After a minute spent with a different colloquium at the following week (whose title was in Latin), Andy Strominger quickly jumps to his main point.

In the early 21st century, black holes seem to play the same universal exploratory role in physics that the quantum harmonic oscillator used to play almost 100 years earlier. The reason of their universal importance is that they’re the simplest and the most complex objects in the Universe at the same moment.

It sounds almost like poetry but it’s actually true although one needs to appreciate many aspects of black holes that general relativity, its semiclassical quantization, and later string theory discovered to appreciate the depth of the summary above.

— Black holes: harmonic oscillators of the 21st century

— Lubos Motl

2012.05.08 Tuesday ACHK

Particle physics phenomenology is the part of theoretical particle physics that deals with the application of theory to high-energy particle physics experiments. Within the Standard Model, phenomenology is the calculating of detailed predictions for experiments, usually at high precision (e.g., including radiative corrections). Beyond the Standard Model, phenomenology addresses the experimental consequences of new models: how their new particles could be searched for, how the model parameters could be measured, and how the model could be distinguished from other, competing models. Phenomenology may in some sense be regarded as forming a bridge between the rarefied, highly mathematical world of theoretical physics proper (such as quantum field theories and theories of the structure of space-time) and experimental particle physics.

— Wikipedia on Phenomenology (particle physics)

2012.05.06 Sunday ACHK

In quantum mechanics and quantum field theory, the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space). In quantum electrodynamics this vacuum is referred to as ‘QED vacuum’ to separate it from the vacuum of quantum chromodynamics, denoted as QCD vacuum. QED vacuum is a state with no matter particles (hence the name), and also no photons, no gravitons, etc.

Theoretically, in QCD vacuum multiple vacuum states can coexist. The starting and ending of cosmological inflation is thought to have arisen from transitions between different vacuum states. For theories obtained by quantization of a classical theory, each stationary point of the energy in the configuration space gives rise to a single vacuum. String theory is believed to have a huge number of vacua – the so-called string theory landscape.

— Wikipedia on Vacuum

2012.05.04 Friday ACHK