There's no obvious reason for choosing that metric signature!

I made this for my PhD (sometimes last century), which shows microlensing in the Einstein Cross. It's still out there, being used :) - hyperphysics.phy-astr.gsu.edu/hbase/Astro/...

Brits take the Gulf Stream for granted, but to understand it's importance you just have to realise that the Titanic hit the iceberg 10 degrees *South* of Britain.

New paper on the arxiv - - arxiv.org/abs/2602.05070

Just finished Heroes (really enjoyed) and about to start Mythos (have Troy and the Odessey lined up).

Tim Berners-Lee talking about the invention of the world wide web at the Sydney Opera House last night. An invention that truly changed the world.

My airplane display has the Milky Way aligned with the Earth's equator and this really bothers me.

New Publication at the Open Journal of Astrophysics: "Rotational Kinematics in the Globular Cluster System of M31: Insights from Bayesian Inference" by Yuan (Cher) Li & Brendon J. Brewer (U. Auckland, New Zealand), Geraint F. Lewis (U. Sydney, Australia) and Dougal Mackey doi.org/10.33232/001...

If you draw a circle within a square, the circle occupies 78.5% of the area. If you step up a dimension to a sphere in a cube, the relative volume of the sphere is 52.4%. As you increase the number of dimensions, the %-volume of the sphere gets smaller and smaller, and goes to zero as n->infinity.

Double rainbow over Rangitoto Island in Auckland #physicsinaction

South American Bin Chickens are prettier than the ones we have in Sydney

Just realised that the spell checker changed Finkelstein to Frankenstein in the General Relativity and Cosmology exam!

The Gravitational Astrophysics group at @sydney.edu.au

"You can teach a physicist finance but you cannot teach a finance person physics." - Jim Simons (en.wikipedia.org/wiki/Jim_Sim...)

They don't do Guy Fawkes in Australia (but I discovered this weekend that they do in New Zealand). But do we celebrate because he was captured, and the gunpowder plot failed, or because he tried?

Oh I just give up (this was on ABC in Australia, source apparently NASA). And every time anyone calls these moons by a stupid name like Beaver, a small astronomy fairy dies.

Dear palaeontologist - please feel free to chat to astronomers about how orbits work so you don’t end up with gaffes like this in your books,

I am dipping my toes into Fast Radio Burst research, and I discovered they have a "sad trombone effect".

Getting ready for my talk in Auckland tomorrow night

Getting one of these off a group of students you have supervised for a year really means something to me.

Time to start posting current reading

Today, people across the world remember one of the greatest tragedies in Welsh history - the 1966 Aberfan disaster - which left a small mining village robbed of an entire generation

I authored a new video for the History of the Universe on just what the Higgs boson is, and how it could destroy the universe. #scicomm #physics #cosmology #particlephysics youtu.be/JNgEMyTxB8E?...

Thursday afternoon deep thought...

🤓 Cosmic Perfection Won’t Last.

Even after being in this country for quarter of a century, bumping into these guys still make me smile.

Having fun "vibe mathing" with copilot tonight. I think I'm at the limit of known mathematics and about to break through into something new!

The greatest trick the Devil ever pulled was convincing Mac PowerPoint users that they have to upload their slides to the session computer before their talk and that their fonts and animations will not be screwed up.

Spotted at Central Station, Sydney - that's quite a train ride.

Spotted at Central Station, Sydney - that's quite a train ride.

Come on down on Saturday to hear a bunch of awesome science talks - including one on how we are building huge radio telescopes and finding tiny stars! ☄️🔭🧪

For those in Sydney on Saturday afternoon, I will be speaking all about cosmology and the Big Bang at this event at the very nice Chau Chak Wing Museum

Not sure the word "Even" is necessary in this headline!

Dear teachers of special relativity - please stop telling students that special relativity can't handle acceleration and they have to wait for general relativity for that. ThX

Being the 80th anniversary of the bombing of #Hiroshima, this image is doing the rounds as a flash shadow of a person. However, I suspect this is not what this is, as it is much more distinct than other shadows and doesn't appear to have a history before 10-15 yrs ago. Anyone have details?

I'm going to be talking at the Southern Highlands Branch of the Royal Society of New South Wales on the 16th October in Mittagong (a wonderful part of Australia). If you want to hear about gravitational lenses, come along. www.royalsoc.org.au/events/south...

Did anyone get the memo that we should be rethinking the origins of the universe? I seem to have missed it.

A little Saturday afternoon culture at the Parramatta Riverside Theatre - and excellent play!

Loving the Yalta episode in @empirepoduk.bsky.social but I have to take issue at your claim of the British love of Churchill. Where I grew up - the Welsh Valleys - he is not a popular figure and is still spoken about negatively (& often with swear words). www.walesonline.co.uk/news/politic...

46 years apart - always part of my Cambridge pilgrimage.

Not everyday you get to see the original model of DNA!

Back in my homeland

Want to hear me talk about lots of different aspects of cosmology, fine-tuning and the multiverse? This video is for you. youtu.be/OejwZqh-F9U?...

Talk at CosmoVerse in Istanbul done! #cosmology

Incredible showing from Australians past, present and future, at #SKAO2025 in Görlitz. All very excited about getting the first data from the SKAO telescopes! Aussie, Aussie, Aussie! #RadioAstronomy

Street art in Goelitz

Sydney radio astronomers (plus a bonus cosmologist) at SKAO 2025! It's great to be here with so many of our team :) @manishacaleb.bsky.social @astrolaura.com @cosmichorizons.bsky.social @ozgrav.bsky.social #RadioAstronomy #SKAO2025

Space street art in Strasbourg

"Existential panic" - no one told me I should be panicking!

At the Multiverse From Home conference, I had a bit of a rant about how science is not about “falsification” (other than in trivial examples) and remembered I wrote about how it had nothing to do with proof either a decade ago. theconversation.com/wheres-the-p...