The Search For A 5th Fundamental Force: The Dark Photon

The Search For A 5th Fundamental Force: The Dark Photon

At the moment we think that 68% of the universe is made of dark energy and 27% is made of dark matter. This means our current theories only explain the 5% that we can see. We currently think that there are four fundamental forces in Physics: the strong force, the weak force, the electromagnetic force and the gravitational force. When you consider that so much of the universe has not even been seen however, it may be sensible to assume that there are more forces that interact with the unknown parts of the universe (the dark sector). At the National Institute of Nuclear Physics in Italy, there is an instrument which is trying to find a possible 5th fundamental force. The experiment is known as Padme (unfortunately not a Star Wars reference) which stands for Positron Annihilation into Dark Matter Experiment.

A stream of antimatter particles called positrons will be shot at a diamond wafer 1/10th of a millimeter thick. When the positions hit their matter counterparts, the electron, they and the electron vanish and release energy. Normally two photons are released but if a 5th force exists, the collisions could occasionally only release one photon along with a dark photon. This is a hypothetical particle and is the equivalent of light in the dark sector.

The dark photon will not interact with the detector and so will be detected by seeing if a missing photon is observed. If a dark photon is observed, then the researches will also be able to measure its mass and energy (dark photons are predicted to have mass unlike photons).

The experiment will run till the end of the year at least and it may be moved to Cornell University in 2021, where there is a more powerful particle accelerator, in order to improve the search for dark photons.

If dark photons are detected, physics will undergo massive changes and we may be one step closer to unifying gravity and quantum theory.



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