This week I travelled to Aachen on the western border of Germany for the COSMO19 conference hosted by TTK, the theoretical physics department of RWTH. The conference, which occurs yearly in different locations around the world, has a very broad scope ranging from particle astrophysics to theoretical cosmology.

Conferences are an important and fun part of academic life. They are an opportunity to find out about the latest work in the field, but also to network with other PhD students, postdocs and academics. Travelling to conferences is one of the perks of being a PhD student, but this year I have been consciously trying to reduce the carbon footprint of my trips. The ICG PhD students all travelled to Aachen entirely by train and the slower pace of the journey meant that we got to see lots of scenery and travel through different cities, such as Lille and Liege. A couple of us even broke up our return journey with a quick trip to the historic centre of Brussels.

Aachen is also a historic town. Charlemagne was crowned in the cathedral (pictured above, as seen from the university’s Super C building) and there are many other ancient buildings clustered around the town hall and main square. There are also hot springs underneath the town, the use of which as a spa dates from the Roman times.

Each day began with two sessions of plenary talks, then after lunch the conference split into three parallel sessions. This format was great, as the plenary talks generally gave a broad overview of a specific topic, and it was easy to switch between parallel sessions to attend the most interesting shorter talks.

Plenary talks that I particularly enjoyed included Vivian Poulin on cosmological hints for dark matter; Lloyd Knox on the Hubble tension; Chihway Chang on weak lensing surveys; and Alkistis Pourtsidou on 21cm radio astronomy.

Some of my favourite parallel talks were given by Francis-Yan Cyr-Racine on early time solutions to the Hubble tension and Meng Xiang-Lin on acoustic dark energy. Special mention must go to my ICG colleagues Chris Pattison and Bill Wright, and my collaborator Simone Peirone, who all did an excellent job of presenting their work on the big stage in the main lecture theatre.

Arguably the most important part of the conference for me was the poster session on Wednesday night, where I was presenting my poster about my (not so) recent work on the interacting vacuum model of dark energy. I was busy talking to people for the whole of the two hour slot and so unfortunately didn’t get much of a chance to check out the other posters! However, the venue for the session was excellent (the top floor of the Super C building) and I got a lot of questions from people about the concept of interacting dark energy and what it can do.

Following the poster session was the conference dinner, held in the huge Coronation Room in the town hall. The food and atmosphere were excellent and the event was a nice continuation of the conference’s social activities. The evening before, we had the choice of taking part in a walking tour, a scavenger hunt, a laser tag game or a trip to the spa. I had a lot of fun doing the scavenger hunt (photos from which were displayed at the conference dinner) and the activities, poster session and dinner were all definitely the best of any conference I have attended.

After the conference ended on Friday afternoon, we had the chance to explore a bit more of Aachen. Chris and I visited Kurgarten park and managed to see some of the elusive red squirrels there. We had lunch at Aachen’s one and only cat cafe, Cafe Milou, which I can highly recommend for both the food (all vegetarian and vegan) and the atmosphere (if you like cats!). Another restaurant I liked was Frittenwerk for its tasty loaded fries and I also recommend visiting the Egmont pub for its vast selection of cocktails and single malts and the fact that you can order food to eat in the pub from the Lebanese takeaway next door!

Chris and I were the last of the ICG contingent to leave Aachen, wending our way back across Europe on Saturday. We had a couple of hours to kill before our Eurostar out of Brussels and so took the train from Brussels Midi to Brussels Central and walked over to the Grand Place, where the city hall, guildhall and city museum are. The square was very busy due to a beer festival taking place, but we still had the chance to wander around and see the beautiful historic architecture (pictured above). If you have a spare hour in Brussels I would highly recommend a visit.

Overall, COSMO19 was well worth attending and many of the talks have given me ideas or inspiration for new directions to take my own work in. Next year’s edition is going to be in Rio de Janiero — I haven’t quite worked out how I’m going to get there without flying!