An expert is a man who has made all of the mistakes which can be made, in a narrow field.
You haven't seen any new hardcore physics
posts entering this blog in recent weeks. Reason is a new role in my professional life, combined with a new science project that I have started in my spare time (if successful, you will definitely read more about the latter here). Both activities currently consume a lot of my time, and as there are only 1015 inches in a day
, something has to give.
A faithful reader of this blog has been asking me
for answers to some of the 42 questions
which were given at an exam for particle physics researcher wannabes in Italy in 2005
. I already provided some answers in a separate post
a few months back, but the reader asked for an answer to some specific exercises which I had not bothered to deal with here. I will do so now.
There exists a tendency in nature to reduce complexity via modularization. This tendency grows when more modules become available. Finally this tendency enables nature to create intelligent and very sophisticated creatures.
I encountered relations in several areas of physics and in human interactions.
Physics is based on relations. Quantum logic is a set of axioms that restrict the relations that exist between quantum logical propositions. Via its isomorphism with Hilbert spaces quantum logic forms a fundament for quantum physics. However, quantum logic only describes static relations. Classical logic is a similar set of restrictions that define how we can communicate logically.
This is the last of the four part series about the Edge discussion between Lee Smolin and Leonard Susskind.
discussed the physics and the philosophical issues. You will have by now understood who won the battle in my eyes. However, I would like to use this final opportunity to stress that we have yet again a clear showcasing of that it is, as so often, sufficient to merely analyze the style of argumentation in order to figure out who is not to be trusted.
It's become so commonplace for large science endeavors to be over budget and long-delayed that both budgets and time frames seem almost meaningless. The James Webb Space Telescope might as well just be issued blank checks
and, in Europe, the ITER nuclear fusion reactor project
is making the overruns and delays of even the LHC look modest.
A new result for the production cross section of Z boson pairs in proton-antiproton collisions at the 2-TeV Tevatron collider is now public, thanks to the efforts of the CDF collaboration. The measurement, in a nutshell, confirms Standard Model predictions nicely: the cross section is determined to be 1.45 picobarns, with an asymmetric error bar of of +0.60-0.51. The Standard Model, on the other hand, predicts that the cross section is 1.21 picobarns. The agreement of the two numbers, within uncertainties, says that all is well in the searched final state, and no unforeseen effects are at work.
Birth of the Universe from the Zero Energy State
1) There was a pair creation of positive and negative energy in the early universe.
2) The total energy of universe is 0.
Stephen Hawking and Alan Guth et al. argued that gravitational potential energy is negative energy, and that such gravitational potential energy can offset all positive mass energy during a period of inflation.
3) The acceleration in the expansion of the universe observed suggests the existence of positive energy out of mass energy, and alternatively, it corresponds to what the overall gravitational potential energy of the universe has positive value, indicating that gravitational potential energy will not able to offset positive energy.
In the past weeks I have been writing a piece about the Large Hadron Collider for a science popularization magazine, and I found myself squeezing my brain for a good analogy to the work of particle hunters. The idea I had was to convey the importance of energy and intensity, two parameters which must both be maximized by a particle accelerator in order to reach deeper in the structure of matter.
Teaching a subnuclear physics course is a quite refreshing experience.
In general, much of the stuff that one has learned through years of sweating on books slowly degrades and becomes "fuzzy". That fuzzy stuff still give you a warm feeling that you have grasped the important concepts and that you have acquired the necessary culture. But much better than the ignorance of culture is the precise knowledge that a continuous study provides. So when one is forced to re-study what one has forgotten, because of the need to teach a course, the result is pleasing.