Question: Scientists can never be 100% sure that there theories and explanations for results are true, for example, the Newtonian physics is very different to quantum physics, its strange that different rules apply to matter of different sizes but all of which are in the same universe. Sometimes, somthing we have always believed to be true can suddenly be disproved by an experiment, so my question is this, do you think that there are some theorys in science that you dont completly agree with? Ideas that were just put in place because we cannot find a way of explaining the results? And do you think anyone will ever disproves certain theories, particlualy those from Einstein, Newton and other big named scientists?

Simone Sturniolo answered on 18 Jun 2013:

This is a very interesting, and very crowded, can of worms you are opening here. Yes, scientists can never be sure about the correctness of their theories. In fact, every theory is just as good as the things it manages to predict; one day or another, virtually, we could be able to find an experiment disproving relativity, or quantum mechanics, or thermodynamics, and we should be ready to throw away those theories and update and improve them. In this sense, being a scientist is hard: you can’t hold on to anything really, and always have to know that all you’re assuming could be potentially found wrong tomorrow, and you’d have to learn it anew.
Do I feel like some theories are unsatisfying? Yes. I don’t know much about cosmology, for example, but I feel that some concepts like “dark matter” and especially “dark energy”, which were introduced to explain some anomalies in the expansion of the universe, are a bit forced and not really satisfying. Saying that something is due to some mysterious force that we cannot see or measure but that must be there in order for the results to be right is little short of saying that a wizard did it. However, this is not my field of studies, so I can’t express myself too much. I also think that it’s normal to give this kind of explanations at the beginning: many scientists who work with them find them equally unsatisfying! “Dark energy” is just a name we give to something we don’t understand: understanding it, and explaining it, is those scientists’ job. I also feel like quantum mechanics, despite working extremely fine, are not very well understood not in the sense that we don’t get how they work, but that we don’t get WHY they work how they do, and what do they really mean. Quantum mechanics does not forbid the existence of a BIG “quantum” object. So how would an object that’s in two places at the same time look like? It’s hard to understand (it also ties in to your other question, the one about quantum computers. Whether or not we can make a big object which behaves in a quantum way is crucial to the solution of that problem).
You ask about this, differences of behaviour at difference scales. This is not as serious a problem as you seem to think: in fact, we already know for sure that Newtonian mechanics are plain wrong. They only work in the normal world because they are an ‘approximation’: not perfect, but good enough. Quantum Mechanics are more precise, and yet they are not perfect either. If you go deeper and you need to explain things like those that happen in the Large Hadron Collider you need something called Second Quantization, Field Theory, and Quantum Chromodynamics. I know very little of those topics myself. It is common belief that there is a fundamental theory – a “Theory of Everything” that is perfectly exact and needs no further approximations. But we’re not really sure about that. We also know that Quantum Mechanics and its derived theories are not fully compatible with Einstein’s General Relativity (the one which claims that gravity bends space-time). We know that one of the two has to be wrong somewhere, or more likely, they both are in some respect. So I won’t be surprised at all if someone finds out how they need to be modified. I would be happy, in fact!
One theory that I believe will not change any soon, instead, is thermodynamics. I think that thermodynamics will survive for a long, long time unchanged, because they substantially are founded upon mathematics and statistics. All thermodynamic concepts are very fundamental: either conservation laws (energy does not disappear nor appear from nothing but only transforms), or laws derived from simple statistics (the second law, stating that entropy can only increase). They are strikingly simple, elegant, and yet they have been found to apply to things as mundane as a car engine, and as odd as a black hole. I think thermodynamics are here to stay.