New theory rejects dark energy

Dark energy, the mysterious resource that came out more than a decade ago to explain why the universe is separating at a faster rate, is no longer needed.

That is the conclusion of a new controversial theory that the rapid expansion of the universe is just an illusion.

What is dark energy?

In Physics of Cosmology and Astronomy, dark energy is an unknown form of energy that accounts for most of the universe and tends to speed up the expansion of the universe. Dark energy is the most accepted theory since the 1990s, indicating that the universe is expanding with increasing speed. According to the Planck team and based on the standard cosmology model, the relative ratio of matter-energy, the visible universe contains 26.8% dark matter, 63.8% dark energy (total 95.1%) with matter usually only accounts for 4.9%. Again, according to the relative energy-to-energy ratio, the density of dark energy (6.91 x 10-27 kg / m3) is very low, even lower than the density of ordinary matter and dark matter in the galaxy. Even so, it dominates the matter-energy of the Universe because it is spread throughout space.

In the new study, two mathematicians presented their solution to Einstein's general equations. This equation is used to describe the relationship between gravity and matter.

This study suggests that our galaxy lies inside a large area of ​​space that the density of matter is abnormally low due to a wave of pre-Big Bang running through the universe.

From our point of view, galaxies other than this area seem to have moved farther than predicted, while in fact they are still in place.

'If accurate, these solutions could explain the rapid expansion of galaxies without the need for dark energy,' said the lead author of the study, Blake Temple of the University of California, Davis. said.

Other experts assess that removing dark energy from cosmic models is commendable. But they also stressed that the new theory could break the foundation of modern cosmology and is something that astronomers cannot accept.

Replace for dark energy

Until 1998, astronomers believed that gravity would slow down the cosmic expansion created by the Big Bang.

That year two independent research groups published data showing that the expansion of the universe is rapidly increasing.

Both research groups observed light from supernovae farther away than expected - suggesting that these star-forming explosions are farther away than their former location if the universe was only affected by gravity alone.

To explain this observation, astronomers began to use the idea of ​​dark energy, a cosmic thrust that is expanding the space-time structure.

However, over 10 years later, no one has dared to assert what the nature of dark energy is - or whether it really exists.

To find an alternative to dark energy, other scientists have proposed a new version of the theory that our galaxy lies in an extended wave, the space band with low density.

Wavy effect

Temple and his colleague, Joel Smoller of the University of Michigan, were the first to provide a mechanism for the formation of such a wave.

Their theory, published this week in the Proceedings of the National Academy of Sciences, shows how big bang has created a large-scale life in space - time called density waves.

When this primitive wave runs in the universe, it leaves low-density ripple with dynamics tens of millions of light-years across, and now envelops the Milky Way.

Meanwhile, matter trapped in front of this wave is pushed out, teleporting to its original position.

This has changed the position of later matter to form stars and galaxies.
When the light of these objects finally reaches Earth, it is dimmer than the original predictions, because these objects are farther away from us if the density wave does not pass through them.

This hypothesis explains why the supernova described in 1998 lies so far away from us.

Combined

However, such a model can violate the very popular theory in cosmology called the Copernican principle.

This theory states that the universe is homogeneous - when viewed comprehensively the different parts of the universe look exactly the same.

The Copecnich principle is assumed to come from Einstein's widely accepted equation, Friedmann-Robertson-Walker space-time space.

'We want uniformity in the equation, because that's what we see in the sky,' said Dragan Huterer, an astrophysicist at the University of Michigan but not involved in the new study. said.

In contrast, Smoller and Temple do not use the Copernican principle because the material inside the ripple has a lower density than the outer material.

The authors of the study emphasize that there is a way that their theory does not go against the Copernican principle: If the big bang's density wave creates many layers of ripple.

In this case, the space still has the same outer appearance when viewed from a far enough point.

The dose is hard to swallow

For astronomers who are really serious about this idea, the new model needs to explain the growing number of observations that favor the dark energy hypothesis.

Huterer said : 'It is not clear whether this model is suitable for data. At the present time, all the statements we have made have the word 'maybe'.

But even when the theory of density waves undergoes tests and experiments, eliminating the idea of ​​a homogeneous universe would be a hard-to-swallow medicine for astronomers.

'The cost is a violation of the Copernican principle, and at the same time a very special structure of the initial state of the universe,' said Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics in Massachusetts.

'So many cosmologists think that such proposals are very difficult to be accepted'.

In addition, new research questions are also questioned like the concept of dark energy.

Huterer said: 'You will have to wonder why we're in the middle of this ripple? Why not another place? '