評論
打印
For the controllers of the GPS, time is everything.
對于GPS的控制者來說，時間是關鍵。
'US naval observatory master clock,
美國海軍天文臺的主時鐘，
'at the tone, mountain daylight time, 18 hours, 48 minutes, five seconds...'
基本對時，山區夏令時，18點48分5秒……
'US naval observatory ma...'
美國海軍天文臺的主時鐘……
For the global positioning system to work,
為了GPS正常運作，
the clocks on board the satellites have to be exactly synchronised with time on Earth.
衛星上的時鐘必須嚴格地與地球上的時鐘同步。
But for the satellites, orbiting 18,000 kilometres above our planet,
然而對于衛星來說，運行在地球1.8萬英里的上空，
Einstein predicts something very strange.
愛因斯坦預言過一些很奇怪的現象。
He predicts that in orbit, time itself runs at a different speed to that on the Earth's surface.
他預言處在軌道上，時間本身的流逝的速度不同于地球表面。
It's incredible for anyone to suggest that time goes at a different rate on the ground than it does in space.
誰都不會想到地面上與太空中相比，時間的速度不同。
What's the difference?
不同在哪里？
Well, the difference is gravity, the closer you are to the Earth, the stronger the gravitational field
不同在引力，你越靠近地球，引力場就越強，
the further you are up into space the weaker the gravitational field.
你越深入太空，引力場就越弱。
What Einstein said was that the stronger the gravitational field, the slower time ticks.
愛因斯坦稱引力場越強，時間的流逝就越慢。
The weaker it is, the faster time ticks.
引力場越弱，時間的流逝就越快。
The link between the speed of time and the strength of gravity
時間速度與引力強度之間的聯系，
is all down to Einstein's prediction that the Earth distorts the space time.
都囊括在了愛因斯坦的地球彎曲了時空的預言里了。
If you put something heavy in space like a planet, a star, the Earth,
如果你將一些大的物體放到空間里，比如行星、恒星、地球，
then that heavy thing bends the space, it curves the space.
那么那些大的物體就會彎曲空間，扭曲空間。
But space and time are intimately linked.
但是空間與時間是緊密聯系在一起的。
So, does the Earth also bend time?
那么地球也彎曲了時間？
Well, yes, it does.
啊，是的。
In the reduced gravity up in orbit, time really does tick a bit faster than time on Earth.
處在引力減少的軌道上，時間真的要比地球上走得快一點。
To keep everything in sync, the controllers have to dial-in a time correction.
為了始終保持同步，控制者必須進行時間校準。
