Dark Matter might leave a ‘fingerprint’ on light, scientists say

Posted on Monday 13 October 2025

Dark Matter, the substance that makes up most of the Universe, could potentially be detected as a red or blue light ‘fingerprint’, new research shows.

Previously assumed to be invisible, the study, from researchers at the University of York, suggests that Dark Matter could leave faint, measurable marks on light as it passes through regions where the elusive substance is present — challenging long-held assumptions that the two never interact.

The presence of Dark Matter is known only through its gravitational pull, which shapes galaxies and holds them together, and it is therefore rarely questioned whether Dark Matter could be detected through light.

Subtle tint

But the York team says the picture may be more complex. Their findings indicate that light could pick up a subtle tint — slightly red or blue — depending on the type of Dark Matter it encounters. Detecting such effects could open up a new way to study the invisible mass that dominates the cosmos.

The theoretical study uses the idea of the “six handshake rule” - the notion that any two people on Earth are connected by just a few mutual acquaintances. They suggest a similar chain of connections might exist among particles.

Even if Dark Matter doesn’t interact directly with light, it might still influence it indirectly through other particles. For example, some Dark Matter candidates, known as Weakly Interacting Massive Particles - or WIMPs - could connect to light via a series of intermediate particles such as the Higgs boson and the top quark.

Next generation

Dr Mikhail Bashkanov, from the University of York’s, School of Physics, Engineering and Technology, said:  “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. 

“It’s a fascinating idea, and what is even more exciting is that, under certain conditions, this ‘colour’ might actually be detectable. With the right kind of next-generation telescopes, we could measure it. That means astronomy could tell us something completely new about the nature of Dark Matter, making the search for it much simpler."

The study outlines how these indirect particle interactions could be tested in future experiments, potentially allowing scientists to rule out some theories of Dark Matter while focusing on others, and so researchers argue that the new study could point to the importance of factoring these possibilities in future developments of telescopes.

Searching the skies

Understanding Dark Matter remains one of the greatest challenges in modern physics, and so the next stage of this work could be to confirm these findings, which could offer a new way of searching for a substance that has, until now, only revealed itself through gravity.

Dr Bashkanov said: “Right now, scientists are spending billions building different experiments — some to find WIMPs, others to look for axions or dark photons. Our results show we can narrow down where and how we should look in the sky, potentially saving time and helping to focus those efforts.”

The research is published in the journal Physics Letters B