Searching for the Heaviest and Lightest Particles in the Universe with Nicholas Rodd

What is the heaviest particle in the Universe? What is the lightest? The answer to these questions could be dark matter. For decades, we have thought that dark matter would be a particle with a mass similar to the particles we already know about, like the proton or the recently discovered Higgs boson. But in the last decade a revolution has taken place in the field, which has led to a dramatic expansion in the range of masses where we believe dark matter could live. In this talk I will review this revolution, and explain how the discovery of dark matter could amount to detecting dark waves at the location of the Earth, or massive explosions happening throughout the Universe.

Nick Rodd is a scientist at Lawrence Berkeley Lab working at the interface of particle physics and astrophysics, who spends his days trying to figure out what dark matter is made of. Nick grew up in Melbourne, Australia, and after receiving his undergraduate degree in law, decided he wanted to do the exact opposite and moved into physics. He moved to MIT in the US for his PhD, which he completed under the supervision of Tracy Slatyer in 2018. His thesis, "Listening to the Universe through Indirect Detection," was recognized with two awards, one as the top thesis in particle physics, and separately as the top in astrophysics. Before moving to LBL, Nick was a faculty member in the CERN theory group in Geneva, where he moved after spending three years at UC Berkeley as a Miller Fellow.

This lecture was originally recorded on Wednesday, June 26, 2024 at the Aspen Center for Physics.

[shawns]

The fundamental phenomenon of dilation explains galaxy rotation curves/dark matter. Mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". A 2 axis graph illustrates its squared nature, dilation increases at an exponential rate the closer you get to the speed of light. A time dilation graph illustrates the same phenomenon, it's not just time that gets dilated. Neil deGrasse Tyson recently spoke about this.
Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. This includes the centers of very high mass stars and the overwhelming majority of galaxy centers.
It can be inferred mathematically that the mass at the center of our own galaxy is dilated. This means that there is no valid XYZ coordinate we can attribute to it, you can't point your finger at something that is smeared through spacetime. More precisely, everywhere you point is equally valid. In other words that mass is all around us.
Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. It has been confirmed in 6 very low mass galaxies including NGC 1052-DF2 and DF4 to have no dark matter, in other words they have normal rotation rates. All binary stars have normal rotation rates for the same reason.

[davidhand]

If we detect a dark matter particle, we really ought to name it a VeraRubinon.

[davidhand]

Why do you think there can only be one DM particle? Maybe the SM particles are just the tip of the iceberg, the tiny selection of particles that just so happen to have U(1) symmetry. Maybe dark matter is the rest of the mass continuum up to the planck mass.

[scenFor]

Will be ironic if Axions are detected using a washing powder foam bubble.

[coastwalker]

Excellent step back and pregeological review. Enthused to check tide gauges and ELF receivers for dark matter waves as you speak :-) Or what about cyclic drift in LIGO? Of course MOND would be even more exciting.