Measuring Gravity Using Superfluid Shielding

Sir Isaac Newton, one of the most influential scientists of all time, was particularly interested in the orbit of the moon around the earth. He reasoned that the force keeping the moon in its trajectory must be gravity and hence gravity must extend over vast distances. From this point on, scientists have been trying to understand what gravity is and how to measure it.

Albert Einstein had a theory that gravity is space itself curved around a mass, attracting objects into its warped domain. Scientists have used this theoretical model and combined it with a set of cosmological explanations in order to try and understand what makes up our universe.

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Dark Matter

Upon observation, there is far too little visible matter in the universe to make up the calculated gravitational energy. Therefore, scientists attributed the ‘empty space’ to dark matter which takes up about 27 percent of the universe.

The ‘Verlindes Hypothesis of Gravity,’ however, tries to eliminate the inconsistencies of dark matter. It describing gravity as an entropic force (a force affected by the systems thermodynamic tendency to increase its entropy) rather than its fundamental interaction previously thought. Recently Verlindes Hypothesis has passed some initial tests.

Measuring Gravity

Our theories and understanding of gravity are far from coherent and establishing a widely accepted theory may help us answer some of the fundamental questions of physics. A recent article published in the journal of Physics Review Letters, December 2016, claims to have found a new way to measure gravity with an accuracy much greater than previous attempts. Researchers with the MIT Department of Physics uses a method called atom interferometry. Atom interferometry is a technique used for precise measurement of the nature of atoms.

Einstein’s theory of wave-particle duality states that particles can be classified as waves or particles. Therefore, this technique can be used to measure the difference in wave phases of atoms in order to calculate the forces acting on them.

Method

A laser is shined through matter in the form of Bose-Einstein Condensates (BEC), one of the five states of matter (gas, liquid, solid, plasma, BEC). BEC is a collection of atoms cooled to within a degree of absolute zero. The atoms barely move relative to each other as there is no free energy to do so. Therefore, the atoms are trapped in the matter and their position relative to the untrapped atoms can be measured.

However, the number of trapped and untrapped atoms are uneven which may introduce errors in measurement. Therefore, this method uses two separate condensates with different magnetic alignments. Each condensate is then subjected to the laser and a magnetic field. The magnetic field causes the atoms to spread evenly between them, thereby increasing the accuracy of the measurement.

Superfluid Shielding

The research team takes this method one step further by introducing Superfluid Shielding. Superfluid Shielding is where BEC’s are immersed in a superfluid bath thereby shielding them from external forces. With less interference, the atoms can be measured for longer.

In addition to providing more accurate measurements, quantum effects can also be observed within BEC’s. This is as a result of the atoms acting as one larger atom when tending towards absolute zero. Therefore, BEC’s may eventually bridge the gap between quantum and Newtonian Physics.

H/T:ScienceAlert

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