Throwing light on the dark side of the Universe

October 21, 2008

Although we may believe humans know a lot about the Universe, there are still a lot of phenomena to be explained. A team of cosmologists from the University of the Basque Country, Spain, are searching for the model that best explains the evolution of the Universe.

We usually have an image of scientists who study the Universe doing so peering through a telescope. And, effectively, this is what astrophysicists do: gather data about the observable phenomena of the Universe. However, in order to interpret this data, i.e. 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: analysing models capable of explaining the evolution of the Universe.

Supernovas, witnesses to acceleration

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. Supernovas are very brilliant stellar explosions that, precisely due to this, provide useful data for exploring very distant regions of the Universe. 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.

Looking for dark energy

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% of the energy of the Universe is dark. The dark energy debate is not just any theory: its existence has not been proved but, without it, standard models of physics would not be able to explain many of the phenomena occurring in the Universe.

So, what is dark energy exactly? What are its characteristics and have these properties always been the same or have they changed over time? These are questions, amongst others, that researchers at the Faculty of Science and Technology at the UPV/EHU, under the direction of Dr. Alexander Feinstein, are seeking to answer.

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. Nevertheless, this phenomenon can only be detected when achieving observationally enormous, almost unimaginable distances. This is why it is so difficult to understand the nature of dark energy.

The theory of phantom energy

To what point can the Universe expand? If this repulsive force is ever more intense, might it be infinite? This is one of the problems that the UPV/EHU researchers are focusing on. 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. Amongst other things, the team has come to this conclusion after analysing the distribution of galaxies and the background microwave radiation which has inundated all of the Cosmos since shortly after the Big Bang. These waves travel in every direction and enable the exploration of what occurred at tremendously remote instants in time, moments close to the start of it all.

Source: Elhuyar Fundazioa, Spain

Explore further: High-altitude observatory sheds light on origin of excess anti-matter

Related Stories

Lava or not, exoplanet 55 Cancri e likely to have atmosphere

November 16, 2017

Twice as big as Earth, the super-Earth 55 Cancri e was thought to have lava flows on its surface. The planet is so close to its star, the same side of the planet always faces the star, such that the planet has permanent day ...

Three-dimensional nanomagnets for the computer of tomorrow

November 15, 2017

Since the late 1960's, electronic devices have stored and transmitted information (bits) in two-dimensional circuits. Now, researchers at the University of Cambridge have created a nanoscale magnetic circuit capable of moving ...

Open-source software for data from high-energy physics

October 31, 2017

Most of the universe is dark, with dark matter and dark energy comprising more than 95 percent of its mass-energy. Yet we know little about dark matter and energy. To find answers, scientists run huge high-energy physics ...

Recommended for you

Study shows how to get sprayed metal coatings to stick

November 21, 2017

When bonding two pieces of metal, either the metals must melt a bit where they meet or some molten metal must be introduced between the pieces. A solid bond then forms when the metal solidifies again. But researchers at MIT ...

Imaging technique unlocks the secrets of 17th century artists

November 21, 2017

The secrets of 17th century artists can now be revealed, thanks to 21st century signal processing. Using modern high-speed scanners and the advanced signal processing techniques, researchers at the Georgia Institute of Technology ...

Physicists design $100 handheld muon detector

November 20, 2017

At any given moment, the Earth's atmosphere is showered with high-energy cosmic rays that have been blasted from supernovae and other astrophysical phenomena far beyond the Solar System. When cosmic rays collide with the ...

A curious quirk brings organic diode lasers one step closer

November 20, 2017

Since their invention in 1962, semiconductor diode lasers have revolutionized communications and made possible information storage and retrieval in CDs, DVDs and Blu-ray devices. These diode lasers use inorganic semiconductors ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Alexa
1 / 5 (2) Oct 29, 2008
By aether Wave Theory (AWT) the Universe appears as being formed by nested density fluctuations of hypothetical inhomogenenous environment of infinite mass and energy density (Aether) and it can be observed via these density fluctuations as well. This approach brings a nonlinearity as a necessary consequence of every observation. We can compare it to the observation of laser ray in atmosphere: if air will be completelly clear, we could see anything because of lack of dispersion. If it will be too foggy, we could see anything as well, because of obscuration. It means, a certain optimal level of dispersion is always related to every observation of reality, despite the scale.

From this point of view we are observing a Universe fluctuations, particles, stars etc... through vacuum like through inhomogeneous bumpy glass, which distorts the objects appearance, the more, the more distant these objects are. This makes an illusion of omnidirectional Universe expansion for us and the acceleration of this expansion (i.e. the dark energy) as well. The existence of dark matter can be understood easily by this approach as well: if space-time expands omnidirectionally, then the light from remote gallaxies is spreading through space by gradually slower speed (compare the "tired light" concept), which makes an observational illusion of presence of thick vacuum surrounding these galaxies, i.e. the presence of dark matter is the same consequence of Universe expansion, like the so called red-shift of remote gallaxies, it's just being observed from another remote perspective.

Was such explanation clear for you?
Alexa
1 / 5 (2) Oct 29, 2008
By AWT the underlying logic of different physical theories is mutually connected by correspondence principle into the same nested foam, like the Aether density fluctuations, so we can derive a virtually infinite number of dual or even plural explanations/intepretations of the same phenomena.

By AWT gravitational field is direct consequence of Universe expansion, the acceleration following from gradient of expanding vacuum density in particular. So we can use a different approach for dark matter explanation: the gradient field of every massive object is behaving like less or more dense blob of vacuum density, surrounding the object. This blob is behaving like mercury droplet and it exhibits the energy of surface tension. At the high energy density/large distance scales the surface tension of gravity field cannot be neglected furthemore, so it will behave like saponate foam and it will create a large streaks of dark matter.

The modified Einstein's field equation can lead to the same result. How? By general relativity theory every space-time curvature is related to certain energy density by Einstein field equation and every energy density is related to certain mass density by E=mc^2 equation. At the high energy/large distances the energy density of space-time curvature cannot be neglected furthemore and it generates an aditional gravity field, which is compensating the action of original gravity field in certain extent (compare the Yilmaz and/or Heim or MOND theories).

Therefore every gravitational field is surrounded by certain calibration field, which manifests itself like spherical cloud of so called dark matter. At the case, the central massive object is rotating, this cloud is of torroidal shape and it affects the light spreading and/or the motion of another massive objects (Pioneer anomaly, Allais effect and rings of dark matter surrounding the galactic clusters in the motion).

In certain extent, dark matter phenomena is the manifestation of gravity quantization and Lorentz symmetry violation, as we can explain later, if you're interested about it.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.