Nov 25, 2016
Note: The Picture of the Day is on hiatus for the holiday. In the interim, here is a favorite from the archives.
New studies suggest that the origin of the strongest cosmic rays is still mysterious.
Cosmic rays are energetic ions from space that arrive in the Sun’s local neighborhood traveling at extremely high velocities. About 90% of all cosmic rays are single protons, or hydrogen nuclei, followed by 5% helium, with the remainder being all other elements in the periodic table.
The term “cosmic rays” is a misnomer and stems from the early days of their discovery. Scientists using electroscopes, the first apparatus ever designed to detect the electric charge on an object, were puzzled by the fact that air inside the chamber housing the instrument would become ionized no matter how well the device was insulated from the environment.
Initially, it was assumed that radiation from the ground was responsible, so several experiments were designed to confirm the theory. In 1910, Theodor Wulf used an electrometer, a more advanced version of the electroscope, to measure the difference in radiation from the top and bottom of the Eiffel Tower. Since his electrometer detected ground radiation, he thought that it ought to diminish as he ascended. To his surprise, it increased in strength.
The Nobel laureate Victor Hess designed an electroscope that was resistant to pressure and temperature changes, so that he could take it up in a balloon. Hess had previously determined that ground radiation levels were undetectable above 500 meters. On April 17, 1912 he rose to 5300 meters in a helium ballon and discovered that his electroscope discharged, confirming that there was a source of ionizing radiation coming from above. It was long thought that the source was electromagnetic in nature, thus the appellation “rays”.
Recently, scientists working with the IceCube neutrino detector at the South Pole announced that “cosmic ray hotspots” have been seen coming from specific locations in space. Since cosmic rays are “only known” to be generated by supernovae or the mysterious Gamma Ray Bursters (GRB), the hotspots are creating confusion: no such sources exist close enough to create such high velocity ions. Cosmic rays are electrically charged, so magnetic fields beyond a certain distance ought to randomize the direction from which they arise and prevent such highly localized conditions.
In an Electric Universe, cosmic rays are accelerated by another method: double layers. Double layers were described in 1929 by the plasma pioneer and Nobel laureate Irving Langmuir. They form when electric current flows through plasma. Another Nobel laureate, Hannes Alfvén, described a double layer as, “… a plasma formation by which a plasma—in the physical meaning of this word—protects itself from the environment. It is analogous to a cell wall by which a plasma—in the biological meaning of this word—protects itself from the environment.”
When plasma moves through a dust or gas, the cloud becomes ionized and electric currents flow. The currents generate magnetic fields that confine themselves into coherent filaments known as Birkeland currents. Birkeland currents squeeze galactic plasma into thin filaments that remain collimated over great distances. Astronomical observations reveal that the material from some galactic jets travels more than 30,000 light-years.
The charged particles that compose the currents spiral along the magnetic fields, appearing as electrical vortices. Surprisingly, Felix Aharonian from the Dublin Institute for Advanced Studies suggested that “… there could be a ‘tube’ of magnetic field lines extending between the source and our solar system, funnelling the cosmic rays towards us.” He is close to the mark, although he believes his theory to be “highly speculative”.
Plasma physicist Alex Dessler wrote: “When I entered the field of space physics in 1956, I recall that I fell in with the crowd believing, for example, that electric fields could not exist in the highly conducting plasma of space. It was three years later that I was shamed by S. Chandrasekhar into investigating Alfvén’s work objectively. My degree of shock and surprise in finding Alfvén right and his critics wrong can hardly be described. I learned that a cosmic ray acceleration mechanism basically identical to the famous mechanism suggested by Fermi in 1949 had [previously] been put forth by Alfvén.”
— Quoted in Anthony L. Peratt, “Dean of the Plasma Dissidents“, Washington Times, supplement: The World and I (May 1988).