An Experiment Could Determine Whether Gravity Is Quantized (forbes.com)

TheAlexKnapp writes: Physicist Brian Koberlein explains an experimental proposal by Großardt et al, which would attempt to determine whether gravity is quantized. "Their idea," explains Koberlein, "is to take a charged disk of osmium with a mass of about a billionth of a gram and suspend it an electric field. This is small enough that its energy levels in the electric field would take on quantum behavior when cooled to temperatures a fraction of a Kelvin above absolute zero, but its also massive enough that its gravitational pull would affect the quantum behavior."

The two primary approaches to a quantum gravity, the "perturbative approach" and "the semi-classical method," predict different results from this type of interaction. So the results of the experiment, could, in principle, elucidate the right approach for developing future theories of quantum gravity.

Comments

arXiv links

[Anonymous Coward]

Proposed experiment: arXiv:1510.01696.
More detailed theory: arXiv:1510.01262.
See also blog post.

A more detailed explanation

[Manywele]

There's a good explanation by a physicist who thinks about experimental validation of quantum gravity here.

a fraction of a Kelvin above absolute zero

[dfn5]

So... a fraction of a Kelvin then.

Re: Cut to the chase

[lgw]

Just to be clear, Planck units have no physical significance

False. The Plank length is the smallest length that it could be possible to measure by any method. Classical ideas of size and distance likely fail many orders of magnitude above the Plank length, but it's certain that a distance or length shorter or more precise than Plank length is non-physical.

It's the smallest scale at which a metric (from which concepts like "distance" and "length" come) makes physical sense. And from relativity we know that the Plank time is the same - no concept of "duration" makes physical sense at finer granularity than Plank time.

The Plank mass is likely unimportant, however, unless those String theorists are actually right about something for once. Color me skeptical.

However, none of this should be taken as justifying a view that the universe has a "frame rate" or could be described in terms of voxels. We know from relativity that those ideas also make no physical sense. (Also, anything like that would have a grain that would be totally obvious. There's no "special" directions at right angles to one another, no preferred physical axes.)