Tag: astronomy
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Everyone in the world is French
M. Luc Arnaud farmed a small plot somewhere in the south of France. Exactly when and exactly where M. Arnaud’s farm was is now no longer remembered, but we can be sure that he had a few cows, a few pigs, a few chickens and one rather moth-eaten and elderly goat. He didn’t have a…
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Measuring line-of-sight shear with Einstein rings
Today I released a paper written in collaboration with Pierre Fleury, Julien Larena and Matteo Martinelli on how we can measure line-of-sight shear from Einstein rings. But what is line-of-sight shear, and why are we interested in measuring it in the first place? To answer these questions, let’s review the phenomenon of strong gravitational lensing.…
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The howling Universe
Before I moved from IFT to IPhT, I filmed a video all about what standard sirens are and why they’re useful for cosmology. The video is now on Youtube, in English with Spanish subtitles. Take a look!
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Implicit none
The first programming language I ever learned was Fortran. And before you ask, no, I’m not seventy years old. It just so happened that during my undergraduate degree, I took two courses on numerical methods for physics which were taught in Fortran, and for good reason: Fortran is still one of the best languages to…
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My first N months as a postdoc (where 0 < N < 12)
How long have I been a postdoc? It’s a little difficult to quantify. I finished my PhD thesis in December 2020, and submitted it in January 2021. I passed my viva in February 2021. I spent a few months climbing the walls waiting for my Spanish visa, and trying to do research at the same…
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My PhD viva
In this post, I’ll discuss how I prepared for my PhD viva exam in cosmology, what the viva itself was like and what happened next. I submitted my PhD thesis on the 4th of January 2021 (which also happened to be my birthday) and had my viva exam on the 3rd of February. This is…
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Writing my PhD thesis
How do you write a PhD thesis? This question sounds like the start of the old joke: “How do you eat an elephant? One piece at a time”. A PhD thesis is a document which must explain, summarise and defend three or more years of research in your chosen field, often running to 40,000 words…
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Thesis off-cuts: the reproducibility crisis in cosmology
As we frequently hear1, we’re now in the precision era of cosmology. What this really means is that we’re in the era of measuring things really well, and we’re getting really good at measuring things because we keep building ever more enormous and powerful telescopes. I remember attending the STFC Introductory Summer School on Astronomy…
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Thesis off-cuts: how special is our place in the Universe?
Thanks to many hundreds of people making dedicated observations of the sky over many decades, we know that the majority of our Universe is comprised of two substances: dark matter and dark energy. Dark matter is an unknown type of matter, referred to as “dark” because it does not interact electromagnetically, meaning that it doesn’t…
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Tribalism in science
Last week, a tweet by Roberto Trotta drew my attention to a recent paper by Simon Portegies Zwart that studied the amount of carbon dioxide emitted by running N-body simulations in different programming languages. The figure that caught my attention was Figure 3, copied below from the version of the paper published in Nature Astronomy.…
Natalie B. Hogg 