Another Sunday is upon us and it’s time to do a review of the top physics news. This includes the top discoveries and news stories from the last week. To receive these news and other cool stuff to your email, register for our newsletter.
Since the introduction of general relativity it has provided a convincing description for gravity, gravitational lensing, black holes and other phenomena. Needless to say, there are things that the great theory of Einstein cannot fully explain. An great example would be the accelerating expansion of the universe.
For these and other reasons, there is a great effort to modify GR to fully explain currently unexplainable phenomena. And like any scientific prediction, modified gravity must be experimentally tested in order for scientists to confirm its validity. Now in a new paper published in Physical Review Letters, Wojciech A. Hellwing, et al., have proposed a new test of modified gravity that is based on measuring the tendency of well-separated galaxies to approach each other.
The physicists show that the galaxy pairwise velocity distribution of many galaxies with a wide range of masses is expected to deviate from the predictions of general relativity by significant amounts: between 5 and 10 standard deviations or higher, depending on the model. Due to these large deviations, this proposed test could potentially offer the strongest evidence in support of modified gravity to date.
The big discovery of the gravitational waves has been recently under a lot of criticism and, the scientists who made the discovery admit that their model is not sufficiently constrained by external public data to exclude the possibility of dust emission bright enough to explain the entire excess signal.
David Spergel, a theoretical astrophysicist at Princeton University, in his paper suggested that the findings could be more easily explained by galactic dust. “We know that galactic dust emits polarized radiations. We see that in many areas of the sky, and what we pointed out in our paper is that pattern they have seen is just as consistent with the galactic dust radiations as with gravitational waves,” Spergel told AFP last week.
For the first time, researchers at CERN have found evidence for the direct decay of the Higgs boson into fermions. This is another strong indication that the famous particle behaves according to the standard model of particle physics. Previously, the Higgs particle could only be detected through its decay into bosons.
“This is a major step forwards,” explains Professor Vincenzo Chiochia from the University of Zurich’s Physics Institute, whose group was involved in analyzing the data. “We now know that the Higgs particle can decay into both bosons and fermions, which means we can exclude certain theories predicting that the Higgs particle does not couple to fermions.”