How did Earth lose Interstellar Travel and electronic technology after Atlantis Sunk?

There was a "Master Class" and a slave Class most places on earth then and only the "master classes" were educated into technology. At the time this was done so knowledge didn't fall into the wrong hands so to speak. But, when Atlanis sunk suddenly no one was left alive who understood how to build and maintain technology.

So, hopefully, the human race has learned enough from this to share knowledge so it isn't lost entirely during the next cataclysm or many cataclysms like Hurricanes, tornadoes, earthquakes, tsunamis or nukes going off.

If scientific knowledge is spread evenly enough among all mankind there need be no time when we have to sink back to no technology at all ever again.

Question:

How many people could survive now on earth without modern technology at present?

I'm thinking the number would have to be 200 million to 1 billion people worldwide maximum.

This is likely all that could survive without technology. This is one reason why a solar storm of the size of the Carrington event is so serious (at least for half the planet hit by it).

Although maybe it is possible for a solar event to last 24 hours or more in which case most electronics on earth could be gone during that period of time.

Showing results for carrington event

 

Solar storm of 1859 - Wikipedia

https://en.wikipedia.org/wiki/Solar_storm_of_1859

The solar storm of 1859 (also known as the Carrington Event) was a powerful geomagnetic solar storm during solar cycle 10 (1855–1867). A solar coronal mass ejection hit Earth's magnetosphere and induced one of the largest geomagnetic storms on record, September 1–2, 1859.

‎Solar storm of 2012 · ‎Geomagnetic storm · ‎List of solar storms

What If the Biggest Solar Storm on Record Happened Today?

news.nationalgeographic.com/.../110302-solar-flares-sun-storms-earth-danger-carring...

Mar 4, 2011 - Repeat of 1859 Carrington Event would devastate modern world, experts say. ... As solar storms go, the Valentine's Day flare was actually modest. ... Solar storms aimed at Earth come in three stages, not all of which occur in any given storm.

A Perfect Solar Superstorm: The 1859 Carrington Event - History in the ...

www.history.com/news/a-perfect-solar-superstorm-the-1859-carrington-event

The flare spewed electrified gas and subatomic particles toward Earth, and the resulting geomagnetic storm—dubbed the “Carrington Event”—was the largest on record to have struck the planet.