03 January 2018

Massachusetts Institute of Technology researchers have proposed an experiment using distant quasars that may close the last major loophole of Bell’s inequality, namely, what physicists refer to as as “setting independence” or “free will”.

This loophole proposes that a particle detector’s settings may interact with events in the shared causal past of the detectors themselves to determine which properties of the particle to measure. This would imply that a person running the experiment does not have complete free will in choosing each detector’s setting. As a result, the experiment produces biased measurements which in turn suggests a correlation between particles that is greater than the real correlation.

David Kaiser, the Germeshausen Professor of the History of Science and senior lecturer in the Department of Physics, along with MIT postdoc Andrew Friedman and Jason Gallicchio of the University of Chicago, have proposed an experiment to close this loophole by determining a particle detector’s settings using distant quasars.

A laboratory setup would consist of a particle generator that produces pairs of entangled particles. One detector measures a property of particle A, while another detector does the same for particle B. A split second after the particles are generated, but just before the detectors are set, scientists would use telescopic observations of distant quasars to determine which properties each detector will measure of a respective particle.

The researchers reason that since each detector’s setting is determined by sources that have had no communication or shared history since the beginning of the universe, it would be impossible for these detectors to interact with anything in their shared past to give a biased measurement.

This experiment is feasible with present technology.

The two experiments that discovered the Higgs boson in 2012 contain data that may point to the existence of a boson even heavier than the Higgs. This was recently announced by both collaborations earlier in December.

The results largely match a rumour that has been circulating on social media and blogs for several days: that both the CMS and ATLAS detectors at the LHC have seen an unexpected excess of pairs of photons, together carrying around 750 gigaelectronvolts (GeV) of energy, in the debris of their proton–proton collisions. This could be a tell-tale sign of a new boson. If true, the particle would be about four times more massive than the next heaviest particle discovered so far, the top quark, and six times more massive than the Higgs.

Marumi Kado of the Linear Accelerator Laboratory at the University of Paris-Sud said that his experiment, ATLAS, had detected about 40 more pairs of photons than would have been expected from the predictions of the standard model of particle physics. Jim Olsen of Princeton University in New Jersey reported that CMS saw merely ten. Neither team would have mentioned the excesses had the other experiment had not seen an almost identical hint.

Experimenters have spent decades validating the standard model, and the Higgs was the last missing piece in that picture. A much heavier particle would open an entire new chapter in the field.

20 Aug 2015

Singaporean student Mark Sim has become the youngest person in the world to score an “A” in the International General Certificate of Secondary Education (IGCSE) physics examination.

Mark was eight years and three months old when he took the exam – consisting of three papers spread out over two days – at the British Council last November.

The feat earned him a place in the Singapore Book of Records when his result was ratified earlier this year.