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David_Kaiser127 karma

In principle, the effects of quantum entanglement should be observable across arbitrary distances, if the experiments can be set up with sufficient care. And in fact colleagues have demonstrated entanglement across some pretty long distances: about 100 miles in some beautiful experiments from a few years ago (e.g., https://arxiv.org/abs/0811.3129 , https://arxiv.org/abs/1403.0009 ); and now well over one thousand miles (https://arxiv.org/abs/1707.01339), using entangled particles emitted from an orbiting satellite. So I think we now have some real-world demonstrations that quantum entanglement need not only be observable across short distances.

Nonetheless, I do think it's interesting that some of the first physicists to think carefully about entanglement were doing so long before they could have imagined the kinds of instruments and technologies with which researchers can conduct these experiments today. It's interesting to wonder about how our own imaginations today might be similarly limited!

David_Kaiser116 karma

That's an interesting question. On the one hand, historical studies suggest that scientific research has never been entirely outside of politics. Aristotle had to navigate difficult political and patronage relationships in his day, and so did Galileo, let alone more recent researchers. So I don't think we should be looking back for some golden age when science was entirely isolated from the politics of the society in which it was embedded.

Nonetheless, we can ask whether the pursuit of scientific research was affected more or less strongly by political forces in other times, or in ways that made certain kinds of research particularly difficult, and whether those past examples might offer any lessons for today. From that perspective, I think a shift to short-term expectations for specific "deliverables" attached to various grants, and volatile funding levels year-by-year make it more difficult to plan for and support certain types of ambitious research projects than might have seemed feasible a few decades ago.

David_Kaiser112 karma

I think Einstein's biography continues to be really fascinating. One thing that becomes clear (which shouldn't really be surprising) is that he was, after all, a person -- a real-live person, with faults and shortcomings and blindspots like any other person, as well as (of course) extraordinary talents and insights. He himself noted later in his life that he had not always treated people as fairly as he (later) wished he had; he admitted to a close friend that he had difficulty forming close relationships and envied friends who had such happier family lives, etc.

His relationship with his first wife, Mileva Maric, ended particularly poorly. A few years before they got divorced, they were barely on speaking terms. Einstein was so confident that he would win the Nobel Prize (which had a large cash component) that he put into his divorce negotiations a promise to hand over the prize money to his ex-wife -- even though he hadn't won the prize yet!

Whereas his personal life was (even by his own, later evaluation) not always what he hoped it would be, he also was at times very brave, speaking out in favor of political causes that were quite unpopular at the time, standing up for positions he believed in.

David_Kaiser112 karma

Yes, thanks -- that's a very good clarification! The *distances* across which entanglement can be measured can be very very large, but the *objects* that are entangled continue to be very, very small. Indeed, it's an on-going challenge among physicists to see just how large an object can be, and still show tell-tale signs of quantum effects like entanglement. There was a very cool recent experiment that got much bigger than single particles, but still much much smaller than the size of everyday objects: https://arxiv.org/abs/1806.10615 .

David_Kaiser19 karma

There are two types of "parallel universes" that theoretical physicists these days sometimes think about: a cosmological context in which our own universe might just be one "bubble" within a sea (maybe an infinite sea!) known as the 'multiverse'; and a quantum-mechanical context, often referred to as the "many-worlds" hypothesis (or the Everett interpretation of quantum theory) which suggests that every time certain types of measurements are performed on quantum objects, the entire universe itself splits into copies, in one of which physicists measured one of the possible outcomes on that object, and in the other of which they measured the opposite outcome. Both ideas are interesting and some physicists are motivated to think about them because of difficult questions about the laws of nature at a very deep, fundamental level -- but it's also important to note that there's no empirical evidence (as yet) that either of these sets of ideas really describes our own world.

As for science education and thinking about the future: my own guess is that focusing on expanding access to quality education for more and more people would have a positive impact on society, over and above trying to manage the selection of subjects (STEM or otherwise) that all those students get to explore. There are so many interesting, difficult, cool questions out there that getting more and more kids excited to learn and ask questions seems like a really important goal.