> it’s conjectured that the colonists already at your destination won’t appreciate you boiling the atmosphere when you hit them with blue shifted radiation.
There's a general principle known as Jon's Law (not sure where the name comes from) that any powerful space drive is by definition a weapon of mass destruction.
You see this in The Expanse when incredibly powerful fusion torchship rockets (a major part of the Expanse 'verse) are attached to asteroids and these are used to kinetically bombard inner planets. The results are far worse than a nuclear attack, from kinetic energy alone.
Anything capable of traveling close to the speed of light would be "death star" level planet killer. We're talking smashing through the crust and boiling off the atmosphere or if it were massive maybe even fragmenting the planet. Obviously anything even wilder like an Alcubierre Drive would be likewise. Anything capable of going to the stars within a human lifetime could annihilate worlds.
Even present-day chemical rockets could be pretty destructive. Get something massive that won't burn up (like a rod of tungsten) up to interplanetary velocities and you can approach the yield of a small tactical nuke from just kinetic energy. This has been studied at least on paper by militaries. I think the phrase "rods from God" was used by DARPA at one point for the rod of tungsten idea.
This is glossed over in the vast majority of space sci-fi. Nobody even asks in Star Trek what happens if you point the Enterprise at a planet and say "warp 9, engage!" I'm guessing it would go poorly for the Enterprise but even worse for the planet.
Most hyperdrives just need to be Neptune’s distance from a star to work - two light hours; the Q-II needs to be five - Pluto’s! This means it can get you from any given human world in Known Space to any other in no more than eleven hours, but also no less than ten hours for any world outside the system.
There’s no intermediate setting. With most hyperdrives, a pilot can leave the helm unattended most of the time. If one does so in a Q-II for more than two minutes, they’re almost certain to crash into a star. It doesn't have an on-off switch, either, it has a grip that has to be kept or the drive turns off.
> There's a general principle known as Jon's Law (not sure where the name comes from) that any powerful space drive is by definition a weapon of mass destruction.
Also known as the Kzinti Lesson, from Larry Niven's Known Space series. I've not read where in that series this term is first introduced, but they're somewhere in all that.
> Obviously anything even wilder like an Alcubierre Drive would be likewise
Not yet known; the original Alcubierre Drive is a toy model that demonstrates the point, but has so many problems with it that, as is, it definitely won't work.
Something else along similar lines that does work? The only thing it won't act like when it hits something, is like being hit by normal matter that's actually moving at the speed of light, because if it did it would also be an infinite free energy source.
I'm thinking of the Lensmen series--the stardrive ejects non-interacting particles and thus doesn't tear things up. And since it's inertialess you can't use it to accelerate an impactor. However, you can go grab something that's already moving how you want, slap an inertialess drive on it and reposition it so that when the drive is turned off it's heading for your target. When it's a planet you fling around that can be pretty dangerous. And when it's a FTL planet (everything is Newtonian, this doesn't cause issues other than for the crew--can't allow one atom of native matter into your ship, can't use one atom from your ship in the drive on the planet) the results are spectacular.
(Note that they also have normal reaction drives in the Lensmen universe--the stardrive will get you to your objective but you still need to match velocities with it. And that does tear things up and we see it's use as a weapon, although not against a peer-class opponent.)
> Even present-day chemical rockets could be pretty destructive. Get something massive that won't burn up (like a rod of tungsten) up to interplanetary velocities and you can approach the yield of a small tactical nuke from just kinetic energy. This has been studied at least on paper by militaries. I think the phrase "rods from God" was used by DARPA at one point for the rod of tungsten idea.
Also known as "Project Thor", it was devised by Jerry Pournelle before he became a science fiction author. More on various iterations of the concept can be found in Wikipedia:
I think that law is basically Newton's second law of motion. F=ma essentially tells you that anything that decelerates a lot, such as a very fast spaceship crashing into the rock of your planet, pushes with an awful lot of force before it stops.
Edit: to be slightly more pedantic, the right form that still remains true with relativity is F = dp/dt, i.e. the force the spaceship would exert is equal to its change in momentum.
in niven's "known space" universe that was known as the "kzinti lesson"; the kzinti
were a warlike race that thought humanity would be easy pickings because their telepathic spies said they had a civilisation completely at peace. turns out humanity figured out really fast that their mining lasers, fusion drives, etc could be used as weapons when the hostiles showed up.
> Even present-day chemical rockets could be pretty destructive. Get something massive that won't burn up (like a rod of tungsten) up to interplanetary velocities and you can approach the yield of a small tactical nuke from just kinetic energy.
Of course, that energy didn't come for free: if the rod came from earth, your rockets have to provide the energy.
> This has been studied at least on paper by militaries.
I thought these weapons were real and deployed. Specifically, I understand that hypersonic missiles don't really need an explosive warhead; a hypersonic tungsten rod would make a bigger explosion than any conventional warhead.
Hypersonic missiles are different. I think the idea with those is whether they have a warhead or not they come in so fast you can't possibly shoot them down. The US, Russia, and China are all either confirmed or rumored to have hypersonic delivery systems like this.
The "rods from God" concept is the idea of creating an artificial meteorite as a weapon that comes in from space. These may or may not already exist, but if they do they'd be secret and would probably violate some treaties.
Regarding the speed: I read somewhere that hypersonics create a "wall" of plasma in front of them. The plasma neither transmits nor reflects radio, so the missile becomes invisible to radar, at least from the front. I have no idea whether that's true.
There's a general principle known as Jon's Law (not sure where the name comes from) that any powerful space drive is by definition a weapon of mass destruction.
You see this in The Expanse when incredibly powerful fusion torchship rockets (a major part of the Expanse 'verse) are attached to asteroids and these are used to kinetically bombard inner planets. The results are far worse than a nuclear attack, from kinetic energy alone.
Anything capable of traveling close to the speed of light would be "death star" level planet killer. We're talking smashing through the crust and boiling off the atmosphere or if it were massive maybe even fragmenting the planet. Obviously anything even wilder like an Alcubierre Drive would be likewise. Anything capable of going to the stars within a human lifetime could annihilate worlds.
Even present-day chemical rockets could be pretty destructive. Get something massive that won't burn up (like a rod of tungsten) up to interplanetary velocities and you can approach the yield of a small tactical nuke from just kinetic energy. This has been studied at least on paper by militaries. I think the phrase "rods from God" was used by DARPA at one point for the rod of tungsten idea.
This is glossed over in the vast majority of space sci-fi. Nobody even asks in Star Trek what happens if you point the Enterprise at a planet and say "warp 9, engage!" I'm guessing it would go poorly for the Enterprise but even worse for the planet.