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Comment by _red | Hacker News Reader

Can someone answer the General Relativity concerns regarding this?

Imagine the same loop as Derek setup in the video, but where it extended into next galaxy (say 1 light year away). In next galaxy there is another switch - we don't know if the position of that switch is open or closed...

Now when Derek connects his switch and light nearly instantly turns on...this is obviously telling us information regarding the switch 1 Light Year away. How does this not violate General Relativity since seemingly that information is traveling faster than speed of light?

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The time between changing the state of the switch and the affect it has on the bulb can not be any faster than the speed of light.

In Derek's example the switch and the bulb are 1 meter away from each other and therefore the time is 1/c seconds, i.e the time light takes to travel 1 meter.

The topic is definitely a little confusion, but there are no GR violations.

>In Derek's example the switch and the bulb are 1 meter away from each other and therefore the time is 1/c seconds, i.e the time light takes to travel 1 meter.

Perhaps I didn't make my example clear. Imagine loop with 2 switches...one switch 1 LY away...another switch 1 meter away.

Derek flips the 1m switch and light instantly turns on: What does that tell you? Derek flips the 1m switch and light doesn't turn on: What does that tell you?

How were you able to find out that information before waiting 1 yr?

It's explained in a comment from a few days ago:

https://news.ycombinator.com/item?id=29283101

From what I understand, in your setup the lightbulb will turn on and quickly turn off, irrespective of the state of the other switch which is 1 yr away. Then after 1 yr passes it will react according to the state of the other switch.

> next galaxy (say 1 light year away).

Nitpick: galaxies are millions of light-years apart. One light-year doesn't even get you to the closest star. The diameter of the Milky Way alone is on the order of 100K light-years.

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