Einsteinians know no limits:

https://www.scientificamerican.com/a...-in-spacetime/
"The notion that spacetime has bits or is "made up" of anything is a departure from the traditional picture according to general relativity. According to the new view, spacetime, rather than being fundamental, might "emerge" via the interactions of such bits. What, exactly, are these bits made of and what kind of information do they contain? Scientists do not know. Yet intriguingly, "what matters are the relationships" between the bits more than the bits themselves..."

Other Einsteinians reject Einstein's spacetime but "don't know what it's replaced by":

https://www.edge.org/response-detail/26563
Nobel Laureate David Gross observed, "Everyone in string theory is convinced...that spacetime is doomed. But we don't know what it's replaced by."

https://www.youtube.com/watch?v=U47kyV4TMnE
Nima Arkani-Hamed (06:09): "Almost all of us believe that space-time doesn't really exist, space-time is doomed and has to be replaced by some more primitive building blocks."

http://www.thebatt.com/science-techn...3aa345281.html
"Arkani-Hamed said."Because of the existence of gravity and quantum mechanics, we believe that the concept of spacetime is doomed and there are many simple thought experiments that tell us that space time is doomed."

https://edge.org/response-detail/25477
What scientific idea is ready for retirement? Steve Giddings: "Spacetime. Physics has always been regarded as playing out on an underlying stage of space and time. Special relativity joined these into spacetime... [...] The apparent need to retire classical spacetime as a fundamental concept is profound..."

http://www.newscientist.com/article/...spacetime.html
"Rethinking Einstein: The end of space-time [...] The stumbling block lies with their conflicting views of space and time. As seen by quantum theory, space and time are a static backdrop against which particles move. In Einstein's theories, by contrast, not only are space and time inextricably linked, but the resulting space-time is moulded by the bodies within it. [...] Something has to give in this tussle between general relativity and quantum mechanics, and the smart money says that it's relativity that will be the loser."

A typical physics student (Bingo the Einsteiniano):

http://www.infonetworkmarketing.org/...anza-paure.jpg

Pentcho Valev