What is dark matter?
Transcript
This chapter, from the episode video's captions · 365 words
4:42basic question from first principles like, what what is dark matter? And sort of understanding why the case why we think the case for the existence of dark matter is so strong. >> Yeah, so dark matter is something that only appears to interact through gravity with, uh, baryonic matter, which is essentially normal matter. >> The stuff you and I are made of. >> Yeah, the stuff that you and I are made of. So, that we know of some forces that mediate interactions between normal matter. So, things like gravity, electromagnetism, uh, the strong force, and the and the weak force. So, dark matter is something that only appears to interact through gravity.
5:23>> Okay. >> So, it doesn't interact, uh, through electromagnetism, which means it doesn't interact with light because light is described by electromagnetism. So, it's something that is out there, it's passing through the Earth, probably through us right now, but because it doesn't have any interactions except gravity, we can't really tell. It only becomes apparent when you start looking through telescopes at the universe that there's more stuff out there than we can see. >> This is interesting. So, the the idea is the the and I I think I remember seeing these statistics of like the actual what we believe to be the uh breakdown between, you know,
6:03uh let's call it normal matter and dark matter. It's It's actually the majority of the universe based on how we see, you know, things interacting with gravity, there has to be what is it like 60, 70, 80% has to be dark matter to account for what we see in the visible light spectrum. >> Yeah, it's about Dark Matter is about five times as abundant as regular matter. Uh but we don't know what it is. So, we're trying to figure it out. >> So, when when we say what's interesting about Dark Matter is it's invisible to us because it doesn't interact with light itself,
6:44but it is not non-interacting because it does interact with gravity, which can subsequently have an effect on objects that do interact with light that we can actually see and measure.
From How Scientists Actually Study Dark Matter
A first principles interview with astrophysicist Dan Gilman on what dark matter is, why strong gravitational lensing matters, and how the next generation of surveys could reveal the universe’s hidden structure.