Ask HN: Delay one major discovery by decades–what changes most?

Thought experiment: Pick one scientific or technological breakthrough and imagine it arrived meaningfully later. How does that change the trajectory of history?

To keep this interesting:

* Keep it plausible—think "transistors delayed 40 years," not "no electricity until 2100."

* Play along with it. Suspend disbelief enough to make it interesting.

* Focus on the _consequences_, not the missing invention. How does this alter the arc of history?

Progress often feels inevitable in hindsight, but it's really a sequence of lucky breaks. Change the timing of one, and everything downstream shifts. What's your parallel universe?