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QCD Cosmology from the Lattice Equation of State
QCD Cosmology from the Lattice Equation of State Michael McGuigan and Wolfgang S¨oldner Brookhaven National Laboratory Upton NY 11973 [email protected] Abstract We numerically determine the time dependence of the scale factor from the lattice QCD equation of state, which can be used to define a QCD driven cosmology. We compare a lattice approach to QCD cosmology at late times with other models of the low temperature equation of state including the hadronic resonance gas model, Hagedorn model and AdS/CFT. 1 Introduction QCD cosmology is important as the Universe exits the radiation dominated era and enters the matter dominated era, eventually evolving into the dark energy dominated era [1, 2, 3, 4, 5, 6, 7, 8, 9]. The effect of the strong interactions on cosmology was considered early on [10, 11] but the nonperturbative nature of the strong interactions at low energy limited the progress of the subject. Today with nonperturbative approaches like lattice QCD [12] and AdS/QCD [13, 14, 15] it is important to revisit the subject to see what can be said quantitatively about QCD cosmology. Also besides the time dependence of the scale factor in QCD cosmology, one can arXiv:0810.0265v2 [hep-th] 8 Oct 2008 also look at the effect of recent advances on the QCD equation of state for exotic astrophysical objects like quark or strange stars [16, 17]. In this paper we consider a spatially flat Friedmann-Robertson-Walker Universe where the radius of the Universe a(t), energy density ε, and pressure p all depend on time. Conservation of the local energy-momentum tensor leads to: d(εa3) d(a3) = p . -
Thermodynamic Temperature
Thermodynamic temperature Thermodynamic temperature is the absolute measure 1 Overview of temperature and is one of the principal parameters of thermodynamics. Temperature is a measure of the random submicroscopic Thermodynamic temperature is defined by the third law motions and vibrations of the particle constituents of of thermodynamics in which the theoretically lowest tem- matter. These motions comprise the internal energy of perature is the null or zero point. At this point, absolute a substance. More specifically, the thermodynamic tem- zero, the particle constituents of matter have minimal perature of any bulk quantity of matter is the measure motion and can become no colder.[1][2] In the quantum- of the average kinetic energy per classical (i.e., non- mechanical description, matter at absolute zero is in its quantum) degree of freedom of its constituent particles. ground state, which is its state of lowest energy. Thermo- “Translational motions” are almost always in the classical dynamic temperature is often also called absolute tem- regime. Translational motions are ordinary, whole-body perature, for two reasons: one, proposed by Kelvin, that movements in three-dimensional space in which particles it does not depend on the properties of a particular mate- move about and exchange energy in collisions. Figure 1 rial; two that it refers to an absolute zero according to the below shows translational motion in gases; Figure 4 be- properties of the ideal gas. low shows translational motion in solids. Thermodynamic temperature’s null point, absolute zero, is the temperature The International System of Units specifies a particular at which the particle constituents of matter are as close as scale for thermodynamic temperature. -
New Quantum Particle
New Quantum Particle Scientists at Amherst College and Aalto University have created, for the first time a three- dimensional skyrmion in a quantum gas. [38] Using lasers, U.S. and Austrian physicists have coaxed ultracold strontium atoms into complex structures unlike any previously seen in nature. [37] A team of researchers has now presented this state of matter in the journal Physical Review Letters. The theoretical work was done at TU Wien (Vienna) and Harvard University, the experiment was performed at Rice University in Houston (Texas). [36] The old question, whether quantum systems show recurrences, can finally be answered: Yes, they do—but the concept of recurrence has to be slightly redefined. [35] Researchers at Purdue University have performed the first experimental tests of several fundamental theorems in thermodynamics, verifying the relationship between them and providing a better understanding of how nanoparticles behave under fluctuation. [34] Identifying right-handed and left-handed molecules is a crucial step for many applications in chemistry and pharmaceutics. [33] A team of researchers from several institutions in Japan has described a physical system that can be described as existing above "absolute hot" and also below absolute zero. [32] A silicon-based quantum computing device could be closer than ever due to a new experimental device that demonstrates the potential to use light as a messenger to connect quantum bits of information—known as qubits—that are not immediately adjacent to each other. [31] Researchers at the University of Bristol's Quantum Engineering Technology Labs have demonstrated a new type of silicon chip that can help building and testing quantum computers and could find their way into your mobile phone to secure information. -
Rydberg Atoms and Polarons
Rydberg Atoms and Polarons Using lasers, U.S. and Austrian physicists have coaxed ultracold strontium atoms into complex structures unlike any previously seen in nature. [37] A team of researchers has now presented this state of matter in the journal Physical Review Letters. The theoretical work was done at TU Wien (Vienna) and Harvard University, the experiment was performed at Rice University in Houston (Texas). [36] The old question, whether quantum systems show recurrences, can finally be answered: Yes, they do—but the concept of recurrence has to be slightly redefined. [35] Researchers at Purdue University have performed the first experimental tests of several fundamental theorems in thermodynamics, verifying the relationship between them and providing a better understanding of how nanoparticles behave under fluctuation. [34] Identifying right-handed and left-handed molecules is a crucial step for many applications in chemistry and pharmaceutics. [33] A team of researchers from several institutions in Japan has described a physical system that can be described as existing above "absolute hot" and also below absolute zero. [32] A silicon-based quantum computing device could be closer than ever due to a new experimental device that demonstrates the potential to use light as a messenger to connect quantum bits of information—known as qubits—that are not immediately adjacent to each other. [31] Researchers at the University of Bristol's Quantum Engineering Technology Labs have demonstrated a new type of silicon chip that can help building and testing quantum computers and could find their way into your mobile phone to secure information. [30] Theoretical physicists propose to use negative interference to control heat flow in quantum devices.