Science

Vanishing dark matter points to a dark future for our Universe

Vanishing dark matter points t...
Researchers suggest the Universe is destined to end up a desolate and nearly featureless place (Photo: Shutterstock)
Researchers suggest the Universe is destined to end up a desolate and nearly featureless place (Photo: Shutterstock)
View 1 Image
Researchers suggest the Universe is destined to end up a desolate and nearly featureless place (Photo: Shutterstock)
1/1
Researchers suggest the Universe is destined to end up a desolate and nearly featureless place (Photo: Shutterstock)

A study conducted at the University of Rome and the University of Portsmouth is suggesting that the amount of dark matter in the cosmos, the catalyst that facilitates the creation of new stars and galaxies, is decreasing as it interacts with dark energy. If this is true it would mean that, as time passes, the Universe could be destined to end up a desolate and nearly featureless place (even more so than it already is).

Since the days of Newton, we've known that gravity attracts ordinary matter closer together. Applied to the vastness of space, this means that the stars and galaxies in the Universe, though they are still traveling further and further apart in the wake of the Big Bang, should gradually slow down, come to a stop and eventually start collapsing toward each other.

But in 1998 when astronomers set out to measure the rate at which the expansion was slowing, they were in for a shock: the Universe, it turns out, is in fact increasing its rate of expansion – a discovery for which the scientists involved were later awarded the Nobel Prize in Physics.

The simplest (though not only) explanation, which is part of the currently accepted standard model of cosmology, is that the vacuum of space features an energy density that is constant both in space and time, a "dark energy" which is gravitationally repulsive and therefore counteracts the attractive effects of gravity, causing the cosmos to expand ever faster.

However, over the past few months, several cosmological surveys have cast doubts on the validity of this model. Cosmic microwave background experiments, such as ESA's Planck space telescope, have been able to precisely measure the parameters at the basis of the currently accepted model, and they have highlighted a few discrepancies. For instance, these parameters overestimate the speed at which galaxy clusters are growing.

Other galaxy surveys, such as the Sloan Digital Sky Survey, are measuring the gravitational potential of distant celestial bodies using so-called "redshift space distortions" and have cast further doubt on the validity of the currently accepted model.

Different theories have been advanced to resolve these discrepancies. One way to explain them would be to consider dark energy that changes slowly over time but does not interact with dark matter. A second possibility could be that neutrinos, electrically neutral subatomic particles, have a larger than expected mass. However, neither approach seems to provide a convincing solution.

Now, a new model advanced by researchers based in Italy and the UK appears to be the most promising yet.

"We found that the data prefer a model where the dark matter slowly loses energy to the dark energy," Prof. David Wands, who led the study, told Gizmag. "This naturally suppresses the growth of structure at late time. Our model gives a better fit to the redshift space distortions."

Prof. Wands tells us that dark matter is usually assumed to be non-interacting with ordinary matter and falls readily into initially overdense regions of the Universe, further increasing their density. Ordinary matter then falls into those same overdensities to form stars and galaxies, although the gravitational potential on large scales is dominated by dark matter, which makes up approximately 27 percent of the mass-energy in the Universe, versus the five percent of ordinary matter. In a sense, then, dark matter is the catalyst that allows new stars and galaxies to form.

"What we are seeing here, in these findings, suggests that dark matter is evaporating, slowing that growth of structure," says Wand. "If the dark energy is growing and dark matter is evaporating we will end up with a big, empty, boring universe with almost nothing in it."

The new model introduces a parameter to describe the transfer of energy from dark matter to dark energy, but does not attempt to explain why this might be happening.

"It remains an open question as to why this occurs, though there have been many attempts to model possible interactions in the dark sector and we could now be seeing evidence of this."

The team's findings appear in a study published in the journal Physical Review Letters.

Source: University of Portsmouth

7 comments
b@man
HAHAHA... flat earth thinkers again:) The universe is infinite and there was no big bang and no beginning, it just IS and always was. Gravity has a wave length in the neighborhood of 50 trillion light years and has properties of wave and particle, just as light does. The wave property accounts for the dark energy and the particle property accounts for dark matter. "Infinite Wave Theory". It's simple, as it should be and makes black holes simple as well. Get your noses off the billboard, back up, waaay up and see what it says:)
habakak
@ b@man....
I agree with you in that the Universe, or matter, has always existed. The only thing that makes sense is that it always existed. Maybe endlessly expanding and contracting as some have suggested. Nothing cannot exists. The default is for something to exists. No matter where you go in the Universe, there's always something. If matter cannot be created or destroyed (and maybe one day we find that is not true, which I find hard to imagine) then it has always existed.
Gianfranco Fronzi
I agree with b@man .
WatchingWithWonder
Under this theory, I wonder how the mass of dark matter being lost relates to the energy consumed in expanding/accelerating the universe against the force of gravity.
e=mc^2, maybe?
TomS
One problem with observations and predictions. The time period that we have data and could observe in enough detail is insignificant compared to the time constant of the universe. Just consider the time constant for the environment of the earth is likely orders of magnitude smaller and our time collecting data an order of magnitude or two longer yet not long enough to predict if climate change is occurring do to man or not. At least there is disagreement about the issue.
Terry Penrose
Good comments guys :-) One of our main issues with understanding any of this is the time slice we have available to us. The longer the time slice the better and more accurate the data is. Comparatively speaking, we have only existed on earth for a couple of minutes and our physical data slice is probably even shorter. So, in universe terms, we haven't even seen the first day out, let alone a whole season. We just haven't been here long enough to know what happened and what will happen, but it sure is fun and exciting to theorise and speculate about. We are like Flies who live for maybe 3 days, speculating about and trying to guess what there lives will be like in a year.
Mel Tisdale
@ tomS
The only disagreement about climate change is in the popular media. 97% of all leading climate scientists agree that the climate is changing and that we are overwhelmingly to blame re. Cook et al. Try skepticalscience.com for the science. Try any publication or TV channel owned by R Murdoch for the non-science.
If you have children, wise up. As things stand they are in for a torrid time of it unless we change our habits and do so urgently. That is surely more important than clinging to a meme that is primarily designed to attract fossil fuel industry advertising, or don't your children matter? Even the oil industry execs are going to have to face up to reality someday and put their families first, assuming their families will not have rejected them in disgust by then.