The most valuable thing aboard the Golden Toad Ship was its Negative Pressure Thruster.
The technology behind the Negative Pressure Thruster itself was not all that unattainable, but its most crucial component, negative mass matter, could only be manufactured at the pinnacle of the micro-particle era.
In other words, with negative mass matter, even a civilization just entering the atomic age could build this kind of thruster, designed specifically for traveling through wormholes.
For humans, negative mass was almost impossible to comprehend.
But it was actually quite simple. Within an inertial frame, it still obeyed the laws of mechanics; it simply moved in the opposite direction from positive mass. Push negative mass forward, and it would accelerate backward.
Not only that, its gravity was also expressed negatively, becoming a repulsive force.
When this material gathered together, it produced powerful negative pressure, otherwise known as tension.
It could tear itself apart in an instant. Without sufficient confinement, the place originally occupied by this material would disperse into a vacuum...
This was also why, after the universe's birth, only matter could be seen, not negative mass matter. Even if it formed naturally, it would dilute itself into invisibility from the instant it came into being... Its density would become something like one particle in each distant corner of the universe, eventually lost amid countless particles of matter.
But sufficiently advanced technology could still manufacture and confine it. The region containing negative mass matter held together in this way would possess powerful negative energy: a reverse curvature of spacetime.
Negative mass repelled all positive matter, so it looked as empty as a vacuum, yet it possessed a powerful repulsive force that warped even spacetime, like a bulging region of space.
If the curvature of a vacuum was defined as zero, then the greater