Warp drive may actually be possible, NASA scientist says
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Re: Warp drive may actually be possible, NASA scientist says
#2> "A trip to Alpha Centauri would take about two weeks. Traveling as fast as we are now currently able, it would take tens of thousands of years."
This isn't true. Nuclear pulse drives built with currently available technology could achieve .05C [1], meaning a 4 light year trip would take ~80 years.
[1]: http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsi...
Re: Warp drive may actually be possible, NASA scientist says
#3Previous discussion: http://news.ycombinator.com/item?id=4534359
Re: Warp drive may actually be possible, NASA scientist says
#4> "A trip to Alpha Centauri would take about two weeks. Traveling as fast as we are now currently able, it would take tens of thousands of years." This isn't true. Nuclear pulse drives built with currently available technology could achieve .05C [1], meaning a 4 light year trip would take ~80 years. [1]: http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsi...
IIRC, that assumes we don't want to decelerate. Adding the fuel to decelerate also increases the fuel needed for the original acceleration itself, which then quickly becomes less feasible. In any case, I'm guessing they were referring to "current, tried and tested" technologies.
Edit: I'm also having a slight chuckle at the estimated costs presented. Somehow, I'd think that just getting 40,000,000 t of spaceship into orbit would cost a bit more than 1 year of US GNP.
Re: Warp drive may actually be possible, NASA scientist says
#5> "A trip to Alpha Centauri would take about two weeks. Traveling as fast as we are now currently able, it would take tens of thousands of years." This isn't true. Nuclear pulse drives built with currently available technology could achieve .05C [1], meaning a 4 light year trip would take ~80 years. [1]: http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsi...
IIRC, that assumes we don't want to decelerate. Adding the fuel to decelerate also increases the fuel needed for the original acceleration itself, which then quickly becomes less feasible. In any case, I'm guessing they were referring to "current, tried and tested" technologies. Edit: I'm also having a slight chuckle at the estimated costs presented. Somehow, I'd think that just getting 40,000,000 t of spaceship into…
The mass added by the "fuel" of the orion nuclear pulse drive is negligible: a nuclear bomb has very little mass compared to the impulse boost you can extract from it.
You could literally lift a city-sized space ship to orbit on the cheap with this technology. The problem is the nuclear fall-out for those left on the ground.
Re: Warp drive may actually be possible, NASA scientist says
#6One issue about warp drives that I never see mentioned is one has to be careful one is not creating a perpetual motion device.
Consider a warp drive that transports you from, say, earth's orbit to pluto's orbit. Now, you fall back towards earth's orbit. This means that the warp drive, in order to not violate conservation of energy, must require at least as much energy as the potential energy difference between the two positions.
Re: Warp drive may actually be possible, NASA scientist says
#7The article doesn't mention exotic matter. Did they find a way to build an engine without exotic matter?
Re: Warp drive may actually be possible, NASA scientist says
#8Earlier quoted context omitted.
IIRC, that assumes we don't want to decelerate. Adding the fuel to decelerate also increases the fuel needed for the original acceleration itself, which then quickly becomes less feasible. In any case, I'm guessing they were referring to "current, tried and tested" technologies. Edit: I'm also having a slight chuckle at the estimated costs presented. Somehow, I'd think that just getting 40,000,000 t of spaceship into…
The mass added by the "fuel" of the orion nuclear pulse drive is negligible: a nuclear bomb has very little mass compared to the impulse boost you can extract from it. You could literally lift a city-sized space ship to orbit on the cheap with this technology. The problem is the nuclear fall-out for those left on the ground.
if the launch system was all on another planet or moon, then this wouldn't be a problem.
I can imagine you'd ride a rocket to the moon, and then the real spaceship is launched this way for inter planetary travel. It'd be like the old days of ocean liners, you stay on it for months on end, and a ship flies out may be once every year or so.
Re: Warp drive may actually be possible, NASA scientist says
#9One issue about warp drives that I never see mentioned is one has to be careful one is not creating a perpetual motion device. Consider a warp drive that transports you from, say, earth's orbit to pluto's orbit. Now, you fall back towards earth's orbit. This means that the warp drive, in order to not violate conservation of energy, must require at least as much energy as the potential energy difference between the tw…
Conservation of energy may or may not be valid in general relativity, at least in a naive understanding of conservation of energy. The technical explanation for this is, that conserved quantities are related to geometrical symmetries via Noethers theorem [1], and on a curved background these symmetries may or may not be there. ( A rather handwaving explanation would be, that there is no straightforward way to define the energy density of a gravitational field.)
In fact it is possible to build a perpetuum mobile by just filling some region of space with dark energy. This region of space will then expand at constant energy density, therefore creating energy.
Re: Warp drive may actually be possible, NASA scientist says
#10Earlier quoted context omitted.
IIRC, that assumes we don't want to decelerate. Adding the fuel to decelerate also increases the fuel needed for the original acceleration itself, which then quickly becomes less feasible. In any case, I'm guessing they were referring to "current, tried and tested" technologies. Edit: I'm also having a slight chuckle at the estimated costs presented. Somehow, I'd think that just getting 40,000,000 t of spaceship into…
The mass added by the "fuel" of the orion nuclear pulse drive is negligible: a nuclear bomb has very little mass compared to the impulse boost you can extract from it. You could literally lift a city-sized space ship to orbit on the cheap with this technology. The problem is the nuclear fall-out for those left on the ground.
As a "fuel", yes, it is pretty efficient. That said, the "optimistic" version of the spaceship (representing the upper bounds of that specific technology), still came in at 400,000 tons, after a sort of miniaturisation. That's a lot of spaceship, and as far as I know, none of those calculations cater for launching from the planet's surface. If nothing else, that would require additional fuel, and it's not negligable, because each ton of extra fuel is pushing the 400,000 tons already loaded. It's a game of (greatly) diminishing returns.