In specific, Wineland, Drullinger, and Walls were concerned with the improvement of spectroscopy. The group wrote about experimentally demonstrating the cooling of atoms through a process using radiation pressure. They cite a precedence for using radiation pressure in optical traps, yet criticize the ineffectiveness of previous models due to the presence of the Doppler effect. In an effort to lessen the effect, they applied an alternative take on cooling magnesium ions below the room temperature precedent. Using the electromagnetic trap to contain the magnesium ions, they bombarded them with a laser barely out of phase from the resonant frequency of the atoms. The research from both groups served to illustrate the mechanical properties of light. Around this time, laser cooling techniques had allowed for temperatures lowered to around 40 kelvins. William Phillips was influenced by the Wineland paper and attempted to mimic it, using neutral atoms instead of ions. In 1982, he published the first paper outlining the cooling of neutral atoms. The process he used is now known as the Zeeman slower and became one of the standard techniques for slowing an atomic beam. Now, temperatures around 240 microkelvins were reached. That threshold was the lowest researchers thought was possible. When temperatures then reached 43 microkelvins in an experiment by Steven Chu, the new low was explained by the addition of more atomic states in combination to laser polarization. Previous conceptions of laser cooling were decided to have been too simplistic. The major breakthroughs in the 70s and 80s in the use of laser light for cooling led to several improvements to preexisting technology and new discoveries with temperatures just above absolute zero. The cooling processes were utilized to make atomic clocks more accurate and to improve spectroscopic measurements, and led to the observation of a new state of matter at ultracold temperatures. The new state of matter, the Bose–Einstein condensate, was observed in 1995 by Eric Cornell, Carl Wieman, and Wolfgang Ketterle. Doppler cooling, which is usually accompanied by a magnetic trapping force to give a magneto-optical trap, is by far the most common method of laser cooling. It is used to cool low density gases down to the Doppler cooling limit, which for rubidium-85 is around 150 microkelvins. In Doppler cooling, initially, the frequency of light is tuned slightly above an electronic transition in the atom. Because the light is detuned to the "blue" (i.e., at higher frequency) of the transition, the atoms will absorb more photons if they move towards the light source, due to the Doppler effect.