Do you think, based on Quantum theory, do you think alternate worlds can exist?

There is the possibility of it. Some theories hold that everyone is capable of action and with action we forsake all other possible actions we could have taken. The theories state that all choices a person doesn't choose happen but only in a parallel universe (alternate world). Thinking behind this has origins in superstring theory/M-theory and the vibration of little strings of sub atomic particles. The vibration wasn't completely explained but still observed. Some scientists hypothesized the vibration could account for the different realities as it could account for randomness and the possibility of different outcomes in all matter. Similarly, there is a many-worlds interpretation and it is meant to solve the paradox issue of quantum theory. This was based on subject-object observation and wavefunction collapse via decoherence(or at least its apperance of decoherence). The result is light/energy being freed from wavelenghts allowing random occurances of the light particles. Possibilities could extend to other forms of energy (and could explain the vibration mentioned earlier). The extention to other forms of energy could apply to neurokinetic energy or even consciousness itself: though the latter is a further leap due to its lack of definition and measurement. With slightly different brain pattern energy or consciousness, its possible people (animals too) take different action based on this decoherence. Just possibilities and theories, but they do lend themselves to the debate without violating basic theory or scientific practise. Backtracking a bit, superstring theory has multiple spacetime dimensions with 5 variants have 10 dimensions while 1 has 26 dimensions of spacetime. It's possible the alternate realities of our own, or completely different realities could be found in a different dimension. In terms of humanity and decision making, think back to the varying choice. There are seemingly thousands upon thousands of choices a person will encounter. Multiply this by the amount of population, and you end up with multiple trillions of possible choices. In thinking of those unseen other choices, each variant of choice from each individual leads to a different dimension. One opposing thought to multiple worlds is hard determinism. People have no free will and everything, energy, matter, time all flow in a specified direction reacting from the very first reaction of all existence. What if an unknown item or energy arrives at the reality? There are a couple of theories that state any unfitting item or energy would influence reality's "flow", even a spec of dust could do this. If matter and reality are truly "one-way" in flow and existence, why is there a possibility of foreign matter/energy interfering with the set existence? If there were no alternate dimensions, it wouldn't matter what foreign matter or energy arrives in reality, things will still continue based on set paths. In this case however we end up with a possible contradiction. Say someone bumped into you right now at your computer. You'd be distracted for a minute due to the disturbance. The person is actually a foreign object. Interaction with that unfitting item cause change in you and thus everything else you'll do from that moment on. A different theory along these lines is free will advocacy. The free will and consciousness are still debated in philosophy even in quantum physics. If its truly free will, wouldn't that result in an anomalies to planned reality? But a counter to this is that the free will is a result of the home universe and actually not a source of interference for determined reality. In any case, one would have to prove what free will and consciousness is, or there would have to be an introduction of foreign matter/energy to the current reality. Other theories and guesses, philosophical debate, based on other observation. People claim things like psychic power, greater intuition, deja vu. There is a possibility of these things being the power of the mind, but on the other hand it could be anomalies in spacetime or "reality". People could be receiving psychic impressions from a future or alternate self. With these unusual occurences however, people don't even have a remote grasp of it all (Deja vu is seemingly the most enigmatic and confusing). People end up having their flash, breakthrough, or impression of the immediate future, but within seconds its gone. Similar to this is spirituality and haunting. There have been claims of ghosts and hauntings being actual people acting out in their own original time but it appears as "ghosts" or hauntings in our present reality. It could be a differential in energies causing these occurences. Overall, this could be another possibility of alternate worlds or an alternate plane of existence.