Your favorite FTL Drive

[Surrealone]

At "Oh My God particle" speed, relativistic mass is 300 billion times greater, so the kinetic energy of even a smallish object is potentially planet killing.

1kg of raw iron (i.e. a little more than 3/4 cup in volume) traveling in a frictionless void at 99% the speed of light would have the kinetic energy of 5.47×10¹⁷ joules. In explosive terms, on impact it would be equal to 132 megatons of TNT or approximately 75 megatons more than the yield of Tsar Bomba, the Soviet hydrogen bomb tested on October 30, 1961, which had a 50 megaton yield ... and which still stands as the most powerful nuclear weapon detonated by mankind, to date.

 

​Now accelerate that 1kg of raw iron to FTL speeds.  It's not just planet-killing at such speeds, it's potentially star-killing -- even if the star's radiation manages to melt the material on its way into the core.

 

​Google 'relativistic bomb' for this one. Wikipedia has the math on it...

[Lawnmower Boy]

Objects travelling at FTL velocities have negative mass, are travelling back in time, and have always been doing so (no acceleration through the speed of light)! They would also radiate gravity waves, which would cause them to lose energy, which would cause them to accelerate to infinite velocities, which would cause them to disappear. So Wikipedia's math on the kinetic energy of tachyon impacts with planets and such should be very interesting. 

 

Now, as to the bowling ball of iron travelling at near-light speed (and remember that you can get its kinetic energy up to infinity --but not beyond-- by accelerating it to exactly c), at a certain point it is just going to punch right through your planet and continue on its merry way, having shed very little more kinetic energy than your regular meteor impact. 

 

Given that you've found some way to persuade your subluminal mass to obligingly deccelerate to rest velocity in the planet's frame of reference (dum-dum rounds?), this will be a very bad day indeed for residents of the poor plant. That being said, however, this is not something-for-nothing. You get out the energy you put in. It is not likely to be cheap or carefree to accelerate a bowling ball to 0.99c. In any fair universe, it will be pretty obvious that you are doing so from a very long way away, giving the planet ample time to dodge out of the way. 

 

Now, with an FTL drive, the question is whether you can achieve luminal velocities without going to all the trouble of obeying the law of conservation of energy. If so, you have perpetual motion and unlimited energy, not to mention that the universe is your oyster, etc, etc. As an SF writer, you are free to imagine this universe. I think it would probably be more economical of versimiltude to requrie starfarers to give this energy back to the universe --and not by blowing up planets, as someone went to an awful lot of trouble to make it, and what thanks do they get?

 

Now get your relativistic missile off the planet, and sit up like a gentleman. Also, would it kill you to call your grandmother once a week?

[Surrealone]

That being said, however, this is not something-for-nothing. You get out the energy you put in. It is not likely to be cheap or carefree to accelerate a bowling ball to 0.99c. In any fair universe, it will be pretty obvious that you are doing so from a very long way away, giving the planet ample time to dodge out of the way. 

The FTL power clearly violates the law of conservation of energy since the power costs no endurance to use -- by a character that can carry a bowling ball or a vehicle that can carry a lot more.  Since RAW basically handwaves the issue, megaplayboy's reltativistic bomb (a la "Oh My God particle") kinda -is- something for nothing (0 END!) in any campaign in which FTL has been permitted, as allowing FTL entails suspension of disbelief with regard to the physics associated with going superluminal (i.e. energy, mass, etc. issues).

[Surrealone]

How would you write this up in HERO?

 

 

HM

That's clearly ED movement...

[Lawnmower Boy]

The FTL power clearly violates the law of conservation of energy since the power costs no endurance to use -- by a character that can carry a bowling ball or a vehicle that can carry a lot more.  Since RAW basically handwaves the issue, megaplayboy's reltativistic bomb (a la "Oh My God particle") kinda -is- something for nothing (0 END!) in any campaign in which FTL has been permitted, as allowing FTL entails suspension of disbelief with regard to the physics associated with going superluminal (i.e. energy, mass, etc. issues).

 

By RAW, you may get 0 End, but you have to pay for every single dice of your planet-destroying energy.

[Surrealone]

By RAW, you may get 0 End, but you have to pay for every single dice of your planet-destroying energy.

Not in a heroic level game where FTL vessels exist ... or where a character has the FTL power.  A bowling ball is merely equipment ... as would be a FTL vehicle.  If you want to hang your hat on it costing -something- because the bowling ball has a MSRP as does the vehicle, well, such things can be stolen, borrowed, or hey, someone with Transform could simply make a lump of material about the size/density of a bowling ball.

[Tasha]

Not in a heroic level game where FTL vessels exist ... or where a character has the FTL power.  A bowling ball is merely equipment ... as would be a FTL vehicle.  If you want to hang your hat on it costing -something- because the bowling ball has a MSRP as does the vehicle, well, such things can be stolen, borrowed, or hey, someone with Transform could simply make a lump of material about the size/density of a bowling ball.

 

That DOES touch on one of the contradictions in many SciFi universes. Esp ones where ships can go Superluminal or accelerate to nearly the speed of light. That Contradiction is that accelerating any mass to that speed creates a VERY destructive weapon (ie your Bowling ball). Now that Bowling ball would probably burn up in the atmosphere of any world with one Being mostly plastic covered resin. It's still quite destructive to things that are in Vac or near vac. The answer to the contradiction is to not ask the question in world, and have everyone be a bit stupid about his rather obvious thing (one could point out that the bowling ball would be pretty easy to dodge since it would be on an easy to work out vector, with no way for it to change it's course).

[CptPatriot]

Personally, I prefer a system that allows for more drama, in the event of a conflict.

 

So, I tend to like

• Warp Drives akin to Star Trek,
• but recently, with the Star Citizen game, they have a jump point or hyperdrive-like system, but engages the player because you need a pilot to navigate the tunnel between points. Here is an example video I cobbled together that shows it off.
  

[Wardsman]

That DOES touch on one of the contradictions in many SciFi universes. Esp ones where ships can go Superluminal or accelerate to nearly the speed of light. That Contradiction is that accelerating any mass to that speed creates a VERY destructive weapon (ie your Bowling ball). Now that Bowling ball would probably burn up in the atmosphere of any world with one Being mostly plastic covered resin. It's still quite destructive to things that are in Vac or near vac. The answer to the contradiction is to not ask the question in world, and have everyone be a bit stupid about his rather obvious thing (one could point out that the bowling ball would be pretty easy to dodge since it would be on an easy to work out vector, with no way for it to change it's course).

The problem is that liquified or plasmafied bowling bowl still has kinetic energy and mass.

It doesn't go away. 

 

Reminds me in in DC animated flick superman uses heat vision to destroy kryptonite. Problem is it wouldn't work. Congratulations you took an element that radioactive and poisonous and rendered it a superheated gas. Have fun inhaling that and taking the rad hits.

[Surrealone]

That DOES touch on one of the contradictions in many SciFi universes. Esp ones where ships can go Superluminal or accelerate to nearly the speed of light. That Contradiction is that accelerating any mass to that speed creates a VERY destructive weapon (ie your Bowling ball). Now that Bowling ball would probably burn up in the atmosphere of any world with one Being mostly plastic covered resin. It's still quite destructive to things that are in Vac or near vac. The answer to the contradiction is to not ask the question in world, and have everyone be a bit stupid about his rather obvious thing (one could point out that the bowling ball would be pretty easy to dodge since it would be on an easy to work out vector, with no way for it to change it's course).

Yup, it's nasty.  Even if the object burns up in the process of an impact, the energy is going to go -somewhere-.   As for dodging it -- maneuverable things like ships could.  Space stations and planets -- not so much -- especially if the missile's release was done in such a way to account for forces (like gravity) acting upon it during its travel to the target.  i.e. Sort of like how we slingshot things around masses using gravity, someone with space navigation, lightning calculator, and bump of direction ... or a nav computer that does such things for him/her... could plot such a missile release for impact with a body in a known orbit through known space.

 

For this to be effective in game, this sort of thing can only really apply as a plot device of some kind -- much like the Death Star's test on Alderaan was.  It's got its place, but dramatic appropriateness should definitely apply whether used by players or the GM.

[Tasha]

The problem is that liquified or plasmafied bowling bowl still has kinetic energy and mass.

It doesn't go away. 

 

Reminds me in in DC animated flick superman uses heat vision to destroy kryptonite. Problem is it wouldn't work. Congratulations you took an element that radioactive and poisonous and rendered it a superheated gas. Have fun inhaling that and taking the rad hits.

 

Yes, but how much of that 15lb mass would boil off during the early stages of reentry. Basically leaving a smoke trail and nothing else. It's really only a plastic shell over a core of Epoxy Resin. It's not going to go very far in the Atmosphere before it burns away leaving nothing. Now something flying high enough could be struck. Beanstalks (Space Elevators) could be in danger of being damaged by this. I doubt that it ever reaches any where near the ground.

[Cancer]

As it happens, that's known (and you are correct, Tasha) ... but only up to "normal" hypersonic velocities, 60 km/s or so. (The paper can be got at http://adsabs.harvard.edu/abs/1993AJ....105.1114H ... free access.) That upper limit is what you can expect to happen given any sort of normal natural Solar System object falling on Earth.

 

But it has not been worked out for drastically higher velocities, the kind of thing where a starship moves across the Solar System in a matter of days. Once you get to velocities a factor of a hundred or a thousand or more higher than that natural limit of 60 km/s, I expect that the bowling ball impactor will penetrate the atmosphere and embed itself in the crust before all that energy is released. It may be plasma at impact, but reducing the travel time through the atmosphere from ten seconds to a tenth of a second or less means the matter won't have time to disperse before impact.

[Sundog]

Actually, I suspect that hitting atmosphere at that speed would be like hitting a brick wall.

At any significant percentage of C, the entire object would flash to energy, primarily heat, virtually instantaneously. It would be like a nuke blast, but many orders of magnitude more intense. Anything in visual range of the impact point would burned off instantly, and the shockwave would cave in that side of the planet.

 

Look at what happened in the Tunguska Event. The object never made it to earth - it probably exploded when it hit the lower atmosphere - but it devastated a huge region of Siberia.

[Cancer]

Tunguska is discussed at several points in the paper I linked, so yeah; see figure 12 in particular.

 

At 10,000 km/s, a 2-kg object has KE of about 25 kilotons. Not as big as I would have guessed before I pushed numbers around. Interesting.

 

Real star-drive speeds as one casually thinks of them are another scale. A spacecraft that moves 40 AU in a day (cross the Solar System in a day or so) is going at roughly a quarter c. Relativity does not yet raise its head there, but now that 2-kg object has a bit more than 1 MT of KE. Unpleasant but not planet-busting class. Probably gets hot enough to give you a gamma-ray flash, but not a real big one.

[Sundog]

Not as big as I'd figured, but still deadly to anything not shielded by Kilometers of atmosphere. Still, if you possess the power to attain .25c, I doubt there's much stopping the attainment of significantly higher velocities.

[Manic Typist]

Not as big as I'd figured, but still deadly to anything not shielded by Kilometers of atmosphere. Still, if you possess the power to attain .25c, I doubt there's much stopping the attainment of significantly higher velocities.

 

 

Or building a bigger bowling ball...

[Christopher]

The FTL power clearly violates the law of conservation of energy since the power costs no endurance to use -- by a character that can carry a bowling ball or a vehicle that can carry a lot more.  Since RAW basically handwaves the issue, megaplayboy's reltativistic bomb (a la "Oh My God particle") kinda -is- something for nothing (0 END!) in any campaign in which FTL has been permitted, as allowing FTL entails suspension of disbelief with regard to the physics associated with going superluminal (i.e. energy, mass, etc. issues).

 

By RAW, you may get 0 End, but you have to pay for every single dice of your planet-destroying energy.

Specifically what you would try to to is a Ranged Attack or move by with Velocity Bonus from FTL. From the point of the ball you are doing a FTL move-through.

But FTL (like any non-combat movement) can not be used for Velocity Maneuvers - because that is way beyond what the given cost is balanced for.

 

This is Hero we are talking about. Asume there is a rule to prevent insanely overpowered stuff like that.

[Zeropoint]

It would be something for nothing in terms of physics, too. If an FTL bowling ball can release enough energy for an Earth-shattering kaboom when it hits, then it has to HAVE that much energy, and therefore that much energy would be required to put it in the FTL state. If the bowling ball can be gotten up to FTL speeds without supplying teratons of energy, then it won't release teratons of energy when it hits a planet--it'll go "through", or just drop out of warp, or do something else interesting that doesn't release any more energy than was put into it in the first place.

[Cancer]

Here's a weird idea: your FTL drive "borrows" the energy from the mass-energy of the star from whose gravity well the drive is escaping, and dumps most or all of it back into the mass-energy of the star whose gravity well terminates the jump. With stellar-mass objects, you won't notice the change. How much you deposit back in the star at the end of the trip is up to the GM making the world to decide.

[Manic Typist]

Oh, that complicates interstellar travel nicely with respect to commerce/major travel hubs. If FTL travel is fairly easy, with significant commerce/passenger traffic, then you could conceivably notice a strain on stars at popular hubs. It could be as simple as regulating traffic in such a way so as to "balance" energy levels between stars... to all out war to prevent someone else's desire for trade from blowing up your home system through rush hour traffic conditions in your system.

[GoldenAge]

Saw this thread on FTL and thought I'd post how we do it in our game (much of it taken from Star Hero and many other sources):

 

Starship Propulsion Systems.pdf

 

Ships of theTGU.pdf

 

Stasrship Combat in the TGU.pdf

[sinanju]

Oh, that complicates interstellar travel nicely with respect to commerce/major travel hubs. If FTL travel is fairly easy, with significant commerce/passenger traffic, then you could conceivably notice a strain on stars at popular hubs. It could be as simple as regulating traffic in such a way so as to "balance" energy levels between stars... to all out war to prevent someone else's desire for trade from blowing up your home system through rush hour traffic conditions in your system.

 

Speaking of rush hour....in David Weber's Honor Harrington novels, wormholes are one of the ways people get around at FTL speeds. You enter the wormhole in System A and pop out a matching wormhole in System B. Every transit destabilizes the wormhole to some degree. For drones or very small ships, it may be unnoticeable or only a matter of seconds. For very large ships (freighters and warships) it can be minutes. For FLEETS of ships, it effectively closes the wormhole for hours. So there are scenes where commanders have to choose between transiting one or two warships at a time at intervals--while not knowing if they're being blasted to atoms on the other side-- by a superior force, or bring a huge honking fleet through all at once...but shut down the wormhole for hours and hours, meaning no escape route and no backup if they find themselves in an untenable situation.

 

Also, huge fleet transits consist of a scout vessel popping into the new system and broadcasting a warning to all the commercial vessels awaiting their turn to travel through the wormhole. The warning is something to the effect of, "Attention! Evacuate the area IMMEDIATELY. Fleet incoming." And all the freighters run (as fast as freighters can run) before millions and millions of tons of warshisp appear out of nowhere....

[Spence]

In the Honerverse they had non-wormhole FTL as well.

 

But the Starfire universe (David Weber and Steve White) was all wormhole.

 

The books are:

  Insurrection
  Crusade
  In Death Ground
  The Shiva Option

 

If I ever do another scifi game, starships will be modeled after the Starfire universe.