By Wendy Williams

ALBERT Einstein once asked, “How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?”

Well, now researchers are trying to find out.

It has long been maintained that the intense passion of a new romance fizzles out after a period of between 18-months and three years.

But in a US study, it has been found that young love and long term love are actually very similar.

When shown a photo of their partner, couples who had been married an average of 21 years showed similar brain activity to those who had just fallen in love.

But crucially they lacked the obsessive component that leads to feelings of uncertainty and anxiety.

California doctor Dr Acevedo, who led the study, explained: “Passionate or obsessive love includes feelings of uncertainty and anxiety.

“This kind of love helps drive the shorter relationships, but not the longer ones.”