Cosmological constant

Feb 17, · The cosmological constant is presumably an enigmatic form of matter or energy that acts in opposition to gravity and is considered by many physicists to be equivalent to dark energy. Feb 23, · The cosmological constant is presumably an enigmatic form of matter or energy that acts in opposition to gravity and is considered by many physicists to be equivalent to dark energy.

The cosmological constant is presumably an enigmatic form of matter or energy that acts in opposition to gravity and is considered by many physicists to be equivalent to dark energy.

Nobody really knows what the cosmological constant is exactly, but it is required in cosmological equations in cosmologicxl to reconcile theory with our observations of the universe.

Albert Einsteinthe famous German-American physicist, whst up with the cosmological constant, which he called the "universal constant," in as a means to balance certain calculations in his theory of general relativity. At the time, physicists believed the universe was static — neither expanding nor contracting — but Einstein's work suggested that gravity would cause it to do one or the other. So, to mesh with the scientific consensus, Einstein inserted a fudge factor, denoted by the Greek letter lambda, into his results, which kept the cosmos still.

Yet a little over a decade later, the American astronomer Edwin Hubble noticed that galaxies were actually moving away from us, indicating the universe was expanding. Einstein called lambda his "greatest mistake. Related: 'Einstein's biggest blunder' may have finally been fixed. Hubble's observations negated the need for a what does oedipus use to blind himself constant for decades, but that changed when astronomers whag distant supernovas in the late s discovered that the cosmos was not *what is the cosmological constant* expanding, but accelerating in its expansion.

They named the mysterious anti-gravity force required to whst for this phenomena " dark energy. In the s, Russian physicist Alexander Friedmann developed an equation, now called the Friedmann Equation, coskological describes the properties of the universe from the Big Bang onward, according to **what is the cosmological constant** online tutorial from Georgia State University.

By dusting off Einstein's lambda and plugging it rhe the Friedmann equations, researchers could model the cosmos correctly — that is, with an accelerating expansion rate. However, no one truly understands what lambda is. Most physicists consider it interchangeable with the concept of dark energy, but that doesn't make things any clearer because dark energy is simply a placeholder describing some unknown anti-gravity substance.

So, we've essentially reverted to using Einstein's fudge factor. One potential explanation for the cosmological constant lies in the realm of modern particle **what is the cosmological constant.** Experiments have verified that empty space is permeated by countless virtual particles constantly popping in and out of existence.

This ceaseless action creates what is known as a "vacuum energy," or a force arising from empty space, inherent in cosmologicall fabric of space-time that could drive conatant the universe. But connecting vacuum energy cosmologjcal the cosmological constant is not straightforward.

Based on their observations of supernovas, astronomers estimate that dark energy should have a small and sedate value, just enough to push everything in the universe apart over billions of years. Yet when scientists try to calculate the amount of energy that should consatnt from virtual particle motion, they come up with a result cosmopogical orders of magnitude greater than what the supernova data suggest.

Related: The worst theoretical prediction in the history of physics. To add to the conundrum, some researchers have proposed that the cosmological constant might not be a constant at all, but rather changes or fluctuates with time. This theory is called quintessence and some projects, such as the Dark Energy Surveyare currently making cosmologidal observations to see if it has any observational support.

In the meantime, cosmologists will continue to use lambda. They may not know what it is, but they know that they how to clean mold stains from fabric it to make the universe make sense.

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Dec 21, · What is a Cosmological Constant? Einstein first proposed the cosmological constant (not to be confused with the Hubble Constant) usually symbolized by the greek letter "lambda" (Λ), as a mathematical fix to the theory of general relativity. In its simplest form, general relativity predicted that the universe must either expand or contract. Cosmological constant is a physics term generally denoted by the symbol lambda. Lambda is a Greek letter that looks like a triangle missing its base. The cosmological constant was developed by Albert Einstein to be a modification to his original Theory of Relativity. The cosmological constant is a measure of the (uniform) energy density associated with space: it is how much "intrinsic energy" each parcel of space has, just matter has an energy associated with it due to its mass. Because of how the equation is typically written, it .

In its simplest form, general relativity predicted that the universe must either expand or contract. Einstein thought the universe was static, so he added this new term to stop the expansion. Friedmann, a Russian mathematician, realized that this was an unstable fix, like balancing a pencil on its point, and proposed an expanding universe model, now called the Big Bang theory. When Hubble's study of nearby galaxies showed that the universe was in fact expanding , Einstein regretted modifying his elegant theory and viewed the cosmological constant term as his "greatest mistake".

Many cosmologists advocate reviving the cosmological constant term on theoretical grounds. Modern field theory associates this term with the energy density of the vacuum. For this energy density to be comparable to other forms of matter in the universe, it would require new physics: the addition of a cosmological constant term has profound implications for particle physics and our understanding of the fundamental forces of nature.

The main attraction of the cosmological constant term is that it significantly improves the agreement between theory and observation. The most spectacular example of this is the recent effort to measure how much the expansion of the universe has changed in the last few billion years.

Generically, the gravitational pull exerted by the matter in the universe slows the expansion imparted by the Big Bang. Very recently it has become practical for astronomers to observe very bright rare stars called supernova in an effort to measure how much the universal expansion has slowed over the last few billion years.

Surprisingly, the results of these observations indicate that the universal expansion is speeding up, or accelerating! While these results should be considered preliminary, they raise the possibility that the universe contains a bizarre form of matter or energy that is, in effect, gravitationally repulsive.

The cosmological constant is an example of this type of energy. Much work remains to elucidate this mystery! There are a number of other observations that are suggestive of the need for a cosmological constant.

For example, if the cosmological constant today comprises most of the energy density of the universe, then the extrapolated age of the universe is much larger than it would be without such a term, which helps avoid the dilemma that the extrapolated age of the universe is younger than some of the oldest stars we observe!

A cosmological constant term added to the standard model Big Bang theory leads to a model that appears to be consistent with the observed large-scale distribution of galaxies and clusters , with WMAP's measurements of cosmic microwave background fluctuations , and with the observed properties of X-ray clusters.

Wilkinson Microwave Anisotropy Probe. What is a Cosmological Constant? A well written, popular account of the cosmological constant and the current state of cosmology. Edward J. Wollack Page Updated: Friday,

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