The free-lunch guide to idea circularity

Why do the same ideas keep coming round again, and again? Why is it that sometimes an idea sticks, and sometimes it just
fades away? Why is it that no technology, or pattern, or method, is ever quite as good as we’re told it’s going to be?
Why are we working harder, even though AI is supposed to be doing the work for us? Is debt inevitable? How do external
factors influence the day-to-day reality of our jobs? In this wide-ranging session, Holly will discuss interest rates,
ahead-of-time compilation, how venture capital works, why our codebases might be feeling the AI hangover, and the future
of developer jobs.

Transcript

1. Holly Cummins IBM The free-lunch guide to idea circularity March 18, 2026 QCon London
2. The Palace of Westminster prior to the embankment of the Thames, Westminster, 1860s
3. The Palace of Westminster prior to the embankment of the Thames, Westminster, 1860s
5. the great stink
6. Michael Faraday “Near the bridges the feculence rolled up in clouds so dense that they were visible at the surface”
7. “pestiferous invader”
8. “pestiferous invader”
9. Benjamin Disraeli “reeking with ineffable and intolerable horrors”
10. Crossness pumping station, by k7hpn on flickr
11. “cistern chapel” Crossness pumping station, by k7hpn on flickr
12. history rhymes
13. throughput
14. poo throughput
15. pooput
16. sewage trade-offs
17. sewage trade-offs
18. sewage trade-offs
19. centralised stink and disease distributed stink and disease
20. Robert Heinlein, The Moon is a Harsh Mistress “TANSTAAFL”
23. grid
24. cloud
25. nothing is new under the sun
27. “maybe let’s not wreck our home”
28. being sustainable optimise for short-term convenience
29. Sources: https://www.greenit.fr/wp-content/uploads/2019/11/GREENIT_EENM_etude_EN_accessible.pdf https://ourworldindata.org/ghg-emissions-by-sector the digital world creates more carbon emissions than aviation
30. Lighter area represents high and low estimates, where available. Sources: https://www.iea.org/fuels-and-technologies/data-centres-networks https://ourworldindata.org/grapher/electricity-demand?tab=table&country=USA~GBR~FRA~DEU~IND~BRA data centres use as much electricity as a medium country
31. Itaipu dam, Brazil, photo by Deni Williams, reative Commons Attribution 2.0 Generic license
32. days are now 0.06 µsec longer three gorges dam
33. earth’s axis tilted 2 cm three gorges dam
34. green software foundation: principles
35. carbon awareness green software foundation: principles
36. carbon awareness green software foundation: principles where
37. carbon awareness green software foundation: principles where when
38. carbon awareness green software foundation: principles hardware efficiency where when
39. carbon awareness green software foundation: principles hardware efficiency where when elasticity
40. carbon awareness green software foundation: principles hardware efficiency where when elasticity utilisation
41. carbon awareness green software foundation: principles hardware efficiency electricity efficiency where when elasticity utilisation
42. algorithms carbon awareness green software foundation: principles hardware efficiency electricity efficiency where when elasticity utilisation
43. algorithms stack carbon awareness green software foundation: principles hardware efficiency electricity efficiency where when elasticity utilisation
44. LightSwitchOps algorithmic efficiency + efficient stacks
45. LightSwitchOps architect things to be turned off and on often
46. algorithms stack carbon awareness hardware efficiency electricity efficiency where when elasticity utilisation green software foundation: principles
47. capacity Source: John O’Hara Setup: • REST + CRUD • large heap • RAPL energy measurement Assumptions: • US energy mix carbon as a function of load (single instance)
48. capacity Source: John O’Hara Setup: • REST + CRUD • large heap • RAPL energy measurement Assumptions: • US energy mix carbon as a function of load (single instance) shorter line means lower max throughput
49. capacity Source: John O’Hara Setup: • REST + CRUD • large heap • RAPL energy measurement Assumptions: • US energy mix carbon as a function of load (single instance) shorter line means lower max throughput higher line means worse carbon footprint
50. Setup: • REST + CRUD • large heap • RAPL energy measurement • multiple instances to support high load Assumptions: • US energy mix Source: John O’Hara carbon as a function of load
52. “lazy/dynamic” “eager/constrained”
56. “a world without servers” “universal clients”
57. git github
58. microservices hyper-distributed
60. hype cycles
62. grid internet of things digital twin model-driven-development low code cloud native kubernetes microservices
63. the morning after the technology before
64. grid internet of things digital twin model-driven-development low code cloud native kubernetes microservices
65. grid internet of things digital twin model-driven-development low code cloud native kubernetes microservices ai
68. – Meredith Whittaker
69. – Meredith Whittaker
70. – Meredith Whittaker “It’s not simply that one piece of technology is overhyped, it’s that hype is a necessary ingredient of the current business ecosystem of the tech industry.”
71. what attracts investment?
72. what attracts investment? stability?
73. what attracts investment? stability? profitability?
74. what attracts investment? stability? profitability? revenue?
75. what attracts investment? growth stability? profitability? revenue?
76. what attracts investment? growth stability? profitability? excitement revenue?
77. what attracts investment? growth stability? profitability? excitement revenue? hiring
78. what attracts investment? growth stability? profitability? excitement revenue? likelihood of selling stake at a profit hiring
79. AI
80. what about the ai-lephant in the room?
81. “a world without developers”
82. low code
83. IDENTIFICATION DIVISION. PROGRAM-ID. COBCALC. ENVIRONMENT DIVISION. DATA DIVISION. WORKING-STORAGE SECTION. 01 PARM-1. 05 CALL-FEEDBACK PIC XX. 01 FIELDS. 05 INPUT-1 PIC X(10). 01 INPUT-BUFFER-FIELDS. 05 BUFFER-PTR PIC 9. 05 BUFFER-DATA. 10 FILLER PIC X(10) VALUE "LOAN". 10 FILLER PIC X(10) VALUE "PVALUE". 10 FILLER PIC X(10) VALUE "pvalue". 10 FILLER PIC X(10) VALUE "END". 05 BUFFER-ARRAY REDEFINES BUFFER-DATA OCCURS 4 TIMES PIC X(10). PROCEDURE DIVISION. DISPLAY "CALC Begins." UPON CONSOLE. MOVE 1 TO BUFFER-PTR. MOVE SPACES TO INPUT-1. * Keep processing data until END requested PERFORM ACCEPT-INPUT UNTIL INPUT-1 EQUAL TO "END". * END requested DISPLAY "CALC Ends." UPON CONSOLE. GOBACK. * End of program. * * Accept input data from buffer * ACCEPT-INPUT. MOVE BUFFER-ARRAY (BUFFER-PTR) TO INPUT-1. ADD 1 BUFFER-PTR GIVING BUFFER-PTR. * Allow input data to be in UPPER or lower case EVALUATE FUNCTION UPPER-CASE(INPUT-1) CALC1 WHEN "END" MOVE "END" TO INPUT-1 WHEN "LOAN" PERFORM CALCULATE-LOAN WHEN "PVALUE"
84. jevon’s paradox
85. jevon’s paradox “efficiency improvements can lead to increased consumption”
86. what we imagine when we widen roads
87. what we get
88. software is not going away
89. 1800s
90. “knocker-up” 1800s
91. “knocker-up” 1800s human alarm clock
92. “knocker-up” 1800s - 1940s human alarm clock
93. “knocker-up” 1800s finite demand - 1940s human alarm clock
94. “knocker-up” 1800s finite demand only employees need waking up - 1940s human alarm clock
95. “knocker-up” 1800s finite demand only employees need waking up no one needs waking up more than once - 1940s human alarm clock
96. the more software we have, the more we want
98. software to do stuff
99. software to do stuff software to do more stuff
100. software to do stuff software to do more stuff software to tell people about software
101. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software
102. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show
103. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software
104. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software
105. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software
106. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software software to manage the software
107. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software software to manage the software software to write the software
108. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software software to manage the software software to write the software software to manage the software that writes the software
109. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software software to manage the software software to write the software software to manage the software that writes the software software to try and avoid skynet
110. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software software to manage the software software to write the software software to manage the software that writes the software software to try and avoid skynet software to work out the meaning of life
111. software to do stuff software to do more stuff software to tell people about software software to bypass advertisements in the software software to bypass the bypass software so ads still show software to gamify software software to monitor the software software to debug the vibe-coded software software to manage the software software to write the software software to manage the software that writes the software software to try and avoid skynet software to work out the meaning of life …
113. ok but
114. usa developer vacancies Source: indeed.com via https://newsletter.pragmaticengineer.com/p/software-engineering-job-openings?publication_id=458709
115. Source: indeed.com via https://newsletter.pragmaticengineer.com/p/software-engineering-job-openings?publication_id=458709 uk developer vacancies
119. “our AI strategy is working”
120. AI-washing
121. overhiring
122. people-stockpiling overhiring
123. economic cycles
124. free money
125. debt financial
126. debt
127. ZIRP
128. “zero interest-rate phenomenon” ZIRP
129. 0%
130. <1%
131. Source: Bank of England uk interest rates
132. Source: Bank of England averting subprime collapse uk interest rates
133. Source: Bank of England averting subprime collapse covid uk interest rates
134. Source: Bank of England averting subprime collapse covid 0.1% (!) uk interest rates
135. Source: Bank of England averting subprime collapse covid 0.1% (!) inflation shortages war uk interest rates
136. Source: Bank of England uk interest rates
137. Source: Bank of England uk interest rates the period most of us remember
138. venture capital
140. baby company
141. baby company
142. baby company
143. funding rounds baby company
144. funding rounds baby company attracted investment
145. funding rounds baby company attracted investment
146. funding rounds baby company attracted investment
147. funding rounds baby company attracted investment
148. funding rounds baby company attracted investment
149. funding rounds baby company attracted investment
150. funding rounds baby company attracted investment
151. funding rounds baby company attracted investment
152. “exit” funding rounds baby company attracted investment
153. “exit” funding rounds baby company IPO attracted investment
154. “exit” funding rounds baby company IPO acquisition attracted investment
155. “exit” funding rounds baby company IPO acquisition attracted investment
156. exit attracted investment baby company
157. exit attracted investment baby company
158. exit attracted investment baby company
159. exit attracted investment baby company risk
160. ZIRP
161. software company ZIRP
162. government bond software company ZIRP
163. government bond risk return software company ZIRP
164. government bond risk return software company high ZIRP
165. government bond risk return software company high 20% - 500% ZIRP
166. government bond low risk return software company high 20% - 500% ZIRP
167. government bond low 0% risk return software company high 20% - 500% ZIRP
168. government bond low 0% risk return software company high 20% - 500% ZIRP
169. government bond low 4% risk return software company high 20% - 500% post-ZIRP
170. government bond low 4% risk return software company high 20% - 500% post-ZIRP
171. less investment means less hiring
172. less investment means less hiring
173. Source: indeed.com via https://newsletter.pragmaticengineer.com/p/software-engineering-job-openings?publication_id=458709 usa developer vacancies
174. Source: indeed.com via https://newsletter.pragmaticengineer.com/p/software-engineering-job-openings?publication_id=458709 usa developer vacancies chatgpt released
175. Source: indeed.com via https://www.citadelsecurities.com/news-and-insights/2026-global-intelligence-crisis/ developer vacancies
176. Source: indeed.com via https://www.citadelsecurities.com/news-and-insights/2026-global-intelligence-crisis/ developer vacancies
177. “a world without coding”
178. “engineering discipline”
180. the return of the spec
181. technical debt
182. vibe now pay later
184. but why can’t you put the [non-engineer]’s vibe-coded feature into production? it looks so pretty …
190. epistemic debt
191. the collapse of competence epistemic debt
192. Edsger Dijkstra, 1975 “The use of COBOL cripples the mind.”
193. code isn’t an asset, it’s a liability
194. even good code is a liability
195. sleep debt
196. “a world without work”
197. “a world without rest”
198. hustle
199. grind
200. the 996
202. average working week 66 hours 1826
206. productivity stayed the same
208. the four day working week 2026
209. 42% decrease in resignations the four day working week 2026
210. 42% decrease in resignations the four day working week 2026
211. the value of slack
212. the value of slack
213. the value of slack
214. the value of slack naming is still the hardest problem in computer science
215. the value of slack
216. the default mode network idle minds can solve hard problems
217. desks are not the only place value is created
218. desks are not the only place value is created
221. 14% took showers specifically for the purpose of coming up with ideas
222. are we taking more showers?
223. professions using ai worked 3.15 hours more per week https://cepr.org/voxeu/columns/ais-power-grows-so-does-our-workday
227. what we get jevon’s paradox in action
228. euphoria fear
229. productivity panic
230. “disposable busyware”
231. workslop is pollution
233. debt tradeoffs circular ideas
235. ecological debt
236. ecological debt financial debt
237. ecological debt financial debt technical debt
238. ecological debt financial debt technical debt epistemic debt
239. ecological debt financial debt technical debt epistemic debt sleep debt
240. debt is a tradeoff with the future
241. ideas come back round when the tradeoff shifts
242. how do you get better at seeing repeating patterns?
243. be old?
244. Philip Greenspun “any sufficiently complicated C or Fortran program contains an ad hoc, informally- specified, bug-ridden, slow implementation of half of Common Lisp” Greenspun’s 10th rule
245. how old was Philip Greenspun?
246. how old was Philip Greenspun? 29
248. - what problem are we trying to solve?
249. - what problem are we trying to solve? - what’s the tradeoff?
250. be curious
251. be curious about the past
252. why are things the way they are now? are there assumptions that have changed?
253. github quarkus opportunity
254. look for opportunities
255. tl;dpa (too long; didn’t pay attention)
256. tl;dpa - nothing is new under the sun. (too long; didn’t pay attention)
257. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. (too long; didn’t pay attention)
258. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. - sometimes there isn’t a trade-off. (too long; didn’t pay attention)
259. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. - sometimes there isn’t a trade-off. - think about sustainability of your IT (too long; didn’t pay attention)
260. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. - sometimes there isn’t a trade-off. - think about sustainability of your IT - for environment (too long; didn’t pay attention)
261. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. - sometimes there isn’t a trade-off. - think about sustainability of your IT - for environment - for people (too long; didn’t pay attention)
262. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. - sometimes there isn’t a trade-off. - think about sustainability of your IT - for environment - for people - fi nancially (too long; didn’t pay attention)
263. tl;dpa - nothing is new under the sun. - there’s almost always a trade-off. fi nd it. - sometimes there isn’t a trade-off. - think about sustainability of your IT - for environment - for people - fi nancially - recycle ideas everyone else has forgotten. (too long; didn’t pay attention)
264. https://hollycummins.com/idea-circularity-qcon/