For example, something we don't know about strings is how strongly they like to interact. It turns out that there are interesting connections, called dualities or symmetries, among the five theories. In the talk, he offered a radical suggestion: perhaps the five string theories weren't so different after all. Related: The history and structure of the universe (infographic)ДЄnd then 1995 happened, when prominent theoretical physicist Edward Witten gave a talk at the annual string theory conference. And so the five string theories represent five different approximations, with no way of being able to decide which one is best. We only have approximations that we hope - but can't prove - are close to the actual theory. They obviously couldn't all be correct descriptions of nature, but which one was the 'real' string theory, and which were the phonies? The problem was (and still is today) that string theory isn't complete - there's no such thing as the final equations of string theory, something that could be printed on a t-shirt, that describes the theory in the same way that we have the Einstein equations for gravity or the Maxwell equations for electromagnetism. And some theories were combinations of other theories.ДЇor reference, in case you're curious, the names of the five string theories are: Type 1, Type IIA, Type IIB, SO(32) heterotic, and E8ењЋ8 heterotic. Some theories only allowed vibrations to travel in one direction on the strings, while others allowed both. Some theories only had closed loops of strings, while others allowed open, wiggling strings. But when it comes to physical theories, details matter, and the five competing string models differed in the details. Our graduates have pursued highly successful careers in academia, industry, finance, and national laboratories.And in all the theories, the ways strings vibrate give rise to the richness of our physical world, from the forces of nature to the building blocks of matter to physical constants themselves. The group at present has over ten graduate students, many of whom are supported by major research grants from the National Science Foundation. Additional research threads include the study of physics beyond the Standard Model of particle physics, especially those extensions motivated by strings the mathematical and formal structure of scattering amplitudes and the study of superconformal field theories, especially those in more than four spacetime dimensions.

This includes the study of strings at strong coupling via M-theory and F-theory, as well as the resulting low energy effective field theories generated by compactifying the extra dimensions predicted by superstring theory. This group seeks to answer questions such as вЂHow can quantum mechanics and gravity be combined in a single theoretical framework?,вЂ™ вЂWhat is the nature of space and time at the Planck scale?,вЂ™ and вЂWhy is the scale of electroweak symmetry breaking so much lower than the Planck scale?вЂ™ The groupвЂ™s work addresses these questions through the study of string theory, the only known consistent theory of quantum gravity. String theorists within the group have a very active weekly UNC-Duke seminar program. Wisc-Milwaukee), Mark Hannam (Cardiff University), and Niels Warburton (MIT). Recently these have included Patrick Brady (Univ. The theory group hosts a number of distinguished visitors each year. The fundamental theory program is also one of the three pillars (along with astrophysics and nuclear physics) of the DepartmentвЂ™s participation in the multi-university CoSMS Institute.Д¬urrent research within the group includes study of sources of gravitational radiation and radiation reaction in general relativity, applications of numerical relativity, calculations in relativistic astrophysics of massive black holes, beyond standard model of particle physics (including dark matter), quantum gravity phenomenology, and foundations of quantum mechanics. This group also has ties to other theorists in the Department, including those in non-relativistic quantum many-body theory, nuclear theory, and astrophysics. The fundamental theory group within the Department encompasses the traditional areas of relativistic field theory that include gravitational physics, physical cosmology, particle physics and high-energy theory, and string theory.

Strings theory