Individuals matter.
Maybe we'd have had to go another few hundred years before someone else conceived it. While we can't prove a negative (we don't know what the alternate Einstein-less universe turns out like), certainly there have been examples of technology that has been forgotten or lost and it can take another thousand years before it is rediscovered.
Definitely. But in his generation?
Some things, like Calculus, pop into human understanding because there comes a time when our existing tools + our understanding of peripheral stuff inevitably intersect.
Other things maybe not.
One of my favorite sci fi short stories, The Road Not Taken, has as its premise that some scientific discoveries might be low-hanging fruit that we happen to overlook in one generation after the next, so we develop along one road and not another.
In this case, simply because no particular Einstein comes along to explain it to us, and because our other discoveries, impressive as they might be, are always one or two circles of overlap removed.
https://en.wikipedia.org/wiki/The_Road_Not_Taken_(short_stor...
Also famously and indisputably invented by one singular unique mind.
https://en.wikipedia.org/wiki/Leibniz–Newton_calculus_contro...
I think we would come to same discovery, but it would be significantly different ie. it would might be more complex. His theories are definitely flavored by his thinking.
Maybe we live in a different world today but my sense is scientific innovation happens in a very different way from the genius model.
Sometime long ago I came across an article arguing that we've replaced the concept of a saint with a genius, as the worldview shifted from religion to science. It was very compelling.
Increasingly I feel like there's only collective recognition. If you're too far ahead of the curve or behind it's all the same. Being at the curve just means you're recognizing everything at the same time as everyone else.
Hilbert derived general relativity 5 days before Einstein [1]. Einstein won the public relations difference because his previous work.
It was that close.
Recall Hilbert was vastly better at the math, and was catching up leaps and bounds on Einsteins intuition at the time.
Dozens of others were also close. Minkowski, Cartan, Poincare, all were doing the same stuff, trying to unify the same items.
So had Einstein done nothing, many others were immediately going to reach the same results.
[1] https://en.m.wikipedia.org/wiki/General_relativity_priority_...
Recall at this time Hilbert was a god in mathematics, and one of the best that ever lived. He did groundbreaking work in n many areas of math and physics.
Of the two, each left alone, it's far more likely Hilbert would have arrived first. Working while corresponding likely made Einstein much faster and Hilbert slightly faster.
Einstein took 8 years to work out general relativity. Hilbert started working on physics in 1912 and by 1915 had gotten to where he was deriving general relativity. The speed he worked in physics and the broad range of topics he influenced in physics far outshines Einstein. Hilbert famously said physicists don't know enough math to do physics. He was right at that time - his math mastery let him plow through physics much faster.
To see the scope of things attributed to Hilbert versus attributed to Einsteins simply look over their Wikipedia pages.
This is just not true. Einstein's earliest GR work is a collaboration with Marcel Grossman. Hilbert's work is so close and overlapping that it takes quite a bit of effort even to verify that Einstein's work was genuinely independent.
I think the most profound work in mathematical physics of Einstein’s generation was done by Emmy Noether and Einstein thought so too.
Her trail really induces modern physics as we no it.
Einstein is overrated. If he hadn't been born other people would have come to the same conclusions.
Physicists today are working on problems that are dramatically harder to solve. It's true that thousands of people can dogpile in a research area where the opportunities are illusory, but most problems succumb to elbow grease and liberal use of trial and error.