11-22-2017, 09:47 AM
Dark matter and dark energy—the mystery forces believed to govern the universe—may not exist after all. In a newly developed model, astronomer André Maeder has found that neither of these concepts are needed in order for the universe to be expanding at an accelerating rate.
It is generally accepted that normal matter—the stuff that makes up everything we see, including stars and planets—makes up just five percent of the universe. Dark matter, which cannot be seen or detected, is said to make up a further 27 percent. Scientists believe it exists because of the gravitational influence it apparently has over galaxies: It is thought that without it, they would rotate so fast they would be torn apart.
The rest of the universe is thought to be made up of dark energy, the force seen as driving the expansion of the universe.
Since their discovery, however, scientists have been unable to define either dark energy or dark matter.
In the new study, published in The Astrophysical Journal¸ Maeder focuses on “scale invariance.” This is the concept that says a feature of an object will not change even if its length or energy scales are multiplied by a common factor.
The universe is normally considered through three main theories: Einstein’s general relativity, Newton’s universal gravitation and quantum mechanics. The most prevalent theory of universe formation is the Big Bang, according to which it started from an infinitely small and dense point and then expanded rapidly after an explosion.
[Image: hubble-universe.jpg]
A Hubble image of the evolving universe. NASA/ESA
Maeder, who is from the University of Geneva, Switzerland, says this model is incomplete. "There is a starting hypothesis that hasn't been taken into account, in my opinion," he said in a statement. "By that I mean the scale invariance of the empty space; in other words, the empty space and its properties do not change following a dilatation or contraction."
Empty space is a cosmological constant—something that does not change and can be used in models of the universe. Maeder uses the idea of scale invariance and applies it to models of the universe. His findings show we do not need dark matter and dark energy to explain the expansion of the universe. His model predicts an accelerated expansion of the universe without dark energy. It can also be used to explain the speeds of galaxies and stars within them—meaning dark matter is unnecessary too.
“The announcement of this model, which at last solves two of astronomy's greatest mysteries, remains true to the spirit of science: nothing can ever be taken for granted, not in terms of experience, observation or the reasoning of human beings," he said.
The findings, however, are likely to be questioned by other physicists. Previous research suggesting dark matter and dark energy do not exist has been largely dismissed by the wider scientific community.
Concluding, Maeder says the research now needs to be expanded with further study: “If true, the hypotheses we made have many other implications in astrophysics and cosmology,” he wrote. “For now these cosmological models evidently need to be further thoroughly checked with many other possible astrophysical tests in order to confirm or infirm them.”
It is generally accepted that normal matter—the stuff that makes up everything we see, including stars and planets—makes up just five percent of the universe. Dark matter, which cannot be seen or detected, is said to make up a further 27 percent. Scientists believe it exists because of the gravitational influence it apparently has over galaxies: It is thought that without it, they would rotate so fast they would be torn apart.
The rest of the universe is thought to be made up of dark energy, the force seen as driving the expansion of the universe.
Since their discovery, however, scientists have been unable to define either dark energy or dark matter.
In the new study, published in The Astrophysical Journal¸ Maeder focuses on “scale invariance.” This is the concept that says a feature of an object will not change even if its length or energy scales are multiplied by a common factor.
The universe is normally considered through three main theories: Einstein’s general relativity, Newton’s universal gravitation and quantum mechanics. The most prevalent theory of universe formation is the Big Bang, according to which it started from an infinitely small and dense point and then expanded rapidly after an explosion.
[Image: hubble-universe.jpg]
A Hubble image of the evolving universe. NASA/ESA
Maeder, who is from the University of Geneva, Switzerland, says this model is incomplete. "There is a starting hypothesis that hasn't been taken into account, in my opinion," he said in a statement. "By that I mean the scale invariance of the empty space; in other words, the empty space and its properties do not change following a dilatation or contraction."
Empty space is a cosmological constant—something that does not change and can be used in models of the universe. Maeder uses the idea of scale invariance and applies it to models of the universe. His findings show we do not need dark matter and dark energy to explain the expansion of the universe. His model predicts an accelerated expansion of the universe without dark energy. It can also be used to explain the speeds of galaxies and stars within them—meaning dark matter is unnecessary too.
“The announcement of this model, which at last solves two of astronomy's greatest mysteries, remains true to the spirit of science: nothing can ever be taken for granted, not in terms of experience, observation or the reasoning of human beings," he said.
The findings, however, are likely to be questioned by other physicists. Previous research suggesting dark matter and dark energy do not exist has been largely dismissed by the wider scientific community.
Concluding, Maeder says the research now needs to be expanded with further study: “If true, the hypotheses we made have many other implications in astrophysics and cosmology,” he wrote. “For now these cosmological models evidently need to be further thoroughly checked with many other possible astrophysical tests in order to confirm or infirm them.”