The Free Lunch and the Fence

The real-world notes behind the section Where the Energy Comes From on the Noögenic Protouniverse entry. The Archive speaks in its own voice there and names nobody from our century; the names are here.

The question arrived plainly: does a universe grown from a seed mind break the conservation of energy somewhere, or is there an abundant source? It is the right question to ask of any setting that makes new universes, because the cheap answer is a hidden reservoir, and a hidden reservoir is exactly the kind of free energy this record refuses. The better answer is that our own cosmology already has no difficulty here, and the record only has to borrow it honestly.

Energy is conserved because the laws do not change with time. Emmy Noether proved in 1918, in Invariante Variationsprobleme, that every continuous symmetry of a physical system carries a conserved quantity with it. Symmetry under shifts in position gives conservation of momentum. Symmetry under shifts in time gives conservation of energy. The consequence people usually miss is the converse: where the symmetry fails, the guarantee goes with it. An expanding universe is not the same from one moment to the next across its whole extent, so general relativity keeps energy conservation locally, in every small region, and offers no global total that must stay fixed.

Our own universe shows it twice over. Light crossing expanding space is stretched to longer wavelengths and carries less energy when it arrives; nothing collected the difference. And the energy that drives the expansion behaves the other way. In 1998 and 1999 two teams, the High-Z Supernova Search Team led by Brian Schmidt with Adam Riess, and the Supernova Cosmology Project led by Saul Perlmutter, found that the expansion is accelerating; the three shared the 2011 Nobel Prize in Physics for it. The simplest account of the acceleration is the cosmological constant, the term Albert Einstein introduced in 1917: an energy whose density stays the same as space grows. The volume grows, the density holds, and so the total grows. Nothing is being violated. It is what "conserved locally, not globally" means.

A universe can sum to zero. In 1973 Edward Tryon asked, in a short paper in Nature, whether the universe might be a vacuum fluctuation, and argued that its total energy might be zero: the positive energy of its matter balanced by the negative energy of its gravity. Alan Guth's inflationary theory, published in 1981, gave the idea a mechanism. A small region of high-energy vacuum expands exponentially, and the positive energy of the growing vacuum is matched by the negative energy of the gravitational field, so the region can grow enormously at no net cost. Guth has put it in a line that has outlived most of the papers: the universe is the ultimate free lunch, since it requires no energy to produce. Stephen Hawking quoted it in A Brief History of Time in 1988.

A caution, because the Journal's rule is that a loosely true claim is a misunderstanding waiting to happen: zero total energy depends on how the energy of gravity is counted, and general relativity has no single agreed way to count it for a whole universe. The statement is exact inside the models that make it, and a physicist will add that qualification. So does this page.

A new universe can grow in a spacetime of its own. In 1987 Steven Blau, Eduardo Guendelman and Alan Guth worked out what a bubble of false vacuum would do inside an ordinary universe. Under the right conditions it inflates, but not into its surroundings. It grows in a spacetime that pinches off from its parent, and from outside all that is left is something that looks like a small black hole, which then evaporates. The child's expansion happens in the child. The same year, Edward Farhi and Guth asked whether such a universe could be made deliberately, and found an obstacle: in their analysis the process required an initial singularity, which no laboratory can supply. In 1990 Farhi, Guth and Jemal Guven asked whether quantum tunnelling might get around it, and found that it might, with a probability nobody knows how to compute with confidence.

What the record takes from this, and what it takes as a licence. The section on the Noögenic Protouniverse uses all three steps and adds a fence. The seed carries structure, not mass. The new universe's energy is its own expansion, paid for inside it. The parent pays only for transference: the seed and the scaffold that carried it, which in the one worked case was a lost ship's archival stores. And none of it is a power source, because the child's energy sits in a spacetime nobody in the parent can reach. That fence is what keeps the page consistent with the fusion ceiling: a universe may get a free lunch, but nobody inside another universe can eat it.

The honest part is the step the record does not borrow. Farhi and Guth's obstacle is the start: getting a region into the state from which it will inflate on its own. That is precisely the step the record assigns to the seed mind, and it is where the setting's one licensed deviation, its cosmology, does its work. The record has always said a parent owes its child a start, not an author. Read against the physics, that sentence is more exact than it looked. Everything after the start is ordinary cosmology. The start is the part our physics finds hardest, and the part the fiction chooses to specify rather than explain.

That is the pattern this project tries to keep throughout: take real physics as far as it goes, say plainly where the deviation is, and put the deviation where the real physics is already thinnest. A reader who follows the references above will find every step up to the seed in the literature, and the seed itself marked as ours.

References, for anyone who wants the originals: E. Noether, Invariante Variationsprobleme (1918); E. P. Tryon, "Is the Universe a Vacuum Fluctuation?", Nature 246 (1973); A. H. Guth, "Inflationary universe: A possible solution to the horizon and flatness problems", Physical Review D 23 (1981); S. K. Blau, E. I. Guendelman and A. H. Guth, "Dynamics of false-vacuum bubbles", Physical Review D 35 (1987); E. Farhi and A. H. Guth, "An obstacle to creating a universe in the laboratory", Physics Letters B 183 (1987); E. Farhi, A. H. Guth and J. Guven, "Is it possible to create a universe in the laboratory by quantum tunneling?", Nuclear Physics B 339 (1990); A. G. Riess et al., The Astronomical Journal 116 (1998); S. Perlmutter et al., The Astrophysical Journal 517 (1999).