# Energy requirement for ftl [closed]

What would be a fair energy requirement (in Watts) for a hyperspace engine to support 1T at 1c? This is how the system works:

1. Gravity affects your ship, so you have to compensate for that (or take the risk that you crash on reentry). The ship has to avoid stars and planets in normal space even though the ship is in hyperspace.
2. It's not infinite-speed, it takes time (speed and energy follow a square law with increases in speed needing the square of the energy, so 2c would be four times as much power).
3. You require constant power or you will drop out of hyperspace or slow down (if it's only power reduction).

I want to make ftl practical for interstellar transportation, at 5-10c, but not overly cheap: you can't do it for fun (unless you're rich). Electricity costs are 5c/Kwh (at current rates, in credits it will be different)

## closed as off-topic by a CVn♦, Hohmannfan, Burki, Frostfyre, Josh KingAug 12 '16 at 12:50

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• How is it faster than light at 1c? You might also want to specify that you're talking about ftl travel. – Annonymus Aug 12 '16 at 6:14
• Current physics says that energy required to accelerate approaches infinity as speed approaches c. So it all comes down to making things up in a way that works for your story. – Euphoric Aug 12 '16 at 6:19
• I'm voting to close this question as off-topic because without knowing more about how this universe works, it is impossible to answer the question as asked. – a CVn Aug 12 '16 at 9:37
• It looks like the OP's FTL drive is neither Newtonian nor Einsteinian if velocity increases according to the square of increases in energy. This suggests if this drive consumes one unit of energy at 1% of lightspeed it will only require ten units of energy to travel at 100% of lightspeed. This also suggests the drive has to be constantly activated for its motion. This is Aristoltean physics. The reason that it is a FTL drive is that presumably it isn't limited to less than lightspeed velocities. At 100 eu, its velocity will be 10 c. Not quite physics as we know it. – a4android Aug 12 '16 at 12:10
• Welcome to Worldbuilding, Matthew! Your question about FTL travel is a sensitive topic here. Can you please clarify your speed & energy rule? if your question is about estimating what the energy consumption should be at a given speed, then we should be able to devise an answer. Your FTL drive is a fictional contrivance not based on the usual science of vehicle dynamics. This has confused the commenters. You may need to edit your question to make it clearer. – a4android Aug 12 '16 at 12:19

Basic lesson in Newtonian physics:

• It does not take any energy to maintain a velocity.
• It takes energy to change your velocity.

This is Newton's First Law of Motion.

So why do you need to feed energy to your bike/car/train/airplane to maintain velocity? This is because friction is providing a resistive force on your vehicle. Force times distance travelled equals energy, and that changes your velocity. So to combat the detrimental influence of friction, that conceptually bleeds you of energy, you need to provide more energy.

In space, this does not apply. You have (almost) no friction in space. So once you reach a certain velocity, you do not need any energy to maintain it. Hence when you ask for "energy consumption at 1c", the answer is 0. If you have reached 1c and you are coasting, you do not consume any energy.

But you do need to put in energy to reach your velocity. And this is where Einsteinian physics trips up your question, because you need an infinite amount of energy to reach 1c. And not even a Kardashev Type III civilization can do that.

• Presumably his ftl drive isn't a rocket and doesn’t work by simply “going faster” in the normal way. – JDługosz Aug 15 '16 at 6:16
• @JDługosz And? What does that have to do with the question? – MichaelK Aug 15 '16 at 6:20
• That's my question to you! Your reply has nothing to do with a “hyperspace engine”. He postulates that it takes power to keep operating. Pointing out that newnonion motion doesn't is beside the point. He postulates a ftl drive. Pointing out that normal motion can't reach ftl is beside the point. – JDługosz Aug 15 '16 at 6:26
• @JDługosz Well then he better come up with some physics for this hyperspace engine as well. All fine and well that he postulates an engine that runs on applied phlebotinium ( tvtropes.org/pmwiki/pmwiki.php/Main/AppliedPhlebotinum ) but unless he also lays down the parameters for this engine, then he cannot expect an answer on a question like this. It is not our job to invent physics for his imaginary engine. – MichaelK Aug 15 '16 at 6:32
• I agree: it is not answerable as asked. That’s a common issue that often gets lumped under POB now, where the answer is “it’s up to you!”. – JDługosz Aug 15 '16 at 14:05