[guitarbill]

> "it’s highly problematic to introduce negative inertial masses because this means the vacuum becomes unstable. If you do this, you can produce particle pairs from a net energy of zero in infinitely large amounts. This fits badly with our observations."

Basically, if you mess the the equation, you have to be very sure you aren't simulating something silly. Which is easy to do, unfortunately I've done it often.

I still need to read the original paper in detail to confirm, but if the post is correct, the N-body simulation might have some issues.

[Izkata]

Waaait a minute, isn't that describing something we've already observed - spontaneous creation of virtual particle pairs in a vacuum?

[aroberge]

We have definitely not observed spontaneous creation of virtual pairs in a vacuum. I do not blame you for thinking so as it is often described this way.

Almost no computation in Quantum Field Theory can be done exactly. What physicists do is using perturbation theory which is very similar to doing Taylor series in introductory calculus. Feynman, in a genius inspiration, found a way to represent the various mathematical terms that occur in these types of calculations as pictures which could be described in words. In this pictorial language, one would say things like "this term correspond to the creation of a virtual pair of particles", etc." The perturbation expansion is a mathematical "trick" done so that we can do obtain approximate results. Each individual term in that expansion has no physical meaning - in spite of the pictorial language used.

[kgwgk]

In infinitely large amounts?