# Between string theorists about the dispute: if dark energy is not constant?

Harvard physicist Qumran Wafa - one of the strongest advocates of string theory. But this summer the other string theorists have jumped on his last sentence, which may discredit their ideas, based on a decade of the assumption that dark energy is constant (constant). Vafa work implies that the value of dark energy changes. Changeable dark energy - a consequence of attempts to Wafa and his staff use string theory to the universe like ours, where the vacuum of space itself has a certain inherent energy.

If his hypothesis (itself string theory) is true, dark energy, the mysterious substance, which accounts for more than 70% of the total mass and energy of the universe, and which accelerates its expansion, will force change. But the constant dark energy has long been the basis for many of the ideas of string theory - so ironic that it is an unstable dark energy can lead to success theory.

## Dark energy and string theory

"For the first time we could learn something from string theory that can be measured," says Timm Vreys scientist from the Institute of Theoretical Physics, Vienna University of Technology in Austria. "But it will happen, I do not know in reality or not."

Let's start from the beginning: we live in a universe which seems to comply with the rules. On the largest scales large objects follow the rules of the general theory of relativity, interacting through gravity. The smallest scale of subatomic particles follow the rules of quantum mechanics and quantum field theory, by interacting fields of force, which manifest themselves as particles transporter force. But the math does not add up when you are trying to explain relativity as a huge expansion in quantum field theory. More ambitious theory - string theory - tries to unite GR with quantum mechanics, and it is represented by each particle is tiny string, in which vibration of a multidimensional space encode properties that scientists observed. However, the theory - this is not entirely accurate. It is, rather, a comprehensive mathematical basis, the framework of which the scientists can extract the theory of our universe, as well as the huge number of other universes allowed. String theorists hope that our universe is one of those opportunities. Others believe that string theory is fundamentally wrong, but now is not about that.

String theory should explain the universe like ours in all aspects, so that they can be considered correct. Our universe seems to consist of 4% of matter (matter that we can see), 25% of the mysterious dark matter, and the rest, as has been observed in 1988, it is necessary to "dark energy." String theorists have worked on the assumption that the strength of dark energy does not change, and they have evolved the theory. But Wafa and his co-authors suggest in the summer, that in order to live by the rules of string theory, our universe should have a field of dark energy, which decreases the value.

"I have dark energy or not - this is important," says Wafa.

If the value of dark energy changes, it will be important for those who rely on the assumption of the theory that dark energy is constant. "Maybe we should go back to basics," says Vreys. it would also change on the evolution of the universe - both in the past and in the future.

Wafa hypothesis was initially quite powerful and has led to "tremendous excitement," says Vreys. She acted as a call to action for the string theorists who felt that the framework was under threat. Some say at once that this is rubbish - a physicist at Stanford Eva Silverstein said Quanta, that assumption was based on different assumptions, and the analysis was "very doubtful". Others use this document as an opportunity to make sure that their theory can really describe the universe like ours. Vreys and other criticism addressed to the Wafa and his group, and their opinions have been published in Physical Review D. Work Vreysa found that some of the alleged properties of our own universe, in particular those associated with the field of the Higgs boson, contradict essentially some mathematical assumptions. For example, the initial assumption was that the physical behavior of the field controlling dark energy is extracted from the mathematical functions without maxima and minima, the line on the graph without peaks and troughs. Vreys discovered that the presence of the force field associated with Higgs, require a peak in this function.

But the work does not rule out the idea Vreysa Wafa - Wafa simply clarified the assumption that it is better to apply to the universe in which we live. There are other similar works, and Wafa agree with updates.

What is really interesting is that we can soon find out whether the job offers Wafa checked during the experiment prediction of string theory. It would be the first demonstrable consequence of string theory. Some experiments could test whether the dark energy changes over time or remains constant, and may do so in the next few years.

So, on the horizon looms a paradigm shift? "Most scientists would not say that this hypothesis is true or false," says Vreys. Wafa himself believes that he, of course, can be wrong, and it also talks about the importance of string theory. "But if Wafa right?" Says Vreys. "It would be the biggest event in string theory - make measurable outlook". Do you think you measure it? Tell us in our **chatting in a telegram.**