Latest Cosmological constant Stories
Quintessence and phantom fields, two hypotheses formulated using data from satellites, such as Planck and WMAP, are among the many theories that try to explain the nature of dark energy.
A popular theory that emphasizes dark energy as a contributor to the acceleration of the universe’s expansion does not fit newly obtained data with regards to one fundamental constant – the proton to electron mass ration – claims a University of Arizona astronomy professor.
New information obtained by scientists using a 10-meter telescope located in Antarctica has strengthened the most widely accepted explanation for the mysterious force that is behind the increasingly rapid expansion of the universe.
Analysis of the new compilation significantly narrows the possible values that dark energy might takeâ€”but not enough to decide among fundamentally different theories of its nature.
A team led by Princeton University scientists has tested Albert Einstein's theory of general relativity to see if it holds true at cosmic scales.
Imagine a time when the entire universe froze. According to a new model for dark energy, that is essentially what happened about 11.5 billion years ago, when the universe was a quarter of the size it is today.
Scientists have traced the expansion history of the universe with unprecedented accuracy and sharpened our knowledge of what it might be that is causing the mysterious acceleration of the expansion of the universe.
The genius of Albert Einstein, who added a "cosmological constant" to his equation for the expansion of the universe but later retracted it, may be vindicated by new research published today in the journal Astronomy and Astrophysics.
Quintessence (Dark Energy) -- Quintessence or dark energy is a hypothetical form of energy postulated to exist in order to explain observations of an accelerating universe. This energy would act like a vacuum pressure, pushing things apart. Other attempts to explain these recent observations involve a non-zero cosmological constant, which has the same effect. Indeed, sometimes quintessence is said to result in a non-zero cosmological constant, and conversely a non-zero cosmological...
Cosmological Constant -- The cosmological constant (usually denoted by the Greek capital letter lambda: Î›) is a value occurring in Einstein's theory of general relativity. The units of Î› are 1/second2; its value is unknown but believed to be positive based on recent observations. The constant is proportional to the energy density of the vacuum Ï, where Ï€ is Pi, G is the gravitational constant and c is the speed of light in vacuum. The term can be postive, negative, or...
Inflation -- Inflation is the idea - first proposed by Alan Guth (1981) - that the nascent universe passed through a phase of exponential expansion that was driven by a negative vacuum energy density (positive vacuum pressure). This expansion can be modelled by a non-zero cosmological constant. As a direct consequence of this expansion, all of the observable universe is posited to have originated in a small, initially causally-connected region. Quantum fluctuations in this microscopic...
Accelerating universe -- In the late 1990s, observations of type I supernova produced the unexpected result that the expansion of the universe appears to be accelerating. These observations appear more firm as new data has appeared. This means that the speed with which a distant galaxy recedes from us increases over time. If this trend continues, eventually we won't be able to see any other galaxies any more. This new theory of the end of the Universe has been called the Big Rip....
- A pivoted catch designed to fall into a notch on a ratchet wheel so as to allow movement in only one direction (e.g. on a windlass or in a clock mechanism), or alternatively to move the wheel in one direction.