tagged w/ Dark Energy
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The book blurb for a new book called The New Universe and the Human Future urges humankind to gather together to write a new, globally-unifying story of the universe and our place in it, an endeavor the authors say is enabled by advancements in a branch of astrophysical science called cosmology.The book blurb for a new book called The New Universe and the Human Future urges... more
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Astronomers using NASA's Hubble Space Telescope have ruled out an alternate theory on the nature of dark energy after recalculating the expansion rate of the universe to unprecedented accuracy nixing the theory that an enormous bubble of relatively empty space eight billion light-years across surrounds our galactic neighborhood. If we lived near the center of this void, observations of galaxies being pushed away from each other at accelerating speeds would be an illusion.
Led by Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, the Hubble observations were conducted by the SHOES (Supernova Ho for the Equation of State) team that works to refine the accuracy of the Hubble constant to a precision that allows for a better characterization of dark energy's behavior.
The observations helped determine a figure for the universe's current expansion rate to an uncertainty of just 3.3 percent. The new measurement reduces the error margin by 30 percent over Hubble's previous best measurement of 2009.
The value for the expansion rate is 73.8 kilometers per second per megaparsec. It means that for every additional million parsecs (3.26 million light-years) a galaxy is from Earth, the galaxy appears to be traveling 73.8 kilometers per second faster away from us.
Every decrease in uncertainty of the universe's expansion rate helps solidify our understanding of its cosmic ingredients. Knowing the precise value of the universe's expansion rate further restricts the range of dark energy's strength and helps astronomers tighten up their estimates of other cosmic properties, including the universe's shape and its component of neutrinos, or ghostly particles, that filled the early universe.
"We are using the new camera on Hubble like a policeman's radar gun to catch the universe speeding," Riess said. "It looks more like it's dark energy that's pressing on the gas pedal."
Dark energy is one of the greatest cosmological mysteries in modern physics. Even Albert Einstein conceived of a repulsive force, called the cosmological constant, which would counter gravity and keep the universe stable. He abandoned the idea when astronomer Edwin Hubble discovered in 1929 that the universe is expanding. Observational evidence for dark energy didn't come along until 1998, when two teams of researchers (one led by Riess) discovered it.
This image at bottom of page shows the location of Cepheid variables found in the spiral galaxy NGC 5584. Ultraviolet, visible, and infrared data taken with Hubble's Wide Field Camera 3 in 2010 reveals Cepheids of varying periods. Those stars with periods of less than 30 days and between 30 and 60 days are marked with blue and green circles, respectively. A small number of Cepheids, with periods larger than 60 days, are marked in red.
The idea of dark energy was so far-fetched, many scientists began contemplating other strange interpretations, including the cosmic bubble theory.
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http://www.dailygalaxy.com/my_weblog/2011/03/epic-discovery-new-hubble-observations-nix-theory-that-an-enormous-bubble-eight-billion-light-years-.htmlAstronomers using NASA's Hubble Space Telescope have ruled out an alternate... more
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Researchers have developed a simple technique that adds evidence to the theory that the Universe is flat.Moreover, the method - developed by revisiting a 30-year-old idea - confirms that "dark energy" makes up nearly three-quarters of the Universe.
:http://www.bbc.co.uk/news/science-environment-11810553Researchers have developed a simple technique that adds evidence to the theory that... more
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suzane
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1 year ago
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In 1998, astrophysicists discovered a baffling phenomenon: the Universe is expanding at an ever-faster rate. Either an enigmatic force called dark energy is to blame or a reworking of gravitational theory is in order. In this new Science Bulletins video, watch a FermiLab team assemble the Dark Energy Camera, a device that could finally solve this space-stretching mystery.In 1998, astrophysicists discovered a baffling phenomenon: the Universe is expanding... more
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You’re looking at the heart of one of the biggest digital cameras ever conceived — 74 CCD sensors that will go into an enclosure the size of a Mini Cooper. The 570-megapixel shooter is being built at Fermilab by an international team of particle physicists and astronomers, who think it will help solve one of the great mysteries of the cosmos: What is dark energy?
Of course, we don’t really know whether dark energy even exists. What we do know is that the universe has been expanding since the big bang. But rather than slowing down like everything else fighting gravity’s pull, this expansion seems to be speeding up. Something must be causing this, and astronomers call that something dark energy. The hope is that scientists can use detailed photos to chart the light from galaxies and supernovas, which will show the growth of the cosmos and at least give them more evidence for the existence and effect of dark energy.
Once the $35 million rig is complete, astronomers will mount it to a telescope in Chile and, over the course of five years, use it to map some 300 million galaxies. It gives a whole new meaning to shooting stars.You’re looking at the heart of one of the biggest digital cameras ever conceived... more
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Mathematicians have proposed an alternative explanation for the accelerating expansion of the universe that does not rely on the mystifying idea of dark energy.
According to the new proposition, the universe is not accelerating, as observations suggest. Instead, an expanding wave flowing throughout space-time causes distant galaxies to appear to be accelerating away from us. This big wave, initiated by the Big Bang that is thought to have sparked the universe, could explain why objects appear to be farther away from us than they should be according to the Standard Model of cosmology.
"We're saying that maybe these expanding waves are actually causing the anomalous acceleration," said Blake Temple of the University of California, Davis. "We're saying dark energy is not really the correct explanation."
The researchers derived a set of equations describing expanding waves that fit Einstein's theory of general relativity, and which could also account for the apparent acceleration. Temple outlines the new idea with Joel Smoller of the University of Michigan in the Aug. 17 issue of the journal Proceedings of the National Academy of Sciences.
While more research will be needed to see if the idea holds up, "the research could change the way astronomers view the composition of our universe," according to a summary from the journal.Mathematicians have proposed an alternative explanation for the accelerating expansion... more
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"There is an awful lot of it about but what it is remains the "most profound mystery in science", says the man who gave it its name: dark energy.
This weird, invisible force that is pushing the galaxies apart at a faster and faster rate accounts for almost three-quarters of the universe, the University of Chicago cosmologist Michael Turner said yesterday.
"It's very different than anything else we know," Professor Turner, who was attending a conference in Canberra, said. "Until we understand what dark energy is, we don't understand the destiny of the universe."
Yesterday astronomers using the Hubble Space Telescope released the most accurate measurement so far of the expansion rate of the universe, based on observations of pulsating stars and recent exploding stars, called type 1a supernovas.
Adam Reiss, of Johns Hopkins University, said his team's results narrowed the possibilities for dark energy.
They supported the simplest idea about the repulsive force: that it was very similar to the cosmological constant Albert Einstein proposed a century ago to explain why the universe did not collapse under the pull of gravity.
Professor Turner said dark energy had some remarkable characteristics.
"It seems to be smoothly distributed throughout the universe," he said.
"The feature that gives it repulsive gravity is that it is extraordinarily elastic. It wants to scrunch up."
Professor Schmidt, of the Australian National University, said the cosmic acceleration meant "the universe is slowly fading away on us".
Much more at link, check it out! Mysterious indeed!"There is an awful lot of it about but what it is remains the "most profound... more
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Physicists can't see it and don't know much about what it is, but dark energy makes up 70 percent of the universe. Meet one of the country's leading scientists trying to understand dark energy and the role it plays in causing our universe to expand.Physicists can't see it and don't know much about what it is, but dark... more
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Discovery-News.com: The Sun is the best known star in our solar system, but how much do you really know about it? Dave Mosher asks three burning questions.
For more space news stories, check out http://dsc.discovery.com/spaceDiscovery-News.com: The Sun is the best known star in our solar system, but how much... more
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"NASA held a phone-in press conference today wherein three astrophysicists reported the latest findings on dark energy. They have now "clearly seen" the effects of dark energy on the most massive collapsed objects in the universe. This new evidence has aligned scientists behind the central belief that 1) dark energy exists, 2) that it explains why we are seeing the universe expanding and accelerating, and 3) that Einstein's General Relativity theory is correct - so long as the cosmological constant is applied (something Einstein himself called his "greatest blunder")."
Look at that chart! Talk about feeling small in the universe, huh?"NASA held a phone-in press conference today wherein three astrophysicists... more
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Discovery-News.com: New findings bolster the argument that dark energy is the reason our universe is expanding. James Williams explores the evidence.
For more space news stories, check out http://dsc.discovery.com/spaceDiscovery-News.com: New findings bolster the argument that dark energy is the reason... more
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Dark energy maybe expanding the universe, but at the same time it is also stopping the growth of galaxies within it.
Excerpt:
The same mystery force that is speeding up the expansion of the universe is also stunting the growth of the objects inside it, astronomers said on Tuesday.
After bulking up rapidly in the first 10 billion years of cosmic time, clusters of galaxies, the cloudlike swarms that are the largest conglomerations of matter in the universe, have grown anemically or not at all during the last five billion years, like sullen teenagers who suddenly refuse to eat.Dark energy maybe expanding the universe, but at the same time it is also stopping the... more
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Washington, Oct 22 : A team of cosmologists from the University of the Basque Country has determined that the accelerated expansion of the Universe can be explained by dark 'phantom' energy.
To explain the majority of the phenomena occurring in the Universe, complicated calculations with a computer are required and which have to be based on appropriate mathematical models.
This is what the Gravitation and Cosmology research team at the University of the Basque Country (UPV/EHU) is involved in: analyzing models capable of explaining the evolution of the Universe.
One of the phenomena that standard models of physics have not yet been able to explain is that of the accelerated expansion of the Universe.
Although Einstein proposed a static model to describe the cosmos, today it is well known, thanks to supernovas amongst other things, that it is, in fact, expanding.
By measuring the quantity of light that gets to us from a supernova, we can calculate its distance from us, and its colour indicates the speed at which it is distancing itself from us.
The more reddish it is, the faster it is travelling. In other words, comparing two supernovas, the one that is distancing itself more slowly from us is a more bluish colour.
According to observations by astrophysiscists, besides supernovas distancing themselves from us, they are doing so more and more rapidly, i.e. distancing themselves at an accelerated velocity, just like the rest of the material of the Universe.
The energy known to exist in the Universe, however, is not sufficient to cause such acceleration.
Thus, the theory most widely accepted within the scientific community is that there exists a 'dark energy', i.e. an energy that we cannot detect except by the gravitational force that it produces.
In fact, it is believed that 73 percent of the energy of the Universe is dark.
The unique characteristic of dark energy known to us is that it possesses repulsive gravitational force. That is, unlike the gravity we know on Earth, this force tends to distance stars, galaxies and the rest of the structures of the Universe from each other.
This would explain why the expansion of the Universe is not constant, but accelerated.
Such powerful dark energy is known as phantom energy, with which the Universe is able to expand to such an extent that the structures we know today would disappear.
This research group considers that the phantom energy model may be the most suitable to explain the accelerated expansion of the Universe. Washington, Oct 22 : A team of cosmologists from the University of the Basque Country... more
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An orbiting observatory has spotted a massive cluster of galaxies in deep space that can only be explained by the exotic phenomenon known as dark energy, the European Space Agency (ESA) said on Monday.
Spotted in a scan by ESA's orbiting X-ray telescope XMM-Newton, the cluster's mass is about 1,000 times that of our own galaxy, the Milky Way, it said.
The huge cluster, known by its catalogue number of 2XMM J083026+524133, lies 7.7 billion light-years from Earth and helps confirm the existence of dark energy, the agency said.
Under this hypothesis, most of the universe comprises "dark energy," an enigmatic force that is causing the expansion of the cosmos to accelerate.
The outward drive of dark energy is such that, in more recent times, massive galaxy clusters have lacked the gravitational glue to be able to form.
So the newly-discovered super-cluster can only have been formed earlier in the history of the universe, a notion that is backed by its huge distance from Earth.
"The galaxy cluster is so big that there can only be a handful of them at that distance," said ESA, likening the achievement to finding a "cosmic needle in a haystack."
The observation was made by a team led by Georg Lamer of the Potsdam Astrophysics Institute, eastern Germany, initially using a photon imaging camera aboard the XMM-Newton.
Intrigued by the indicators of scorching gases spewed out by X-ray sources, the astronomers followed up by getting a deep exposure image of the region from a large binocular telescope in the Arizona desert.
"Dark energy" is believed to comprise more than 72 percent of the detected universe and "dark matter" -- heavy particles still waiting to be discovered -- accounts for around 23 percent, according to cosmological theory.
That leaves less than five percent of normal, or baryonic, matter, the category for the protons and neutrons that compose it.
An orbiting observatory has spotted a massive cluster of galaxies in deep space that... more
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10. The WOW! signal
9. Pioneer's Funky Voyage
8. Female Orgasms
7. Dark Energy
6. The Speed of Light
5. The Placebo Effect
4. Cold Fusion
3. Yawning
2. Dark Matter
1. What Came Before, What Will Come After
10. The WOW! signal
9. Pioneer's Funky Voyage
8. Female Orgasms... more
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