A very nice explainer why "if you're so worried about quantum computers, why haven't they factored 21 yet?" isn't a very convincing argument. Look at the labels of the graph, and how extremely close the various lines are for factoring 21 and 2048 bit numbers. Polynomial scaling remains polynomial, unfortunately, and by the time you can factor 21 you're almost ready to break RSA.

https://bas.westerbaan.name/notes/2026/04/02/factoring.html

Factoring is not a good benchmark to track Q-day

Homepage of dr. Bas Westerbaan, principal research engineer at Cloudflare, working on making the Internet post-quantum secure

@sophieschmieg A physicist I used to work for said quantum computing is very good right now for getting grant money to develop very nice ADC's and detector circuitry, which is useful for astronomy and particle physics.

He admitted when I pressed him that he agrees that the actual computing part is complete bunk and going nowhere.

@poleguy @sophieschmieg

I remember similar opinions in the 80s when people would bring up Reagan's "Star Wars"/SDI.

@danmcd @sophieschmieg And how do we feel those opinions aged?

@poleguy @sophieschmieg

I don't know, given I don't know what SDI money got put to what use. GPS? IF so then that's not a bad deal.

@danmcd @sophieschmieg the opinions back then were that Star Wars/SDI was science fiction and it would never work... and I think that is still true. There is no space based laser defense system and nobody sees that in the timeline, right?

The groundwork for GPS work pre-dates SDI.