Neutrinos are in the news again, this time due to a recent paper in Science from the IceCube Neutrino Observatory. One of the goals of the observatory is to pinpoint the source of very high energy neutrinos, and this latest paper presents some initial results. One of the challenges with neutrino observatories is that neutrinos don’t interact strongly with other things. …
Astral Projections
You can’t make an accurate flat map of the entire Earth. Since the Earth is not flat, a map is typically a projection of the Earth onto a flat surface. As a result, the shapes of the continents are distorted. Perhaps the most famous example of such a projection map is the Mercator projection, which distorts the size of polar regions …
A Broader View
A while back I wrote about how atomic line spectra can be used to determine the motion of a star or galaxy. This is possible because light from a moving source will become slightly redder (redshift) if the object is moving away from you, and slightly bluer (blueshift) if it is moving toward you. The entire spectrum of a star …
Close Encounters
Earlier this year, a 50 meter rock was heading straight for us. On February 15, it missed us by a hair’s breadth in cosmic terms, coming within 3 Earth radii. At its nearest approach, it was closer to the Earth than a geosynchronous satellite. It passed through the spot Earth was just 20 minutes earlier. While that sounds like a …
Sticky Sticky Bubble Gum
One of the challenges of understanding the formation of planetary systems is just how small clumps of matter become bigger clumps of matter. On scales large enough for gravity to play a significant role, we can model meteoroids and planetoids as as clumping due to their gravitational weight, but for small dust particles and clumps of molecules, gravity plays almost …
Private Time
You are probably familiar with the basic idea of relativity, specifically the fact that a clock appears to tick more slowly if it is moving relative to you. This time dilation effect has been observed experimentally, and it has some interesting consequences.
Splitting Hairs
As I wrote earlier, the electrons of an atom don’t actually orbit the nucleus of an atom. Instead they exist in regions around the nucleus known as orbitals. Part of the reason for this is that electrons are not particles in the way we traditionally think of particles. Instead they are quanta, which have both particle-like features and wave-like features. …
Big Badda Boom
The figure below from a recent article in Nature is a rather puzzling observation. It shows a dramatic rise in the level of carbon 14 around 774 AD.
Color in the Lines
A couple days ago I wrote about how atoms and molecules emit (or absorb) light at only certain colors, and how this produces line spectra. The pattern of bright or dark lines is unique to the type of atom or molecule, so we can use them to identify the atoms and molecules in a star. I mentioned in passing that there …