In unify theory if 4D structure at plank scale + if randomness is fundamental then we will have probabilistic universe? This 2 has to meet or just fundamental randomness is enough? To make probabilistic universe. and 4d strucure will be ok to stay classical just like right now its in quantuum field theory?

♦It was recognized almost from the original formulation of general relativity that the theory was incomplete because it dealt only with classical, rather than quantum, matter. What must be done in order to complete the theory has been a subject of considerable debate over the last century, and here I just mention a few of the various options that have been suggested for a quantum theory of gravity. The aim of what follows is twofold. First, I address worries about the consistency and physical plausibility of hybrid theories of gravity—theories involving a classical gravitational field and quantum matter fields. Such worries are shown to be unfounded. These hybrid theories—mongrel gravity—in fact comprise the only current, actual theories of gravity that incorporate quantum matter, and they also offer legitimate promise as tools for discovering the full theory of gravity. So my second aim is to highlight these theories as providing an interesting example of scientific revolution in action. I begin to try to draw some philosophical lessons from mongrel gravity theories, but more importantly I try to convince philosophers of physics that they should pay more attention to them. read less

Let's break it down. You're talking about the Planck scale, 4D structure, and randomness in a unified theory. If randomness is fundamental, it could lead to a probabilistic universe, but it's not the only factor. The 4D structure at the Planck scale would likely be governed by quantum rules, not classical ones. In QFT, spacetime is treated as classical, but a unified theory might need to merge quantum mechanics and gravity, potentially making spacetime itself probabilistic. Can you clarify what you mean by "4D structure will be ok to stay classical"? Are you thinking about spacetime geometry or something else? read less

Mind blown 🤯! Let's break it down. You're asking if a 4D structure at Planck scale + fundamental randomness = a probabilistic universe. Two things: 1. Fundamental randomness might be enough for a probabilistic universe. Think quantum mechanics - inherent randomness is a core feature. 2. A 4D structure at Planck scale could still be compatible with a probabilistic universe if it's governed by probabilistic laws (like QFT). To clarify, are you asking if classical behavior emerges from this 4D structure + randomness, while the underlying universe remains probabilistic? read less

1. What makes a universe “probabilistic”? A universe becomes probabilistic if its fundamental laws include randomness—not just because we don’t know things, but because outcomes are intrinsically uncertain. This is exactly what happens in Quantum Mechanics: Even with complete information, you can only predict probabilities of outcomes. This comes from things like the wavefunction and its probabilistic interpretation (Born rule). 👉 So yes — fundamental randomness alone is enough to make the universe probabilistic. 2. What about 4D structure at Planck scale? The idea of spacetime being 4-dimensional (3 space + 1 time) comes from General Relativity. At very small scales (~10⁻³⁵ m), called the Planck Scale: We expect spacetime may not be smooth. It might be discrete, foamy, or have some quantum structure. But here’s the key point: 👉 The dimensionality (4D) does NOT by itself make physics probabilistic. You could have: A 4D universe that is completely deterministic (classical physics) OR a 4D universe that is probabilistic (quantum physics) So the 4D structure and randomness are independent ingredients. 3. Do they need to “meet”? Not necessarily. There are three logically possible scenarios: (A) Classical spacetime + fundamental randomness This is basically what current Quantum Field Theory does: Fields live on a smooth 4D spacetime Outcomes are probabilistic ✔ This already gives a probabilistic universe (B) Quantum spacetime + randomness In candidate theories of Quantum Gravity: Spacetime itself may be quantum Randomness could be even more fundamental Examples include: Loop quantum gravity String theory (C) Deterministic underlying theory (hidden variables) Some interpretations (like Bohmian Mechanics) suggest: The universe is actually deterministic Probabilities arise from hidden variables So even randomness itself might not be fundamental. 4. Your core question (direct answer) Is fundamental randomness enough to make a probabilistic universe? ✔ Yes. That alone is sufficient. Does it need to connect with 4D Planck-scale structure? read less

If randomness is fundamental, that alone can make the universe probabilistic. The 4D structure at the Planck scale doesn’t necessarily have to be quantum. It could stay classical, like spacetime in Quantum Field Theory. As long as the underlying rules include true randomness, outcomes become probabilistic. The main difficulty then is explaining why the probabilities follow the exact rules seen in Quantum Mechanics. read less