What if they make some experiment that annihilates the entire universe?
This is virtually impossible, because the vacuum is conditionally stable. Without it every black hole would initiate the phase transition of Universe already. But the same cannot be said about the matter. Because the matter is principially unstable in contact with vacuum, we aren't supposed to be here at all... For creation of matter and antimatter from radiation you'll need the photons of energy at least 0.5 MeV each. On the other hand, the same huge energy will be released during anihillation. Therefore the dynamic equillibrium between matter and energy is shifted towards the energy inside of our Universe generation. We can see, the matter is transforming and evaporating into energy (i.e. "glowing") whenever possible and the speed of such transmutation is the higher, the higher is gravitational field / the density of matter. This is why, the huge black holes are converting the matter into energy of accretion radiation nearly completelly. Therefore by placing of sufficiently huge and dense particle of matter into every massive object it's possible to achieve the release of energy hidden inside of matter and conversion of it into energy of gamma radiation.
Here many other examples, how to illustarate such concept by Aether theory. You can think, the matter is formed by condensed mercury dropplets, which are separated mutually by the forces of surface tension. At the moment, the surface tension at the center of pile of mercury dropplets will be released for example by adding of surfactants or other dense liquid metal (the molten gallium, for example), the whole pile of mercury dropplets will collapse and condense like the nest full of eggs. You can test such behavior by adding of small amount of spirit into soap foam - the local decreasing of surface tension will result into immediate collapse of foam inside its whole volume. This process can serve as illustrative model of placing dense strangelet inside of Earth's core, because the existence of matter inside of our Universe is virtual by the same way, it's a sort of metastable foam only, which had appeared in subtle amounts as a byproduct during huge space-time transforms (so called "Big Bang").
This is why, these experiments are so dangerous, when carried out near Earth or even bellow the Earth surface. The common argument is, the Earth is bombarded by particles of comparable energies in the form of cosmic radiation without long term effects. But the particles of cosmic radiation are heavy just because of their high relativistic speed, they're formed by quite common protons, in fact. By Aether theory, theirs energy is caused by the large volume of vacuum dragged by the motion of particle, not by rest mass of particle as such and it's not concentrated into particle center. Furthemore, just because of this high speed, these particles cannot spent a lotta time during passing through Earth. While the situation at the case of LHC collision experiments is quite different. During this the extremely heavy particles will appear in head-to-head collision with potentially zero momentum and resulting speed, of course. They'll have the opportunity to react with matter at the moment, they will not decompose readilly, so they can leave the accelerator.
Not saying we save the money for deep vacuum, 
