Tachyon* Tagger [GURPS 4E, Timewatch]
A Tachyon Tagger typically looks like a small wand. When pointed at something else, the Tagger irradiates the target with a stable particles that travel backwards in time. This means, effectively, that any scanners that can detect these particles will be able to track down the item in the past. The exact ‘frequency**’ of these particles can be specifically set, allowing for only someone with the right ‘signature’ to track the item; or it can be set to be detectable by all scanners. Either way: the temporal range for these particles is about two thousand years before they decay, and most scanners will only be able to pick them up within a thirty mile range. Amusingly, the user has to jump back in time in order to confirm that the Tagger worked: this device cannot be used to track an item into the future.
This item is a staple in time travel investigations – assuming that the investigators have access to Tachyon Taggers. The idea is to tag an item, then use a series of temporal jumps to retroactively trace its physical location; this allows for the rapid elimination of false leads, can reveal the existence and operations of smuggler’s networks, and so forth. No one has ever reported on any side effects from using a Tachyon Tagger, but note the use of the verb ‘reported.’
GURPS stats: Tachyon Tagger (TL11^). $10,000, 2 lbs, B/60 charges, LC0. Any Ultrascanner can pick up the radiation, providing that the scanning frequency is known.
Timewatch stats: Difficulty +1, Future, Super-Science. Any autochron can track the tagged item.
*Note: these items do not actually use tachyons: they actually use a type of particle that only registers on most 21st century equipment as part of a rounding error (as you can see, even the description of the particles in question is effectively gobbledygook at our current level of scientific development). However, since ‘modern’ society at least has the concept of ‘traveling backwards in time,’ and since tachyons supposedly do so – ‘Tachyon Tagger’ it is. At least this way you can adequately describe what the item does.
**Again: this is like attempting to describe the exact mechanics of an excimer laser to Sir Isaac Newton. ‘Frequency’ is the wrong word; but there are no right ones at this time.
“Amusingly, the user has to jump back in time in order to confirm that the Tagger worked: this device cannot be used to track an item into the future.”
I’ve seen Bill and Ted’s Excellent Adventure. I’ll just leave a note for someone in the future to activate the device and which frequency to use.
Sure. That drawback’s not in there for game balance: it’s in there because time travel creates weird situations, like the fact that you might only tag an item because it shows up on your scans, which means that at some point you’re going to tag that item, and failure to do so might generate temporal paradox…