# How can I send messages from the past to the present day (Time Travel Question) **URL:** \ **Category:** Factual Questions\ **Created:** [May 29, 2004, 12:05pm UTC](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669 "2004-05-29T12:05:47Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Fish](https://avatars.discourse-cdn.com/v4/letter/f/bc8723/32.png) [@Fish](https://boards.straightdope.com/u/Fish)\ **Post date:** [May 29, 2004, 8:57pm UTC](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669/21 "2004-05-29T20:57:41Z")
Wouldn’t it? I figured that Kepler, Galileo, Brahe, Copernicus and others would take a keen interest in any local satellites, given their interest in floating rocks as far away as Neptune. Maybe set up radio repeaters on the moon designed to rebroadcast your transmissions to a station on the Dark Side. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [May 29, 2004, 10:02pm UTC](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669/22 "2004-05-29T22:02:02Z")
> [@Fish](#): > > Wouldn’t it? I figured that Kepler, Galileo, Brahe, Copernicus and others would take a keen interest in any local satellites, given their interest in floating rocks as far away as Neptune. Not a problem. The only way they’d see the probe (assuming you didn’t put lights on it) is if it occulted the body they were looking at at the moment they were looking at it. Now, given all possible orbits, all bodies of interest, and all hours of the day, how likely is this? > [@Doug Adams](#): > > Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the drug store, but that’s just peanuts to space. > [@](#): > > Maybe set up radio repeaters on the moon designed to rebroadcast your transmissions to a station on the Dark Side. Another idea, but vastly more expensive, and more likely to be noticed. (Of course, if you were going to be launching from Pangaea, I suppose people noticing it wouldn’t be a concern. The Great Old Ones might take an interest, however.) ---
**Author:** ![Fish](https://avatars.discourse-cdn.com/v4/letter/f/bc8723/32.png) [@Fish](https://boards.straightdope.com/u/Fish)\ **Post date:** [May 29, 2004, 10:21pm UTC](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669/23 "2004-05-29T22:21:00Z")
Even on a satellite without man-made lights, **Derleth** , wouldn’t it reflect light from the sun in the same manner as other celestial bodies? I figure they might detect those repeaters on an episode of **CSI: Ry’leh.** Anyway, considering the cost of designing a time machine, it’d be very reasonable to put transmitters on the moon! 🙂 ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [May 29, 2004, 10:43pm UTC](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669/24 "2004-05-29T22:43:25Z")
> [@Fish](#): > > Even on a satellite without man-made lights, **Derleth** , wouldn’t it reflect light from the sun in the same manner as other celestial bodies? Again, practically impossible to notice unless you happen to be looking at _exactly_ the right spot at _exactly_ the right time. This is a serious problem when it comes to detecting near-Earth asteroids. We have no real method for detecting potential extinction-causers until they’re _this close_ in relative terms. The Hubble can only be pointed at so many objects at once, as can all of the other telescopes we’ve made, and space is _farging huge_. Some of these things are the size of small houses, some are larger, and we can’t see them without looking really hard at trillions of cubic miles of mostly-empty space. The odds of us spotting one that’s going to hit us a year before touchdown are amazingly small. ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [May 30, 2004, 12:38am UTC](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669/25 "2004-05-30T00:38:47Z")
> [@SpaceDog](#): > > The problem I had with the plastics is that I’m fairly sure they don’t last forever. Steel might be a way to go. If you’re going that far back though you might have problems with things (like bits of land) moving around. Working out where a spot is now and then finding where that spot was then (when you are back then) might not be that trival. > > SD Well, I was just hoping that the plastics inside plastics inside several durable boxes would last. I wanted to put things like mamoth and sabertooth tiger blood and hair and my diary. And it wouldn’t matter if _I_ could find the spot in the future, because I wouldn’t be coming back. I would just want to somehow mark the land in a way that would tell modern day humans “let’s dig here.” [Previous page](https://boards.straightdope.com/t/how-can-i-send-messages-from-the-past-to-the-present-day-time-travel-question/247669.md?page=1)