The nature of dark matter is one of the greatest mysteries in modern astrophysics. Actually that isn’t quite true. We do know of one type of dark matter, and we’ve even detected this dark matter in experiments on Earth. This particular type of dark matter is more commonly known as neutrinos.
Invariable Plane
One aspect of our solar system is that it is essentially a closed system. The stars are so widely separated that it would be rare for a stray asteroid or other object from beyond the Oort cloud to enter our solar system. This means that nearly all the rocky material orbiting the Sun now was also part of the solar system billions of years ago. This has a few consequences, one of which is the tendency for the solar system to lie in a plane.
Fiat Lux
In 1671, Isaac Newton submitted a letter to the the Royal Society outlining a new theory of light and color. While Newton is probably most famous for his theory of gravity—and the mythical apple—he was also deeply interested in the nature of light, and made one of the first detailed studies of the properties of light. The work he describes in this 1671 paper is so brilliantly simple you can do it at home. All you need is some sunlight and a couple of prisms.
State of Decay
One aspect of quantum particles is that they can decay into lighter particles, releasing energy. For example, a free neutron will tend to decay into a proton, electron, and anti-neutrino. Most particles undergo this kind of decay. Some decay rather quickly, while others tend to take longer to decay. There are a few particles, however, that don’t decay. The electron is stable, as is the lightest neutrino. Then there is the proton, which might be stable, but we’re not entirely sure why.
Six Degrees of Isaac Newton
There is a hexagonal cloud pattern at the north pole of Saturn. It was first discovered by Voyager in 1981, and was still there when Cassini arrived at Saturn in 2006. So it seems the pattern has been stable for more than 30 years. There’s been a great deal of debate about just how such a stable geometric shape could form in Saturn’s clouds, but it turns out the solution is surprisingly simple, and it traces back to some early experiments of Newton.
Gravitational Constant
Astrophysics works with the assumption that the laws of physics are the same everywhere. That’s a huge assumption given that our most distant space probe has barely left the solar system. So how do we know our assumption is valid?
Symmetry
Symmetry is something we all tend to recognize, but probably find hard to quantify. Things like mirror symmetry are easy to describe, but what about the image above. It gives a feeling of symmetry, but exactly how would you describe it?
Duality
When quantum theory is presented in popular science, it is often presented as a strange or spooky thing where particles can act like waves and waves can act like particles. It usually focuses on experiments such as the double-slit experiment where the photon or electron “knows” how the experiment is done and alters its behavior accordingly. This is rather unfortunate, because although quantum theory can seem strange, it is hardly mysterious. It basically comes down to a concept known as duality.
Free Willy
There’s a story going around the popular press about using quasars to determine whether free will exists. This stems from an MIT press release which talks about using quasars to “close the free will loophole.” Needless to say, the actual paper published in Physical Review Letters isn’t really about free will, but rather about an interesting effect of quantum mechanics. …