Physicists say they have discovered how to create matter from light - a feat thought impossible when the idea was first theorized 80 years ago. There is just one problem. In order to test the newest hypothesis, a new& machine would have to be built.

In just one day over several cups of coffee in a tiny office at Imperial College London, three physicists believe they worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934. Yes, they solved a puzzle that has eluded the rest of the world in an afternoon. Well, on paper.

In this blog, I will review my thoughts on the action of general relativity, how it is used for the field equations and equations of motion.  There is much to consider, so perhaps this will create a means for discussing this deep subject.

The Action

Two months after the controversial BICEP2 announcement, The Washington Post writes « Big Bang backlash: BICEP2 discovery of gravity waves questioned by cosmologists » and National Geographic emphasizes « Big Bang Discovery Comes Under Fire.

"Subatomic particles act in quantum ways—they have a wave-like nature—and so can atoms, and so can whole molecules since they're collections of atoms," Schwab says. "So the question then is: Can you make bigger and bigger objects behave in these weird wave-like ways? Why not? Right now we're just trying to figure out where the boundary of quantum physics is," says Keith Schwab, Professor of Applied Physics at Caltech. 

And that means finding a way to make measurements that go beyond the limits of quantum physics.

I receive much crackpot email. There is a very common misunderstanding often central, one I have not seen a good answer to anywhere. This is partially due to that few who write about physics counter crackpot theories well. Allow me to explain this point with a new personal story before explaining why energy seems quantized, why photons seem to be little packets of energy rather than a concept that describes quantum interactions more or less well.

Very recently, a combination of the precise measurements of the mass of the top quark obtained by the CDF and DZERO experiments at the Fermilab Tevatron collider with those produced by the ATLAS and CMS experiments at the CERN LHC collider has been produced, obtaining a result of 173.34 GeV, which surprised nobody -of course- with a very small total error bar: 0.76 GeV, a mere 760 MeV, not even a proton's mass.
"In the case where the dark matter particle is light (less than 1 GeV) and the interactions is either contact or mediated by light (but not massless) particles, there is parameter phase space that cannot be probed by current underground detectors even with substantially lowered energy thresholds. This region of the parameter space can be probed by shallow site detectors with low energy thresholds. However, since in this case dark matter particles will be very effectively stopped if coming upwards (i.e. below the detector), we argue that a search for a daily modulated dark matter signal is probably the best strategy for probing this part of the parameter space."

Neutron stars are extraordinarily dense stellar bodies created when massive stars collapse. They host the strongest magnetic fields in the universe -- as much as a billion times more powerful than any man-made electromagnet.

But some neutron stars are much more strongly magnetized than others and no one is sure why.

A paper by McGill University physicists Konstantinos Gourgouliatos and Andrew Cumming
in Physical Review Letters  sheds new light on the expected geometry of the magnetic field in neutron stars and could help scientists measure the mass and radius of these unusual stellar bodies, and thereby gain insights into the physics of matter at extreme densities.

This must be the boosted b-jets season... Just a few days ago I discussed here the nice new observation of boosted Z->bb decays pulled off by the ATLAS collaboration using 8-TeV proton-proton collisions recorded in 2012. And today I am pleased to see in the Arxiv a new study by D. Ferreira de Lima, A. Papaefstathiou, and M. Spannowsky on the possibility to measure the pair production of Higgs bosons in their decay to two pairs of b-quark jets.
I was delighted today, as I checked the page of public ATLAS results, to find a very beautiful new result. The signal ATLAS found and just published on the arxiv is not one anybody could doubt to be there: no surprise whatsoever. And yet, it is a difficult one to extract, and one on which I myself have spent several years of my research work on the CDF experiment.