Recent content by Xu Shuang

Local realism is not simply a combination of locality and realism, realism alone dictates ## (a,b)=f(\hat a , \hat b,{\cal R}) ## , in which ##\cal R## denotes "the reality" of the system in question, ##(a,b)## are two measurement results, and ##\hat a## and ##\hat b## denotes how the...

The contradiction between quantum state being reality and the definition of probability is the biggest turn off of many world interpretation for me too. :frown: I think that we can speculate that the answer lies in metaphysics. The universe with low quantum probability may simply cannot be...

Still can't wrap my head around this. How exactly do we characterize entities made of fermions as bosons? If we have a bunch of cooper pairs, and they become a condensate, what exactly is the state of system look like if we return to the characterization of a bunch of electrons?

I'm currently writing a paper about Quantum Hall Effect, and I've run into these two concepts during my research. And as far as I am concerned, Landau level doesn't fully explain QHE and the "butterfly" is only remotely related. Quantum Hall effect is more of the result of mathematics than...

Based on the experience of space shuttles, recovering the first stage doesn't mean the cost of the first stage is gone. The first stage would still need serious renovation before reuse. For space shuttles, the engine need to be replaced every three missions. For the rocket, the renovation cost...

Only the first Stage rocket is recovered,which could cut the expense by half, at most.

I did it again, yours is right.

I think what determines the outcomes is neither inside the light crone or FTL, its outside of spacetime. My view is that there is no causality between those measurements, and quantum information exists outside of spacetime. For simplicity, let's consider perfect anticorelation scenario. The...

It is arguably true that there is no communication between entangled particles, after all EPR paradox satisfies two-way no signal. There is no way to tell what happened to one particle by measuring the other. Bell inequality is based on two assumptions. One assumption is no FTL causality, the...

Are you sure? It was a full paper of calculation.

I think this is a misguided problem. The left side of the box is not in a particular number state, which means if you measure the number of particles of the left half of the box, the result would be probabilistic.

This is just x component. 4-dimensional space-time is too much for my math.

I think mathematics is more fundamental than understanding, since our thinking and consciousness exist only as mathematical structures in our brain. Basically, anything we think and feels are no more physical than mathematics. We really don't know if the universe is actually anything more than...

I think dimension is most clearly defined mathematically, if a space need at least N numbers in anyone of its coordinate systems, then the space is of N dimension. The space-time we live in is 4 dimensional, which includes 3 number to denote location, and one number to denote time.

This can best be understood with measurement. In quantum mechanics, there is no this particle or that particle. (of a particular kind) There is only: if you measure somewhere, what's the probability of finding N particles. In the case of electron, its either 0 or 1 at the same exact place. In...