ELIF: how is time relative?
In: Physics
It’s kind of hard to put succinctly, but the basic notion is, we have an intuition that everyone can agree that an event, say, a light turning on, occurred at a particular place, and at a particular time. We also intuit that if I think two lights came on at the same time, that everyone else will also agree they came on at the same time.
But the universe doesn’t actually work that way. Everyone with the same velocity will agree on when and where something happened, and will agree on which happened simultaneously, but other observers at a different velocity won’t agree. They’ve got a different view of the universe, in which events happened at different times, in different places, and may see that things we thought were simultaneous weren’t. Both are just different descriptions of the same underlying reality, and you can convert from one to the other using a bit of maths called the Lorentz transform.
All we really mean by time being relative is I might say that events A and B were 5 seconds apart by my measurements, and your measurements say that A and B were 6 seconds apart. Both are accurate descriptions of reality, it just means that you’re going faster than me; a little bit more than 40% of the speed of light faster. At speeds much much slower than the speed of light, like the ones we live our lives at, the difference is so small we never notice.
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