent only, and therefore, not directly coming from big bang nothing?