Objects in each universe are essentially confined to the D-brane of their universe, but may be able to interact with other universes via gravity, a force which is not restricted to D-branes.

Black hole-like black p-branes are identified with D-branes, which are endpoints for strings, and this identification is called Gauge-gravity duality.

Joseph Polchinski realized that obscure string theory objects, called D-branes, which he had discovered six years earlier, are stringy versions of the p-branes that were known in supergravity theories.

In string theory, D-branes are a class of extended objects upon which open strings can end with Dirichlet boundary conditions, after which they are named.

Although rigid in the limit of zero coupling, the spectrum of open strings ending on a D-brane contains modes associated with its fluctuations, implying that D-branes are dynamical objects.

When D-branes are nearly coincident, the spectrum of strings stretching between them becomes very rich.

In this sense, then, one can say that string theory " predicts " electromagnetism: D-branes are a necessary part of the theory if we permit open strings to exist, and all D-branes carry an electromagnetic field on their volume.

Since endpoints are restricted to lie on D-branes, it is evident that a string may interact with a string, but not with a or a one.

Among his contributions to theoretical physics, D-branes are the best known.

However, unlike D-branes, O-planes are not dynamical.

They are defined entirely by the action of the involution, not by string boundary conditions as D-branes are.

Some models in string theory that are promising by way of realizing our familiar standard model are the perturbative heterotic string models, 11-dimensional M-theory, Singular geometries ( e. g. orbifold and orientifold ), D-branes and other branes, flux compactification and warped geometry, non-perturbative type IIB superstring solutions ( F-theory ).

Similarly, the branes in these models are only topological approximations to the full dynamical objects that are D-branes.

T-duality acting on D-branes changes their dimension by + 1 or-1.

D-branes were discovered by Dai, Leigh and Polchinski, and independently by Hořava in 1989.

When two D-branes approach each other the interaction is captured by the one loop annulus amplitude of strings between the two branes.

In recent years, this has been done by building black holes out of D-branes.

In the late 1990s, Ashoke Sen conjectured that the tachyons carried by open strings attached to D-branes in string theory reflect the instability of the D-branes with respect to their complete annihilation.

The total energy carried by these tachyons has been calculated in string field theory ; it agrees with the total energy of the D-branes, and all other tests have confirmed Sen's conjecture as well.

More technically, quantum geometry refers to the shape of the spacetime manifold as seen by D-branes which includes the quantum corrections to the metric tensor, such as the worldsheet instantons.

His other contributions include a simplified proof of the positive energy theorem involving spinors in general relativity, his work relating supersymmetry and Morse theory, his introduction of topological quantum field theory and related work on mirror symmetry, knot theory, twistor theory and D-branes and their intersections.

Dirichlet boundary conditions and D-branes had a long ` pre-history ' before their full significance was recognized.

He currently works on mathematical problems that have their roots in physics, for example, topological field theories, fractional quantum Hall effect, and D-branes in the presence of B-fields.

It is now known that string theory in addition to the fundamental strings which define the theory perturbatively also contains other one-dimensional objects, such as D-strings, and higher dimensional objects such as D-branes, NS-branes and M-branes partially wrapped on compact internal spacetime dimensions, while being spatially extended in one non-compact dimension.

The arrangement of D-branes constricts the types of string states which can exist in a system.

The zero-mass states in the open-string particle spectrum for a system of N coincident D-branes yields a set of interacting quantum fields which is exactly a U ( N ) gauge theory.

He has also worked on Dirichlet boundary conditions in string theory which have led to the postulation of D-branes.

This is true irrespective of the charge of the D-branes.

In physics, a quiver diagram is a graph representing the matter content of a gauge theory that describes D-branes on orbifolds.

Hořava is less well known for his discovery of D-branes, usually attributed to Dai, Leigh and Polchinski, who discovered them independently, also in 1989.

The word brane, derived from " membrane ", refers to a variety of interrelated objects, such as D-branes, black p-branes and Neveu – Schwarz 5-branes.

The strings make closed loops unless they encounter D-branes, where they can open up into 1-dimensional lines.

In particular, following the work of Ashoke Sen, it has been useful in the study of tachyon condensation on unstable D-branes.

49 387 ( 2001 ); < BR > W. Taylor and B. Zwiebach, " D-branes, tachyons, and string field theory.

In physics, K-theory and in particular twisted K-theory have appeared in Type II string theory where it has been conjectured that they classify D-branes, Ramond – Ramond field strengths and also certain spinors on generalized complex manifolds.

In string theory the K-theory classification of Ramond – Ramond field strengths and the charges of stable D-branes was first proposed in 1997.

Recent research on instantons links them to topics such as D-branes and Black holes and, of course, the vacuum structure of QCD.

The situation changed in 1995 when Andrew Strominger and Cumrun Vafa calculated the right Bekenstein-Hawking entropy of a supersymmetric black hole in string theory, using methods based on D-branes.

Today one may also use D-branes to engineer gauge symmetries.

Today we know that, using D-branes for example, gauge symmetries can be introduced in other 10-dimensional theories as well.

In 1995, Polchinski identified D-branes with black p-brane solutions of supergravity, a discovery that triggered the Second Superstring Revolution and led to both holographic and M-theory dualities.