So, if we placed a satellite six hundred billion miles out in space (tenth of a light year)focused on the Earth, how far could we see into the past? (trick question)
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Feel free to reply to any comment by clicking the "Reply" button.It would pick up signals from what is happening today a tenth of a year later, and beam them back to earth which would take another tenth of a year. Therefore, to someone in the future the person would be be receiving information that was a fifth of a year out of date. That's like reading today's headlines of a newspaper in early December. It's easier to just pop down to the newspaper's offices just before Christmas and ask to see the archives!
Petter
Level 9
Sep 6, 2020
2
So, if the camera played back what was happening on Earth, we could watch a replay?
@PondartIncbendog That's basically what it is doing. It is bouncing back a light signal, so all it would need to be is a massive mirror.
It's similar to an old fashioned audio time delay device being used to create an echo-chamber, or standing on a rock over a valley, shouting loudly and hearing your echo.
@Petter So, if we placed it on the moon, we would get a one and a half second replay? And about at five hundred thousand we get three seconds?
@PondartIncbendog Man has already done something like that. There's a prism mirror on the moon that is used to bounce back a timed laser beam. That is nowadays how a regular check is carried out on the moon's distance from earth. (It's increasing by around an inch per year, meaning it is 2 metres further away than when I was born.)
@Petter Yes. There are five. Three USA. Two USSR. They are simple radar reflectors.
@Petter So, if we pointed the Hubble Space telescope toward Earth, we could watch the past? Like a delayed replay?
@PondartIncbendog Hardly delayed. Just a few milliseconds later, like listening to a bad international phone call.
@Petter and @PondartIncbendog
Comment... Remember, everything we 'see' is delayed. It's just that most of the time we aren't quick enough to (or need to) keep track of it.
It's kind of profound when you think about it -- the vast web of interlocking time and energy we live in.I
RCC Edit: Removed the word 'replay'. We're seeing it for the first time. Lol.
If It focused its camera on the microwave background radiation, nearly to the big bang. If it focused it on earth, one tenth of a year for light to reach it, and one tenth of a year for the message to come back to us therefore about seventy days. But since it would have to journey to its position at lower than light speed, that would still be a time after the launch day.
Now, have I done enough to earn the laugh, when you tell me the silly reason why I am wrong.
Fernapple
Level 9
Sep 6, 2020
0
That's the right answer. But it depends if you are on the satellite or on Earth?
@PondartIncbendog I am assuming an unmanned satelite, since it says 'we' as in collective us. Still if there was a job on offer, and it gives you a chance to get a tenth of a light year from here. Hm, think about it.
@Fernapple That was the "trick" part. Defining "we".
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