Pistol shrimp. Even if the name isn’t familiar there is a good chance you will have heard of this special shrimp (more technically known as alpheidae family of snapping shrimp). Rather that the regular catching and grappling mechanisms that shrimp can use to defend and attack the pistol shrimp has been granted a special ability. Their claws are asymmetric and the larger of the two can be slammed shut to create a large snapping sound. Anyone who hasn’t heard of this shrimp will probably be thinking “so what?” This sound puts the shrimp as a contender for the loudest creature in the sea. The snap creates a bubble which collapses under the water pressure. Getting hit by this bubble collapsing bubble (which can be thrown 4cm from the shrimp’s claw); travelling 60 miles per hour; under an acoustic pressure 80 kPa; and probably reaching a temperature of 5000K spells the end for any small sea creature caught in the way and a hefty stun for anything bigger.
Most people are now very aware of at least the words gravitational waves. A considerable number know that they were discovered because of two black holes spiralling into each other, no other event could be as massively (very literally) catastrophic as to produce such waves. The common wisdom would probably end when asked how big a black hole is. The confused faces that result from question stem from the misleading that you can never escape a black holes gravitational pull. Of course we’re all getting pulled by black holes right now, every piece of mass in the universe attracts every other. If the Sun was to suddenly turn into a black hole with the same mass, the Earth’s orbit wouldn’t change. All the Earth knows is that there is a big mass resulting in a gravitational pull forcing it to go in a circle, the size (as in volume) of the object, whether it is a star or a black hole is quite irrelevant.
Predictions of the future are interesting things. Some would say that the further the future, the harder to predict, but this is not always the case. It is certainly true that if I asked you on the 1st of January whether the evening temperature would be higher or lower on the 1st of February, your guess would be close to a fifty fifty. If I asked you to make the same prediction, higher or lower, about the temperature reading for the 1st of June then you could quite confidently say that June will be hotter. Add an extra six months to return to the 1st January but a year later and your prediction returns to a coin flip. Our confidence in predictions rises and falls but trends are what matter.
Rivers almost always lead to the sea (they can also lead to evaporation planes, in fact, every river in Uzbekistan does this) and in doing so they follow a very distinct geometry which can be aptly described as a branching network. It is through these networks that water flows and carries with it sediment and debris and it through this action that rivers evolve and change the landscape around them.
Methanol is the simplest chemical with the alcohol functional group (unless you get really technical and count water) being written as H3C-OH. It is this OH which defines a chemical as an alcohol. It is also this OH which is responsible for providing methanol with hydrogen bonds in its liquid state. The oxygen atom, being very electronegative, pulls strongly on the electrons in the covalent bond between the oxygen and its adjacent hydrogen resulting in the hydrogen gaining a slight (but significant) positive charge. This then leads to the lone pairs (pairs of unbonded electrons in the outer shells of atoms) on the oxygen of other methanol molecules being attracted to these slightly positive hydrogens creating what is known as a hydrogen bond.
Stopping power is the ability of a material to slow down charged particles (stopping power is only used for charged particles) passing through it by removing their energy through interactions with the particles in the material. In the early 1930s a physicist named Hans Bethe developed the Bethe formula for calculating the average energy loss over a distance within a material:
where me and e are the mass and charge of an electron; I is the average potential of the electrons in the material and n is their number density; and v and z both refer to the particle being retarded, being velocity and charge respectively (it should also be noted that this is a simplification for a non relativistic particle. Electrons and fast moving particles require corrections to the above formula). Continue reading Calculating Distance Over Which Charged Particles Pause
I have briefly written before about a physical theory called the electron gas where the electrons in a metal, having become separated from their ions, can be treated like an ideal gas. This involves the homogenising of the background positive charge caused by the metal ions and also ignoring the Coulomb repulsive force between the electrons. When this force is added the situation becomes known as the electron liquid model and it requires advanced computational methods to solve the many body problem that results (as all electrons modelled will exert some repulsion on each other).