Tag: cosmology
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The road (back) to Madrid
On Friday last week I signed my contract and started my job as a postdoctoral researcher at the IFT in Madrid. It feels extremely good to type that. I have also been waiting a very long time to write this post. I was offered this job on the 12th of April 2020 — when the…
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Using a Jupyter notebook to make presentation slides
TL;DR: Open a blank Jupyter notebook. Add a cell and convert it to Markdown (either esc + m) or by using the drop down menu at the top of the notebook. Add your text, equation or image to the cell (images can be added via the edit menu, though some HTML tags may be needed…
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Running, paper revisions, talk writing
I started this morning in unusually energetic fashion, by going for a run before starting work. It was a bit chilly but the sky was clear blue and the sun was shining. The birds were singing and the blackthorn blossom has topped the newly green trees and hedges with a creamy white glaze. The daffodils…
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Philosophy and cosmology
I’ve decided it’s time to improve the consistency of my writing and practice makes perfect, as they say. So, starting from today, I’m going to a write a blog post every day for thirty days (excluding weekends and holidays). By my calculation, this means the last post in the thirty day sequence will come on…
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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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The distance duality relation
The distance duality relation tells us how, assuming that photons propagate on null geodesics in a pseudo-Riemannian spacetime and that their number is conserved, luminosity and angular diameter distances are related, via where dL is the luminosity distance, dA the angular diameter distance and z the redshift. This relation was introduced by Etherington in 1933,…
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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 