Editing Talk:2920: Survey Marker

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"datums." [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 14:38, 16 April 2024 (UTC)

FWIW, there is a marker at the end of my street, and I have seen others. I know "in the ground" is a figure of speech; all I have seen near here were set in rock (often with molten Lead/Zinc) so they didn't travel. My road we have boulders nobody is likely to move. Other places like Appalachian Trail, set in the mountain stone. In sandy South Jersey they dump a couple tons of concrete and set the marker in that. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 23:41, 16 April 2024 (UTC)


I like to think our myriad calendars & leap days & time zones & daylight savings time & mapping coordinate offsets, are all orchestrated specifically to complicate time travel. Have fun materializing halfway into the ground, or entirely out of the ecliptic, time travel wankers.   
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 06:30, 17 April 2024 (UTC)
:A fairly old 'time travel failure' trope is a time machine that ''only'' travels in time. If you go back (or forward) six months, you find yourself in space in exactly opposite the Earth (which is now half way round its orbit).
:Yes, there's also solar-galactic motion and galactic-extragalactic, and tends to date back to an era where a universal/local æther was predominant as 'the one true frame of reference'. But even a more arbitrary-frame 'locking' isn't movement-free. H.G. Wells's traveler in time apparently sat still in his location, but seems to ignore/handwave all kinds of issues of long-term soil accumulation/weathering, tectonics, etc. Or the very basic (but vital) acknowledgement that only in freefall can you ''not'' be in a continually revised 'frame', as merely standing still under gravity you're accelerating.
:However much detail there is, in the source material, there's pretty much always a fudge in a object-type time-machine (as opposed to a portal-style, which will have its own 'rules') that also gives it a "necessary secondary supwerpower" of space-movement, even if only to stay (apparently) in the same place and not then try to merge its atoms with whatever solid things (gases, even liquids, generally being already handwaved as inconsequential!) might happen to be in the 'landing zone'.
:It's gross failures (or 'exact word' strictness) in the space-travelling element that can cause plot-driving surprises to the protagonist(s) involved. (Perhaps I'm here at least in part harking back to the 'retro-canon-crossover' work that was ''{{w|The Space Machine}}''.) [[Special:Contributions/172.69.43.164|172.69.43.164]] 09:47, 17 April 2024 (UTC)
::Oh, I'm ''quite'' familiar with that concept! That's what put the idea in my head. If the frame of reference isn't fixed, you'd need fairly precise coordinates to arrive at, but even with a Wells type time-machine that somehow stays in "place", any plans to travel to the time of a specific event, could be severely impacted by an offset of hours or days or sometimes weeks ''(I blame Salem Saberhagen for the 13 day festival of Bobunk getting lost in the switch to the Gregorian calendar)''. I like to imagine our messed up time & calendar system is a defense intentionally maintained by a Section 31 type organization, to make it harder for "enemy" time-travelers to know exactly when (& potentially where) pivotal historic events occurred. The rest of the multiverse could be running on a Mayan calendar & using sidereal clocks or Unix time et cetera, while our one reality has us split into ''zones'' that may or may not use "daylight savings", & anything farther back than a skipped leap day, would require an extra wait or time jump for a Wells type machine & would likely result in a total miss for machines that need exact coordinates. On its own, security through obfuscation is a ''lousy'' defense, but if we presume the existence of a "temporal security" force, even a 1hr time difference could grant some opportunity to interdict the errant traveler. Switching it up in a few places every so often, could ''really'' frustrate travelers.   
::"Help defend our timeline, make the switch to Swatch time 'today'!"   
:: [[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 13:50, 17 April 2024 (UTC)

This reminds me of the prime meridian that's laid out on the ground at the Greenwich Royal Observatory for tourists to stand on. Unfortunately, it uses an old datum and the actual prime meridian under WGS84 is about 100 metres to the East. Fortunately, the British Isles are moving slowly North East so the two meridians will coincide at some point. [[User:Jeremyp|Jeremyp]] ([[User talk:Jeremyp|talk]]) 09:09, 17 April 2024 (UTC)

::I use to live in a flat about a mile south of the Greenwich observatory and there was a marker for the meridian in the pavement (sidewalk) outside the flat.--[[Special:Contributions/172.70.85.13|172.70.85.13]] 07:54, 18 April 2024 (UTC)
:::The other day I had reason to pass by a 'countryside' Prime Meridian sign (and plaque-on-a-brick-plinth, IIRC), at a [https://www.openstreetmap.org/#map=17/53.67901/0.00000 seemingly arbitrary point] very near where it eventually crosses the coast into the North Sea (if they don't have a sign ''on'' the coast, I'd be surprised, but I had no cause to go across that way too).
:::Having manually adjusted that URL to be ''explicitly'' zero east/west, it may well be that map-zero doesn't match the 'signed' zero. The physical location would likely be (without checking StreetView for accurate confirmation) that little stub of apparently inconsequential footpath, north off Welwick Road, just a little to the east of the "P"arking spot (a rough layby, clearly intended purely for the odd passerby who wishes to park up and peruse the signage). Which might well be 100m W (minus adjustment for approximately 2° latitude's additional longitudinal curvature) of the web-page centre when forced to display a nominative 0° position. [[Special:Contributions/172.70.163.49|172.70.163.49]] 12:12, 18 April 2024 (UTC)

:::: Interesting.  Back in the sixties we had family holidays in Cleethorpes, the other side of the Humber, and I remember a mark on the coastal footpath indicating the meridian.--[[Special:Contributions/172.70.90.114|172.70.90.114]] 07:54, 19 April 2024 (UTC)

:::: "''map-zero doesn't match the 'signed' zero.''" Well spotted. I would not even call that a 'layby'. MAPS plots the true zero several furlongs right. Streetview and Satellite: https://postimg.cc/gXrtgc14  https://postimg.cc/rRrnLnVr    --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 04:19, 20 April 2024 (UTC)