Light - If you view the Earth from far enough away can you observe its past?

Re:Light - If you view the Earth from far enough away can yo... by marcamillion on Friday July 08, 2011 @07:29AM (#2742014)

This is something I have always wondered about.

Can the reverse be true too? i.e. if you are on the moon and can see what happens 1000km away, before someone else on earth 2000km away from that event, is that the future? Is that possible?

Can that then be extended to 27 lightyears into the future too?

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Re:Light - If you view the Earth from far enough away can yo... by seats on Friday July 08, 2011 @08:05AM (#2742081)

Yes, but you could never signal faster than the information arriving on earth in a straight line at the speed of light.

To understand why picture the triangle between the start point (A), end point (B) and the moon (M). The distance AMB is larger than AB.

Google or Wikipedia 'light cone', pretty interesting stuff.

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Re:Light - If you view the Earth from far enough away can yo... by datr on Friday July 08, 2011 @07:56AM (#2742066)

The man in the moon is not really observing the future he just becomes aware of the event before the man on earth.

If it wasn't light that was being transmitted the man on the moon could warn the man on earth about what's happening before it's reaching him in the same way that people near the epicentre of an earthquake can use twitter to warn people further away before it hits: http://recovery.doi.gov/press/us-geological-survey-twitter-e...

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Re:Light - If you view the Earth from far enough away can yo... by tuhin on Friday July 08, 2011 @07:44AM (#2742042)

I think it is relative. Your argument considers time as a non relative entity and the past and present as static points in a timeline. So the same "event" is one man's past and one man's future. It depends on your space coordinates from the coordinates of the even if this is your past or present or how back in past.

Disclaimer: This is deduced logic and not scientific information.

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Re:Light - If you view the Earth from far enough away can yo... by evilswan on Friday July 08, 2011 @08:28AM (#2742150)

It's not the future, it's just an earlier indication of the event - seen at 1000km versus 2000km. The event still happened at the same time.

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Re:Light - If you view the Earth from far enough away can yo... by ignifero on Friday July 08, 2011 @09:38AM (#2742348)

"At the same time" with respect to its own frame of reference.

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Re:Light - If you view the Earth from far enough away can yo... by evilswan on Friday July 08, 2011 @10:27AM (#2742514)

Yes.

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Re:Light - If you view the Earth from far enough away can yo... by andreyon on Friday July 08, 2011 @08:54AM (#2742215)

forget 27 years, give me 1 minute and I'll be a rich man( I'll do sport betting :D )

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Re:Light - If you view the Earth from far enough away can yo... by stellar678 on Friday July 08, 2011 @12:53PM (#2743186)

To circle around a bit back to a hacker news favorite topic - this is exactly why high-frequency traders put their equipment in data centers as close to the action as possible. They're seeing the and trading on the future if your frame of reference is some data center in California.

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Re:Light - If you view the Earth from far enough away can yo... by Wilduck on Friday July 08, 2011 @01:39PM (#2743357)

Until just now, I always thought this was a silly practice. My line of reasoning was "What difference does a 30ms ping make?" I guess I hadn't thought about it too much though.

Now, after reading a comment elsewhere in this thread, which talks about how a cpu can execute six instructions in the time it takes the light from my monitor to reach my eyes, the data center thing seems a lot more reasonable.

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