Neutrons Bouncing on Glass
Gravity Awesome Science Neutrons
So, today our physics department had our Journal Club, where one of the professors/grad students get to share a journal article or two that they found in the vast amount of physics literature available to academia. Today our resident dark matter-seeking professor gave the talk, and boy was it awesome.
The researchers whose papers he found were bouncing neutrons on glass and looking at their quantum states due solely to the potential energy caused by gravity. Quantum mechanics with gravity.
For those of you who don't understand how ridiculously awesome this is, let me put it in terms of Classical Mechanics: when a classical object is under the influence of a uniform gravitational potential (like that near Earth's surface), it follows parabolic trajectories. Imagine a ball bouncing on a table; it forms a series of parabolic bounces, each one smaller than the last due to friction and lost energy due to sound and such. This is essentially what this group did, but with neutrons and glass.
However, because neutrons are not classical particles and instead behave quantum mechanically, they don't bounce in parabolic trajectories. Instead, they abide by the laws of quantum mechanics, which means that there are only certain heights above the table at which they are likely to be found and certain heights that they cannot be found. So, a neutron in the ground (lowest) state of this system is most likely to be found at about 10 microns (thousandths of a millimeter) above the glass.
Also, when this was published back in 2005, it was the first time quantized energy levels due to Earth's gravitational potential alone were ever observed experimentally; the theory has been known for a while, but this is the first time anyone has in any way verified it.
Now, this group is attempting to test the properties of the force of gravity using this apparatus and their neutrons. HOW AWESOME IS THAT?!
This blog entry brought to you by SCIENCE!