Astrophysicists propose 'Planck star' are core of black holes

This artist's concept depicts a supermassive black hole at the center of a galaxy. 

The blue colour here represents radiation pouring out from material very close to the black hole. 

The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. 

Credit: NASA/JPL-Caltech

Two astrophysics, Carlo Rovelli, Centre de Physique Theorique de Luminy and Francesca Vidotto, Radboud University Nijmegen, have uploaded a paper to the preprint server arXiv in which they suggest that a structure known as a Planck star exists at the center of black holes, rather than a singularity.

Carlo Rovelli

This would suggest, they note, that black holes at some point return all the information they have pulled in, to the universe.

The current thinking regarding black holes is that they have two very simple parts, an event horizon and a singularity.

Because a probe cannot be sent inside a black hole to see what is truly going on, researchers have to rely on theories.

The singularity theory suffers from what has come to be known as the "information paradox"—black holes appear to destroy information, which would seem to violate the rules of general relativity, because they follow rules of quantum mechanics instead.

This paradox has left deep thinking physicists such as Stephen Hawking uneasy—so much so that he and others have begun offering alternatives or amendments to existing theories. In this new effort, a pair of physicists suggest the idea of a Planck star.

Francesca Vidotto

The idea of a Planck star has its origins with an argument to the Big Bang theory, this other idea holds that when the inevitable Big Crunch comes, instead of forming a singularity, something just a little more tangible will result, something on the Planck scale.

And when that happens, a bounce will occur, causing the universe to expand again, and then to collapse again and so on forever back and forth.

Rovelli and Vidotto wonder why this couldn't be the case with black holes as well—instead of a singularity at its center, there could be a Planck structure, a star, which would allow for general relativity to come back into play.

If this were the case, then a black hole could slowly over time lose mass due to Hawking Radiation, as the black hole contracted, the Planck star inside would grow bigger as information was absorbed.

Eventually, the star would meet the event horizon and the black hole would dematerialise in an instant as all the information it had ever sucked in was cast out into the universe.

This new idea by Rovelli and Vidotto will undoubtedly undergo close scrutiny in the astrophysicist community likely culminating in debate amongst those who find the idea of a Planck star an answer to the information paradox and those who find the entire idea implausible.

More information: Planck stars, arXiv:1401.6562 [gr-qc] arxiv.org/abs/1401.6562

Russia Proposes Giant Solar Power Station in orbit Earth

Russia is planning to build a giant solar power station capable of collecting energy and beaming it to Earth.

This idea was put forward by Central Scientific Research institute for Engineering, a subsidiary of the Russian Space Agency, Roskosmos.

The concept of such a power station was formulated by Peter Glasier in the US in 1968.

It is aimed at beaming energy to Earth using giant solar panels.

To generate necessary power, the panels should have an area of several square kilometers.

The power would be converted to electricity on board the spacecraft and sent to wherever it is needed on Earth by a large microwave-transmitting antenna, and then fed into a power grid.

The scientific research institute suggests using lasers instead of microwaves because radio beams are difficult to focus, and an area of several square kilometers will be needed for the receiving antenna.

In case of a laser beam this area would be ten times smaller. However, at present, there are no such powerful lasers, although many infrared lasers distributed over the panel could be used instead.

Their radiation would be focused or combined and beamed down to Earth.

The US, Japan, Europe and China plan to build solar power stations between 2030 and 2040. It is not surprising that Russia will join them, says Academician Alexander Zheleznyakov.

"Russia should study this problem. If energy from space is cheaper, it is beneficial because Earth has been experiencing an energy deficit. There is a need to think of the future. We are building power plants on Earth, and if we can build a solar power station in space, we should not miss this opportunity," Alexander Zheleznyakov said.

However, deputy editor-in-chief of the Novosti Kosmonavtiki" magazine Igor Lisov insists that this is a beautiful idea but it needs huge investment and consequently, it is not feasible.

"There is a need to watch the situation with open eyes without indulging in wishful thinking. None of the countries is conducting serious work that could shift to experimental studies of supplying energy from space," Igor Lisov said.

The project is based on the myth that mankind will exhaust energy in the near future. This will be true if the only sources of energy remain oil and gas. But mankind will probably develop other sources of energy including thermonuclear energy.

With the appearance of such power plants, there will be no need to build space solar power stations, says Corresponding Member of the Russian Academy of Cosmonautics Andrei Ionin.

"It will be very expensive to place a power station in orbit and exploit it. It may also have a negative impact on ecology. We do not know what could happen to Earth if a laser beam turns the wrong way. Perhaps, it may burn the ozone layer. If this happens, the consequences will cost a hundred times more than the price of the power generated. I believe that the Scientific Research Institute for Engineering should study reports by ecologists," Andrei Ionin said.

This project will not be implemented in the near future. However, it's necessary to study the problem, experts say. This may breed new technical solutions, such as more effective lasers or solar batteries.