Jenny Wagner: What If We've Been Wrong About Dark Matter For Decades?

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Previously titled “Jenny Wagner: The "Inverse Problem" Of Dark Matter Is Insane” — renamed by the publisher on Aug 3, 2026

Theories of Everything with Curt Jaimungal 2h 31m 1 speaker 8 chapters transcribed 22 days ago
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What is the main claim about dark matter and why does Jenny Wagner disagree with the standard view?

Jenny Wagner 0:00
I saw the equations and suddenly this is my gravitational lensing problem. He just said, Oh finally, you got it. 30 years after we found out, and it was quite astonishing, how disruptive you think something could be.
Curt Jaimungal 0:17
Dark matter. 85% of the universe's matter is supposedly missing. But what's the technical truth behind the popular science headlines? Dr. Jenny Wagner, a scientist at the Institute of Astronomy and Astrophysics and the Helsinki Institute of Physics, and winner of the Prize for Courageous Science, disagrees about how we got that number. This is because she proved mathematically that most of what we call evidence for dark matter. Is driven by the models we insert and not the data we collect. On this channel, I, Kurt Jimongle, interview researchers regarding their theories of reality with rigor and technical depth. Today's episode is no different. Wagner found that when you strip out the model's assumptions, the only information that the data gives you is local.
Curt Jaimungal 1:04
This means every grand dark matter map you've ever seen is extrapolation. Now it's not wild speculation. That's not what she's saying at all. Specifically, she's saying a profusion of models can all fit the same data equally well. This is called lensing data. By the end of this podcast, Wagner makes the case that this is what Einstein predicted over a century ago. The homogeneous, isotropic, spherical cow model of the universe eventually needs to be replaced by the next level of detail. Today, she shows us how we may finally be there. What do we actually know about dark matter?
Jenny Wagner 1:42
Dark matter. Dark matter is something that I wouldn't say it's something that we know about. It's rather something, it's a term that came up because we missed matter when we looked at our observations. And so dark matter was the replacement or was the substitute for this missing mass in our explanations of certain observations. For instance In observations of the cosmic microwave background in the very early universe, but also in the late universe, where we have cosmic structures that seem to be uh hold together in a gravitationally bound object. But then, if this object is actually gravitationally bound, then we miss a lot of matter because the luminous matter that we see, the baryonic matter, This is too too little matter in order to keep this structure together.
Jenny Wagner 2:38
So if we do not have dark matter, then these structures would dissolve over cosmic time, and then we wouldn't see them as they are.
Curt Jaimungal 2:47
So what's the problem with dark matter? Why are you w what's the matter with matter? What's the matter with dark matter?
Jenny Wagner 2:52
The matter with Mather is that um I would say in uh the modern cosmology, people started out with observations, with observing stars, observing gas clouds, observing X-rays from the from the cosmos. And all of this seemed to be fine until we suddenly realized if we take a look at all of these things and we want to explain them in the way that we want to explain. Stuff on Earth, like to transfer the loss from Earth to the cosmos, we realize that matter is missing. And first people thought, okay, we can just uh improve our telescopes in order to get a better estimate of all of these um missing masses. But on the other hand, if we now estimate forward how much mass are we actually missing, it's eighty-five percent of the entire matter content of the universe that seems to be missing.
Jenny Wagner 3:45
And this is something that we cannot just make up by this stuff, for instance, small small scale planets or a very very light very faint gas that we haven't detected. So a lot of mass seems to be missing. And this is the puzzling thing that we think we need dark matter in order to explain all of the structures, how they behave, and all of the cosmic structure evolution as well, how the galaxies formed.
Curt Jaimungal 4:11
So what does gravitational lensing have to do with any of this? I know you have a wine glass, so why don't you tell the audience or explain or visually or show the audience what is gravitational lensing and then what the heck does it have to do with dark matter?

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