Dark energy

From Conservapedia

Dark energy is one of two concepts (the other is dark matter) that Big Bang cosmologists and astrophysicists have invented to explain the most serious differences to date between astronomical observations of an expanding universe and their own expectations. It is "the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate";^[1] Astronomers and cosmologists have been speculating on the nature of this dark energy for ten years.

Contents 1 Introduction of the concept 2 Nature of dark energy 3 Implications of dark energy 4 Proposed investigations 5 Young Earth Creation Science View 6 References

Introduction of the concept

In 1998, the Supernova Cosmology Project observed 42 Type Ia supernovae, most of these from the ground, in an effort to measure the rate of deceleration of the expansion of the universe.^[2] (Type Ia supernovae are objects of nearly uniform brightness and thus are favorite objects for standardization of redshift and hence of the speed of expansion.) These supernovae were actually much dimmer than expected, a finding that indicated an acceleration of expansion, not the deceleration that gravitational attraction would produce. A competing group, the High-Z Supernova Search Team, reported similar results from their observations of 14 other supernovae.^[3] (The symbol z stands for redshift in this context.) The findings of an accelerated universe came as a profound surprise to all interested observers and commentators.^[4]

Saul Perlmutter, Michael Turner, and Martin White appear to have coined the term dark energy to name the phenomenon that is causing the apparent acceleration.^[5] The term appears again in the more comprehensive paper of Bahcall, Ostriker, Perlmutter, and Steinhardt, that proposes that a heretofore unsuspected form of energy "overcomes the gravitational self-attraction of matter and causes the expansion [of the universe] to speed up."^[6][7]

In 2001, Reiss and his colleagues used the Hubble Space Telescope to capture on film the furthest supernova then seen, SN1997ff, at a distance of 10 billion light-years. The magnitude and redshift of this object were consistent with a decelerating expansion. This is consistent with the model that Reiss and others were forming at the time, stating that the expansion of the universe was initially decelerating and later accelerated after its matter density dropped below a critical level.^[8]

In 2003, a survey of 11 Type Ia supernovae by the HST confirmed the earlier findings of an accelerated expansion of the universe. Astronomers consider this the most definitive evidence to date for the existence of dark energy.^[9]

Nature of dark energy

Dark energy today is inferred, not detected. The calculated quantity of dark energy is the apparent excess of energy that somehow abruptly accelerated the expansion of the universe. Current estimates of the time that has passed since this acceleration occurred vary from 5^[10] to 7.5 billion years.^[11][12]

Conventional cosmologists estimate that 70 percent of the total energy in the universe consists of dark energy.^[11] Dark matter occupies another 25 percent. The remaining portion is the familiar, or baryonic matter of which all objects are made.^[12]

uniformitarian cosmologists have three theories of what form this energy might take:

1. It is a fundamental property of the universe, as Albert Einstein originally suggested. Einstein's original idea was that this force, which he called a "cosmological constant," would exactly counterbalance gravity and thus keep all galaxies and other objects of similar size in the same place. Einstein initially discarded his own findings after Edwin Hubble showed that the universe was expanding. Some modern cosmologists suggest that Einstein might have been right after all.^{[8][7][11][12][10]}
2. It is a previously unknown type of energy fluid or field, and perhaps even a fifth elemental force, in addition to the previously known four forces of gravity, the electromagnetic force, and the weak and strong nuclear forces. Some scientists name this new force "quintessence" (literally, fifth essence), a term that ancient Greek philosophers once coined for a fifth "element" of nature in addition to the four elements that they thought they knew (fire, air, earth, and water).^[7][11]
3. It is not a new property or force but a manifestation of an error of our understanding of an old one, namely gravity.^[7][11]

David Cline wrote in Scientific American in 2003 the following: "We know little about that sea. The terms we use to describe its components, dark matter and dark energy, serve mainly as expressions of our ignorance.”^[13] Similarly, David Shiga authored an article in 2007 published by New Scientist titled "Is Dark Energy and Illusion?".^[14]

Implications of dark energy

Conventional cosmologists have thus far realized only that their understanding of cosmology is incomplete. They now know that the universe is expanding, that this expansion is accelerating, and that their existing models cannot account for this acceleration or begin to suggest a cause. They believe also that dark energy can explain the current temperature of the Cosmic Microwave Background radiation.^[10][15] But they are no closer to defining the nature of dark energy than they were when Perlmutter et al. first coined the term.

This has not stopped them from speculating on what might happen to the universe in the future. They currently recognize three possibilities:^[12]

1. The universe will expand indefinitely and isolate our galaxy.^[10]
2. The "quintessential" substance will reverse its repulsive effect and become attractive. This will stop the expansion and contract the universe into a point, an event they call the "Big Crunch."
3. The universe will expand rapidly enough to tear the fabric of space and ultimately cause all baryonic matter to disintegrate, an event they call the "Big Rip."

Other scientists raise the question of whether the proportion of dark energy in the universe is a fundamental quantity of space. If it is not, they say, then this universe is only one of many.^[16]

Proposed investigations

Fermilab's Experimental Astrophysics Group has proposed a Dark Energy Survey, using a special 500-megapixel camera mounted on a ground-based telescope.^[17]

NASA and the United States Department of Energy have also proposed a Joint Dark Energy Mission, essentially a new, very-high-resolution space telescope. Three different telescope designs are now under study.^[18]changesff

Young Earth Creation Science View

Dr. Walt Brown wrote about the concept of dark energy the following:

“

Neither “dark matter” (created to hold the universe together) nor “dark energy” (created to push the universe apart) has been seen or measured. We are told that “most of the universe is composed of invisible dark matter and dark energy.” Few realize that both mystical concepts were devised to preserve the big bang theory.[19]

”

Dark energy is a mathematical convenience. Some authorities admit that it may never be detectable. One reason why no one would ever detect it is that it represents an error. Conventional cosmologists have admitted that dark energy might represent an error of their understanding of gravity. Creationists suggest that the error is far more fundamental.

John Hartnett, in Starlight, Time and the New Physics,^[20] reminds his readers that Moshe Carmeli first formed a new model, called cosmological relativity, and through this model predicted that the universe would in fact appear to be accelerating. He made this prediction in 1996, two years before the publication of the Type Ia supernova data and the introduction of the idea of "dark energy" into cosmological discussions. In making this prediction, Carmeli did not invoke either dark energy or dark matter.

The astronomers of the Supernova Cosmology Project and the High-Z Supernova Search Team did not use Carmeli's model, but instead relied upon the Friedmann-Lemaître cosmological model. That model could not fit the observations without the invocation of dark matter, to account for galaxies spinning too rapidly for Newtonian gravity to hold them together, and dark energy, to account for the observed acceleration of universal expansion.

Hartnett continued Carmeli's calculations and applied them to the explicit statements in the Bible concerning the universe' beginnings. The Bible says that God created an expanse of space and then, on Day Four of creation, stretched it out very rapidly. Thus the most distant objects would show evidence of that expansion. Hartnett also calculated that the initial universe was about eight million light-years in radius before the expansion, and is 13.5 billion light-years in radius today. The expansion itself produced tremendous time dilation in the terrestrial frame of reference, so that the light from even the most distant objects in the universe could still have reached the earth for Adam to see.

References