Extra Attraction Generated by Spacetime Fluctuations

We show that, due to the nonlinear nature of gravity, fluctuations in spacetime curvature generate additional gravitational attraction. This fluctuation-induced extra attraction was overlooked in the conventional understanding of the cosmological constant problem. If the quantum vacuum of matter fields possesses positive energy and negative pressure, it would produce enormous gravitational repulsion, resulting in a catastrophic explosion of the universe -- the acceleration of the universe's expansion would exceed the observed value by some 120 orders of magnitude. We argue that such an enormous repulsion produced by the violent matter fields vacuum can be completely suppressed by the even more substantial attraction generated by the zero-point fluctuations in the spacetime curvature. As a result, the predicted catastrophic explosion of the universe is averted. Furthermore, at small microscopic scales, the structure of spacetime becomes locally highly inhomogeneous and anisotropic. When averaged over large macroscopic scales, the zero-point fluctuations of spacetime itself could drive the observed slow acceleration of the universe's expansion through a subtle parametric resonance effect.Comment: 29 page

Decision-making in Proactive Remanufacturing Based on Online Monitoring

AbstractConsidering the uncertainty quality of the remanufacturing, this paper presents the proactive remanufacturing which is actively carried at an optimal time. To identify the optimal time, the decision-making model is given based on online monitoring signals. Informed by wavelet-packet de-noise and singular value decomposition, establishing the mapping relationship between components failure and using feature of products. With the simulating test on crankshaft of engine, the vibrating signals of different wear condition in crankshaft journal are analyzed, extracted and compared, which can establish the mapping relationship. Thus, it could make the proactive remanufacturing decision with the optimal wearing condition in crankshaft

Can the fluctuations of the quantum vacuum solve the cosmological constant problem?

The cosmological constant problem arises because the magnitude of vacuum energy density predicted by quantum mechanics is about 120 orders of magnitude larger than the value implied by cosmological observations of accelerating cosmic expansion. Recently, some of the current authors proposed that the stochastic nature of the quantum vacuum can resolve this tension [Q, Wang, Z. Zhu, and W. G. Unruh, Phys. Rev. D 95, 103504, 2017]. By treating the fluctuations in the vacuum seriously and allowing fluctuations up to some high-energy cutoff at which Quantum Field Theory is believed to break down, a parametric resonance effect arises that leads to a slow expansion and acceleration. In this work, we thoroughly examine the implications of this proposal by investigating the resulting dynamics. First, we improve upon numerical calculations in the original work and show that convergence issues had overshadowed some important effects. Correct calculations reverse some of the conclusions in [Q. Wang, Z. Zhu, and W. G. Unruh, Phys. Rev. D 95, 103504, 2017], however the premise that parametric resonance can explain a very slowly accelerating expansion appears to remain sound. After improving the resolution and efficiency of the numerical tests, we explore a wider range of cutoff energies, and examine the effects of multiple particle fields. We introduce a simple model using the Mathieu equation (a prototypical example of parametric resonance), and find that it closely matches numerical results in regimes where its assumptions are valid. Using this model, we extrapolate to find that in a universe with 28 bosonic fields and a high-energy cutoff 40 times higher than the Planck energy, the acceleration would be comparable to what is observed.Comment: 19 pages, 12 figure