We often speak of gravity as a force. More accurately it is a feature of spacetime. Even more accurately, we don’t know what it is.
The Four Horsemen
There are four fundamental forces in the universe, and each of them plays a crucial role in astrophysics.
Need for Speed
Scientists have not proven the speed of light isn’t constant.
Wishing Doesn’t Make It So
When our science fiction dreams run into the limitations of science itself, some barriers simply can’t be broken.
Grading on the Curve
A team of physicist have measured a variation of gravity known as curvature for the first time.
And Then There’s Maude
In modern physics, matter in the universe is made up of quanta or “particles” such as electrons, protons and neutrons. These particles can be said to interact through various forces or fields (strong, weak, electromagnetic, gravitational) for which there are corresponding “field quanta” such as photons and gluons. These quanta can are often seen as the particles that make up these fields, and while things are a bit more complicated it is the right basic idea. We have a lot of experimental evidence for these quanta, but there is one that’s often mentioned for which we have no experimental evidence. That’s the graviton.
Imaginary Neutrinos
A new paper proposes that neutrinos may be tachyons. This is being presented in the press as a claim that neutrinos move faster than light, but that’s not the focus of the paper. Instead the paper argues that the electron neutrino could have an imaginary mass.
But No Simpler
Recently there’s been a flurry of news articles claiming that “Quantum physics just got simpler!” as if new research has finally solved a big mystery of physics. Not so, when you look at the actual research. The work looks at a connection between particle-wave duality, and something known as entropic uncertainty.
And the Number Shall Be Three
In earlier posts about dark matter, I’ve written about how neutrinos would seem to be a good candidate, but there simply aren’t enough of them to account for all of dark matter. As far as we can tell, there are three types (flavors) of neutrinos, and we know the upper limit of their mass from the distribution of galaxies in the universe. So the three known neutrino flavors can’t be the solution to dark matter.