Some had hoped it might be just an illusion. But it looks like dark energy is real and here to stay, as astronomers “image” the mysterious entity in action.

In 1998, astronomers found that distant supernovae were dimmer, and thus farther away, than expected. This suggested that the expansion of the universe is accelerating – and “dark energy” was named as the culprit.

Since then, astronomers have struggled to explain what dark energy actually is – leading some to speculate that it may not exist at all. Some have claimed that uneven distributions of matter within the universe could distort our measurements of the distance to supernovae, fooling us into thinking that they are farther away than they are.

To find an independent check on the existence of dark energy, István Szapudi at the University of Hawaii in Honolulu, US, and colleagues turned to the cosmic microwave background (CMB) – relic radiation from the big bang. Detailed maps of the CMB show hot and cold spots that reflect variations in the density of the early universe.

When dark energy was proposed, astronomers realised that it should create additional temperature bumps on the map.

This extra dark energy effect is generated because the temperature of a photon zipping across the universe can be changed depending on whether it has passed through a region of dense matter or a sparser region.

Shallow well

A photon gains energy when it enters a dense region with enhanced gravity – such as a galaxy cluster – as though it is falling into a well. When it leaves the cluster and climbs back out of the gravitational well, it loses energy.

In a universe without dark energy, the energy gained and lost during the crossing would be equal and would cancel out. But in the presence of dark energy, the universe expands quickly enough to stretch the gravitational well while the photon is still inside. This makes the well shallower and easier for the photon to climb out.

That means that a photon travelling through a cluster gains more energy than it loses, giving it a little energy kick so that it creates a hotter spot than would be expected on images of the CMB. Similarly, a photon that has passed through a void would leave a cold spot.

It’s tough to detect this effect because dark energy gives only a slight nudge to the temperature, which is easily swamped by the normal temperature variations seen in the CMB, says Szapudi.

Extreme density

To get around this, his team looked at regions of extremely high and extremely low density, where you would expect to see the biggest effect.

Using data from the Sloan Digital Sky Survey, they chose over 3000 superclusters of galaxies and 500 “supervoids” of relatively empty space, and they found that the regions did indeed .

Other teams have reported signs of this effect in the past, but those have been open to alternative explanations, says Szapudi. By contrast, his calculations suggest that there is less than a 1 in 200,000 chance that the match up his team saw is down to anything other than dark energy.

“We have shown the imprint on the CMB of dark energy at work,” says Szapudi. “In this sense, we have imaged dark energy.”

The finding should rule out any notion that dark energy is an illusion, he says. “We’ve really attacked the dark energy question in a different way from supernovae measurements. It’s difficult to argue that an illusion could be responsible for this effect.”

Warped space

Thomas Buchert at the University of Lyon in France, one of the physicists who suggested that dark energy may be an illusion, is impressed by the thoroughness of Szapudi’s work. “People have discussed this effect, but this is the first really clear-cut signal,” he says.

However, Buchert is not ready to abandon alternatives to dark energy just yet. He points out that a similar effect might be produced if space-time is significantly warped around the voids and clusters – something that isn’t usually considered in standard calculations.

He also notes that Szapudi’s team observed a temperature effect that was stronger than expected from dark energy. “This could be a hint that there may be something else happening here that’s worth investigating,” he says.

Cosmology – Keep up with the latest ideas in our .

The UK Parliament’s Innovation, Universities, Science and Skills committee examined the causes of the physics funding crisis which emerged in December 2007. The Science and Technology Facilities Council – the UK’s main funding body for physics and astronomy, and which looks after some of the largest science centres in the country – was faced with a deficit of £80m after an unfavourable government spending review last year.

To plug the hole, the STFC withdrew from key international physics projects including the International Linear Collider, the Gemini Observatory and ground-based solar terrestrial physics. The sweeping cuts also left some university physics departments in fear of closure.

The move stunned physicists, who had received little warning that UK involvement in the projects was in jeopardy. They argued that the measures were taken with little warning or consultation. , based on evidence provided by STFC bosses, civil servants and physicists at three hearings earlier this year, comes to a similar conclusion.

The report condemns the decision-making process behind the cuts as “ineffective” and “secretive” and describes the STFC’s peer-review system as “weak”.

The pounds stop here

The committee laid most blame at the head of the STFC, Keith Mason. In January, solar physicists issued a vote of no confidence in Mason after the STFC axed support for ground-based solar-terrestrial physics projects. The MPs were unconvinced by Mason’s attempts to defend these cuts at committee hearings, describing his arguments as “inaccurate” and “unacceptable”.

The new report stops short of demanding Mason’s resignation, but the committee does call for “substantial and urgent” changes to give the STFC “the leadership it desperately needs”.

The fates of nearly 30 STFC-funded programmes still hang in the balance, with Jodrell Bank in Cheshire, the and the (UKIRT) – the world’s largest telescope dedicated to infra-red astronomy, based in Hawaii – facing an uncertain future.

Final cuts were due to be announced in July. The report calls for the STFC to postpone these until the government-appointed “” into the state of UK physics is published in September.

Now what?

In a statement the STFC said that it had already accepted that it had to “consult more widely on its future programme and to improve its communication with staff and its research community.”

Jim Wild, a solar physicist at the University of Lancaster in the UK who was hit by the cuts, believes the committee has drawn the right conclusions. “This is a vindication of what almost all UK physicists have been saying – that this is no way to run world-leading science.”

The question now, says Wild, is how to move forward. He points out that it is probably too late to help several UK research groups already affected by the cuts, but damage must now be limited. “At the very least, we hope that there will be a moratorium on future irreversible cuts until the outcome of the Wakeham Review is known.”

We’re right to be terrified, say physicists. Children generate poltergeist activity by channelling energy into the quantum mechanical vacuum.

Pierro Brovetto, whose last known address was the Instituto Fisica Superiore, in Cagliari, Italy and his colleague Vera Maxia wanted to explain the origin of poltergeist phenomena, characterised by objects flying around the room “of their own accord”.

The researchers note that poltergeist encounters have been reported around the world and across different cultures, but tend to have one thing in common.

“Poltergeist disturbances often occur in the neighbourhood of a pubescent child or a young woman,” the authors note in their paper.

So Brovetto and Maxia have come up with a mechanism to explain just how these women and children create such havoc. Like so many problems that arise in adolescence, puberty gets the blame.

“Puberty is a modification of the child body which involves various organs, chiefly the brain,” they state.

Teenage telekinesis

Brovetto and Maxia hypothesise that the changes in the brain that occur at puberty involve fluctuations in electron activity that, in rare cases, can create disturbances up to a few metres around the outside of the brain.

These disturbances would be similar in character to the quantum mechanical fluctuations that physicists believe occur in the vacuum, in which “virtual” particle and antiparticle pairs pop up for a fleeting moment, before they annihilate each other and disappear again.

Brovetto and Maxia believe that the extra fluctuations triggered by the pubescent brain would substantially enhance the presence of the virtual particles surrounding the person. This could slowly increase the pressure of air around them, moving objects and even sending them hurtling across the room.

The poltergeist paper will appear in the journal .

We contacted , a Nobel laureate physicist who is on the editorial board of Neuroquantology.

“This looks distinctly flaky to me,” Josephson commented.

Journal reference:

Quantum World – Learn more about a weird world in our comprehensive special report.