Warp Drive vs Hyperdrive: Star Trek and Star Wars comparative speeds (WOIN)

[Morrus]

Throwing rocks is pretty impressive in the sense that a rock hitting a planet at sufficient speed kills it. It does need to be *that* big or *that* fast compared to the velocities ships can achieve with nonchalent ease.

And if you can do so at FTL speeds, relativity missiles would kill plents easily. They wouldn't even need to be big.

 

[Umbran]

Throwing rocks is pretty impressive in the sense that a rock hitting a planet at sufficient speed kills it. It does need to be *that* big or *that* fast compared to the velocities ships can achieve with nonchalent ease.

Yes, and if your goal is "make the culture on this planet not a going concern" then it works well. If you have any desire to use the planet, you may have to wait decades or centuries for that - and that's if you don't toss the planet into some runaway ecological state. So, it may not make strategic sense for many cases.

And if you can do so at FTL speeds, relativity missiles would kill plents easily. They wouldn't even need to be big.

Ah, well, that depends on your FTL technology. For example, if you are using "hyperspace", or wormholes, or one of several other FTL styles, your ship doesn't end up with a high speed as far as normal space is concerned.

If you want a novel about using such bombardment - try Larry Niven's book, Footfall.

 

[Morrus]

Yes, and if your goal is "make the culture on this planet not a going concern" then it works well. If you have any desire to use the planet, you may have to wait decades or centuries for that - and that's if you don't toss the planet into some runaway ecological state. So, it may not make strategic sense for many cases.

I wasn't really comenting on the wisdom of it. Just debating the cited "impressiveness" metric.

If you want to end a war, that'll do it. If you want to invade, obviously not so much. It's a nuclear option (in ana age where a nuclear option is actually far less destructive than simply throwing a rock).

Ah, well, that depends on your FTL technology. For example, if you are using "hyperspace", or wormholes, or one of several other FTL styles, your ship doesn't end up with a high speed as far as normal space is concerned.

May the hypergates accelerate their contents out into realspace. Who knows? It's all just magic!

If you want a novel about using such bombardment - try Larry Niven's book, Footfall.

One of my first 'hard' sci-fi experiences!

I recall a book I read a few years back which opens with our solar system's civilization being destroyed by a relativity bombardment from Alpha Centauri. Just lots of high velocity projectiles. I don't recall if they were FTL or subluminal, but they were enough to do the job just from velocity. I can't remember what it was called.

 

[Beleriphon]

Throwing rocks is pretty impressive in the sense that a rock hitting a planet at sufficient speed kills it. It does need to be *that* big or *that* fast compared to the velocities ships can achieve with nonchalent ease.

And if you can do so at FTL speeds, relativity missiles would kill plents easily. They wouldn't even need to be big.

True, and actual RKV is pretty dang impressive in the amoutn of damange it can do. I was more referring to the fact that if you can build the Death Star, who really cares if you can throw rocks right? I mean the fact that Death Star was built, by all accounts, as massive project but not something was considered particularly difficult is way more impressive than throwing some rocks at high velocity.

I'll just leave this nifty link to an RKV Calculator here though:
http://xeriar.com/node/10

 

[Morrus]

True, and actual RKV is pretty dang impressive

What's RKV? You've mentioned it a couple of times now, but I'm not familiar with the term.

I was more referring to the fact that if you can build the Death Star, who really cares if you can throw rocks right? I mean the fact that Death Star was built, by all accounts, as massive project but not something was considered particularly difficult is way more impressive than throwing some rocks at high velocity.

Ture, but the Death Star is a colossal waste of money to to something that can be achieved by simply accelerating an asteroid at a planet!

Deaths Stars are still awesome though.

​

 

[Beleriphon]

What's RKV? You've mentioned it a couple of times now, but I'm not familiar with the term.

Sorry should have mentioned that earlier. RKV is a Relativistic Kill Vehicle. Its basically a lump of iron accelerated to some kind of stupid percentage of light speed that is hurled at a planet. Functionally its what we're talking about.

Ture, but the Death Star is a colossal waste of money to to something that can be achieved by simply accelerating an asteroid at a planet!

Deaths Stars are still awesome though.

​

Oh, it sure is a colossal waste of money, but the fact that it can be built as a colassal waste of money (seriously they build a frigging moon!) and done so with any level of skill says a lot about the Empire. Also, using Star Destroyers to slag a planet is called as being more efficient, but not as scary.

Also, a 1^3 metre block of iron accelerated to 98% of C would impact a planet with 3,764,224,652,104.396 gigajoules, or 899,671,283,963.7657 tonnes of TNT (that's what 899 gigatonnes?).

 

[Umbran]

May the hypergates accelerate their contents out into realspace. Who knows? It's all just magic!

You know how well telling a physicist, "It's all just magic," works, right?

And, if it is "magic", then it is fantasy, not science fiction

I was more just noting that fast interstellar travel does not, in and of itself, imply the ability to make things move at very high speeds in realspace terms.

I recall a book I read a few years back which opens with our solar system's civilization being destroyed by a relativity bombardment from Alpha Centauri. Just lots of high velocity projectiles. I don't recall if they were FTL or subluminal, but they were enough to do the job just from velocity. I can't remember what it was called.

That sounds really wasteful. Unless there were other tactical or strategic issues at hand - boosting a whole lot of rocks to relativistic speeds all the way from α-Centauri takes a lot of work. Unnecessary work, as you don't *need* relativistic speeds. Mere orbital speeds will do. You can doom the Earth with one robot probe in the asteroid belt dropping rocks on us. With just a nudge they just *fall*, with little extra energy required.

 

[Umbran]

Sorry should have mentioned that earlier. RKV is a Relativistic Kill Vehicle. Its basically a lump of iron accelerated to some kind of stupid percentage of light speed that is hurled at a planet. Functionally its what we're talking about.

As I mentioned previously - you don't need to reach interesting percentages of the speed of light to do the trick. The rock that killed the dinosaurs wasn't moving at relativistic speeds, and was itself perhaps six miles across.

Also, a 1^3 metre block of iron accelerated to 98% of C would impact a planet with 3,764,224,652,104.396 gigajoules, or 899,671,283,963.7657 tonnes of TNT (that's what 899 gigatonnes?).

Yes, but conservation of energy bites you on the butt. In order to get that energy out of the block of iron, you must first put it *into* the block of iron, accelerating it to that speed without destroying the block in the process. And, whatever you are using for an FTL drive probably *doesn't* do the job - sci-fi FTL is generally about getting up beyond lightspeed without mucking about getting *to* lightpseed, thus getting around the energy requirements of going fast in normal space.

Meanwhile, the dinosaurs were killed with kinetic and potential energy that was already just floating around in the asteroid belt.

Thus, while flashy, RKV is wasteful in the extreme.

 

[Beleriphon]

As I mentioned previously - you don't need to reach interesting percentages of the speed of light to do the trick. The rock that killed the dinosaurs wasn't moving at relativistic speeds, and was itself perhaps six miles across.

Yeah, that's mass and velocity right there. Mind you its just an extinction level event, if you want to obliterate a planet, you need more energy.

Yes, but conservation of energy bites you on the butt. In order to get that energy out of the block of iron, you must first put it *into* the block of iron, accelerating it to that speed without destroying the block in the process. And, whatever you are using for an FTL drive probably *doesn't* do the job - sci-fi FTL is generally about getting up beyond lightspeed without mucking about getting *to* lightpseed, thus getting around the energy requirements of going fast in normal space.

Meanwhile, the dinosaurs were killed with kinetic and potential energy that was already just floating around in the asteroid belt.

Thus, while flashy, RKV is wasteful in the extreme.

That number requires a gun that is .25 of a LY long, so yeah take that as you will. Again, if you have the technology, and ability build stuff like that why are you throw rocks right?

 

[Umbran]

Yeah, that's mass and velocity right there. Mind you its just an extinction level event, if you want to obliterate a planet, you need more energy.

Yeah, but who really needs to actually obliterate a planet in an uncontrolled matter like that?

That number requires a gun that is .25 of a LY long, so yeah take that as you will.

No, that number requires a block of iron moving at 0.98c. One way to get that is with a really long railgun, but that's ineffecient - folks come up with those ideas because they're flashy and make cool soundbites. A Bussard ramjet engine, for example, will do the trick given some time, and isn't nearly so impractical as a quarter-light-year-long construction.