Let’s suppose for a moment that I invented a way to visualize the past with a neato device that I’ll call the timevideographer (hey, if you have a better name, you’re welcome to suggest it and I’ll give you a cut on my profits). Evidently, I can only see the past, not change it.
The problem is, when I activate it, I just get a video of empty space. That’s because I can specify any time in the past, but it will only show what was at this particular point of my current spatial coordinate… and I know I’m not getting results because the earth is moving thru space, our solar system is moving thru the galaxy, the galaxy is moving in the universe and the universe itself is expanding etc etc.
So, how difficult would it be (for example) to calculate spatial coordinates relative to our current coordinates and launch a space probe with my timevideographer to those coordinates to film (let’s say) the Normandy invasion on June 6th 1944?
You could try looking at multiples of one nanosecond in the past. Light moves less than a foot in one nanosecond, so you should be able to identify what the changes in position were just by looking. That’ll give you relative spatial coordinates.
it would be a complicated conversion from now to normandy involving earth’s orbial plane, the galaxy’s, and the universe’s expansion rate… along with the exact time of the big bang… i think. anyway, i dont think its possible at this point in time. we could probably get close, but the accuracy of the measurements would be off just enough, over such large space, that… put it this way, if we could pin point earth at that time with your “whatevergrapher” at the time of the battle, locating the battle with those measurements would just as likely set you “whatevergraphing” my great gerat great grampa in germany take a bath.
On topic, I’d say the best way to do this is devise a system for the timevideographer to pilot itself by focusing on earth at the present and then work backward from there. Even better would be to have the videoscope aimed at the sun, keep it at the right distance for Earth’s orbit, and go back based on the Sun’s location to the right year, and then locate the Earth from there. (If you focused on the Earth, you would have to follow it’s few hundred orbits around the Sun, which would take a lot more time than following the Sun.)
If the videoscopeographitic device could only see what was happening within a few feet of its location, just drop it to where Earth was a few hours ago, and have it read the infrared light emitted from the center of the Earth. Have the ship move to maximize the infrared light (i.e. heat) at all times while it keeps looking further backward in time. Through the joys of negative feedback you can pinpoint the Earth precisely.
On preview, it looks like rowrrbazzle already suggested something much like this.
On thinking, though, I wonder if it is possible to relate any point in current space-time to a point in past space-time, since there would be no absolute coordinate system in common between them (due to relativity).
Ohhh, there’s a story on this? I’ll have to read it! Thanks!
Ok, how about this…
I set the chronoscope to june 6th, 1944.
I get a 360 degrees picture of space (and stars!)
I use starcharts to find direction and distance compared to my current position
I move to that position
repeat to 1 till we get close enough to the battlefield.
They’re we’ll be some imprecision, but repeating the process will take care of this…
But… Does anyone know how far I would have to travel in space before I reach the spatial coordinates of Normandy, june 6th 1944? I’m guessing really really far…
Lighting bug: I’m thinking I can’t get the chronoscope to follow the Earth, as it is moving at close to 30km per second thru space! The sun might be a good thing to track, but if I just go back directly to the desired date, I’m now thinking that I can get pretty good relative coordinates to my current position… I’m not sure I follow you on the relativity/coordinates system.