Dark Matter’s “Nightmare Scenario” Looks More Likely Than Ever
The X-ray (pink) and overall matter (blue) maps of various colliding galaxy clusters show a clear separation between normal matter and gravitational effects, some of the strongest evidence for dark matter. The X-rays come in two varieties, soft (lower-energy) and hard (higher-energy), where galaxy collisions can create temperatures ranging from several hundreds of thousands of degrees up to ~100 million K. Meanwhile, the fact that the gravitational effects (in blue) are displaced from the location of the mass from the normal matter (pink) shows that dark matter must be present. Without dark matter, these observations (along with many others) cannot be sufficiently explained. Credit: NASA, ESA, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland; University of Edinburgh, UK), R. Massey (Durham University, UK), T. Kitching (University College London, UK), and A. Taylor and E. Tittley (University of Edinburgh, UK)
Our great hope is that today’s indirect, astrophysical evidence will someday lead to successful direct detection. What if that’s impossible?
There’s an enormous puzzle to the Universe, and it’s one that might be doomed to remain puzzling for a long time: dark matter. For generations, it has been recognized that the known law of gravity, Einstein’s general relativity, combined with the matter and radiation that’s known to exist in the Universe — including all the particles and antiparticles described by the Standard Model of physics — doesn’t add up to describe what we see. Instead, on a variety of cosmic scales, from the insides of individual galaxies to groups and clusters of galaxies all the way up to the largest filamentary structures of all, an additional source of gravity is required.
It’s possible that we’ve got the law of gravity wrong, but if that’s the problem, it’s wrong in an extremely complicated way that also seems to require an additional source of matter (or something that behaves equivalently). Instead, the most common and successful hypothesis is that of dark matter: that there’s an additional form of matter out there, and we feel its gravity, but have yet to experimentally detect it directly, the way we’ve detected all other confirmed particles. That hope, of direct experimental confirmation, is only possible if dark matter interacts with either itself or normal matter in a way that leaves a detectable signature. If dark matter’s only interactions are gravitational, direct detection might truly be a physical impossibility for us.
Unfortunately, that “nightmare scenario” might be exactly what’s really happening here in our Universe, as all the evidence we have fails to turn up even a hint of an interaction beyond the purely gravitational. Follow the link below to see what we’re facing as this great nightmare starts looking more and more like our reality.
(Source: Big Think)
