Dark Matter and the Dark Sector

Dark Matter Might Lurk in Its Own Shadow World

• Dark matter could be an entire dark sector of the universe, with its own particles and forces.

• Everything we know about dark matter comes from measuring its gravitational pull

• Gravity is the weakest of nature’s forces

The Mystery of Dark Matter

• Dark matter shapes galaxies and large structures in the universe but is transparent to photons.

• The Milky Way is submerged in dark matter, but its forces cannot touch the regular matter we’re made of.

The Limitations of Gravity

• Gravity is the weakest of nature’s forces.

• Electromagnetic forces that bind atoms are enough to counteract the gravitational force of the entire Earth.

• We need more than gravity to unlock the secrets of the dark side.

The Search for Dark Matter

• The past three decades of the search for dark matter have been characterized by null results.

• Researchers have been looking for a single particle to explain dark matter.

The Dark Sector Hypothesis

• Dark matter might be a whole hidden sector of dark particles and forces.

• In this dark sector, particles would interact through their own independent forces and dynamics, creating a hidden world of cosmology running parallel to our own.

• There could be dark atoms made of dark protons, dark neutrons, and dark electrons held together by a dark version of electromagnetism.

• The carriers of this force, the dark photons, might have mass, allowing huge dark atomic nuclei—so-called nuggets—to form.

• The interactions of nuggets in galaxies could help form supermassive black holes in the centers of galaxies, causing them to grow larger than they otherwise would.

Gaining Traction

• As other, simpler theories of dark matter have failed to find experimental confirmation, the dark sector concept has gained traction.

• Condensed matter physics techniques are used to attempt to uncover a sector of the cosmos we’ve never searched for before.

The Focus on the Weak Force

• In 2005, physicists were focused on searching for dark matter whispers from the weak force.

• The weak force is much stronger than gravity.

• Experiments were built underground to attempt to hear such murmurs.

• Astrophysicists were also seeing unexplained data coming from the center of the Milky Way that might have been a sign of dark matter producing a haze of photons from some kind of interaction with the weak force.

• It seemed premature to focus the search for dark matter on theories related to the weak force because many processes from ordinary physics produce the microwave photons that were emanating from the center of our galaxy.

The Bet

• A bet was made at a dark matter conference with Dan Hooper of the University of Wisconsin–Madison.

• Hooper thought that observations were caused by dark matter within the next five years.

• The stakes of the bet: whoever lost would have to say that the other was right in each of their scientific talks for one year.

Dark Matter Paradigm

• The traditional paradigm is that dark matter is a single type of particle.

• An increasingly popular idea suggests that dark matter might be made of an entire