Harvard physicist Qumran Vafa is one of the strongest supporters of string theory. But this summer, other theorists strings pounced on his last sentence, which may discredit their ideas, based on a decade of the assumption that the dark energy is constant (constant). Vafa work implies that the value of dark energy is changing. Irregular dark energy is a consequence of attempts Vafa and his staff to apply string theory to the Universe, such as ours, where the vacuum of space has some inherent energy.

If his hypothesis (and the string theory) is true, the dark energy, this mysterious substance, which accounts for more than 70% of the total mass and energy of the Universe and accelerates its expansion will change. But the constant dark energy has long served as the basis for many ideas of string theory — so paradoxically it is non-permanent dark energy can lead to success theory.

## Dark energy and string theory

“The first time we could learn something from string theory that can be measured”, says Timm, Bras from the Institute for theoretical physics Vienna University of technology in Austria. “But I don’t know, it will happen in fact 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 General relativity, interacting through gravity. In the smallest scale of subatomic particles follow the rules of quantum mechanics and quantum field theory, interacting through force fields, which manifest themselves as particles-carriers of force. But the math doesn’t add up when you are trying to explain General relativity as a huge extension of quantum field theory. More ambitious theory — string theory attempts to merge General relativity with quantum mechanics and each particle represented a tiny string, which vibration in a higher dimensional space to encode the properties that is observed.

However, the theory is not entirely accurate. It is, rather, a comprehensive mathematical framework, the framework from which scientists can derive a theory about our Universe and the immense number of different universes are allowed. String theorists hope that our universe is one of these possibilities. Others believe that string theory is fundamentally wrong, but now not about it.

String theory must explain a universe like ours in all aspects, to be considered correct. Our universe, apparently, consists of 4% matter (matter that we can see), 25% of a mysterious dark matter, and the rest, as shown by the observations of 1988, accounts for “dark energy”. String theorists worked under the assumption that the strength of dark energy does not change, and their theories evolved. But Wafa and his coauthors suggested in the work this summer that in order to exist according to the rules of string theory, our universe must have a field of dark energy, whose value decreases.

“Changing dark energy or not — is important,” says Wafa.

If the value of dark energy is changing, it will be important for those theories which rely on the assumption that dark energy is constant. “Maybe we need to go back to the Foundation,” says Bras. Also it would change the representation of the evolution of the Universe — both in the past and in the future.

The Vafa’s hypothesis initially was quite powerful and led to the “great excitement” says Bras. She acted as call-to-action for string theorists, who felt that the framework was under threat. Some just said it was nonsense, a physicist from Stanford Eva Silverstein told Quanta that the assumption was based on other assumptions, and the analysis was “highly questionable”. Others use this document as an opportunity to ensure that their theory can actually describe the Universe, such as ours.

Bras, and other criticism referred to the work of Vafa and his group, and their opinions were published in Physical Review D. the Work of Vraca found that some expected properties of our own universe, in particular those associated with the field of the Higgs boson, contrary to essentially some mathematical assumptions. For example, the original assumption was that the behavior of physical fields, control dark energy, is derived from a mathematical function without the highs and lows, the line on the graph without the peaks and valleys. Vras found that the presence of the force field associated with the Higgs boson requires a peak in this function.

But the work of Brasa does not exclude the idea of the Wafa — Wafa just said an assumption that it is better applicable to the universe in which we live. There are other similar work, and Vafa concurs with the clarification.

What is really interesting is that we may soon see the work of Vafa check in the course of the experiment a prediction of string theory. It would be the first demonstrable result of string theory. Some experiments could test whether changes in dark energy with time or remains constant, and may do so in the next few years.

So, on the horizon looms a paradigm shift? “Most scientists will not say that this hypothesis is correct or incorrect,” says Bras. He Vafa thinks that he may be wrong, and it also talks about the importance of string theory. “But if Wafa is right?”, says Bras. “It would be the biggest event in string theory is to make a measurable prediction”.

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