Heat Isolators on a Vacuum Flask

The thing which makes the vacuum flask system useful is the vacuum between the two bottles. Producers of the vacuum flask try to create a perfect vacuum between the two bottles, but it is impossible. Little air goes inside, too. This situation creates my experiment and research question. There are many heat isolators so can there be any material that can be more successful in conserving the temperature of the liquid added than the vacuum flask system? To find an answer to my question, I chose 3 heat isolators (perlite, fire brick and silicone) and put them into the flasks instead of the vacuum. In order to investigate their performance and compare with the vacuum flask system, I planned four experiments. I added to the flasks different liquids, water at the different temperature and water at different amounts and measured the temperatures of the added liquids in different times. According to the results from these 4 experiments, I reach to a conclusion that these isolators couldn’t perform a better performance than vacuum in conserving the temperature of the liquid

Nonzero Mean Squared Momentum of Quarks in the Non-Perturbative QCD Vacuum

The non-local vacuum condensates of QCD describe the distributions of quarks and gluons in the non-perturbative QCD vacuum. Physically, this means that vacuum quarks and gluons have nonzero mean-squared momentum, called virtuality. In this paper we study the quark virtuality which is given by the ratio of the local quark-gluon mixed vacuum condensate to the quark local vacuum condensate. The two vacuum condensates are obtained by solving Dyson-Schwinger Equations of a fully dressed quark propagator with an effective gluon propagator. Using our calculated condensates, we obtain the virtuality of quarks in the QCD vacuum state. Our numerical predictions differ from the other theoretical model calculations such as QCD sum rules, Lattice QCD and instanton models.Comment: 8 pages, no figures, 4 tables Our previous version had an error, and the results in this new version are quite different

The vacuum bubbles in de Sitter background and black hole pair creation

We study the possible types of the nucleation of vacuum bubbles. We classify vacuum bubbles in de Sitter background and present some numerical solutions. The thin-wall approximation is employed to obtain the nucleation rate and the radius of vacuum bubbles. With careful analysis we confirm that Parke's formula is also applicable to the large true vacuum bubbles. The nucleation of the false vacuum bubble in de Sitter background is also evaluated. The tunneling process in the potential with degenerate vacua is analyzed as the limiting cases of the large true vacuum bubble and false vacuum bubble. Next, we consider the pair creation of black holes in the background of bubble solutions. We obtain static bubble wall solutions of junction equation with black hole pair. The masses of created black holes are uniquely determined by the cosmological constant and surface tension on the wall. Finally, we obtain the rate of pair creation of black holes.Comment: 3 figures, minor including errors and typos corrected, and refs. adde

Cosmological and Astrophysical Probes of Vacuum Energy

Vacuum energy changes during cosmological phase transitions and becomes relatively important at epochs just before phase transitions. For a viable cosmology the vacuum energy just after a phase transition must be set by the critical temperature of the next phase transition, which exposes the cosmological constant problem from a different angle. Here we propose to experimentally test the properties of vacuum energy under circumstances different from our current vacuum. One promising avenue is to consider the effect of high density phases of QCD in neutron stars. Such phases have different vacuum expectation values and a different vacuum energy from the normal phase, which can contribute an order one fraction to the mass of neutron stars. Precise observations of the mass of neutron stars can potentially yield information about the gravitational properties of vacuum energy, which can significantly affect their mass-radius relation. A more direct test of cosmic evolution of vacuum energy could be inferred from a precise observation of the primordial gravitational wave spectrum at frequencies corresponding to phase transitions. While traditional cosmology predicts steps in the spectrum determined by the number of degrees of freedom both for the QCD and electroweak phase transitions, an adjustment mechanism for vacuum energy could significantly change this. In addition, there might be other phase transitions where the effect of vacuum energy could show up as a peak in the spectrum.Comment: 28 pages, LaTeX, 7 figure