Claudia de Rham: The Theory of Gravity That Shouldn't Exist
episodePreviously titled “The Theory of Gravity That Shouldn't Exist” — renamed by the publisher on Aug 3, 2026
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What is massive gravity and why consider a massive graviton?
When I was doing my PhD, I had just bought in into all of these theorems. They were written by very famous people, but we realized that we were able to violate these no go theorems. General relativity can't be the final answer.
What if gravity itself has mass? This seemingly simple question challenges decades of foundational physics. In this second conversation with Professor Claudia Duram of Imperial College London, we venture even deeper into her revolutionary theory. Duram didn't set out to overturn any established physics, she was searching for an explanation for the cosmos's accelerating expansion. However, In doing so, she discovered that the impossible may indeed be possible. Gravity itself may have mass. This is known as massive gravity. This potentially solves the so called cosmological constant problem that has puzzled physicists for nearly a century. As we explore the implications of this massive gravity, we talk about well, what does that even mean?
We'll also discover how symmetries emerge from
How did Claudia de Rham first challenge the no‑go theorems in gravity?
Chaos, why energy may be a concept that we need to abandon in dynamically curved spacetime, and what recent cosmic observations tell us about the fate of our universe. Tell me about a time where there was some established physics theorem and you found a way around it. What was that theorem or folklore or concept and and how? How did you find a way to circumvent it?
Um so one thing I've done is related to a no go theorem related to massive gravity. So maybe I need to unfold this a little bit what massive gravity is and what the no-go theorem is. Um so we understand gravity thanks to Einstein's theory of general relativity, and there's a little bit of this um tell that tells us that or we don't know how to reconstruct. Reconciliate um gravity with quantum field theory. Actually that's not quite true in Einstein's theory of general relativity. We do understand how we can describe gravity as a particle. We can call this particle the graviton, and that doesn't matter too much. Um but we do understand that very well. So we can embed uh gravity, as in Einstein's theory of general relativity, into a standard field theory framework and represent the force of gravity a little bit like the other forces of the standard model of particle physics, like the electromagnetic force.
Um so for instance we know how gravitational waves are a little bit the analogue of Electromagnetic waves. And we can ask ourselves in principle the question as to Um the gravitational waves which are carried by light, light uh gravit uh we can in principle ask ourselves the question as to light, um, which are electromagnetic waves, whether the particle that carries them may be a massive particle. So in the Stoner model, as we understand it at the moment, we think of light, we think of electromagnetic waves as being a massless phenomenon carried. by a massless particle. But in principle we can think of it as a massive particle and we can put a bound on how massive the photon, the particle carrier of light, would be.
And there's no issue with that. We have bounds from observations on how heavy if you were electromagnetism or light would be. And so we can ask ourselves the same question in fact for for gravity. There's a very sensible question to ask ourselves. In fact it's the first question we should really ask ourselves when we think of gravity as being carried by a fundamental particle like the graviton, you may ask yourself what What is the mass of this particle? Is it massless or could in principle have a mass? And if so, what is the constraints from observations on that mass? And this is where the hiccup comes in. This question was already been addressed or tried to be addressed almost now a hundred years ago, already since uh Fiat and Pauli in uh 1939.
They already try to establish whether it would be possible for the graviton or um a field that would behave like the graviton to be a massive particle. And it comes up with all sorts of different luggage along the way. And they realize that it it is in principle if you just wanted it to be completely
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Chapters
8 chapters
1
What is massive gravity and why consider a massive graviton?
0:00–1:06
2
How did Claudia de Rham first challenge the no‑go theorems in gravity?
1:06–9:26
3
Why does giving the graviton a mass lead to instability and negative‑energy modes?
9:26–16:17
4
How could a massive graviton address the cosmological‑constant problem?
16:17–25:08
5
What are the implications of massive gravity for causality and energy conservation?
25:08–47:37
6
How does massive gravity affect the propagation of gravitational waves and dark energy?
47:37–1:17:17
7
What are positivity bounds and how do they constrain massive‑gravity models?
1:17:17–1:55:10
8
What future observations could test massive‑gravity predictions?
1:55:10–2:02:49
Speakers
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