All the methods to prevent or reverse aging begin with the same assumption: aging is universal. It happens to everyone. But that isn’t strictly true. The only processes that age are rooted in time. Your mind has thoughts, your cells in your body undergo thousands of changes per second, and even your genes, which are permanent, trigger all kinds of activities that are temporary. This whole structure rooted in time will age.

When people think about growing old, they blame the passage of time—the years roll by, and the body stops looking younger year by year. But the latest science disputes this view. A person ages because the cells in their body age, and cells live only in the present. This is one reason memory remains such a mystery. Brain cells function through electrochemical activity that occurs the instant a chemical reaction or electrical impulse is able to occur. There are no pauses to think about reacting; if the potential is there, the action must follow.

Whatever a brain cell does, it can’t go back to the past. So how do we seem to go back into the past when we remember a childhood birthday party or our first kiss? No one knows, but when the answer is found, it won’t involve time travel, either forward or backward. If you expand this to every cell in the body, they too must function instantly in the present moment when any two molecules interact. So the problem of aging can be stated as the gap between how a cell lives and how a person lives. As people, we repeat the past, get stuck in old habits, cling to stubborn beliefs, fear the future, and in general occupy mental states that are not in the now.