Dark energy is real, say astronomers

A visual impression of the data used in the study representing the relevant extra-galactic maps as shells of increasing distance from Earth from left to right. The closest thing we see is our Milky Way galaxy, which is a potential source of noise for scientists’ analysis. After this, we see six shells containing maps of the millions of distant galaxies used in our analysis. These maps are produced using different telescopes in different wavelengths, and are colour-coded to show denser clumps of galaxies as red and under-dense regions as blue. There are holes in the maps due to data quality cuts. The last, largest shell shows the temperature of the cosmic microwave background from the WMAP satellite (red is hot, blue is cold), which is the most distant image of the Universe we can see, some 46 billions light-years from us. Scientists on this study have detected (at 99.996% significance) very small correlations between these foreground maps (on the left) and the cosmic microwave background (on the right). Image credits: Earth: NASA/BlueEarth; Milky Way: ESO/S. Brunier; CMB: NASA/WMAP

A visual impression of the data used in the study representing the relevant extra-galactic maps as shells of increasing distance from Earth from left to right. The closest thing we see is our Milky Way galaxy, which is a potential source of noise for scientists’ analysis. After this, we see six shells containing maps of the millions of distant galaxies used in our analysis. These maps are produced using different telescopes in different wavelengths, and are colour-coded to show denser clumps of galaxies as red and under-dense regions as blue. There are holes in the maps due to data quality cuts. The last, largest shell shows the temperature of the cosmic microwave background from the WMAP satellite (red is hot, blue is cold), which is the most distant image of the Universe we can see, some 46 billions light-years from us. Scientists on this study have detected (at 99.996% significance) very small correlations between these foreground maps (on the left) and the cosmic microwave background (on the right). Image credits: Earth: NASA/BlueEarth; Milky Way: ESO/S. Brunier; CMB: NASA/WMAP

Dark energy, a mysterious substance thought to be speeding up the expansion of the Universe is really there, according to a team of astronomers at the University of Portsmouth and LMU University Munich.

After a two-year study led by Tommaso Giannantonio and Robert Crittenden, scientists conclude that the likelihood of its existence stands at 99.996 per cent. Their findings are published in the journal Monthly Notices of the Royal Astronomical Society and appear on astro-ph e-print service today.

Professor Bob Nichol, a member of the Portsmouth team, said: “Dark energy is one of the great scientific mysteries of our time, so it isn’t surprising that so many researchers question its existence.

“But with our new work we’re more confident than ever that this exotic component of the Universe is real – even if we still have no idea what it consists of.”

Over a decade ago, astronomers observing the brightness of distant supernovae realised that the expansion of the Universe appeared to be accelerating. The acceleration is attributed to the repulsive force associated with dark energy now thought to make up 73 per cent of the content of the cosmos. The researchers who made this discovery received the Nobel Prize for Physics in 2011, but the existence of dark energy remains a topic of hot debate.

Many other techniques have been used to confirm the reality of dark energy but they are either indirect probes of the accelerating Universe or susceptible to their own uncertainties.  Clear evidence for dark energy comes from the Integrated Sachs Wolfe effect named after Rainer Sachs and Arthur Wolfe.

The Cosmic Microwave Background, the radiation of the residual heat of the Big Bang, is seen all over the sky. In 1967 Sachs and Wolfe proposed that light from this radiation would become slightly bluer as it passed through the gravitational fields of lumps of matter, an effect known as gravitational redshift.

In 1996, Robert Crittenden and Neil Turok, now at the Perimeter Institute in Canada, took this idea to the next level, suggesting that astronomers could look for these small changes in the energy of the light, or photons, by comparing the temperature of the radiation with maps of galaxies in the local Universe.

In the absence of dark energy, or a large curvature in the Universe, there would be no correspondence between these two maps (the distant cosmic microwave background and relatively closer distribution of galaxies), but the existence of dark energy would lead to the strange, counter-intuitive effect where the cosmic microwave background photons would gain energy as they travelled through large lumps of mass.

The Integrated Sachs Wolfe effect was first detected in 2003 and was immediately seen as corroborative evidence for dark energy, featuring in the ‘Discovery of the year’ in Science magazine. But the signal is weak as the expected correlation between maps is small and so some scientists suggested it was caused by other sources such as the dust in our galaxy. Since the first Integrated Sachs Wolfe papers, several astronomers have questioned the original detections of the effect and thus called some of the strongest evidence yet for dark energy into question.

In the new paper, the product of nearly two years of work, the team have re-examined all the arguments against the Integrated Sachs Wolfe detection as well as improving the maps used in the original work. In their painstaking analysis, they conclude that there is a 99.996 per cent chance that dark energy is responsible for the hotter parts of the cosmic microwave background maps (or the same level of significance as the recent discovery of the Higgs boson).

“This work also tells us about possible modifications to Einstein’s theory of General Relativity”, notes Tommaso Giannantonio, lead author of the present study.

“The next generation of cosmic microwave background and galaxy surveys should provide the definitive measurement, either confirming general relativity, including dark energy, or even more intriguingly, demanding a completely new understanding of how gravity works.”

4 total comments on this postSubmit yours
  1. Very recently there have been unexpected advances in understanding dark energy. In fact if the claim of the Egyptian Scientist M. S. El Naschie is correct, then there is no more a mystery regarding dark energy. El Naschie’s solution is disarmingly simple and was presented at two conferences which were almost entirely devoted to his work. The first was held in Bibliotheca Alexandrina early October 2012 and the second was in Shanghai a week or so ago. On both occasions El Naschie presented a revision of Einstein’s theory leading to an equation very similar to that of Einstein’s namely Energy equals mass x the square of the speed of the light. However unlike Einstein’s equation, the result is divided by 22. His explanation of 22 is as follows: As in the old string theory of strong interaction, space time of relativity should have been considered 26 dimensional. Taking 4 only is what Einstein did and that is how he got his famous result. Nevertheless Einstein ignored 22 dimensions. This is a scaling factor following Nottale’s theory as argued by El Naschie. Even in simpler terms, he reasons that Einstein knew only one elementary messenger particle namely the photon. He knew nothing about the other 11 messenger particles of the standard model which were not known in 1905. Adding 11 super partners it turned out that Einstein did not know about an additional 22 elementary particles. These are the particles needed to explain the missing dark energy. In this way El Naschie was able to show that 95.5% of the energy of the Universe is missing. Alternatively this energy was never there to start with because space time is a fractal and although it looks puffed up it boils down to very little similar to cotton candy. In addition the compactified 22 dimensions are the cause for the negative pressure which increases the acceleration of the Universe’s expansion. He claims to have tested his theory using 25 different methods including Witten’s M-Theory and reached the same result. Even more importantly this result agrees completely with observation. In other words mathematics and physics have been substantiated by measurement which led last year to the award of the Nobel Prize to the 3 team who obtained this incredible measurement and data. Click on this link to get more info re the above (under news) http://www.msel-naschie.com/ and also http://mohamed-elnaschie.blogspot.com/.

  2. I understand where Prof. Bob Nichol is coming from but I also sympathize with the intrinsic truth of what Haddad wrote about Mohamed El Naschie’s theory. In essence both are correct on a deep philosophical level. El Naschie simply revised Einstein’s famous equation by dividing the total energy by 22. He gave convincing arguments that the inverse of 22 is a missing factor in Einstein’s energy mass relation. On the other hand we have to remember that this 22 came from real things in a sense. The 22 is what remained from the 26 bosonic string dimensions. El Naschie supposed that they really exist. Highly compactified dimensions if they exist are surely real. The effect on the final numerical value of the energy is in agreement with measurement. The inverse of 22 is about 4.5% of what the simple classical equation of Einstein wrongly predicted. Ontologically as Mohamed El Naschie argued it is the same situation or is it? You say that dark energy does not exist but 22 compacitifed dimensions exist is tautology compared to saying dark energy exists but the 22 compactified dimensions do not exist. The simplest way out is to stick to old fashioned science. El Naschie has a formula which is very similar to Newton’s Kinetic energy which in turn is very similar to Einstein’s energy. The only difference is the scaling factor and the constancy of the speed of light. Then we have measurement which agrees with the new formula and is identical with Einstein’s except for dividing by 22. There is a rational explanation for the 22 in terms of compactified dimensions or in terms of 11 bosons which Einstein did not know about in 1905 when he conceived of his theory. When a theory agrees with experiment then it is correct in the old fashioned sense as long as there is a rational mathematical explanation for the new theory. That way two opposed views could be seen as different philosophical ways of looking at the same situation. Click on this link for more info: http://mohamed-elnaschie.blogspot.com and http://msel-naschie.com

  3. Some are of the opinion that dark energy interpreted as the effect of true vacuum is incompatible with super symmetry. I differ on this point. If the comment of Nader and his interpretation of the Egyptian Professor Mohamed El Naschie is correct then there is ample room for super symmetry as well as vacuum being the real thing behind dark energy. A pack of envelope analysis can convince us of this fact with unheard of simplicity. Take Newton’s kinetic energy and scale it as follows: we have 11 missing bosons from Einstein’s one degree of freedom special relativity and then take the super partner and add them to the 11 then you have 22. Here again we have the inverse of 22 as the magical scaling which El Naschie proposed following presumably Laurent Nottale and before Nottale many others. The accelerated expansion is clearly because of an intrinsic curvature which has nothing to do with matter. This intrinsic curvature increases as far as the 22 compacitifed dimensions of strings is concerned, as much as we expand. The more expansion the more the 22 dimensions curl up and the more repulsive gravity we obtain. What happens after that is not clear from the comment of Nader above and from my superficial reading of El Naschie as well. So far El Naschie’s theory seems to be persuasive. I agree however that the most persuasive point is the agreement between his theory and the cosmological measurement which in a sense uses the entire universe as a laboratory. Curiously no one has ever tested Einstein’s original equation experimentally. This may be due to a myth that Einstein’s equation Energy equals to the mass multiplied by the square of the velocity of light has anything to do with atomic reactors or the atomic bomb. In both cases there is no direct conversion of matter into energy. It is a fundamental misunderstanding of Einstein’s equation to think otherwise in the context of atomic energy. Some textbooks on the subject are misleading. One should read only the masters on this point such as: Wolfgang Rindler and Penrose.

  4. if thr universe is only 14 billion years old how can we see the most distant image at 46billion light years?

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