Centrum Light, Homeline Dark.

[AlexanderHowl]

I general use a paratronic distortion field in my games to prevent any problems. A paratronic distortion field is a 100 metric ton device that gives a -10 to skill when attempting to leave or enter a 10 kilometer radius area centered around the device. A smaller 1 metric ton device protects an area 1 km in radius and a portable 10 kilogram device protects an area 100 meters in radius for one hour on a C-cell. Centrum and Homeline have the larger paratronic distortion fields in every major urban area and/or military base on their home timeline to prevent crosstime attacks.

[Johnny1A.2]

Originally Posted by AlexanderHowl

I general use a paratronic distortion field in my games to prevent any problems. A paratronic distortion field is a 100 metric ton device that gives a -10 to skill when attempting to leave or enter a 10 kilometer radius area centered around the device. A smaller 1 metric ton device protects an area 1 km in radius and a portable 10 kilogram device protects an area 100 meters in radius for one hour on a C-cell. Centrum and Homeline have the larger paratronic distortion fields in every major urban area and/or military base on their home timeline to prevent crosstime attacks.

The setting probably requires something along these lines to make sense. Otherwise the mobility parachronics offers opens up so many lines of mischief it's hard to contain it.

[Phil Masters]

You’ll probably end up with the situation you get with the teraport area denial system in Schlock Mercenary; basically, any sensible community which knows what’s going on saturates their territory with denial fields, with the occasional well-guarded gap at arm’s length distances from any community (and one valid military tactic is “do whatever’s necessary to disable the enemy’s TAD”).

Of course, this is no comfort at all to any other timeline which isn’t in on The Secret but is a target for crosstime malice.

(Which reminds one of the other thing about crosstime terrorism. While terrorists with nukes is everyone’s worst nightmare, for very good reasons, nukes aren’t even necessary for a terrorist group with a working conveyor to cause insane amounts of harm. Simply being able to jump in and out of the basement of the White House, or any skyscraper or airport, with a couple of crates of dynamite, would be quite enough.)

[PTTG]

Yeah, those disruption fields make a lot of sense. To block psi jumpers, one might need to rely on woo like feng shui or something.

For added flexibility, add the ability to "synch" your conveyor to a field. This allows even port facilities to be shielded, and also makes for a new risks like people stealing synch codes.

And hey, now Vanish settings have been explained. They're worldlines that put up global shield nets.

[AlexanderHowl]

True, if the radius increases tenfold with every 100× increase in mass, twelve one million metric ton device placed stategically would shield a world out to an orbit of 10,000 kilometers (with substantial overlap in case of sabotage or accidental damage). I would personally have the paratronic distortion field inhibit all types of paratronic travel (magical, psionic, technological, etc), but that is only my preference.

[PTTG]

That would explain why most worlds are modern tech or lower; once they get past a certain point, they figure out crosstime travel and how to shield against it.

[Flyndaran]

Originally Posted by AlexanderHowl

True, if the radius increases tenfold with every 100× increase in mass, twelve one million metric ton device placed stategically would shield a world out to an orbit of 10,000 kilometers (with substantial overlap in case of sabotage or accidental damage). I would personally have the paratronic distortion field inhibit all types of paratronic travel (magical, psionic, technological, etc), but that is only my preference.

Save for that one hunted Jumper with the Cosmic enhancement.
Or that one scary mage using Lovecraftian cosmic magic.

[ericthered]

Originally Posted by AlexanderHowl

I general use a paratronic distortion field in my games to prevent any problems... Centrum and Homeline have the larger paratronic distortion fields in every major urban area and/or military base on their home timeline to prevent crosstime attacks.

I usually pair or replace something like this with sensory tech that can pick up incoming jumps. The compensations made right before the jump project a trace at the destination. You can have that conveyor show up with guns pointed at it, or

Note the RAW setting does have detection technology. It requires triangulation to get a position, and I think it detects the moment of the jump, which is no good for nuclear charges. Infinity and Centrum do canonically use these widely on worlds they've taken over (which presumably includes their homeworlds).

Originally Posted by PTTG

Yeah, those disruption fields make a lot of sense. To block psi jumpers, one might need to rely on woo like feng shui or something.

Yep, I'd leave psi and magic as needing to be independently blocked. You might be able to do a little with technology, but its fun for jumpers to be a loophole of sorts. It also makes Reich-5 a little more sinister.

[Johnny1A.2]

Originally Posted by Phil Masters

You’ll probably end up with the situation you get with the teraport area denial system in Schlock Mercenary; basically, any sensible community which knows what’s going on saturates their territory with denial fields, with the occasional well-guarded gap at arm’s length distances from any community (and one valid military tactic is “do whatever’s necessary to disable the enemy’s TAD”).

Of course, this is no comfort at all to any other timeline which isn’t in on The Secret but is a target for crosstime malice.

(Which reminds one of the other thing about crosstime terrorism. While terrorists with nukes is everyone’s worst nightmare, for very good reasons, nukes aren’t even necessary for a terrorist group with a working conveyor to cause insane amounts of harm. Simply being able to jump in and out of the basement of the White House, or any skyscraper or airport, with a couple of crates of dynamite, would be quite enough.)

Don't forget assassination and kidnapping/'extractions'. With the ability to materialize out of thin air and the element of surprise, it would be easy enough to kill or snatch the President (or King or CEO or Lindbergh's kid or whoever) and be gone before the security people even knew anything had happened.

If you don't have some way to block parachronics, the only defense against this tactic would be to maintain absolute secrecy about your location(s).

(Or, if your own intel is good enough, you could potentially establish deterrence by a policy of ruthless reprisal, you mess with us and we mess with you and your kids and your friends and everybody, immediately and without mercy. Which would work until it didn't.)

[jason taylor]

Originally Posted by Johnny1A.2

Don't forget assassination and kidnapping/'extractions'. With the ability to materialize out of thin air and the element of surprise, it would be easy enough to kill or snatch the President (or King or CEO or Lindbergh's kid or whoever) and be gone before the security people even knew anything had happened.

If you don't have some way to block parachronics, the only defense against this tactic would be to maintain absolute secrecy about your location(s).

The most effective terrorism often is simply using assassination a whole lot. That is how the "army-yakuza" paralyzed the Japanese government in the 1930s.

For one thing standing up to extremists usually requires some one willing to lead. That in turn means someone willing to paint a target on their back. And Victor Lazlo's are not bulk package items.