I like that you gave it this much thought.
I don't think it feels right to use the phrase "Nexus," but that's only cause the book that comes before it has Nexus in its title.
Tachyon is a cool word too, but for the same reason Cipher does not fit, I'm not feelin it...
Maybe something that has similar meaning to Nexus and Knot but cooler sounding.
Then allow me to make a case for Tachyon...
(this is real life, by the way. Your reader could verify this much watching space/time math documentaries)
a tardyon is anything that travels less then the speed of light
a tachyon is anything that travels faster then the speed of light
In EInstein's (in)famous Relativity equations, velocity (speed) is in an equation that also contains T (time)
as Velocity (speed) increases, time (T) decreases
with a velocity (speed) of c (speed of light)... Time (T) literally becomes zero
thus...
slower that the speed of light, time is normal.
but if you go fast *enough*, you begin to see time slow down
(this is REAL. GPS was inaccurate, until they applied the time offset from the satellite's high speed, slowing time down)
now, since time *actually* begins to slow down when you go at insanely high speed?
The equations w-o-r-k.
The famous "Twin's Paradox"
one identical twin stays on Earth
the other identical twin, travels at 90% of the speed of light for one year
when the twin comes back from his one year spaceship travel? He has been gone... one year.
the twin that remained n Earth? Is sixty years older.
this was always held to be the "Twin's Paradox", because there was no way it was real.
fast forward to geosynchronous satellites.
a geosynchronous satellite, is just one that is always directly overhead.
The Earth by he way, is about 28,000 miles around the equator.
the Earth, rotates one complete revolution, every day.
so at the equator? just standing still, you're moving at...
28,000 miles / 24 hours = 1,166 miles per hour
but circles are strange creatures.
if you are far overhead (satellite) you are actually going farther every day, staying overhead.
(the "circle", is a lot bigger that high up)
hence, you are going faster.
GPS was initially fairly IN-accurate. No one could figure out why.
someone noticed the SPEED the GPS satellites were actually traveling by staying overhead.
in the equations to triangulate position, elapsed time happened to be squared (multiplied by itself)
this *aggravated* the very slight time "lost" from time slowing down at high speed.
(from the point of view of the satellite, versus the point of view of us on the ground)
everyone laughed, but, once they accounted for Einstein's time dilation?
GPS suddenly gained the ability to be accurate.
I'm talking, going from...
accurate to within a couple hundred feet?
to, accurate to under an INCH.
the "Twins Paradox" ?
was no paradox... it was proven to be R-E-A-L.
this freaked everyone out, naturally.
and... when they plugged in the speed of lightr into the same equations...
time (T) "falls out" of the equation and becomes zero
(no matter how "long" the trip? you arrive at the same time you left)
and when you plug in Tachyonic velocity (faster than light...)
well, T begins to yield a negative number.
so, to wit :
if you intend to at any point, go backwards in time?
you would necessarily have to go faster then the speed of light.
(and anything traveling faster than light, is... a Tachyon)
the faster you travel, the more you go back in time per second of your trip.
the GPS satellites finally proved this is correct and works, by the way.
the only *impossible* part?
is actually going fast enough.
editors note: I still haven't leaped into science fiction yet... this is just all Physics 101
just making my case for "Tachyon" actually meaning something, to deserve being in the title.
"Paradox", too.
since this was all proven to be very real, and to work in real life?
if you could somehow stand on a light beam.
say, the light traveling to your eye, from a distant star in a distant galaxy.
the universe being perhaps 40 billion years old...
then a galaxy almost 40 billion light-years away...
the light that reaches you, today?
you are seeing that galaxy as it was, just after the universe was created.
because a light year is the distance light travels in one year?
when we see a star go supernova (explode)...
if that star that went supernova was 1,000 light years away?
you're not seeing the supernova happen. Not really.
you're seeing what happened... 1,000 years ago.
It took the light that long to reach you.
but from the "point of view" of that beam of light?
T (time) is z-e-r-o at the speed of light, remember.
from the view of the light beam (or anyone standing on it...)
the trip took no time at all.
it was instantaneous.
you arrive as soon as you decide to leave.
so.
when The James Webb telescope imaged a galaxy 40 billion light years away...
from our point of reference, it took the light 40 billion years to reach us.
but from the point of view of the light?
the trip took no time at all, it was instantaneous.
so if there *was* a particle that WAS a real life Tachyon particle...
it would experience T (time) moving in the negative increment
the Tachyon particle? would actually arrive at its destination, before it left.
how in the *&^% would you even expect to "see" it, detect it, prove it exists?
it would be moving backwards in time
(I *still* haven't left reality, and started in on science fiction yet)
of course, if one were curious...
I *could* give a couple paragraphs or so.
maybe... the dialog of the professor, explaining how the two devices worked to the students.
One was "the Paradox". (it moves forwards in time)
and the other, well...
"the Tachyon" moves backwards in time.
and yes, you arrive before you left.
of course, I doubt you'd be interested at *all* in the "Singularity Drive".
Which is, naturally, the core device that makes it all work.
