As we humans grow older and wiser, it's not unusual to feel as if time were whizzing by, quietly gathering¹ speed with every year.

随着我们人类年龄和智慧的增长，我们常常会感到时间在飞快地流逝，而且每年都在悄悄地加快速度。

Mechanical engineer Adrian Bejan from Duke University now thinks he has figured out why, and just like ageing, he suspects the experience is both universal and inescapable.

来自杜克大学的机械工程师Adrian Bejan现在认为他已经找到了原因，就像衰老一样，他怀疑这种体验是普遍的，也是不可避免的。

Adhering to the physical laws of life and evolution, Bejan argues that as our eyes fatigue² and our brains grow slower, it is only natural to feel as though we are losing time.

Bejan坚持生命和进化的物理规律，他认为，当我们的眼睛疲劳，大脑发育变慢时，感觉时间流逝是很自然的。

"People are often amazed at how much they remember from days that seemed to last forever in their youth," he said.

他说:“人们常常会惊讶地发现，在他们年轻的时候，那些似乎永远不会消失的日子，他们却能记住那么多。”

"It's not that their experiences were much deeper or more meaningful, it's just that they were being processed in rapid fire."“这并不是说他们的经历更深刻或更有意义，而是他们的经历被迅速处理了。”

Anyone who has ever watched water come to boil knows intuitively that their "sense of time" is only a perception. Far from being a reliable measurement, it's more like a mental construct, constantly changing over time.

任何见过水烧开的人都直观地知道，他们的“时间感”只是一种感知。它远不是一个可靠的测量方法，更像是一个随着时间不断变化的心理构造。

This essentially³ means that the seconds, minutes, and hours we keep in our heads are inherently different to the ones we count on our clocks.

这本质上意味着我们头脑中的秒、分和小时本质上不同于我们依靠时钟计算的秒、分和小时。

"The time that you perceive is not the same as the time perceived by another," writes Bejan.

“你感知的时间和别人感知的时间是不一样的，”Bejan写道。

"Why? Because the young mind receives more images during one day than the same mind in old age."“为什么?因为年轻的大脑一天内接收到的图像比年老时多。”

Put simply, an older brain takes longer to process the present. Just look at any baby and you'll notice that their eyes dart⁴ about much faster than your own, taking in the scene at a rapid pace.

简单地说，老年人的大脑需要更长的时间来处理此时此刻。只要看看任何一个婴儿，你就会注意到他们的眼睛比你的快得多，快速地捕捉到场景。

"Said another way, if the lifespan is measured in terms of the number of images perceived during life, then the frequency of mental images at young age is greater than in old age," writes Bejan.

Bejan写道:“另一种说法是，如果寿命是用一生中所感知到的图像数量来衡量的，那么年轻时大脑中图像的频率要比年老时高。”