Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Reelya]

I'm still hoping for FTL travel. Physical travel past the speed of light has been disproven (though I believe it's possible, breaking the sound barrier was impossible until it was done), however the technology which is being researched which bends space looks promising. http://techland.time.com/2012/09/19/nasa-actually-working-on-faster-than-light-warp-drive/

Given the exponential rate of technological advancement, I'd love to see this in my lifetime. I want to visit another star in my lifetime.

Bullets etc could already break the sound barrier before we did it with a plane. But nothing in the universe tops light speed. Totally different, to e.g. heavier than air flight which was "impossible" before the Wright Brothers. But birds have done it forever.

One problem with travel even near the speed of light is that stationary protons etc become waves relative to your travel. They become supercharged particles, so light speed travel is like sitting inside a particle collider. We need something that could withstand the direct beam of the LHC and not kill people with the radiation. Near light speed there is no time for the heavy particles to go around you, so they go through you, but blue shifted into high energy spectrum..

 My money is on the idea that literally raising the dead will be scientifically more achievable than FTL travel.

[wierd]

Thats kinda an interesting thing with the alcubierre metric though.

It creates a kind of shock-front horizon that would be an impassible barrier for matter outside the transiting pocket of spacetime being carried by the spacewarp. That's why it has some of the problems it has. 

Like nuking the solar system you drop out of warp in.

The particles dont go through to the pocket's interior, they get smeared over that shock front instead, and stick there like bugs on a windshield.  When the bubble collapses, that barrier disapears, and BOOM.

For short jumps, it might be doable-- but long haul warp travel would be very dangerous.


I mention alcubierre metric based warp drive, because that is essentially what the EagleWorks Q-Thruster appears to be exhibiting on a low grade scale. (The NASA funded warp drive research mentioned previously.)

[mainiac]

Hmm....wonder if a nuclear pulse propulsion would work as an effective brake.

But then you are only getting half the delta-v out of your nuclear drive.

[Starver]

I'm still hoping for FTL travel. Physical travel past the speed of light has been disproven (though I believe it's possible, breaking the sound barrier was impossible until it was done), however the technology which is being researched which bends space looks promising. http://techland.time.com/2012/09/19/nasa-actually-working-on-faster-than-light-warp-drive/

Given the exponential rate of technological advancement, I'd love to see this in my lifetime. I want to visit another star in my lifetime.

Bullets etc could already break the sound barrier before we did it with a plane. But nothing in the universe tops light speed. Totally different, to e.g. heavier than air flight which was "impossible" before the Wright Brothers. But birds have done it forever.

One problem with travel even near the speed of light is that stationary protons etc become waves relative to your travel. They become supercharged particles, so light speed travel is like sitting inside a particle collider. We need something that could withstand the direct beam of the LHC and not kill people with the radiation. Near light speed there is no time for the heavy particles to go around you, so they go through you, but blue shifted into high energy spectrum..

 My money is on the idea that literally raising the dead will be scientifically more achievable than FTL travel.

That's... a stranger argument than I would have given.

More realistically, the laws of physics create a 'barrier' from passing light-speed because as one starts to approach light-speed (w.r.t. any other datum, for the purists), you'll still find that light is going at "light speed" past you anyway, and you've made no headway.  From an external observer, this is primarily because of time dilation (meaning that time passes for you slower and slower (not to mention the mass and distance problems, etc), and so all applied effort ends up counting for less and less in a "you'll never reach it" situation, for any time period less than "forever".

("There's no time for particles to go around you" is an argument used against supersonic flight, and that manages well enough.  But can't be easily analogued to light-barrier-breaking.)

Interestingly, if you're something that habitually travels at >c (should there be such a thing), the same laws lay down reasons why you can't slow down to the speed of light.  And 'speed of light' things can only go the speed of light, for similar reasons (though, for example, light through a refractive medium ends up going 'slower' because it's not going straight through... ...is probably the best explanation for this post, and Wave/Particle duality is a tricky thing to discuss, from cold).


FTL travel might be possible be "shortcut" methods (i.e. non-FTL travel along alternate, shorter, paths), but there's a whole lot of "maybe" in those concepts.  The operation of the Alcubierre Drive is in this area, but shares territory with wormhole creation when it comes to needing 'exotic' space-warping to achieve the ultimate goal.

[Reelya]

But I wasn't talking about an argument for the light speed barrier.

This is an argument against something that is achievable with known physics - very fast travel below the speed of light. e.g. if you travel close to light speed time dilation means that little subjective time has passed. So a trip to alpha centauri could e.g. take weeks rather than years. That would allow personal interstellar flight except for that fact that ...

http://gizmodo.com/5957697/super-fast-space-travel-would-kill-you-in-minutes

Super-Fast Space Travel Would Kill You in Minutes

A paper published in Natural Science brings some boring common sense to the speed-of-light-travel table. In order to travel huge distances in next to no time, people need to travel close to the speed of light. In so doing, travelers cover extremely large distances very quickly and, thanks to the quirks of relativity, would feel like it took mere minutes because of an effect known as time dilation, which squashes perceived time.

Unfortunately, as spaceship velocities approach the speed of light, interstellar hydrogen H, although only present at a density of approximately 1.8 atoms/cm3, turns into intense radiation that would quickly kill passengers and destroy electronic instrumentation. In addition, the energy loss of ionizing radiation passing through the ship's hull represents an increasing heat load that necessitates large expenditures of energy to cool the ship.

In other words, travel close to the speed of light and you'll be bombarded with so much radiation that you kick the bucket. The knock-on effect is that even if it's possible to create a craft capable of traveling close the speed of light, it wouldn't be able to transport people.

[LordBaal]

Not saying that Alcuberre drive or something else would be entirely impossible on the long (really long run).

But our most realistic bet on current foreseeable technologies (in the next couple hundred years) would be to slow down ageing for mankind up to the point we live several hundreds or thousands of years be it by cybernetics, DNA tampering or whatever. Then a trip on a nuclear powered ship that last, let's say 20 years or 100 years wouldn't be too much different as the old exploring travels around the world that lasted for years at the time.

Also our space exploring life would be greatly eased if we had the means to put tons upon tons of materials on orbit for building ships. A space elevator would be nice, however Earth seems unlikely with current materials. I would say let's go to Mars and build one there (which is totally possible with current materials). Problem is, we probably need one here first to be able to build one there in an acceptable time frame, unless the building materials are found in Mars and we are able to stablish a colony that expands quickly enough to provide everything there (including labourers), but that still would need a lot of time (at the very least one generation).

[Reelya]

Yeah, that sort of goes with what I was saying about beating death would be more feasible than inventing some unknown physics. Maybe people will view things differently once we can actually live for thousands of years, a few decades to get to a nearby star won't seem like a deal breaker any more.

[Starver]

But I wasn't talking about an argument for the light speed barrier.

Well, I misread the nature of your objection, then.


Although "Weeks instead of years".  Ignoring the need to accelerate (a very big 'ignore', to start with, but just to illustrate), you'd need to be going at (back of the envelope calculation here, so may be a tad off) 0.9998(ish)c to travel to a star in as many (subjective) weeks as you're actually going to take in (objective) years.

Getting to that acceleration rate (or above it, to make up for the time you were still winding up below it, and to be reflected around the midpoint turnaround for the somewhat similar deceleration phase) would be... interesting.  Especially when trying to traverse shorter distances (e.g. to Alpha Centauri).  And fighting, for much of that, against the law of diminishing returns (albeit partially mitigated by the expulsion and therefore loss of reaction mass, if you're on a Big Dumb Rocket, starting with truly stupendous amounts of reaction mass and of course engine(s), which probably means your midpoint can be later, if you don't mind higher decelerating forces) in reaching the 0.several9s of c you'd need.

I think the radiation element would be a minimal issue, compared with the other issues.  Certainly not what I'd call the main argument against approaching 'c'.  But that's just me.

[Arx]

Philae may have been moved, shutting it off again.

[alway]

Official cause of SpaceX accident: not enough struts.

A strut holding a helium canister failed, it dumped extra helium into the 2nd stage tank, causing the overpressure event and subsequent disintegration of 2nd stage. They also mentioned changing suppliers since the strut was supposed to be rated for 5x the load it was under.
http://spaceflightnow.com/2015/07/20/support-strut-probable-cause-of-falcon-9-failure/

[GiglameshDespair]

They should have played more KSP.

[i2amroy]

Like nuking the solar system you drop out of warp in.

Seems like there is a pretty easy solution to that:
1) Warp to a spot just parallel to the solar system you want to travel to. Release the giant pulse of destruction in both directions from your ship (for exceptionally long distances maybe do multiple shorter hops to keep down on the size of the pulse).
2) Perform a single very short hop sideways into the solar system you want to travel into. End your trip pointed perpendicular to the solar system disk.
3) Travel the last little bit on non-alcubierre drives.

It's really more of a "you must have a designated flight path" type of thing than a "this problem renders this type of travel impractical" one.

[TheDarkStar]

You assume that the massive amount of energy propelled in front of you ever stops. It doesn't. It's just a matter of what ends up being nuked; if you're lucky, you can aim it right at a black hole and never worry about it. If you're unlucky, you just wiped out an entire planet.

But it's going to disperse.

[Bumber]

You assume that the massive amount of energy propelled in front of you ever stops. It doesn't. It's just a matter of what ends up being nuked; if you're lucky, you can aim it right at a black hole and never worry about it. If you're unlucky, you just wiped out an entire planet.

Space is mostly empty. Black holes themselves send out massive gamma bursts all the time. We haven't been obliterated yet, at least.

[Gentlefish]

Well, the "mostly empty" portion only works out if you're not considering infinite distance. If you draw a straight line, you're bound to hit something; it just might be... far, is all.

But it's going to disperse.