I read that paper as well this morning (also without wading too deeply into the mathematics) and I had exactly the same question! If I start to understand what is going on I will edit this reply, but otherwise I am eager to hear what others think about this. I have been playing with wormholes for a number of years and I have never been able to solve the negative energy problem (although I may have some ideas using Skyrmions -- another group scouped me on this and concluded they don't work, but I am still going to press forward and see if there is anything they missed)

Dear Marshall,

I analyzed the work and within the assumptions that exist in the physical and consistent.

However we will do a more fundamental breakdown of theories to have a vision of the real possibilities exist.

Energy and matter are the same entity observed by different angles.

The matter of the clear printout to be condensed energy.

The energy takes multiple forms but interchangeable.

But anergy in the form of electromagnetic waves or photos and the most important point for this analysis.

A photon with different frequency ie having appropriate enegia, eg 1.02 Mev materializes a pair of electron, the positron.

Another photon with energy in the range of 2 Gev proton or neutron can materialize.

Be the proton or neutron are formed of three quarks.

A neutron outside the nucleus has a half life of about 16 minutes and decays into a proton, an electron and a neutrino to electron.

Ie quarks change their identity because who undergoes disintegration and one down quark which becomes up.

Here comes the Inquire who are unanswered:

Because the neutral outside the core disintegrates.

Because there is not free quarks outside a particle?

Because the energy of three quarks and around a hundredth of the energy of the particle.

Because the mass of atomic nuclei demonstrates that protons and neutrons have different mass element as they are added?

And precisely this difference that allows mass energy exists in nuclear fusion!

Because there is the confinement of protons and neutrons in the atomic nucleus?

And we see the philosophical synthesis is any kind of boson or fermion can be created with energy or energy turn this indicates that there is logically a single entity that assumes different identities as the the situation around you.

With these questions without a clear explanation and integrating all the response and coherently and logically impossible to determine what exactly may be the level of WORMHOLE!

And QCD this far to give a coherent explanation for these questions we know the answers but not because of the answers!

The gluons are the magic particle that solves everything, but were never seen in isolation and are a simple derivation of the model ie no one can guarantee that it works well!

The standard model itself and not a theory but a compilation of knowledge and experiments that every new information is added it!

Because it does not make prediction about nothing only describes what is known already!

The simple fact not exist explanation because the elements of numbers 43 and 61 in nature, which are radioactive and because the elements above bismuth also be radioactive, already shows that there is much to understand how the heart of the matter works!

I think I have found the answer to all these questions and more, in a single model of the universe and everything referenced to only 4 numeric values!

A string theory in 5 dimensions.

Which proposes that the universe and massively parallel quantum computer where the element that renders the quantum information and a string!

And the operations of this machine projects a figure of interference ie a hologram we call the universe!