Again??? Were they EVER?
Sure. End of the 19th century, beginning of the 20th century up to the first world war, the childhood heroes would have been inventors, engineers, builders and so forth. Professional sports were just taking off, and cinema was still in its infancy. The geeks meanwhile were building skyscrapers, huge passenger liners, bridging chasms, building dams, building huge machines, power plants, etc. Little kids love that stuff, and society in general was fascinated by all this new stuff.
Other than geeks, the 'cool' in this era was largely owned by the heroic age explorers like Roald Amundsen and (in a slightly different form) Buffolo Bill. This is 'World's Fair' and 'National Geographic' era (not incidently chaired by Alexander Graham Bell).
I can't think of a single time in history where this has EVER been true - even prior to 1950 you'd find kids more likely to know Joe Dimaggio and Jackie Robinson than Albert Einstein or Robert Oppenheimer.
By 1950 the geeks had undermined themselves by creating a diseminatable visual arts culture, spawning the modern celebrity culture and creating 'fame' as we now it. Although there are great players before Babe Ruth, prior to the Babe Ruth era few people could follow the exploits of a great athelete. And, I think you underestimate the celebrity status of Albert Einstein.
This was a totally different time. As a semi-tangental example, this was a time when Army and Navy were college football superpowers because soldier was the 'sexy' status accruing profession of the day. Today, every schoolboy could name you ten QB's in the NFL, but almost none of them could name you 10 commanders in the field - former or at present. There is something very basic at work here. You could make the mistake of thinking that the problem here is money, but that actually reverses cause and effect. The money is with whatever it is with because that is the idolized, status accruing profession, socially exalted profession that gets you invited to parties - or to put it bluntly - what a man does if he wants to get laid (or at least keep that option open). If you change what is idolized, if you change the cultural interests, and if you change where the competition is, then the money follows it. Culture is everything.
In Ancient Rome kids were more likely to know Spartacus than Archimedes.
I can't speak for that era. I don't honestly know who Roman children would have idolized beyond obvious figures like Julius and Augustus. Gladiators? Generals? Orators? Poets? (There really was an era when poets were treated like rock stars and lived like it, see for example Lord Byron.) Chariot Racers? Mystics? I don't know. Records from the era are so relatively scanty and framentary that I'm not sure anyone really knows, nor am I really sure that anyone at the time would have cared to record anything like that.
Augustine's Confessions indicate to me that things must not have changed to much, because his description of life in the street gangs of Carthage could almost be 20th century in some aspects. His boyhood idol was Cicero though, and I'm fairly sure we can't take a nerd like him (charismatic as he apparantly was) to be fully typical of who young Roman children.
It's an interesting topic, and I'd love to have an answer.
But I agree that it's more likely to be in the future than the past. Geek Chic has never been more prevalent than today -- one of CBS Network's top shows is Big Bang Theory, after all.
There is a possibility of the return of 'geek cool', but I don't think we are fully on that path yet.