Feeling Gravity's Pull: Claudia de Rham Speaks to Fotini Markopoulou for Nautilu

Zeeya Merali

FQxI physicists Fotini Markopoulou and Claudia de Rham, of Imperial College London, chatted about de Rham's research on gravity for Nautilus magazine recently. De Rham has worked on massive gravity, a framework in which the graviton (the particle hypothesized to be associated with the force of gravity and usually assumed to be massless) has some mass, and moves at less than the speed of light. The benefit of positing a massive graviton is that it could explain the acceleration of the expansion of the universe, doing away with the need to invoke some mysterious dark energy. Read more: https://nautil.us/feeling-gravitys-pull-861220/

Lorraine Ford

Re: Two theoretical physicists have a lively conversation about how abstract concepts can feel down-to-Earth. By Fotini Markopoulou, September 13, 2024.

Sorry, but I think that conscious feelings and inspiration are interesting, but not relevant. The real issue is the real world, and the way that human beings need consciousness and agency to symbolically represent the real world, and what this method of symbolic representation means about the nature of the real world.

In mathematics and physics:

The mathematicians and physicists are conscious of the symbols that represent categories, numbers and relationships, and
The mathematicians and physicists move and change the symbols that represent the numbers that apply to the categories.

But if you cut the mathematicians and physicists out of the picture, there is a belief that

A real-world mathematical system would automatically know its own categories, numbers and relationships, and
A real-world mathematical system would automatically move and change its own numbers that apply to the categories.

That belief is clearly wrong. In addition to the categories-numbers-relationships aspect, every standalone real-world mathematical system also needs the crucially important aspects that were provided by the mathematicians and physicists:

An aspect that knows/ is conscious, and
An aspect that can jump the numbers.

The real issue is that, not just high-level living things (including physicists) need consciousness, but the real low-level mathematical world itself also needs a low-level consciousness/ information/ knowledge/ logic aspect.

Lorraine Ford

Fotini Markopoulou: That pure spacetime, a universe with no matter, causes much of the trouble in quantum gravity, too. I never understood why we are so committed to this idealization. Why can’t we say that this is not the universe we live in, our world has matter, isn’t it great that matter helps us solve problems? You get much resistance if you advocate for this.
Claudia de Rham: That resistance was very much my experience in my field, too. There is a great aspiration for the most abstract, the most grandiose. The bigger the symmetry group, the better. I saw it as natural as to set up our canvas or set up a box, the real-world context that we work inside. That’s what physics is. We lay our tools on the table and set them up to start the conversation. Without that, it can be disconnected from reality.

Fotini Markopoulou: You write about how gravity tastes or feels. We spend so much time with gravity that we do taste it, feel it, play with it. …
I think most physicists work this way, but talking about it is tricky. … When my Ph.D supervisor talked like that, he was seen as a wise elder, but a woman will be labeled “intuitive” in a derogatory way. It can be depleting if you have to watch what you say.
Claudia de Rham: I know exactly what you mean. Can you allow yourself to show more of how you really do science? That it’s not just a hard logical process but it’s also feeling your way and having human stories for it? Some people are allowed to, depending on others’ preconceptions, others risk being taken less seriously if they show this. …

Fotini Markopoulou : That’s the belief that science is descriptive, not normative. Ideally disembodied. The Lord speaks through you, so the more disembodied the better.
Claudia de Rham: I’d start with the normative side of things. Being part of it. If you put yourself in it, you can’t help but change things. Maybe that’s the difference with some of my colleagues who feel “this is the truth, these are the equations.” They do not see themselves in them at all.

Yes.

We can never transcend the world; we are not outside the world looking in. We particles, atoms, molecules and living things are always inside the world; we are made out of the stuff of the world; we are what the world is; and when we die, we break down back into the world.