Dark matter is a puzzling problem for scientists. Put simply, dark matter is material that we are fairly sure exists – because we can measure its gravitational effect on nearby objects – but we can’t see it, as it doesn’t scatter or reflect electromagnetic radiation. While we have some very sophisticated imaging equipment (telescopes, radio arrays), we can’t physically see something if it doesn’t interact with our probe – electromagnetic radiation, in this case. An analogy you can draw is envisioning a squad full of military snipers, all dressed in black and hiding on a dark field at night. The snipers certainly have an effect on any enemies that are around, but you can’t actually see the snipers. You can infer that they exist based on the behavior of other people around them, but you can’t put an eyeball on them directly.
Any clump of matter exerts a gravitational pull on surrounding objects. Based on fluctuations in the orbits of planets and asteroids that we can see, we know that something close to them is exerting a gravitational pull; however, we can’t see enough visible objects to fully account for the effects that we see. Thus, some of the nearby objects must (by definition) be “dark matter”.
One mystery that has existed for some time is the “solar composition problem”. To summarize all of the technical particle physic jargon, essentially the mystery is that our models for how atoms behave would predict that the Sun would have a difficult time transporting energy from its core (where the intense heat and pressure produce energy through nuclear fusion) to its surface (where the energy is emitted as heat and light). The models that we use – including the Holy Grail of modern physics, the “Standard Model” – seems to be a little inadequate for explaining the suns behavior. One group of scientists from the Centre for Theoretical Physics at Oxford believe that dark matter can explain this discrepancy.
The theory is that dark matter is comprised of massive particles that only weakly interact with non-dark material. If the Sun was comprised of a large amount of dark matter, it would explain why energy transfer to the surface is so much more rapid than we would normally predict. The Sun has been flying through the galaxy for approximately five billion years, and could have acted as a “cosmic vacuum cleaner”, sucking up dark matter scattered throughout space via gravity and concentrating at its core.
This theory may not sound all that important. Whether or not there is a mysterious dark substance at the center of the Sun doesn’t sound very relevant to our day to day activities here on the Earth. However, the history of modern physics shows very clearly that physics is the foundation stone upon which larger, more applied, scientific research can be built. Without a close understanding of physics, chemistry is not possible; without chemistry, there is no biology; without biology, there is no medicine. Physics in turn is based on mathematics, which is the most basic of the sciences. Understanding precisely why our Standard Model doesn’t fully explain the Suns behavior will have trickle-down effects in all of the other sciences.
Proving this new theory may be difficult. It’s obviously not possible to get a sample of the suns core to analyze it, and I’ve already mentioned that we have a hard time imaging dark matter. The researchers at Oxford have suggested that we instead look for neutrinos. Neutrinos are a type of particle emitted when dark matter collides with other particles of dark matter. Because they are extremely light – some studies suggest they may not even have a mass – the neutrinos don’t interact with most materials and simply fly straight through at close to the speed of light. This gives neutrinos a very particular signal that we could attempt to monitor. Neutrino detectors are currently being constructed in multiple locations and if neutrinos are found in the correct amounts in solar output, it may be the final proof that the brightest object in our solar system is, in fact, quite dark.