“And because it’s a tremendously large number, and it gets something nontrivial in real world particle physics correct, we should take it seriously and study it further,” Halverson says.įurther study would involve uncovering stronger connections with the particle physics of the real world.

“It’s somehow surprising and actually also rewarding that it turns out to be in the strongly coupled string theory regime, where geometry helped us.”Ī quadrillion-while it’s much, much smaller than the size of the landscape of solutions in F-theory (which at last count was shown to be of the order of 10 272,000)-is a tremendously large number. “This is by far the largest domain of standard model solutions,” Cvetic says. The new work shows that there are at least a quadrillion solutions in which particles have the same chiral spectrum as the standard model, which is 10 orders of magnitude more solutions than had been found within string theory until now. For example, the quarks and leptons in these solutions come in left and right-handed versions, as they do in our universe. In particle physics lingo, the solutions reproduce the exact “chiral spectrum” of standard model particles. The F-theory solutions found by Cvetic and colleagues have particles that also exhibit the handedness, or chirality, of the standard model particles. Now, Cvetic, Lin, James Halverson of Northeastern University in Boston, and their colleagues have used such techniques to identify a class of solutions with string vibrational modes that lead to a similar spectrum of fermions (or, particles of matter) as is described by the standard model-including the property that all fermions come in three generations (for example, the electron, muon and tau are the three generations of one type of fermion).

“The geometry is really the key… it is the ‘language’ that makes F-theory such a powerful framework.” “They provide us physicists a vast toolkit,” says Ling Lin, also of the University of Pennsylvania. Mathematicians have been independently studying some of the geometric forms that appear in F-theory. This means that string theorists can use algebraic geometry-which uses algebraic techniques to tackle geometric problems-to analyze the various ways of compactifying extra dimensions in F-theory and to find solutions. “An intriguing, surprising result is that when the coupling is large, we can start describing the theory very geometrically,” says Mirjam Cvetic of the University of Pennsylvania in Philadelphia. However, in the past two decades, a new branch of string theory called F-theory has allowed physicists to work with strongly interacting, or strongly coupled, strings. Much of this effort has involved a version of string theory in which the strings interact weakly. Some string theorists have focused their efforts on trying to find ways to connect string theory to properties of our known, observable universe-particularly the standard model of particle physics, which describes all known particles and all their mutual forces except gravity. Each solution describes a unique universe, with its own set of particles, fundamental forces and other such defining properties. In string theory, a “solution” implies a vacuum of spacetime that is governed by Einstein’s theory of gravity coupled to a quantum field theory.

And for consistency with our familiar everyday experience of the universe, with three spatial dimensions and the dimension of time, the additional six dimensions are “compactified” so as to be undetectable.ĭifferent compactifications lead to different solutions. For mathematical consistency, these strings vibrate in 10-dimensional spacetime. Physicists who have been roaming the “landscape” of string theory-the space of zillions and zillions of mathematical solutions of the theory, where each solution provides the kinds of equations physicists need to describe reality-have stumbled upon a subset of such equations that have the same set of matter particles as exists in our universe.īut this is no small subset: there are at least a quadrillion such solutions, making it the largest such set ever found in string theory.Īccording to string theory, all particles and fundamental forces arise from the vibrational states of tiny strings.

Strings theory