Tag: physics
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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.…
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Year Four
My early efforts at blog writing were somewhat sporadic, but I did mark some key moments during my PhD, in the posts Year Two and Year Three. In the former, I reflected on the major review that every Portsmouth PhD student must pass in order to progress to their second year. In the latter, I…
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How asking a question on Stack Exchange kick started my career in research
I did my undergraduate degree at Aberystwyth University in Wales. I took the astrophysics course, which ran in parallel to the plain physics degree for the first two years, covering all the basics such as mathematical methods, classical mechanics, waves, optics, thermodynamics and so on. In the third year the astrophysics became the main focus,…
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Thesis off-cuts: the ancient history of general relativity
I have recently been thinking a lot about what introductory and background material I want to include in my PhD thesis, as my self-imposed December deadline continues to hurtle towards me at an alarming speed. Concurrent with this thinking, I’ve also recently been enjoying a fantastic book called The Poincaré Conjecture by Donal O’Shea, all…
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The joy of journal clubs
Presenting papers in journal clubs is one of my least favourite things to do. While I enjoy reading in general, I find reading academic papers a chore, especially if the writing is uninspired or the results obscured by reams of unfamiliar theory. However, papers are the currency of academia and, to stretch the analogy, journal…
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Paper day! Madrid week seven
Today my first paper as first author came out on the arXiv! You can check it out here: https://arxiv.org/abs/2002.10449. In this work, we reconstruct a coupling function between dark matter and vacuum energy. Such models are generally motivated as solution to problems such as the Hubble tension, so we were keen to update our previous…
Natalie B. Hogg 