Dark Energy (Wikipedia) Adding the cosmological constant to cosmology's standard FLRW metric leads to the Lambda-CDM model, which has been referred to as the "standard model" of cosmology because of its precise agreement with observations. Dark energy has been used as a crucial ingredient in a recent attempt to formulate a cyclic model for the universe.[8] Nature of dark energy[edit] Many things about the nature of dark energy remain matters of speculation. The evidence for dark energy is indirect but comes from three independent sources: Distance measurements and their relation to redshift, which suggest the universe has expanded more in the last half of its life.[9]The theoretical need for a type of additional energy that is not matter or dark matter to form our observationally flat universe (absence of any detectable global curvature).It can be inferred from measures of large scale wave-patterns of mass density in the universe. Effect of dark energy: a small constant negative pressure of vacuum[edit] .
Dynamic method From Wikipedia, the free encyclopedia The dynamic method is a procedure for the determination of the masses of asteroids. The procedure gets its name from its use of the Newtonian laws of the dynamics, or motion, of asteroids as they move around the Solar System. The procedure works by taking multiple position measurements to determine the gravitational deflection caused when two or more asteroids move past each other. Because the method relies on detecting the amount of gravitational deflection induced during an interaction, the procedure works best for objects which will produce a large deflection in their interactions with other objects. Mathematical analysis[edit] The simplest way to describe the deflection of the asteroids is in the case where one object is significantly more massive than the other. Here is the angle between the asymptotes of the hyperbolic orbit of the small object relative to the large one, and References[edit]
New transparent solar cells can be used on windows, smartphone screens (Science Alert) This new type of transparent solar cell can be used to cover windows, buildings or smartphone screens to produce solar energy. Named a transparent luminescent solar concentrator and developed by researchers in Michigan State University in the US, this material can be used to cover anything that has a flat, clear surface. Transparent solar cell technology has been attempted before, but the energy the cells produced was poor and the materials they were made out of were highly coloured. "No one wants to sit behind coloured glass,” said one of the researchers behind the technology, chemical engineer Richard Lunt, in a press release. "It makes for a very colourful environment, like working in a disco. We take an approach where we actually make the luminescent active layer itself transparent.” The new transparent solar cells are made from tiny organic molecules that absorb invisible wavelengths of sunlight such as ultraviolet and near infrared light.
Inflation (Wikipedia) In physical cosmology, cosmic inflation, cosmological inflation, or just inflation is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10−36 seconds after the Big Bang to sometime between 10−33 and 10−32 seconds. Following the inflationary period, the Universe continues to expand, but at a less rapid rate.[1] Inflation was developed in the early 1980s. In 2002, three of the original architects of the theory were recognized for their major contributions; physicists Alan Guth of M.I.T., Andrei Linde of Stanford and Paul Steinhardt of Princeton shared the prestigious Dirac Prize "for development of the concept of inflation in cosmology".[5] Overview An expanding universe generally has a cosmological horizon, which, by analogy with the more familiar horizon caused by the curvature of the Earth's surface, marks the boundary of the part of the Universe that an observer can see. Space expands . . Few inhomogeneities remain Duration Reheating Notes
Dark flow A possible non-random component of the peculiar velocity of galaxy clusters In astrophysics, dark flow is a controversial hypothesis to explain certain non-random measurements of peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a possible small velocity flowing in a common direction. Very large scale correlated flow, called bulk flow is proposed in this model to be related to certain models of inflationary cosmology. The researchers had suggested that the motion may be a remnant of the influence of no-longer-visible regions of the universe prior to inflation. The results appeared in the October 20, 2008, issue of Astrophysical Journal Letters.[1][2][3][4] Location[edit] In a study from March 2010, Kashlinsky extended his work from 2008, by using the 5-year WMAP results rather than the 3-year results, and doubling the number of galaxy clusters observed from 700. Criticisms[edit] See also[edit] References[edit]
What’s New in 3D Printing? :: ChemViews Magazine 3D Printing is Coming to Our Lives! 3D printing is not a novelty, it is more than 20 years old. However, the first monograph on it has only just appeared [1]. I learned about it only recently, when this manufacturing technique made its way into chemistry [2,3]. Today, rapidly developing 3D printing offers numerous marketed applications. Figure 1. The article “Print me a Stradivarius” with a cover picture of a printed violin was published in The Economist two years ago [8, 9]. Figure 2. 3D-printed lampshade. © 3Dizingof.com (Designer: Dizingof) Contrary to “complex structures made in expensive and complex ways that come together in even more complex ways” [10], applying 3D printing consists of consecutive depositing of layers of an appropriate material and their subsequent fusion. Mary Gehl states that the 3D printing was patented in the late 1970s but no source has been given for this information [12]. The Process of 3D Printing and Its Advantages The advantages of 3D printing are:
Black Hole (Wikipedia) A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping.[1] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole.[2] Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[3][4] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. History General relativity
Culmination The passage of an astronomical body across the meridian During each day, every celestial object appears to move along a circular path on the celestial sphere due to the Earth's rotation creating two moments when it crosses the meridian.[2][3] Except at the geographic poles, any celestial object passing through the meridian has an upper culmination, when it reaches its highest point above the horizon, and nearly twelve hours later, is followed by a lower culmination, when it reaches its lowest point. The time of culmination (when the object culminates) is often used to mean upper culmination.[2][3][4] Cases[edit] Three cases are dependent on the observer's latitude (L) and the declination (δ) of the celestial object:[citation needed] Period of time[edit] The Sun[edit] From the tropics and middle latitudes, the Sun is visible in the sky at its upper culmination (at solar noon) and invisible (below the horizon) at its lower culmination (at solar midnight). Circumpolar stars[edit] See also[edit]
Heart The heart pumps blood through both circulatory systems. Blood low in oxygen from the systemic circulation enters the right atrium from the superior and inferior vena cavae and passes to the right ventricle. From here it is pumped into the pulmonary circulation, through the lungs where it receives oxygen and gives off carbon dioxide. Oxygenated blood then returns to the left atrium, passes through the left ventricle and is pumped out through the aorta to the systemic circulation−where the oxygen is used and metabolized to carbon dioxide.[2] In addition the blood carries nutrients from the liver and gastrointestinal tract to various organs of the body, while transporting waste to the liver and kidneys.[citation needed] In the healthy organism each heartbeat causes the right ventricle to pump the same amount of blood into the respiratory organ as the left ventricle pumps to the body. Structure The human heart is in the middle of the thorax, with its apex pointing to the left.[12] Heart wall
Neutron Star (Wikipedia) Neutron stars contain 500,000 times the mass of the Earth in a sphere with a diameter no larger than that of Brooklyn, United States A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Neutron stars are the densest and tiniest stars known to exist in the universe; although having only the diameter of about 10 km (6 mi), they may have a mass of several times that of the Sun. Neutron stars probably appear white to the naked eye. Neutron stars are the end points of stars whose inert core's mass after nuclear burning is greater than the Chandrasekhar limit for white dwarfs, but whose mass is not great enough to overcome the neutron degeneracy pressure to become black holes. The discovery of pulsars in 1967 suggested that neutron stars exist. Neutron star collision Formation[edit] Properties[edit] Gravitational light deflection at a neutron star. Given current values Structure[edit]
Commensurability (astronomy) Proportionality of orbital periods for two celestial bodies Commensurabilities are normally the result of an orbital resonance, rather than being due to coincidence. New Type Of Chemical Bond Confirmed Chemistry students around the globe are pretty familiar with ionic, covalent, hydrogen, and van der Waals bonds, but a study has demonstrated the existence of one more: vibrational bonding. The phenomenon was first suggested over 30 years ago, but no evidence existed to support it, until now. Recent work with exotic isotopomers has been the key to finally explaining this peculiar interaction, whose qualities defy traditional chemical explanation. A description of the work was published in the journal Angewandte Chemie International Edition, with Donald Fleming from the University of British Columbia as lead author. Elements are defined by the number of protons in each atom’s nucleus, though the number of neutrons can vary. Muonium (Mu) is an exotic atom with an antimuon nucleus orbited by one electron, making it considerably lighter than the hydrogen isotope protium (1H), though they have similar chemical attributes. [Hat tip: Scientific American]