Greg Egan

I am a science fiction writer and computer programmer.
Latest novel: SCALE.
Latest collection: INSTANTIATION.
Web site: gregegan.net

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npub1qqm7nu2qf25xd3mw6y6cyp4v2wr7ktf43ymp5wqz4u8jvz76ymtsjj5nhv

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[email protected]

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nprofile1qqsqqdlf79qy42rxcahdzdvzq6k98plt956cjds68qp27rexp0dzd4cpz4mhxue69uhhyetvv9ujumt0wd68ytnsw43q7wa3h3

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relay.mostr.pub

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npub1qqm7nu2qf25xd3mw6y6cyp4v2wr7ktf43ymp5wqz4u8jvz76ymtsjj5nhv

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Last Notes

2024-08-08 15:48:51

“A feature documentary about two out of work actors attempting the impossible task of mounting a full production of Hamlet inside the ultra violent world of Grand Theft Auto Shot entirely in game.”
https://www.undiscoveredcountryfilm.com

2024-08-07 09:17:12

Things we’ll now check at compile time:
“The new IPC Template Type defined 21 input parameter fields, but the integration code that invoked the Content Interpreter with Channel File 291’s Template Instances supplied only 20 input values to match against.”
https://www.crowdstrike.com/wp-content/uploads/2024/08/Channel-File-291-Incident-Root-Cause-Analysis-08.06.2024.pdf

2024-08-01 13:09:31

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@npub1knz…c73p Thanks! It’s going to take me a while to digest all this.

2024-08-01 10:44:30

I don’t mind that “efflorescence” *also* means “the formation of a powdery deposit on the surface of brickwork as a result of loss of moisture on exposure to air” but that the mini OED on my computer lists this *before* anything about flowers, or cultures, in bloom is depressing.

2024-07-29 23:55:21

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@npub1c9m…9xjd This is what happens when you go hiking in the Garden of Forking Paths.

2024-07-27 15:48:36

Trying to imagine the pitch meeting for “Greta”:
“It’s a stalker movie! With *all* the clichés!”
“So … it’s a tongue-in-cheek metafictional parody, like ‘Cabin in the Woods’?”
“No.”
“A fresh take, with an astonishing new angle?”
“No.”
“Um, OK. Here’s a budget and some stars.”

2024-07-27 06:23:15

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@npub16tg…rfyq Thanks!

2024-07-27 00:36:45

Quantum effects might make it impossible to form black holes by immensely concentrating light, because photon collisions create particle-antiparticle pairs that the electromagnetic field accelerates to escape the collapse.
https://physics.aps.org/articles/v17/119

2024-07-23 15:38:17

Definitely going to write my next novel this way:
https://www.abc.net.au/news/2024-07-23/guinness-world-record-to-type-alphabet-with-nose-at-speed/104131164

2024-07-23 15:33:44

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@npub1zad…szcu Luckily I’ve now managed to find a sensible one like that, which I will give as the gift instead of the terrible one.

2024-07-23 09:12:02

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@npub1pal…cy7v Yes!

2024-07-23 06:38:11

Some product designers are idiots. I bought a 2-hotplate induction unit as a gift, then realised you can’t turn off hotplates individually, and removing one pan makes it beep for a minute. Keeping this for myself for when my old stove dies, but would never inflict on anyone else.

2024-07-21 11:52:20

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@npub1pst…gnrd Yeah, I should have stated that I’m talking about wholly synthetic running shoes, not leather shoes. I’ll edit the post to add that.

2024-07-21 08:13:00

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@npub1kva…xqsq No, these were fine for the same walk, dozens of times, back when they were the shoes I wore most of the time.

2024-07-21 08:07:09

How much does “wearing in” shoes involve (A) the shoe becoming less stiff & deforming, vs (B) the wearer’s gait adapting & their foot callousing at rub points?
Just walked 16km in shoes I hadn’t worn for 18 months (much used & comfortable back then) and ... ouch, seems mostly B.

2024-07-20 00:19:06

On Guam, they tried to protect nesting boxes for birds from brown tree snakes by placing them on top of smooth, slippery poles.
Snakes: We call this lasso mode.
https://www.youtube.com/watch?v=iRjrawDTFXU
Article in Science:
https://www.science.org/content/article/guam-s-invasive-tree-snakes-loop-themselves-lassos-reach-their-feathered-prey
I heard about this on the wonderful “What the Duck” podcast:
https://www.abc.net.au/listen/programs/what-the-duck/snakes-and-ladders/104010396

2024-07-19 09:23:19

Crowdstrike have advised that the world will be reverted to its last valid backup set, dated 7 Jan 2014, within the next 30 minutes. Please make paper notes of anything important to you from the intervening period, and tape them to your refrigerator door in a prominent position.

2024-07-15 12:38:45

I must confess I’m enjoying “Land of Women” as a guilty pleasure, largely thanks to Carmen Maura as the naughty grandmother giving me flashbacks to all her great roles in early Almodóvar films.

2024-07-13 11:26:16

The story of Maurice Hilleman, a wonderfully sweary virologist from Montana responsible for vaccines that currently save 8 million lives a year, “noted by some researchers as having saved more lives than any other scientist in the 20th century”.
https://radiolab.org/podcast/great_vaccinator

2024-07-13 06:03:46

Australian taxpayers: At this time of year, as many as 0.01% of the emails you receive claiming that you have a new message in your myGov inbox can be genuine emails from the Australian Tax Office. Stay alert, to minimise the risk of deleting this 0.01% along with all the scams.

2024-07-12 06:25:01

This was the cringiest thing I’ve heard on the AI front, period. Apart from the fact that all but the crappiest LLMs do a better job at faux-conversation than this, foisting such an obnoxious toy on people in aged care would be a form of torture.
https://www.abc.net.au/listen/programs/radionational-breakfast/robot-developed-to-work-in-aged-care-homes/104089424

2024-07-10 05:54:12

A fascinating and disturbing look at how finite-element engineering simulations, though potentially very accurate, are nonetheless sometimes wildly wrong thanks to old/misused code, and dodgy shortcuts that Gilbert Strang calls “variational crimes”.
https://www.scientificamerican.com/article/how-the-math-of-cracks-can-make-planes-bridges-and-dams-safer/

2024-07-04 11:14:23

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@npub1knz…c73p I’m confused. This seems to be describing an event on August 8, 2023, so why are you saying it’s connected to what happened last night?

2024-07-04 08:30:01

“Since [the 4 fireballs seen over Melbourne last night] were on distinctly different orbits, we know they were not related to a common origin, such as breaking off a larger structure.”
Unless they were all fragments from one time-reversed explosion …
https://www.abc.net.au/news/2024-07-04/mysterious-fireballs-seen-crossing-melbourne-sky/104058816

2024-07-02 08:40:36

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@npub1c9m…9xjd My 2007 iPod shuffle is still going strong! I have no idea how to download music to it from my MacBook, but luckily I still have a 2007 iMac that does the job.

2024-06-21 10:33:22

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@npub1knz…c73p
Franklin also totally messed up the QCD colour charges.

2024-06-21 09:24:46

Breaking: Leaked modelling commissioned by the Australian opposition puts a price tag of $1B, over five years, to train a hundred engineering graduates to pronounce the word “nuclear”.

2024-06-19 13:19:22

Apple TV thoughtfully asking my age twice, just in case I’m in a superposition of older and younger selves.
https://media.mathstodon.xyz/media_attachments/files/112/643/002/128/675/505/original/fcf1d1d572cd213c.png

2024-06-15 13:12:28

This is MacOS (13.6.7) content indexing failing.
Two near-identical files, but only the 2nd can be found by content.
I’d be curious to know if the same thing happens for other Mac users, or if it’s specific to my machine (though the bug remains when I rebuild the index.)
https://media.mathstodon.xyz/media_attachments/files/112/620/332/687/665/142/original/1e47164f85d65e42.png

2024-06-14 09:24:24

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@npub1knz…c73p No, I’ve never really got into minimal surfaces.

2024-06-14 08:13:45

“Alice in Wonderland: Simple Tasks Showing Complete Reasoning Breakdown in State-Of-the-Art Large Language Models”
H/T https://x.com/ChombaBupe/status/1801298035802079640
https://arxiv.org/abs/2406.02061

2024-06-12 10:30:33

Here’s a thought, online shoe stores: maybe let the customer enter their shoe size, and filter the choices on offer by whether you have that size in stock, rather than making us check case after case individually?
Either that, or let us send our own SQL queries to your database.

2024-06-07 06:11:23

A complete globe of the world made from a material that can be bent but not stretched or sheared (thus preserving local distances and angles) will be rigid — but if you cut out large enough portions at high latitudes, what remains can be reshaped so the equator becomes an ellipse.
https://media.mathstodon.xyz/media_attachments/files/112/573/380/251/264/238/original/e6b1f2d8870ba611.mp4

2024-06-04 10:45:56

Wow, lucky people in Sydney are seeing a fairly rare kind of soliton cloud known as a “roll cloud”: tubular clouds that appear to be rolling across the sky.
https://www.abc.net.au/news/2024-06-04/nsw-sydney-roll-clouds-explainer/103934424
https://en.wikipedia.org/wiki/Arcus_cloud#Roll_cloud
https://media.mathstodon.xyz/media_attachments/files/112/557/471/530/557/763/original/c9f73f577defe390.png

2024-05-30 12:48:24

Gram negative bacteria have been laughing at us:
https://pubmed.ncbi.nlm.nih.gov/20419407/
but now we might finally have our revenge, with lolamicin:
https://www.nature.com/articles/d41586-024-01566-8

2024-05-27 06:38:18

“exeme” sounds like some new-fangled technical term from the cutting edge of genetics or information theory ... but actually it’s just an archaic Scottish word meaning to release or exempt.
https://en.wiktionary.org/wiki/exeme

2024-05-16 09:07:45

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@npub1knz…c73p
“You can have various mixed-halogen things, all of which are reactive and toxic and are distinguished by their various degrees of vileness.”

2024-05-07 06:38:26

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@npub1c9m…9xjd I was kind of hoping it would turn out to be a version of “The Purple Rose of Cairo”.

2024-05-03 05:12:49

Are you OK, Science magazine?
“The therapy, an injectable monoclonal antibody callnative to antimalarials used in areas where malaria is endemic; those drugs have to be taed L9LS, offers a possible alterken for several days each month to be protective.”
https://www.science.org/content/article/news-glance-infrared-telescope-debuts-gm-rice-stumbles-maternal-mortality-drops

2024-05-01 05:27:13

If you’re in Australia or New Zealand, you can help epidemiologists keep track of influenza and Covid by answering a very short weekly questionnaire. I’ve been doing this for a few years, and it takes about 15 seconds to click through the multiple choice responses.
https://info.flutracking.net

2024-04-24 12:30:25

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@npub1knz…c73p
It’s not hard to check that the determinant of my $C(j,n)$ matrices is:
\[1+(j^2+4 j n+4 n^2)(1+\omega+\omega^2) = 1\]

2024-04-24 02:45:32

Heard on the radio this morning: “M*sk is a free speech absolutionist.” [sic] I guess that entails an absolute right to be absolutely forgiven for saying absolutely anything.

2024-04-23 01:17:52

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@npub1knz…c73p
–3/2 is the dot product between two nearest neighbours among the set of points on the hyperboloid whose 2X2 matrices have Eisenstein integer entries.

2024-04-23 01:13:15

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@npub1knz…c73p
I figured out the dot product between hexagon centres, when all the *vertices* of the hexagons lie on the same horosphere and the dot product between vertices is –5/4 ... and it is indeed –3/2!

2024-04-22 16:44:47

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@npub1knz…c73p
Right, sorry, I was confused about that. I’ll see if I can figure out the correct distance between the hexagon centres.

2024-04-21 09:26:26

No smooth curve that lies on a sphere can contain an inflection point (a point where the curvature is zero).
But on a surface of constant negative curvature, like this tractroid, no such obstacle exists, and every non-meridian geodesic on the tractroid has 2 inflection pts (black).
https://media.mathstodon.xyz/media_attachments/files/112/308/018/651/774/660/original/8556afd6712d6131.png

2024-04-15 15:10:45

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@npub1psd…9sr7 I like the line that article quotes from a Nicholas Ray movie, Wind Across the Everglades:
"the only tree that carves its initials into you."

2024-04-09 09:02:48

My new novel MORPHOTROPHIC is available now!
You can read the first two chapters here:
https://www.gregegan.net/MORPHOTROPHIC/00/MorphotrophicExcerpt.html
https://media.mathstodon.xyz/media_attachments/files/112/239/978/574/551/730/original/b383977da3c0b966.png

2024-04-04 15:48:24

It’s 30 years this month since PERMUTATION CITY was first published. But of course, all the same letters had been present in other books for centuries before, they just hadn’t been read in that order.
Excerpt at:
https://www.gregegan.net/PERMUTATION/Excerpt/PermutationExcerpt.html
https://media.mathstodon.xyz/media_attachments/files/112/213/257/528/650/020/original/14ce7cc2e2086142.jpg

2024-03-27 02:26:14

You can read the first two chapters of my new novel MORPHOTROPHIC here:
https://www.gregegan.net/MORPHOTROPHIC/00/MorphotrophicExcerpt.html
https://media.mathstodon.xyz/media_attachments/files/112/167/411/609/335/313/original/f008e88df993056e.png

2024-03-26 18:32:10

My new novel MORPHOTROPHIC will be published on 9 April.
Amazon is now accepting preorders for the ebook; other venues will follow soon.
There will also be print-on-demand editions from Amazon available on 9 April, but they can't be pre-ordered.
https://www.amazon.com/dp/B0CZ46L396

2024-03-23 09:52:32

Saw someone hyperventilating over LLMs “passing the mirror test”, so …
TL;DR This short program “recognises itself”: show it a file containing its own source code and it will print “This is me!”
Underwhelmed? You should be! But I did have to type a lot of backslashes.
https://media.mathstodon.xyz/media_attachments/files/112/144/149/186/749/381/original/b0dbfeb1f000a669.png

2024-03-15 08:26:59

Of course you can estimate π by dropping needles on the floor, but it’s much more fun to do it by integrating the Gaussian curvature across the surface of any 3-holed doughnut, then dividing the result by –8.
https://media.mathstodon.xyz/media_attachments/files/112/098/515/987/368/510/original/2a8547ca26eafdc6.mp4

2024-03-02 03:52:51

“A supernova has been observed in great detail just 3.5 light years from Earth... and that's close!”
WTF, Science Show? The story itself is a perfectly reasonable account of the new evidence for a neutron star remnant for 1987A, 168,000 ly away, so ... ?
https://www.abc.net.au/listen/programs/scienceshow
https://media.mathstodon.xyz/media_attachments/files/112/023/827/450/045/919/original/cdeaa9984742fd54.png

2024-02-29 09:55:40

If you think leap years are a nuisance, spare a thought for the poor people of Apophis as they struggle to prepare for the 2029 bug:
“Earth will perturb Apophis from an Aten-class orbit with a semi-major axis of 0.92 AU to an Apollo-class orbit with a semi-major axis of 1.1 AU.”

2024-02-22 13:42:05

The 19th century was a golden age for the differential geometry of surfaces. Gauss blazed the trail, and then many successors continued in the same vein in later decades.
One vast chapter of this work involved surfaces of constant negative curvature, like those shown below.
https://media.mathstodon.xyz/media_attachments/files/111/975/183/082/654/727/original/11b1af2c28409f25.mp4

2024-02-14 11:48:43

Gemini nailing organic chemistry — and also failing it at the same time — by fire-hosing the user with different answers, at least one of which might turn out to be right, even if they all contradict each other.
https://media.mathstodon.xyz/media_attachments/files/111/929/439/826/159/017/original/4a5d13e0e037e2f7.png

2024-01-25 15:25:50

“Today, ESA’s Science Programme Committee approved the Laser Interferometer Space Antenna (LISA) mission, the first scientific endeavour to detect and study gravitational waves from space.”
https://www.esa.int/Science_Exploration/Space_Science/Capturing_the_ripples_of_spacetime_LISA_gets_go-ahead

2023-11-30 00:30:54

"You could always have just written, 'Isla Gorge that way', but then if it didn't say, 'Trust me not Google', they would have said, 'How do they know?', because Google knows everything."
This farmer paid $1000 out of his own pocket for a sign to stop travellers getting lost, when Google Maps directed them across his property towards a tourist spot which could not actually be accessed by that route.
(Google finally fixed the problem after a journalist contacted them.)
https://www.abc.net.au/news/2023-11-30/grazier-makes-sign-trust-me-not-google-after-maps-confusion/103142386
https://media.mathstodon.xyz/media_attachments/files/111/496/397/639/893/340/original/515c480ff05f1725.png

2023-10-08 07:46:55

Take a 600-cell in 4D with 120 vertices ±v_i, i=1…60
Define F(x)=𝚷_i v_i·x
Stereographically project F from a 4-sphere to 3D, then Fourier-transform from momentum space to position space.
Result: this hydrogen wave function, with energy level n=61.
More at:
https://www.gregegan.net/SCIENCE/SymmetricWaves/SymmetricWaves.html
https://media.mathstodon.xyz/media_attachments/files/111/197/803/320/661/908/original/544ecb5078253e2d.mp4

2023-09-02 12:50:18

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@npub1knz…c73p
It is both photovoltaic and thermal.
https://www.pv-magazine-australia.com/2020/03/20/arena-boosts-funding-for-raygens-solar-hydro-power-plant/
“The Melbourne-based startup generates renewable energy and large scale energy storage by focusing sunlight with a field of aligned mirrors or heliostats onto a tower-mounted receiver containing an array of PV Ultra modules made of gallium arsenide PV cells. The heat extracted from the PV Ultra modules is then stored as hot water in a reservoir acting as a store. The ability to co-generate electricity and heat, the latter a captured by-product, makes the whole facility highly efficient.”

2023-09-02 12:37:26

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@npub17lk…l3x2 The people who built it will be surprised to learn that you know better than them, and that their photovoltaic modules are figments of their imagination.

2023-09-02 02:09:27

Concentrated solar photovoltaic, but the water that cools the PV modules is retained as a heat store, and some of the electricity drives a chiller to cool a second mass of water. The temperature difference drives a turbine, for ~17hrs of stored power.
https://www.abc.net.au/news/2023-08-31/raygen-resources-opens-new-solar-and-thermal-power-plant-carwarp/102798366

2023-09-01 13:02:11

A tragedy that shatters her childhood drives Charlotte to become an astronomer, in the hope of finally determining the shape of the universe.
My story “Didicosm” is now free to read online:
https://www.gregegan.net/DIDICOSM/Complete/Didicosm.html
with some supplementary material:
https://www.gregegan.net/DIDICOSM/Loops/Loops.html

2023-07-04 15:37:48

I knew geckos relied on van der Waals forces to cling to walls, and I assumed most insects and animals with similar abilities did the same.
But no ... ants wet their feet and use capillary adhesion.
Text article:
https://www.abc.net.au/news/science/2023-01-18/sticky-animals-ants-ceiling-geckos-walls-nature/101579912
Audio:
https://www.abc.net.au/radionational/programs/what-the-duck/what-the-duck!/14058326