According to physicists, dark matter is an unseen material that creates gravity and prevents our Universe’s galaxies from dispersing into millions of disassociated pieces. In fact, dark matter’s impact on our Universe is so great that it could make up nearly 27 percent of its mass (whereas regular matter constitutes a paltry 5 percent).
While modern searches for dark matter have focused on weakly interacting massive particles (WIMPs) the effort hasn’t turned up any clues about the nature of this mysterious material. In an attempt to redirect the search for this significant weft in the Universe’s fabric, a group of researchers now believe dark matter may be built upon macroscopic particles.
“The community had kind of turned away from the idea that dark matter could be made of normal-ish stuff in the late ‘80s,” said Glenn Starkman, a University of Cape Town physics professor. “We ask, was that completely correct and how do we know dark matter isn’t more ordinary stuff— stuff that could be made from quarks and electrons?”
In Starkman’s view strange nuclear matter, like quarks and baryons, could have been made during the birth of the early Universe and come together in large arrangements to produce our concept of dark matter. Starkman calls these arrangements Macros.
According to this new view, Macros would have been created at temperatures hovering around 2.5 trillion degrees Celsius (similar to the temperature at the core of a supernova) and would abide by the following limits:
• A minimum of 55 grams. If dark matter were smaller, it would have been seen in detectors in Skylab or in tracks found in sheets of mica.
• A maximum of 1024[DA1] (a million billion billion) grams. Above this, the Macros would be so massive they would bend starlight, which has not been seen.
• The range of 1017 to 1020 grams per centimeter squared should also be eliminated from the search, the theorists say. Dark matter in that range would be massive and would require gravitational lensing to affect individual photons from gamma ray bursts in ways that have not been seen.
If dark matter is within this allowed range there are reasons it hasn’t been seen:
• At the mass of 1018 grams, dark matter Macros would hit the Earth about once every billion years.
• At lower masses, they would strike the Earth more frequently but might not leave a recognizable record or observable mark.
• In the range of 109 to 1018, dark matter would collide with the Earth once annually, providing nothing to the underground dark matter detectors in place.
While Starkman’s ideas are certainly tantalizing—mostly because they seem to fit into the Standard Model – it may be a while before his ideas are tested, or even taken seriously by his peers. Regardless, Starkman’s Macros are an intriguing notion that’s worth exploring further, even if it’s in disbelief.
Source: Case Western Reserve Blog