Why would it require a computer the size of the universe?
Well, it's not me who said it. I read it somewhere. The idea is that if we want to put the universe on record, then we have to store all of its quantum data. So for every quantity or quality of every atom that could be represented as a bit (qubits), we need to store that. But that would also be effectively the smallest information store that we would have in a physical world. So, for each qubit, we need to store it, and for each qubit that we stored, we'd need a qubit. We'd need to store all the information of all the particles in the universe, which would in turn require the total usage of the same number of particles, and thus we'd need to use up all the particles in the universe. That's the theory, anyway.
Potentially, if there was redundancy, then we could compress that data. But there's 10^18 atoms in the known universe. So we'd have to discover a heck of a lot of redundancy in the universe. If even half of all the data in the universe was completely redundant, we'd still need a quantum supercomputer that was half the particles in the universe.
The uncertainty principle says nothing of the nature of reality, only the nature of our current methods of detecting reality.
That's correct by itself. However, you have to remember that it was based on our current knowledge of physics, and the laws of physics themselves. To find a new method to measure more accurately than the Uncertainty Principle says we can, we'd need to discover a whole new area of physics, say, subspace. So it's not about "our" current methods of detecting reality. The Uncertainty Principle is actually about what CAN be detected and measured, even by other particles in the interactions of the universe, according to "our" current understanding of physics.
In addition, physicists have also done experiments to see if Heisenberg was right. They've been able to determine using experiments that at certain times, energy has disappeared from very small areas, which violates the law of conservation, only to reappear a few micro-moments later, and a bit of energy appears out of nowhere, only to disappear a bit later. The amounts have been calculated to be below the Uncertainty Principle's threshold. So the principle seems to have been validated empirically. But it also means that the law of conservation of energy is only an approximation, and is in reality being violated all the time.
WTF is the dirac sea? I googled it, it says dirac sea is another word for vacuum, which exists in our universe.
Paul Dirac took on the challlenge of marrying relativity with electromagnetism. It was an awesome challenge. To achieve it, he came up with his own algebra, called the
Dirac Algebra. He came up with the answer in the form of the
Dirac Equation, which describes all of the known behaviours of electrons, in one simple equation. Well, it's simple, in that it's incredibly short. It only has 4 terms. But each term is really complex. Anyways, once he had the equation, he realised that it had 4 solutions, 2 of which are cases of known matter, but 2 of which are the exact opposites, which we call
anti-matter. He thus concluded that anti-matter must exist as a natural by-product of the ways that matter works.
According to his equations, if an electron and an anti-electron, called a
positron, collide, they will convert into pure energy. Energy is also capable of converting back into an electron and a positron. He then worked out that the matter in our universe could only be the result of all these collisions of matter and anti-matter. The entirety of our universe are the leftovers of such collisions. But the leftovers of such collisions would be tiny in comparison to the particles themselves. So in reality, there would have to have been much more miniature particles of matter and anti-matter constantly colliding and being formed from energy, than the total matter of the universe. One might say that our universe is the top of a giant ocean of such particles, which became known as
the Dirac Sea.
One could describe the vacuum of our universe as the Dirac Sea. In a fashion, it's true, because we never see the Dirac Sea. We only see the matter of the universe that are the leftovers. But only if that vacuum is incredibly dense and chock-full of particles, and far more than that of the entire universe.
Hmm, I think you're right. How can you know how particles on the edge of the 1 light year radius will behave unless you calculate the particles outside the range which can affect it?
I guess you can make non exact predictions for 1 year using a 1 light year radius.
That's because big particles are more or less electrically neutral, and not pushed around as much by EM field.
Also they have more mass, which makes it harder to push them around.
That's basically how we do calculations. Most of our calculations are based on trillions of trillions of particles. E.G. the standard measure for the number of particles is the
Avogadro Constant. It's the number of atoms in 12g of Carbon-12, which holds about 6x10^23 atoms, or 600 billion, trillion atoms. That's only in 12 grams. There's about 1 gram of carbon graphite in an average pencil. So that's 50 billion, trillion atoms, and that's not even including the wood.
So usually, even when we look at a speck of dust, we're still probably looking at least 1 trillion atoms just there. So in reality, almost every calculation we are dealing with, involves bodies with trillions of atoms in each one. We're rounding off to the nearest trillion, and our calculations are based on averages of trillions of atoms colliding with each other.
Take the law of conservation of matter/energy. Imagine if you had to assess the maximum fluctuation in the number of cars on the road, to the nearest trillion. There probably wouldn't even be a billion cars in existence for a hundred years. You'd end up concluding that on any one day, the changes to the nearest trillion are so small, that they're insignificant, and for all practical purposes, the number of cars stays the same. So you'd end up concluding that the number of cars is conserved. Well, that's what happens with matter, energy and momentum. Even if it was changing all the time, we'd still see changes that are far too insignificant to measure.
We'd only see changes on the individual level, by following a particular car's lifespan from production to destruction. That's what physicists are doing when they measure the small changes on the subatomic level, and there, we do see particles being created and destroyed, which shows that the energy levels of the universe are fluctuating. They're just far too small to even measure on any level above the level of subatomic physics. So the amount of energy in the universe
appears to be conserved.
