Steffen Gielen
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sgielen.bsky.social
Steffen Gielen
@sgielen.bsky.social
120 followers 120 following 35 posts
Mathematical physicist at University of Sheffield. Quantum gravity and cosmology. Looking for crap 90's football on here. (Update: Finally found Crap 90's Football!)
Posts Replies Media Videos
Reposted by Steffen Gielen
markpendleton.bsky.social
Management at Sheffield have aggressively ramped up their attacks on striking staff, but we @sheffielducu.bsky.social are unbowed: www.bbc.co.uk/news/article...
University of Sheffield staff 'intimidated' by pay forfeit warning
University of Sheffield to withhold pay if staff do not make up for teaching missed while striking.
www.bbc.co.uk
December 2, 2025 at 8:24 PM
sgielen.bsky.social
Sheffield to Madrid by train! Visited Complutense University in Madrid for a few days. First day Sheffield-Montpellier - TGV in France fast and efficient as always, fantastic views! Then direct from Montpellier to Madrid with even better views from the train. @seatsixtyone.bsky.social
View of Montpellier Saint-Roch station at night with tram tracks and a few people in the foreground View from the bistro car on a Spanish train, beautiful countryside and mountains in the background View from the fast moving train, French pyrenees in the background. Slightly gloomy grey sky View of the side facade of Prado Museum in Madrid, statue of Goya in the foreground, beautiful blue sky
October 12, 2025 at 7:55 PM
sgielen.bsky.social
Another train travel adventure in Europe! Sheffield to Berlin, then Warsaw and Krakow (including a tour of Auschwitz). Lots of cultural and social experiences - the journey back from Krakow only took two days 😀 Even managed to be in Seat 61 once! @seatsixtyone.bsky.social
View from Siegessäule (Victory Column) in Berlin. One can see Tiergarten in the foreground and Reichstag, Alexanderplatz TV Tower, Brandenburg Gate, Dom and various other attractions in the background. Mostly blue sky with a few small clouds View of downtown Warsaw from the viewing platform on top of the Cultural Palace. It is an interesting mixture of modern towers and old socialist prefab-concrete construction. Sunny sky A picture showing that I was indeed in Seat 61 (on the Warsaw-Krakow fast train). It's a window seat indicated by "Okno-Fenster-Okno-Window". View over the famous main square in Krakow. St Mary's Basilica in the background and Cloth Hall visible in the central-right part of the picture. It's clear blue sky and a very hot day. There is a sprinkler for cooling down people with water. One can also see market stalls.
August 26, 2025 at 10:25 AM
sgielen.bsky.social
Exciting few days in Edinburgh 🏴󠁧󠁢󠁳󠁣󠁴󠁿 - visited the University and today sightseeing and a hike up Arthur's Seat!
View from Calton Hill towards Edinburgh city centre, with castle in the distant background. Clear blue sky! Selfie with view towards Edinburgh centre, castle in the distance View from Arthur's seat. Rocks in foreground, large parts of Edinburgh in background, view over the sea. A few clouds in the sky
July 12, 2025 at 9:21 PM
Reposted by Steffen Gielen
brexitbin.bsky.social
We didn't dream it! 😡💥
The respectful way Keir Starmer talked about foreign workers when he was running for Labour leader is the exact OPPOSITE of the Farage-cloned way he talks about them now. But to see it here in black & white is still SHOCKING!
#RejoinEU 🇬🇧🇪🇺
May 12, 2025 at 5:35 PM
Reposted by Steffen Gielen
coldwarsteve.bsky.social
May 13, 2025 at 3:50 PM
Reposted by Steffen Gielen
sheffielducu.bsky.social
Sheffield UCU took part in the Workers Day of Action on Trans Rights from our picket lines today! The UK Trade Union movement stands behind our trans siblings
#tradeunionists4transrights
May 7, 2025 at 10:47 AM
sgielen.bsky.social
Bank holiday hike from Hathersage up to Stanage and Higger Tor. So beautiful
view along Stanage Edge in the Peak District, greyish sky Selfie in front of Stanage Edge with typical Peak District vegetation, greyish sky map of the hiking route
May 5, 2025 at 5:15 PM
Reposted by Steffen Gielen
kityates.bsky.social
As Liverpool win the Premier League for the second time, they complete the opening of a quite remarkable sequence, 33 years in the making.

#Fibonacci
A table showing the number of imes teams have won the Premier League in ascending order. The sequence goes 1, 1, 2, 3, 5, 8, 13 - the first seven terms of the Fibonacci sequence.
April 27, 2025 at 5:10 PM
sgielen.bsky.social
Returning to England on St George's Day, as seems appropriate. They love St George in Freiburg too! On the way back, time to see Notre Dame both in Kaiserslautern (as Lego) and finally again in Paris!
Schwabentor, one of the medieval gates in Freiburg. There's a painting of St George as dragon slayer and the inscription "St. Georgius patronus freiburgi", which is Latin I think LEGO model of Notre Dame and the square in front of it during the time of the French revolution. There's actually a guillotine installation and you can see Marie Antoinette awaiting her execution, with some severed heads. Selfie in front of Notre Dame cathedral in Paris, grey sky.
April 24, 2025 at 7:31 PM
sgielen.bsky.social
Exploring Freiburg and the Black Forest. Found Germany's tallest tree!
Münsterplatz in Freiburg. Cathedral on the right and Historisches Kaufhaus on the left. Some market stalls in the middle Waldtraut vom Mühlwald, known as Germany's tallest tree. It's a Douglas fir, about 100 years old Fantastic view over Black Forest landscapes with a partially cloudy sky
April 19, 2025 at 4:21 PM
Reposted by Steffen Gielen
sciencex.bsky.social
New theoretical insights suggest black holes might not be endpoints but transitions to white holes, potentially reshaping our understanding of time and dark energy in the universe. doi.org/g8748h
Black holes: Not endings, but beginnings? Theoretical study delves into 'white holes'
Our understanding of black holes, time and the mysterious dark energy that dominates the universe could be revolutionized, as new University of Sheffield research helps unravel the mysteries of the cosmos.
phys.org
March 12, 2025 at 3:47 PM
sgielen.bsky.social
Black Hole Singularity Resolution in Unimodular Gravity from Unitarity - our work in Physical Review Letters today: journals.aps.org/prl/abstract...
Black Hole Singularity Resolution in Unimodular Gravity from Unitarity
We study the quantum dynamics of an interior planar anti--de Sitter black hole, requiring unitarity in the natural time coordinate conjugate to the cosmological ``constant of motion'' appearing in uni...
journals.aps.org
March 11, 2025 at 7:47 PM
sgielen.bsky.social
Kingfisher in Endcliffe Park in Sheffield - not a great quality picture but very exciting!
Kingfisher sitting on a branch of a tree above some water in Endcliffe Park
February 16, 2025 at 6:18 PM
sgielen.bsky.social
Today I realised that this is where I'm supposed to be delivering lectures in a few weeks. Not too sure how I can make this work yet...
Picture of a small meeting room with about 10 chairs around a table, a not too big TV and a whiteboard.
January 17, 2025 at 6:14 PM
sgielen.bsky.social
Berlin at the end of 2024. Believe it or not, the U-Bahn runs at 3:15 on a Tuesday morning.
Selfie in front of Reichstag building in Berlin. Giant Christmas tree visible in front of Reichstag Misty view over Berlin darkness from Neue Nationalgalerie Museum. Cranes in the foreground and hotel neon lights in the background visible through the mist. Overground S-Bahn in Berlin, station entrance Tiergarten with an old pub that offers "Warme Speisen", graffiti and bins Selfie in the Berlin underground (U7 Karl-Marx-Str.) at 3:15am
December 31, 2024 at 3:58 PM
sgielen.bsky.social
No points at home this time, sadly. On the plus side, time for lots of cool London sightseeing and a long visit to the Tate Modern.
View of Gtech Community Stadium from near a corner after the match has finished. Most people have left. Road signs at Ealing Road, Brentford. Sign towards the left says "Brentford F.C." whereas one pointing to the right says "Brentford Community Stadium" View over the Thames and London sights, London Eye on the left, Parliament and Big Ben on the right. Intense sunlight St Paul's Cathedral at night, illuminated and with a Christmas tree in front.
December 23, 2024 at 5:40 PM
Reposted by Steffen Gielen
coldwarsteve.bsky.social
November 6, 2024 at 8:07 AM
sgielen.bsky.social
Old Trafford today. Now the 14th football ground I have visited in England. Uwe's granddad bombed the Stretford End. Sadly no points (as usual away from home)
Side view of Old Trafford stadium in Manchester, with the text "Manchester United". Quite nice almost blue sky Selfie inside Old Trafford stadium Manchester, with "Stretford End" visible in background.
October 19, 2024 at 8:02 PM
sgielen.bsky.social
Exploring the Yorkshire coast - pretty exhausted after 4 days of hiking 👴🛌😂
view from Flamborough Head, East Yorkshire, chalk cliffs and sea in background view of cliffs and sea near Bempton, large number of birds (gannets) visible on the cliff view of Ravenscar hill with coastline and sea view of parts of Whitby abbey, grey sky and misty background
September 23, 2024 at 7:00 PM
Reposted by Steffen Gielen
retrotechdreams.bsky.social
LAN parties
August 28, 2024 at 4:26 PM
sgielen.bsky.social
Mini break visiting Brighton and the beautiful Sussex coast. It's been so long since I've done something like this and it is so easy to organise.
View of a main road near Brighton seafront, Brighton i360 in background. Sun close to sunset in background View of the sea at Brighton beach on a windy day. Grey sky and a lot of waves on the sea. Selfie in front of cliff and coastal path on Sussex coast. Weather fairly nice.
August 16, 2024 at 8:38 PM
sgielen.bsky.social
Breakfast next to Tyne Bridge for £2.85 -- talk about value for money 😀 #newcastle
A Greggs coffee and breakfast roll on table with Tyne Bridge in the background
August 6, 2024 at 6:12 PM
Reposted by Steffen Gielen
edithcharles.bsky.social
Man I just want slightly nicer trains
"Labour is committed to the nuclear deterrent triple lock" with a picture of sir kid starver looking aggressively Sensible (or his best approximation of this at least)
June 3, 2024 at 7:28 AM
Reposted by Steffen Gielen
coldwarsteve.bsky.social
May 22, 2024 at 4:55 PM