시간이 있습니까? 우리가 어떻게 알아?

우리의 전체 삶은 시계에 의해 규제되지만 시계가 측정하는 것은 덜 확실합니다. 시간이 실제로 있다는 것을 어떻게 확신할 수 있습니까? 전문가 Kazuya Koyama와 이야기할 시간입니다.

알람은 아침에 울립니다. 아침 기차를 타고 사무실로 갑니다. 점심을 먹습니다. 당신은 야간 열차를 반환합니다. 당신은 한 시간 동안 간다. 저녁을 먹고. 잠자리에 들다. 반복한다. 생일을 축하하고 기념일을 기록하며 죽음을 기념합니다. 새로운 국가가 탄생하고 제국이 흥망성쇠합니다.

인간의 모든 존재는 시간의 흐름과 연결되어 있습니다. 그러나 우리는 그것을 볼 수도 만질 수도 없습니다. 그렇다면 그것이 실제로 존재하는지 어떻게 알 수 있습니까?

Koyama는 “물리학에서 우리는 ‘절대 시간’이라는 개념을 가지고 있으며 다양한 변화를 일련의 사건으로 설명하는 데 사용됩니다.”라고 시작합니다. “우리는 사물이 어떻게 움직이는지를 설명하기 위해 뉴턴 물리학을 사용하며, 시간은 그 핵심 요소입니다.” Koyama는 우주론 및 중력 연구소의 우주론 교수입니다.[{” attribute=””>University of Portsmouth.

To this day, classic Newtonian thought on time – where time is constant throughout the universe – is still a good approximation of how humans experience time in their daily lives. We all experience time in the same way and we all synchronize our clocks in the same way, no matter where we are in the world, whether that be London, Tokyo, New York, or Buenos Aires.

There’s no time without space

Physicists though have discovered that time can actually behave differently and is not as consistent as Newton thought.

“When we speak of time, we need to think of space as well – they come in a package together,” Koyama says. “We cannot disconnect the two, and the way that an object moves through space determines how it experiences time.”

In short, the time you experience depends on your velocity through space as the observer. This works as outlined through Einstein’s special relativity, a theory of how speed impacts mass, time, and space. Additionally, according to Einstein’s general theory of relativity, the gravity of a massive object can impact how quickly time passes. Many experiments have been undertaken that have since proven this to be true.

Physicists have even found that black holes warp the immediate space-time around them due to their immense gravitational fields. Supported by the European Research Council, Koyama continues to investigate this theory.

“A good, solid example to get your head around all of this is to look at how we use GPS,” Koyama continues. “GPS works due to a network of satellites orbiting the Earth. They’re placed at a very high altitude and thus the gravity they experience is weaker. Therefore, time should actually go faster for them than it does for us on the ground, where we experience higher gravity. But because the satellites are traveling at very high speeds around the planet, this in effect helps to slow time down, compensating for the lack of gravity.”

Understanding how these two effects work and influence each other is essential for ensuring that the global GPS network functions correctly. And a crucial ingredient in this is a consistent theory of time that explains how objects move. So clocks aren’t telling us falsehoods: time indeed exists outside of our own perception.

Could we ever go backward in time?

Finally, the question of whether time travel could one day be possible had to be put before Koyama. As a professor of cosmology at the University of Portsmouth, he is best placed to tell us the truth.

“I’m sorry to disappoint you but for time travel to be possible, we would need to discover a completely new type of matter that has the power to change the curvature of time and space,” Koyama says. “Such matter would require properties that simply do not exist in nature. We physicists strongly believe that going back to the past is simply impossible – but it’s nice to fantasize about it.”

Click here to find out more about Koyama’s research: Challenging the general theory of relativity