Dark Matter Might Leave A Faint Colour Mark In Light, Say Scientists

Dark matter accounts for 80% of all matter in the universe, yet it doesn't emit, absorb or reflect light, making it effectively invisible. Scientists detect it only through its gravitational pull on galaxies. A new study from the University of York suggests that light passing through regions dense with dark matter could gain an extremely subtle red or blue tint. This feeble colour "fingerprint" could one day help astronomers study the cosmos' most mysterious substance.

Subtle Colour Fingerprints in Light

As per a Science Direct report, York physicists propose that dark matter might have an indirect influence on light via a series of particle interactions. They use a "six-handshake" rule: any two particles can be connected through intermediate links. Therefore, even dark matter candidates such as hypothetical WIMPs could very faintly alter photons through intermediate particles (for instance, the Higgs boson).

In other words, co-author Dr Mikhail Bashkanov says, “It's a fairly unusual question to ask in the scientific world, because most researchers would agree that Dark Matter is dark, but we have shown that even Dark Matter that is the darkest kind imaginable – it could still have a kind of colour signature.”

Hunting Dark Matter with Light

Scientists warn that a colour change, if any, would be very subtle and outside the capabilities of today's instruments. The York group states that it is "an extremely weak signal that cannot be detected by present telescopes" and that it could probably only be "measured with futuristic ultra-sensitive observatories."

In that case, the signal might be a completely different way to see dark matter. According to Bashkanov, next-generation telescopes "have the potential to reveal entirely new things about the nature of Dark Matter, thereby greatly simplifying its detection."