What is the Quantum theory? Why did Einstein oppose it ?

Answer 1

At a very basic level it says that everything in the world comes in 'packets'. there will be some fundamental smallest packet, or quanta for everything. This holds true for both matter and energy. Quantum theory says that even light comes in small packets called photons. You can never have anything smaller than the fundamental quantum. There is no such thing as half a photon for instance.
Quantum theory works very well for things on the smallest of scales like atoms... however it falls short when you get to larger scales like the scale of planets and galaxies. It makes some crazy and illogical predictions once you get to those sorts of sizes. The problem that Einstein had with Quantum theory is that it incorporates some level of uncertainty, as defined by the Heisenburg uncertainty principle. It says that you can not know both the velocity and the position of an object at the same time. You can know one to very precise degree but the more pricesly you measure location, the less precise the measurement of velocity becomes. And vice versa. Einstein didn't like such uncertainty and said that "God doesn't play dice".

it turns out that neither theory works well in all situations.. Einsteins theories don't work as well on small scales but work well on massive scales. Quantum is the opposite. Science is still searching for the grand unified theory which will work in all situations and explain everything.

Answer 2

BZ is pretty much correct. The quantum equations were derived empirically; then they were later validated through experiment. Their accuracies in what they predict vs what is observed go waaaaaay out in the decimal point. That is, they are very accurate.

The fundamental equations of quantum theory specify momentum and location of quanta as probability density curves. Although they are applied to a wide range of quanta (like bosons, muons, quarks, etc.), they are best explained by the ordinary electron, which is also a quantum.

The old Bohr model of electrons revolving around their atomic nuclei like planets around the Sun served us well in HS physics. But has been shown to be wrong. Instead, electrons form a sort of probability cloud around the core according to quantum theory. And the volume where that cloud density is thickest for a given electron is the place we are most likely to find the electron in any delta time.

But, and this is a big BUT, the cloud is something like a normal or Bell curve, but in three dimensions. So there is in fact some finite probability the electron could be somewhere out in the thinner parts of the cloud. And, in fact, there is even some, even smaller probability that the electron could show up inside the core of an atom.

And this uncertainty, measured by probability density curves, is what Einstein objected to. Throughout his career, he stuck to the concept that the universe was deterministic, not probablistic. Which is one reason he failed to unify gravity into his theory of relativity. Gravity is a quantum (called a graviton) apparently; and it behaves probablistically rather than deterministically.

Answer 3

Quantum theory, at least in terms of atomic structure, stated that the probability density functions of electrons about an atom could be characterized by a series of integral numbers that indicated orbital, suborbital, specific suborbital, and magnetic spin. I am not aware that Einstein opposed it; he had enough with relativity theories to keep him busy.

Answer 4

He didn't like the uncertainty. He said God doesn't play dice. Quantum theory is mathematical formulas that describe the location of electrons as a range.