The Epoch of Reionization


Astrophysicists are interested in tracing the development of large scale structure during the so-called Epoch of Reionization - the period in the history of the universe in which the first luminous sources turn on and ionize neutral hydrogen in their vicinity.  Prof. Adam Lidz studies the theory of how to detect and gain information from radition emitted during this period.


David Rittenhouse Laboratory - Walnut Street view

DRL is the academic home of the Mathematics and Physics and Astronomy departments at Penn.  It is named for David Rittenhouse, a noted American astronomer born near Germantown, Philadelphia.  Rittenhouse was one of the first to build a telescope in the United States and was Professor of Astronomy at Penn starting in 1779.


DNA-Carbon Nanotube Hybrid

Single-stranded DNA and carbon nanotubes are chemically compatible and readily self-assemble into DNA-carbon nanotube hybrids (pictured here).  These materials have applications in nanoelectronics, medicine, environmental safety and homeland security.  Dr. Robert R. Johnson of the University of Pennsylvania has used computer simulation to study the structure of these nanomaterials.



Penn physicists study graphenes, atomically thin sheets of carbon atoms in a honeycomb lattice. Graphene is the prototype Dirac material hosting a solid state realization of an ultra-relativistic electron gas and accessing new phenomena that are controlled by electric and magnetic fields and by the atomic registry when graphenes are stacked.

Premelting of Colloidal Crystals

Premelting is the localized loss of crystalline order at surfaces and defects at temperatures below the melting transition.  This result is from the lab of Prof. Arjun Yodh.