So The GM and I have been having a bit of an exercise here trying to figure out, can you summon a spirit in a moving vehicle. His argument is there is no movement in the astral plane as such, instead you pretty much will or think yourself to the location you need to be at, so when materialization happens, any vehicle moving faster than a spirits movement speed is going to just fly right past them.

My argument is that since the planet is already moving at a good fraction of the speed of light, if there was no absolute motion than any summoned spirit is just going to be a lonely speck in the cold hard reaches of space if the spirit isn't already matching speeds as it were. Thus it should be conserving whatever absolute velocity it was using in keeping up with the summoning mage to materialize in a place maintianing the same speed relative to the magician.

So we've decided to put it in front of you. Is it possible to prevent a spirit from materializing by making sure the mage is moving very fast?

Astral space and the metaplanes are linked to sourcess of life such as the Gaeasphere, so Earth's hurtling through interstellar space should not be a problem. Within the Gaeasphere, theoretically one could be traveling so fast the spirit would be left behind, but how do you propose to travel over six thousand kilometers an hour while summoning?

Six thousand Km/H? max speed for a spirit in the material plane is about 45 miles per hour.

Well, either it manifests - in which case it's still Astral and can move plenty fast enough - or it Materializes in which case it will simply be sitting in the van like everybody else.

Either way I think a spirit would have no problems with a moving vehicle.

The spirit doesn't have to materialize after being summoned. it is on the astral plane and can communicate with the summoner from there. So, it can travel at astral speeds.

But a spirit can always jump to astral, catch up with you, manifest.

Magic + Physics makes heads explodes.

When Summoned the Spirit comes from the metaplane instantly to the appropriate spot in the astral plane, and then it materializes right there.

It "magically" appears right there direct from the astral Green Room.

The astral Green Room is everywhere.

That's why we have the phrase, "It's magic." It doesn't have to conform to physical laws, because it's magic.

Thanks for the info so far. This should clarify.

It's a complex action to materialize. So that means it should take about 3 seconds. When the spirit is materializing, it's in the material plane, which means it is limited to it's max speed, (somewhere between 20 and 50 miles per hour). So if something is moving faster than that, the spirit is going to be incapable of hitting that moving target, the location it was attempting to materialize into is passing too swiftly for the spirit to pop into it.

I say no, the spirit should be able to match speeds and it should be the equivalent of jumping from one moving train to another.

GM thinks I'm wrong, the spirit stops moving at astral speeds so it would be like trying to jump onto a moving train from a quick run at best, with the result being you land on the empty tracks looking forlornly in the directions of the passing vehicle.

Really need to start working with frame of reference and relativity principles.

Here's some simple thoughts. There is nothing that says a spirit takes the entire 3 seconds to Materialize. There is nothing that says a spirit cannot be moving while materializing.

So what happens if the Spirit is materializing instantly at some point during those 3 seconds?

And the moving train to moving train is the better idea, it means the spirit is in the same frame of reference and is moving at the same relative speed.

The final thing to think about, really, if there was a problem with spirits Materializing in moving objects, it would be in the rules or fluff somewhere. The real killer if that was true is that in certain frames of reference the entire planet is moving at an appreciable fraction of light speed and if a spirit Materialized at a fraction of c there wouldn't be a planet anymore.

Physics + Magic makes planets explode.

Ok.
Forget about physics.
Forget about rules.

Think flavor, think "how would you expect it to work if magic was real?". That's how it will work.

That was part of my argument. Unfortunately, it also measn that astral velocity is conserved, which means that hypothetically, you could bring a spirit into the material place moving at 6000 km/h. Which means that it's probably moving fast enough to act a bit like a Rod from God. I call it the Murder Ball option. Of course that's pretty much instsant death to the spirit, the target and a bunch of items int he surrounding area, instantly gets your mage locked into a hated by spirits category and is probably the silliest idea I've come up with.