Team simulates the expansion of the Universe

March 7, 2016
The gravitational waves generated during the formation of structures in the universe are shown. The structures (distribution of masses) are shown as bright dots, gravitational waves by ellipses. The size of the ellipse is proportional to the amplitude of the wave and its orientation represents its polarization. Credit: © Ruth Durrer, UNIGE

The Universe is constantly expanding. It changes, creating new structures that merge. But how does our Universe evolve? Physicists at the University of Geneva (UNIGE), Switzerland, have developed a new code of numerical simulations that offers a glimpse of the complex process of the formation of structures in the Universe. Based on Einstein's equations, they were able to integrate the rotation of space-time into their calculations and calculate the amplitude of gravitational waves, whose existence was confirmed for the first time on February 12, 2016. The study is published in the journal Nature Physics.

Until now, scientists studied the formation of large-scale cosmological structures based of Newtonian gravitation. These codes postulate that space itself does not change, it is said to be static, while time goes on. The simulations that it allows are very precise if the matter in the Universe moves slowly (i.e., about 300 km per second). However, when the move at high speed, this code only allows approximate calculations. Furthermore, it does not describe the fluctuations of . Constituting 70% of the total energy of the Universe (the remaining 30% is made of dark matter and ordinary matter), it is responsible for the accelerated expansion of the Universe. Therefore, it was necessary to find a new way to simulate the formation of cosmological structures and allow the study of these two phenomena.

The theory of general relativity applied

Ruth Durrer's team from the Department of Theoretical Physics in the Faculty of Science at UNIGE, has thus created a code, named gevolution, based on Einstein's Theory of general relativity. Indeed, general relativity considers space-time as being dynamical, that is to say that space and time are constantly changing, unlike the static space of Newtonian theory. The goal was to predict the amplitude and the impact of and frame-dragging (the rotation of space-time) induced by the formation of cosmological structures.

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Self-regulating calculations

To do so, the physicists from UNIGE analysed a cubic portion in space, consisting of 60 billion zones with each containing a particle (that is to say, a portion of a galaxy), in order to study the way they move with respect to their neighbors. Thanks to the LATfield2 library (developed by David Daverio from UNIGE), which solves nonlinear partial differential equations, and the Supercomputer from the Swiss Supercomputer Center in Lugano, the researchers were able to study the motion of particles and calculate the metric (the measure of distances and between two galaxies in the Universe) using Einstein's equations. The resulting spectra of these calculations allow to quantify the difference between the results obtained by gevolution and those coming from Newtonian codes. This allows to measure the effect of frame-dragging and gravitational waves introduced by the formation of structure in the Universe.

Gravitational waves and frame-dragging predicted by gevolution

Indeed, frame-dragging and gravitational waves have never been included in simulations until the creation of the gevolution code. This opens the way for the comparison of simulation results of the evolution of the Universe with observations. With their new code, the physicists at UNIGE will be able to test the theory of on much larger scales than at present. In order to open research to a maximum in this field, Professor Ruth Durrer and her team will make their gevolution code public. Perhaps soon light will be shed on the mysteries of dark energy.

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Elegant approach

Explore further: Light from galaxy clusters confirms theory of relativity

More information: General relativity and cosmic structure formation, DOI: 10.1038/nphys3673

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RealityCheck
1 / 5 (5) Mar 07, 2016
Even if the universe was not expanding, the timeline until the Earth was formed 4 billion years ago would mean that any nearby supernovae blasts directed at Earth would have passed by long ago. So. assuming only expansion 'cosmological constant' taking supernovae far enough away, is putting the conclusion before the logic. This seems to be another inadvertent confirmation biased 'exercise' and 'result' which had the conclusion built-in from the get-go. Why didn't they realize that their argument for expansion and then their conclusion of expansion is circuitous argument in this exercise/conclusion? How many times do we have to read about such mere assumptives-riddled, confirmation-biased, circuitous-argument-dependent 'exercises' as some sort of 'valid science results' which 'support' predetermined Big Bang/Expansion/Dark Energy speculation built into the 'exercise'? Time to rethink what they're doing and curb their confirmation bias before offering more of this GIGO stuff.
RealityCheck
1 / 5 (5) Mar 07, 2016
Oops. Posted to wrong thread. Now posted to correct thread; please see: http://phys.org/n...ant.html

Thanks.
Azrael
4.1 / 5 (9) Mar 08, 2016
Even if the universe was not expanding, the timeline until the Earth was formed 4 billion years ago would mean that I am a crackpot, and any nearby supernovae blasts directed at Earth would have passed by long ago. So. assuming only expansion 'cosmological constant' breaking English rather severely supernovae far enough away, is putting the conclusion before the logic that I am incapable of understanding. This seems to be another inadvertent confirmation biased 'exercise' and 'result' which I am an enormous dork, and a rabid lunatic....


...Let it go, mate.

swordsman
1 / 5 (2) Mar 08, 2016
This theory totally dependent on space-time variation theory that is flawed since it is based on the Minkowski relationship. Unfortunately, Minkowski made a big Boo-Boo in his interpretation of his equation. It is not a vector but it appears in the exponent of an eigenvector and is therefore and eigenvalue. This is verified by examining the equation for transverse radiation of electromagnetic waves. This is also a flaw in Einstein;s theory, which is based on the Minkowski equation. All they had to do was to simply plot the waveforms that are obtained from the antenna radiation model of electromagnetic radiation. All this money and effort for false results.
RealityCheck
1.6 / 5 (7) Mar 08, 2016
Hi Azrael. :)
I am an enormous dork, and a rabid lunatic....
I see your subconscious mind made a Freudian Slip there, mate. Never mind, your childish troll mentality will soon forget that you ever admitted it like that, and so proceed to repeat the Freudian Slips again and again in future useless posts from you. Take your hand off it, mate, or you'll grow up to be an even worse troll than you are at this juvenile stage. Let it go, mate. :)
compose
Mar 08, 2016
This comment has been removed by a moderator.
Captain Stumpy
3.7 / 5 (6) Mar 09, 2016
For further reading: New 'static universe' theory challenges the Big Bang, Observational evidence favors a static universe
@ZEPH
but you epically fail because Protoplasmix dealt with that here
A tired light "curvature cosmology", Zeph? That paper has 64 references, and not one of them is to the measurements made by WMAP showing how flat the universe is – as far as we can see in all directions, flat to within 0.4% margin of error. See NASA > Our Universe > Shape
http://map.gsfc.n...ape.html

read more at: http://phys.org/n...html#jCp
compose
Mar 09, 2016
This comment has been removed by a moderator.
torbjorn_b_g_larsson
4.2 / 5 (5) Mar 09, 2016
"How the flatness of universe is supposed to contradict the tired light hypothesis?"

"Tired light" doesn't work out of the box since observations out to ~ 6 kyrs (IIRC) suffice to reject it.

But even if was viable the current cosmology predicts what we see from a much smaller and more likely set of parameters. E.g. a flat universe predict a homogeneous universe, while there is no reason for the universe - without the current gravity mechanisms but instead Newton's magical immediate action - would be static and flat in the never successful 'static universe' models.

Give it a rest. Even if someone started to publish actual results in peer review we now know that the universe isn't static in the same way we know Earth isn't flat: we see too far, and static/flat isn't what we see.

And that is all anyone can say on that. It is balderdash, with a large pinch of buffoonery, and since it goes against observation it isn't even science. Keep the garbage at the crackpot sites.
viko_mx
1 / 5 (2) Mar 09, 2016
"The Universe is constantly expanding. It changes, creating new structures that merge."

How a person can know that when the universe is expanding cosmic structures merge, if do not read this article?
But this favorite mantra do not explain what of the universe is expanding? How can geometric space to expand when it does not physical properties?
viko_mx
1 / 5 (2) Mar 09, 2016
After the order ca not be defined without absolutes, the GR is wrong from the begining and the benefits of such kind of simulations is zero.
cantdrive85
1 / 5 (2) Mar 09, 2016
G-G-G-GIGO! An expansive amount of it...
SCVGoodToGo
3 / 5 (4) Mar 09, 2016
G-G-G-GIGO! An expansive amount of it...


Are you referring to the article or the nonsense you spout?

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