So you folks know that I been dealing with weird notions like the oft seen headlines Spacetime is Doomed.
Just google it if you’re curious. You’ll see Nima Arkani-Hamed come up a lot, then Hoffman will start popping up, which is why I’ve been getting familiar with the mumbo jumbo.
“The Unknown Question” –The End of Spacetime Posted on Jun 22, 2019
dailygalaxy - com/2019/06/the-unknown-question-the-end-of-spacetime/
The Doom of Spacetime
Why It Must Dissolve Into More Fundamental Structures
We have studied fundamental physics for 2,000 years and understand the field very well. So, Arkani-Hamed said, it is particularly jarring when something that seemed like an essential element of how we think about the universe turns out to be wrong. He said that where we are today.
20th century scientists revolutionized physics with the theories of quantum mechanics and spacetime, which together form quantum field theory. Those concepts led to predictions accurate up to 12 decimal places, when tested. And that accuracy is what makes doubts about their accuracy so disturbing.
Arkani-Hamed then described the two “storm clouds” he sees for spacetime and quantum mechanics. The first storm cloud suggests that spacetime is doomed. The second, that quantum mechanics are limited.
To explain the first cloud, Arkani-Hamed presented a thought experiment. To see what exactly is going on at arbitrarily small distances, we must use high energies. In a world without gravity, there is, in principle, no limit to scaling the size of the detector to see what is going on at increasingly small distances. But we live with gravity, and where there is too much mass, we get a black hole that traps light – meaning that if we build too big a detector, we will create a black hole that will prevent us from seeing what happens at the smallest distances. Thus, gravity limits our ability to measure spacetime, which means our current understanding of spacetime is merely approximate and not fully accurate.
Similarly, the second cloud is explained by the problem of measuring quantum mechanics. To measure such quantum observables, our precision improves by how many measurements we take. But, to take the infinitely many measurements required to reach almost exact precision, would require an infinitely large measuring apparatus, which is again limited by gravity. This limitation means quantum mechanics is also an approximation.
Since spacetime and quantum mechanics are limited and approximately, Arkani-Hamed said they cannot be fully accurate. To be fully accurate, we must rethink our most basic understandings of physics, as there are no measurements of any sort in the interior of space and time that can belong as precise properties of the world. …
So because they figured out a mathematical trick to split spacetime geometry, he can split it again, and again, and golly gee, at some point trapped within the feedback of it’s own Zeno’s Paradox , the supercomputer melts down, and the profession gets to gloat that he’s slain spacetime. Bully for him.