Two of the most distant galaxies seen to date are captured in these Webb pictures of the outer regions of the giant galaxy cluster Abell 2744. cience credit: NASA, ESA, CSA, STScI, and Tiger Hsiao (Johns Hopkins University). Image processing: Alyssa Pagan (STScI).

As astronomers we are always looking for clear dark skies so we can better see the stars, planets, moons, comets, nebulae, galaxies and any other weird and wonderful things and stuff out there in the blackness. You may have seen in the news the amazing first images sent from the new super-duper most powerful James Webb Telescope, the JWST, stationed in space at 1 million miles from us. 

 One image (see pic) shows a spattering of the earliest galaxies whose light has just reached us from 13 billion years ago, the deepest we have ever looked into the Universe. The JWST is a time machine looking back to almost when the Big Bang occurred, and the Universe came into being 13.8 billion years ago. So, eventually we should be able to see everything that is out there, blobs of stuff dotted around in empty space. 

But, to quote Jim Lovell from the ill-fated Apollo 13 mission, “Houston, we have a problem”. Looking into space we thought we could account for everything existing but lots of stuff seems to be missing. There is about 85% of the mass of our universe which we can’t account for. It has been called DARK MATTER and is the mysterious stuff that fills the universe but which no one has ever seen or detected. What we can see, the visible matter in the Universe consists of baryons – an overarching name for subatomic particles such as protons, neutrons and electrons that form the atoms that make up everything we see from galaxies to stars to planets and, of course…to us!  

The theory of the existence of dark matter can be traced back to the 1930s and the pioneering discoveries of Fritz Zwicky and Jan Oort who found that the motion of galaxies and of nearby stars in our own Galaxy, do not follow the expected motion based on Newton’s law of gravity. Since then, data from experiments and many precise measurements including the rotational speeds of stars and galaxies, provide strong evidence for the existence of dark matter in the form of strange sub atomic particles.

But we still do not have any direct evidence for dark matter. We only assume it exists because without it, the behavior of stars, planets and galaxies simply wouldn’t make sense. Dark matter is completely invisible as it emits no light or energy and so cannot be detected by conventional sensors and detectors but it does have a mass that seems to have a gravitational effect on everything. Future experiments with the new upgraded and more sensitive Large Hadron Collider (LHC) may eventually be able to detect dark matter particles produced in collisions of proton beams. Until then, scientists can still only speculate what dark matter is made of. We are still very much in the dark! 

By Glynn Bennallick