ETH Master Thesis in Physics
on Quantum Reference Frames

Short introduction coming soon!

For more details, see here.

ETH Semester Project
on Black Hole Information
& Analogue Gravity

For my master in physics I wrote a semester project in theoretical physics on the black hole information loss paradox in the context of analogue gravity models. Roughly speaking, the information loss paradox is a contradiction between quantum field theory in curved spacetime and black hole thermodynamics: The former predicts that black holes lose mass through so-called Hawking radiation, and that the entropy of said radiation always increases. The latter says that the entropy of a black hole decreases as its mass decreases. For the two to be compatible, the entropy of the black hole must always be larger than that of the radiation. But the exact opposite happens (see figure below).

Page curve
Increase of Hawking radiation entropy (predicted by quantum field theory in curved spacetime), compared to the decreasing black hole entropy (predicted by black hole thermodynamics). To solve the paradox, the radiation entropy could for instance follow a so-called Page curve.

Analogue gravity models are physical systems in which wave propagation mathematically resembles the propagation of a field (typically a massless scalar field) in curved spacetime. Thus, certain aspects of the system behave mathematically analogously to a field in curved spacetime. Interestingly, such analogue models can describe spacetimes of black holes, and one can even find Hawking radiation in those models. This leads to the question of whether the information loss paradox can also be described in analogue gravity models.

analogue model
Blue lines indicate the flow of a fluid; its speed increases towards the left. The red cones indicated 'sound cones', i.e. the trajectories of sound waves sent out towards the left and right. H marks a so-called 'apparent horizon': it can be traversed by sound only from right to left. This fluid is a simple analogue model for a black hole in one spatial dimension, with sound propagation in the fluid being analogous to light propagation in spacetime.

The goal of the semester project was to investigate this question: I argued that the analogy does not extend to the paradox, because black hole entropy has no useful analogy in the model. As a by-product, I developed a new approach to introducing a large class of analogue gravity models, including two of the most important ones.

For more details, see here.


In my spare time I take images of the moon, stars, galaxies and other night sky objects with my Celestron telescope and either a Nikon DSLR camera or a ZWO ASI astro camera. You can find more details and all my images here. Below is an overview of my best images as well as my latest image.

Some of my best images so far: globular cluster m92, the moon, the Orion nebula (left to right)

My astrophotography images are protected under the CC BY-NC-SA 4.0 license: Creative Commons License

© Copyright 2017-2023 by Sébastien Garmier, sebastiengarmier.ch.

m42 - The Orion Nebula

The Orion nebula is relatively large and bright, which makes it visible for the naked eye. It was one of the first objects I photographed. After a long break from astrophotography, I returned to it in early 2023 together with my girlfriend Anna Bickel.

M42 - Orion Nebula
M42 - Orion Nebula, taken on 2023-02-09. Celestron CGX EdgeHD 925, ZWO ASI 294 MC pro cooled astro camera, ZWO ASI 120MM guide camera, Celestron guide scope. 6x5min ~ 30min, Gain 0, -5°C

M51 - Whirlpool Galaxy

M51 is a spiral galaxy in the constellation Canes Venatici. It is accompanied by a smaller, irregular galaxy which we can see on the left on one of the spiral arms.

M51 - Whirlpool Galaxy
M51 - Whirlpool Galaxy, taken on 2021-06-14. Celestron CGX EdgeHD 925, ZWO ASI 294 MC pro cooled astro camera, ZWO ASI 120MM guide camera, Celestron guide scope. 25x5min ~ 2h 5min, Gain 200, -10°C

Random Mandelbrot Image of the Day

Each day, a little program I made renders a randomly chosen part of the mandelbrot fractal and uploads the image here. See here for past images and more information.

mandelbrot image
center: -0.654627 + -0.475471i, width: 3e-09

About me

Sébastien C. Garmier, 1999

PHD student in Theoretical Physics at ETH Zurich, Switzerland (since 2023)

hobby astrophotographer

Master of Science ETH in Physics (2023)

Bachelor of Science ETH in Physics (2021)

Swiss matura diploma Kantonsschule Wohlen AG (2017)

Sébastien Garmier

photo: Janosch Abel


If not stated otherwise, all content on this website (sebastiengarmier.ch) is protected by the CC BY-SA 4.0 license:

Creative Commons License

© Copyright 2017-2023 by Sébastien Garmier, sebastiengarmier.ch.