"What does a physicist have for…

“Fish and chips” became “fission chips” from several punsters in the 1940s, at the start of the nuclear age. “Fission chips” has been cited in print since at least March 1947.

A joke was cited in 2001:

Q: What did the Nuclear Physicist have for lunch?
A: Fission Chips.

“What do sea monsters eat?”/“Fish and ships” is another “fish and chips” riddle.

Wikipedia: Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei). The fission process often produces free neutrons and gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.

Wikipedia: Fish and chips
Fish and chips is a hot dish of English origin, consisting of fried battered fish and chips. It is a common take-away food.

St. Agnes (Cornwall)
Fission Chips
Dont miss St. Agnes Fission Chip Shop, tucked away in the corner of Churchtown Square. Serving quality fish and chips for over 50 years!
Contact: Simon Miney
20 Churchtown
St. Agnes
TR5 0QW
T: 01872 553513

28 March 1947, Boston (MA) Herald, “Top o’ the Morning” by George Ryan, pg. 50, col. 6:
If we ever really got that atomic cookery, J. W. R. says he’ll be looking forward eagerly to fission chips.

Google News Archive
13 August 1947, Toledo (OH) Blade, “Press Will Meet Miss Split Atom,” pg. 4, col. 2:
HOLLYWOOD, Aug. 13 (UP) An industrial exposition on the theme “Atomic Energy in Peacetime” today promised to produce “Miss SPlit Atom” with “a remarkably unstable collection of beautiful girls” moving in orbits about her.

Invitations to the press from a publicity firm read:

“There will be all kinds of refreshments at the Oak Ridge bar (our Manhattans are a project) and a veritable assembly line of a buffet with mushrooms Bikini, fission chips and other delicacies.”

Google News Archive
28 February 1948, Pittsburgh (PA) Post-Gazette, “Hollywood” by Hugh Dixon, pg. 2, col. 3:
“Punch” magazine reports that atomic energy will soon be used or cooking and adds “that means we’ll be eating fission chips.”

Google News Archive
8 May 1948, The Evening Citizen (Ottawa, Ontario), “Once Over Lightly,” pg. 32, col. 3:
From Bob Abra of our favorite Sports Dept. comes this: “If people start cooking with atomic power, their favorite dish will be fission chips, and most likely it will give them atomic-achie.”

Google News Archive
23 November 1953, Spencer (IA) Daily Reporter, “Hollywood Today!” by Erskine Johnson, pg. 3, col. 2:
IT’S ON THE MENU
A Hollywood eatery lists “Nuclear Scientists’ Special” on its menu.

It turns out to be “Fission Chips.”

Google News Archive
4 March 1955, Glasgow (Scotland) Herald, “An Editorial Diary,” pg. 6, col. 5:
Topical Touch
The proprietor of a restaurant recently opened near an atomic energy plant in an American city has a nice sense of humour. One of the items on the menu is “Fission Chips.”

Google Groups: novell.community.chat
Coming out of lurk mode….
.(JavaScript must be enabled to view this email address)
8/21/01
Q: What did the Nuclear Physicist have for lunch?
A: Fission Chips.

Google Groups: alt.humor.puns
Puns of the Weak 9/21/01
Stan Kegel
9/22/01
(...)
What do sailors eat on-board a nuclear submarine? Fission chips (Ken Shugart and Jim Ertner independantly)

Google Groups: atl.arno
This Neutron-
PawPaw
9/10/03
(...)
Q: What did the Nuclear Physicist have for lunch?
A: Fission Chips.

Twitter
Andrew West
‏@krypto
slowly waking up. What did the nuclear physicist have for lunch? Fission chips!
6:31 AM - 11 Mar 2007

Google Books
Dim Wit:
The Funniest, Stupidest Things Ever Said
By Rosemarie Jarski
New York, NY: Random House
2008
Pg. 302:
What did the nuclear physicist have for lunch?
Fission chips.
Anon.

Google Books
A Prairie Home Companion
Pretty Good Joke Book (FIfth Edition)
Introduction by Garrison Keillor
Minneapolis, MN: HighBridge
2009
Pg. ?:
What did the nuclear physicist have for lunch?
Fission chips.

The Escapist Forums
Science and maths jokes anyone?
XJ-0461
POSTED: 27 October 2009 3:58 pm
I’ve got quite a few, mainly due to science teachers:
Gold walks into a bar and the barman says “AU! Get out!”
And
What does a physicist have for lunch? Fission chips!

Twitter
Geoff Saunders
‏@geoffsau
“@PenguinGalaxy: What did the nuclear physicist have for lunch? Fission chips.” Is that some kind of fusion cookery?
1:17 AM - 21 Jul 2011

Google Books
1001 Amazing Jokes
By Jack Goldstein
Andrews UK Limited (andrewsuk.com)
2013
Pg. ?:
What’s a nuclear physicist’s favorite meal?
Fission chips!

OCLC WorldCat record
Military history: Dinner at the Fission Chips
by Mark Peplow
Article Article
Publication: Nature, v495 n7442 (20130327): 444-445
Database: CrossRef

Twitter
Elise Aasen
‏@TheEliselise
Or fusion food. RT @WasimZahid: What is a physicist’s favourite food? Fission chips.
5:20 PM - 28 Dec 2013

“What does a physicist have for lunch?”/“Fission chips.”