BBC NEWS | Health | Scientists probe meditation secrets

An article from BBC titled Scientists probe meditation secrets
describes how meditation can affect states of mentality "scientifically", here a quote from the article

"... compared the brains of these experienced practitioners with people who had never meditated and found that there were differences in the thickness of certain areas of the brain's cortex, including areas involved in the processing of emotion."

Professor Williams from Oxford said: "All of these things are just thoughts. And, they will come up in meditation and learning to recognize what they are as thoughts, and let them go, can be enormously empowering for anybody."

I say science is still quite immature when used for reasoning about the human mind... so for the time being the best way for anyone in doubt is to try to understand it by getting some first hand experiences...