Key tenet of general relativity upheld in quantum experiments

It is often presumed that there is a fundamental schism between the two major domains of physics -- quantum theory and relativity. Unification theory demonstrates that there is no real separation between the quantum world and the relativistic domain -- only a conceptual dichotomy existing in the mind of scientists. This is exemplified in the holographic mass solutions of physicist Nassim Haramein, where the same equation that describes the source of mass for large, macroscopic, strongly gravitating bodies like black holes describes the mass of small subatomic nucleons like the proton.

Now, with advances in atom interferometry researchers are investigating key principles of general relativity at the scale of single atoms -- the domain of quantum mechanics. Such techniques allow for direct testing of unified physics. Testing so far has revealed that atoms in a quantum state still feel the same "tug of gravity" as when the atoms are in a more classical state. This shows that such energetic states of atoms still experience an equivalence between their inertial mass under acceleration and their weight under the force of gravity -- a principle of general relativity known as the equivalence principle. The equivalence principle requires that the total rest mass-energy of a body, the mass-energy that constitutes its inertia, and the mass-energy of its weight must all be the same value.

Considering hydrodynamic descriptions of quantum states, such as that found in pilot wave theory -- it would be expected that even when a group of atoms are interacting in a wave-like manner they will obey the equivalence principle of relativity.

Manipulating rubidium atoms with lasers, scientists led by researchers from Italy gave the atoms an upward kick and observed how gravity tugged them down. To compare the acceleration of normal atoms with those in a superposition, the scientists split the atoms into two clouds, put atoms in one cloud into a superposition, and measured how the clouds interacted. These clouds of atoms behave like waves, interfering similarly to merging water waves. The resulting ripples depend on the gravitational acceleration felt by the atoms.

The scientists then compared the result of this test to one where both clouds were in a normal energy state. Gravity, the researchers concluded, pulled on atoms in a superposition at the same rate as the others — at least to the level of sensitivity the scientists were able to probe, within 5 parts in 100 million. -- Quantum test of the equivalence principle for atoms in superpositions of internal energy eigenstates

Interestingly, such tests are also being performed with anti-hydrogen, which should be able to answer the enduring question of whether or not antimatter experiences a "positive" or "negative" gravitational interaction with normal matter. As well several experiments have already tested the free-fall of different isotopes of a given atom, bosonic versus fermionic isotopes, and atoms with different spins. So far, general relativity has not shown evidence of being violated in any of the experiments.

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