[geordief (OP)]

I have heard(and wondered)  as much. Can anyone put any flesh on the bone?

If the sum total (at the "outset" or at least some starting point presumably) is/was different from zero  could that be assessed in any way ?

What consequences might follow?

Could it have any bearing on any possible size to the entire (ie not just directly observable) universe?

Or on the rate of expansion?

Is it possible that the sum total of energy at the/an "outset" could have been  actually zero?

[Halc]

If the sum total (at the "outset" or at least some starting point presumably) is/was different from zero  could that be assessed in any way ?

It has not been accurately measured, but estimates are such that zero is a very likely possibility.

What consequences might follow?

It seems to prevent a violation of conservation of energy while other nonzero values need to explain their nonzero values.

Could it have any bearing on any possible size to the entire (ie not just directly observable) universe?

Seems not.  If the energy density for any given large section is zero, making the universe larger will not change it.  Just more zeros.

Or on the rate of expansion?

The expansion rate seems tuned to form complex structures such as observers.  It seems unrelated to the zero energy thing since universes with different expansion rates would still have zero energy, but would collapse quickly into itself or expand almost immediately into haze with little interaction.  Neither of those scenarios would support observers, so those conditions are not what is expected to be observed.

Is it possible that the sum total of energy at the/an "outset" could have been  actually zero?

I think the question is if a nonzero value makes any kind of sense.

[geordief (OP)]

Is it possible that the sum total of energy at the/an "outset" could have been  actually zero?
I think the question is if a nonzero value makes any kind of sense.

I suppose so.

 Could  there be any possible relationship between the  extremely asymmetric matter/antimatter split which has been observed  and any possible non zero sum total of energy?

[Halc]

Could  there be any possible relationship between the  extremely asymmetric matter/antimatter split which has been observed  and any possible non zero sum total of energy?

Hard to see how.  Antimatter is still positive energy.  If I had a kg of antimatter, I could generate a helluva lot of electricity from it, assuming I could find a jar to put it in.

[evan_au]

Is there a zero sum energy theory of the universe?

Not yet, but cosmologists are trying to find some fundamental reason why it has the value it has (which may be zero).

Just like they are trying to find some fundamental reason for the value of other fundamental constants in our universe, like:
- The relative strength of the 4 forces we know: gravity, electric forces, weak and strong nuclear forces.
- The ratio of matter & antimatter
- The ratio of matter & Dark Matter
- Why cosmological inflation should come in waves
- etc

This search is for an ultimate theory nicknamed the "Theory of Everything" (TOE).

See: https://en.wikipedia.org/wiki/Theory_of_everything

[jeffreyH]

If the universe did not have an origin and was always there then at some point in the past entropy would have changed from a negative to a positive value. Meaning that entropy started with a value of negative infinity. This is an untenable position.

[geordief (OP)]

If the universe did not have an origin and was always there then at some point in the past entropy would have changed from a negative to a positive value. Meaning that entropy started with a value of negative infinity. This is an untenable position.

I wish I understood that (not meaning that  I dispute it;just that entropy is difficult for me to understand despite my various attempts).

If you are right  that would seem to be a very interesting finding (I have of late been predisposed to the "beginning" of the universe being infinitely long  and so would welcome this being shown to being erroneous)

[yor_on]

Sure there is. It's about 'negative energy' taking out 'positive energy' leaving a 'net sum' of zero.