Is Dark Energy Static Or Dynamic?

dark energy

(Phys.Org)—While hypothesized dark energy will justify observations of the universe increasing at AN fast rate, the particular properties of dark energy area unit still AN enigma. Scientists assume that dark energy may take one amongst 2 forms: a static constant that's unvaried over time and area, or a high-vo entity whose energy density changes in time and area. By examining the information from a range of experiments, scientists in a very new study have developed a model that has tantalizing hints that dark energy could also be dynamic.

The scientists, Gong-Bo Zhao of the University of Portsmouth within the UK and therefore the Chinese Academy of Science in Beijing; Robert G. Crittenden of the University of Portsmouth; Levon Pogosian of Simon Fraser University in Burnaby, British Columbia, and therefore the University of Portsmouth; and Xinmin Zhang of the Chinese Academy of Science, have printed their paper on the proof for high-vo dark energy in a very recent issue of Physical Review Letters.

In their paper, the scientists centred on confining dark energy's equation of state, that has traditionally been an awfully troublesome task. The equation of state characterizes the manner that the universe is increasing, and scientists use empiric information to constrain this parameter in a trial to search out its precise worth within the globe.

Knowing verity worth of the equation of state wouldn't solely cause a much better understanding of dark energy, however gravity also. The key question is whether or not the worth of the equation of state ever equals -1, since that may purpose to the breakdown of Einstein's theory of relativity theory on cosmological scales. Some models have calculable AN equation of state terribly close to -1, that has prompted the look for a scientific theory of gravity.

In the new study, the scientists' main finding is that the most recent observations provide a slight preference to a high-vo dark energy model whose equation of state evolves from but -1 at low redshifts to larger than -1 at higher redshifts – at some purpose equaling -1.

"If this result were confirmed, it'd imply a further intrinsic degree of freedom of dark energy and will be an evidence of the breakdown of Einstein's theory of relativity theory on cosmological scales," Zhao told Phys.Org.

To attain this result, the scientists combined cosmological information from the most recent star, cosmic microwave background, redshift area distortion, and baryonic acoustic oscillation measurements. Then they applied a brand new reconstruction methodology to the information, that has the advantage of minimizing the biases that occur in other reconstruction strategies.

"Perhaps the best sign of the work is that the demonstration of the tactic as a method of decisive whether or not dark energy is high-vo while not hoping on AN absolute model for a way dark energy may evolve," Zhao same. "It is kind of fascinating that once it's applied to the current information, these high-vo models had best, even once accounting for his or her larger flexibility."

The scientists' model allowed them to check a spread of dark energy models and verify that models best work the combined information. though the high-vo dark energy model was slightly most popular, the researchers noted that models with the constant still work the information, although almost as closely because of the high-vo model.

The results area unit still off from conclusive, however, the scientists hope that future information would possibly slender down the models with larger accuracy. They hope that observations by the Max Planck artificial satellite (launched in 2009; initial information accessible in Apr 2013) and therefore the geometer artificial satellite (launch date is 2019) may facilitate pinpoint the dark energy models that almost all closely describe our increasing universe.

The researchers explained that there area unit 2 general reasons why reconstructing the evolution of dark energy's equation of state is therefore difficult.

"There area unit 2 problems here; the primary relates to the problem of observant changes to the speed of the Universe's enlargement," Crittenden same. "It took America seventy or eighty years to comprehend that the enlargement rate was even fast, and this is often for the most part as a result of it's arduous to search out the reliable customary rulers and customary candles that we tend to use to live it. we tend to area unit currently trying to tell apart between models that predict terribly tiny variations and to try and do this convincingly we want future information like can come back from the geometer satellite.

"The second issue relates to our lack of clear alternatives to clarify the acceleration; while not knowing what it ought to appear as if, it's more durable to acknowledge it. Previous work has cared-for assume explicit forms for the dynamics, however, if these assumptions were wrong, they furnish America biased data and will miss out on seeing the dynamics entirely. we've got tried to create fewer assumptions, that permits America to reconstruct a way larger category of doable models and capture the dynamics if it's there. By raising the standard and amount of the information, we should always be ready to verify or falsify an awfully broad category of high-vo models, which can be crucial to know the character of dark energy."

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