Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
This year marks the 40’th anniversary of the Unruh effect as described at the first Marcel Grossmann meeting in 1975. We revisit it with emphasis on the observability issue which might be a concern at first sight, since the linear acceleration needed to reach a temperature 1 K is of order 10^20 m/s^2 . We close the talk by emphasizing that the Unruh effect does not require any verification beyond that of relativistic free field theory itself. The Unruh effect lives among us.
The quantum Zeno effect is often very controversial in the context of consciousness problems.
Frequent direct measurements of a quantum system freeze its time evolution.
Then what happes if an observer continuously watches a Schrodinger's cat from the start of the experiment?
Naively this looks like a yes-no measurement of a unstable atom decay, which emits a gamma ray as a trigger of the cat execution.
The problem of the gravitational collapse of small mass in the higher derivative and ghost free theories of gravity is discussed. It will be demonstrated how higher derivative and non-local modifications of gravity equations regularizes static and dynamical solutions. Boosting a static solution of the linearized equations for the gravitational potential of a point mass we obtain a solution for the field of the ultra-relativistic source (gyraton). Using the latter we construct solutions for the collapsing spherical (thin and thick) null shell.
In 1981 Bill discovered an analogy between the propagation of fields in the vicinity of
astrophysical black holes and the that of small excitations in fluids. He postulated that this
analogy allows one to test, challenge and verify, in tabletop experiments, the elusive
processes of black hole mass and angular momentum loss. Indeed, 34 years later
analogue gravity experiments are carried out all over the world to implement his idea.
The last decade has seen the impressive development of quantum information science, both in theory and in experiment. There are many measures that can be used to assess the achievements in the field: new algorithms, new applications and larger quantum processors, to name a few. The discovery of quantum algorithms has demonstrated the potential power of quantum information.
As pointed out by Bill some years ago, to realize this potential requires the ability to overcome the imprecision and imperfection inherent in physical systems.
I review the contentious question, "Does a uniformly
accelerated detector radiate?" As Audretsch and Muller
pointed out long ago, this is partly a semantic dispute. The
talk draws on recent discussions with Alex Calogeracos and George
Matsas.
We evaluate the one-graviton loop contribution to the vacuum polarization on de Sitter background in a 1-parameter family of exact, de Sitter invariant gauges. Our result is computed using dimensional regularization and fully renormalized with BPHZ counterterms, which must include a noninvariant owing to the time-ordered interactions.
Check back for details on the next lecture in Perimeter's Public Lectures Series