The 95% Mystery The visible universe that we currently perceive, including Earth, the Sun, stars, and other galaxies, is composed of protons, neutrons, and electrons, which combine to form atoms. Perhaps one of the most astonishing discoveries of the 20th century is that this ordinary matter accounts for less than 5% of the total mass of the universe. The remaining portion is believed to consist of dark matter (25%) and dark energy (70%).
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According to experts, the existence of dark matter and dark energy helps explain the motion of stars and the expansion of the universe. However, despite their significant mass, scientists have never directly observed dark matter or dark energy. A new endeavor, led by Dr. Mauro Raggi from Sapienza University (Italy), has been launched to search for the elusive “dark forces” that bind ordinary matter with dark matter and dark energy.
The hope of success may be slim, but if achieved, experts believe it will be the most groundbreaking discovery in the history of physics. “At present, we don’t know what over 90% of the universe is made of,” according to Dr. Raggi. “If successful, humanity will open the door to a new world and gain understanding of the molecules and forces that bind the dark sector of the universe,” predicts the researcher in Rome.
Currently, physicists only recognize four fundamental forces of nature that enable the cohesion of matter. For example, the electromagnetic force allows for mobile phone calls, the strong interaction ensures the stability of atomic nuclei, the weak interaction operates in the field of radiation, and gravity keeps human feet on the ground.
However, it is also possible that there are other undiscovered physical forces. These forces are believed to govern the behavior of the particles that constitute dark matter, and they are provisionally referred to as the fifth fundamental force. Dr. Raggi and his colleagues will rely on a device called Padme, located at the National Institute of Nuclear Physics near Rome, Italy. Padme will record the events that occur when a 0.1 mm thick diamond plate is bombarded with positron beams, the antiparticles of electrons. The machine is designed to search for particles up to 50 times heavier than an electron, a weight range that experts hope will include the “dark photon” and uncover traces of the “dark forces”. Padme will continue to operate from the end of September until the end of 2018, before plans are made to transfer the device to Cornell University in 2021 for the next phase of deployment.
In addition to Sapienza University, efforts to search for the dark photon are also underway in other laboratories around the world. Bryan McKinnon, a PhD student at the University of Glasgow (Scotland), is participating in similar efforts at the Thomas Jefferson National Accelerator Facility in Virginia, USA. “The dark photon, if it exists, will serve as a gateway to a new world,” says McKinnon.