![]() He wrote an extremely important paper in 1968 that sent shockwaves through the theoretical physics community, It was called " Construction of a crossing-symmetric, Regge behaved amplitude for linearly-rising trajectories.” Gabriele Veneziano is the person who developed much of the framework for what would become string theory. But even more disturbing was that there were so many (and ever-growing in numbers) different species of hadrons that we felt at a loss with field theory – how could we cope with so many different states in a QED-like framework? We now know how to do it and the solution is called quantum chromodynamics (QCD)." ![]() One reason was the strength of the strong coupling compared to the electromagnetic one. We had an example of a relativistic quantum theory that worked: QED, the theory of interacting electrons and photons, but it looked hopeless to copy that framework for the strong interactions. Per the Cern Courier, "In the mid-1960s we theorists were stuck in trying to understand the strong interaction. ![]() However, the finding that really kick-started research into string theory was the discovery of a strange particle called the hadron. Some, like baryons, exhibited characteristics of mass and spin (a baryon is a member of the quark and fermion family, which means it participates in one of the four forces: the strong interaction - something scientists were struggling to understand at the time). We found that these elementary particles can be broken down into their further constituent parts, like quarks. ![]() It wasn't until we started slamming particles together at extremely high speeds that we began finding and classifying all of these different types of particles - the Higgs Boson should come to mind. How can something have no size at all? And if it has mass, does the zero size mean it has infinite density?" The answer to that is no, for the record, but that's just one of the many mysteries surrounding point particles They do, however, sometimes exist in quantum states that give them mass and charge. This statement has raised more than one eyebrow. Extended particles have a size, but the boundary or exactly where an extended particle ends is fuzzy.įermi Lab ponders, "Point particles are much more bizarre and are sometimes said to have zero size. One exception is the electron.Įxtended particles don't have a well-defined surface, instead, they are more like the atmosphere of the Earth, which is the thickest near the surface of the Earth and it gets thinner with altitude. The Standard Model of Particle Physics, which is the definitive starting point to all things subatomic, tells us that every particle known to exist is an extended particle except for three: quarks, bosons, and leptons. In traditional physics, we have so-called point particles and extended particles. Recordings of past talks can be found here: understand string theory, there are several things we must explore first, beginning with quantum physics. Please register at /forms/d/e/1FAIpQLSf0jLgoqiOgDnxbEBGiuIWiOmh9WX8caH-pr13qDBZOO91lmg/viewform to receive mails regarding our online seminars. Links to join the seminars will be sent to your registered email address. We run an online virtual seminar whose schedule can be found at . This is apart from the steady flux of visitors attending ICTS programs.įor more details, we invite you to contact us or see the individual faculty pages. We interact closely with the group at the Indian Institute of Science. Our members have focused on understanding scattering in anti-de Sitter space, the applications of this correspondence to cosmology and condensed matter physics, and the deep problem of information loss in black holes. This is interesting because it provides us with a non-perturbative definition of quantum gravity, in a setup that is rich enough to permit black holes, non-trivial scattering, and is related to cosmological models. This correspondence relates quantum gravity in a spacetime that asymptotes to anti-de Sitter space with an ordinary quantum field theory that lives in one lower dimension, and has a symmetry under angle-preserving (conformal) transformations. The string theory group at the International Centre for Theoretical Sciences focuses on a particularly interesting aspect of this field called the AdS/CFT correspondence. String theory is a framework to build models of quantum gravity.
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