参考消息网6月28日报道 （文/Adam Mann 亚当·曼）
Every once in a while， a science-fiction book， movie or TV show will feature characters who can do what we all wish: Stop time.
But is such a thing possible？ Answering that question requires a deep dive into the farthest corners of physics， philosophy and human perception.
First， we have to define time. “To a physicist， it's not that mysterious，” Sean Carroll， a theoretical physicist at the California Institute of Technology， told Live Science. “Time is just a label on different parts of the universe. It tells us when something is happening.”
For him， it makes little sense to talk about stopping time. We know that a car is moving because， at different moments of time， it's at a different location in space， he said. “Motion is change with respect to time，so time itself can't move.” In other words， if time stopped， all motion would stop too.
While sci-fi has sometimes given us protagonists who can pause time for everyone else， such situations raise a great deal of questions. “Are you stopping the air from moving？” Carroll asked. “Because if so， then you're imprisoned by the air.”
A time-stopping character would also likely be unable to see anything， he added，because light rays would no longer reach their eyeballs. “There's not really any consistent scenario in which time stops.”
So much for physics. But time is more than just something read on a clock. It's also a feeling that we have in our heads and bodies， as well as the natural rhythms of the world. Yet in those cases， time can become something subject to personal whims.
“Thinking about the subjective impression of time gets interesting，” Craig Callender， a philosopher who specializes in time at the University of California， San Diego， told Live Science.
He described a well-known psychological illusion known as “chronostasis，” in which a person places a clock at the edge of their vision and then stares at something else for a moment. Glancing back at the timepiece and focusing on the second hand will make it pause.
The question then becomes， what is the relationship between our perceptions of time and the time physicists are talking about？ Callender has written a number of books that attempt to explore the connection between the two， and as yet， there isn't much consensus on a final answer.
Regarding the ultimate flow of time， Callender favors a picture “where there's nothing flowing， but the story of yourself is flowing.”
And what does he believe regarding the possibility of stopping time？ “If we think of our subjective sense of time， then we can stop portions of it with chronostasis，”Callender said. “But that's probably the closest we can do.”