Is there ANY realistic mode of interstellar travel?

[Dunderman]

@Measure for Measure

I’m not so sure.

This proposal calls for ultralights attached to 10 mile wide sails and powered by orbital lasers. It might reach 10% of the speed of light or more - fast enough to reach alpha Centuri in 40 years.

So we travel to Alpha Centauri in 40 years (which is a tad longer than what I was looking for, but never mind for now), put an orbital laser there and travel back in 40 years. Doesn’t this mean that much more than 80 years have passed on Earth in the meantime?

Let’s pretend for a moment that we can create stable wormholes. How would travel through them work practically? Would you have a spaceship creating a wormhole in front of it and going through it? Would you have a constant wormhole on the ground and a vehicle going through it on rails or something? Could you even use it to get to Alpha Centauri (for example), since the other end of the wormhole would have to be there? Could we theoretically, once we have mastered all that pesky negative mass, put the other end there?

[Exapno_Mapcase]

@Priceguy

So we travel to Alpha Centauri in 40 years (which is a tad longer than what I was looking for, but never mind for now), put an orbital laser there and travel back in 40 years. Doesn’t this mean that much more than 80 years have passed on Earth in the meantime?

No. I’m not going to work through the math, but the relativistic time differential at 10% C is pretty small.

Also you can’t get to Alpha Centauri in 40 years by that method. Remember that there’s no way of stopping from 10% C except by reversing the process and slowing down at the same rate. So it takes you more than 20 years to get to the halfway point, at a top speed of less than 10% C, and more than 20 years to slow down to 0 so you can orbit around the star. And then the same amount of time back. This is far more than 80 years. Again I’m not going to do the math, but it pushes it well over a century.

Let’s pretend for a moment that we can create stable wormholes. How would travel through them work practically? Would you have a spaceship creating a wormhole in front of it and going through it? Would you have a constant wormhole on the ground and a vehicle going through it on rails or something? Could you even use it to get to Alpha Centauri (for example), since the other end of the wormhole would have to be there? Could we theoretically, once we have mastered all that pesky negative mass, put the other end there?

Once we start pretending we have stable wormholes, we can do anything.

You can’t even begin to speculate on this. It’s all total wishful thinking. Absolutely nothing we can imagine with current physics can begin to tackle any part of the problem.

[kanicbird]

@Exapno Mapcase

Once we start pretending we have stable wormholes, we can do anything.

Well we might have to create the wormhole here, then send one end conventionally to the far end, which could take centuries, then we can use it.

[Exapno_Mapcase]

@kanicbird

Well we might have to create the wormhole here, then send one end conventionally to the far end…

With what, UPS? Fed Ex?

Again, once you start with imaginary physics, anything might hapen, including moving a wormhole! But nothing you say about it will be more meaningful than anything else.

[Measure_for_Measure]

@Priceguy

So we travel to Alpha Centauri in 40 years (which is a tad longer than what I was looking for, but never mind for now), put an orbital laser there and travel back in 40 years. Doesn’t this mean that much more than 80 years have passed on Earth in the meantime?

Um, yes. This proposal assumes an unmanned, one-way flight.

This Nasa site on interstellar travel mentions the sail concept:

@NASA's Webpage

Robert Forward proposed using a 10-million-gigawatt laser to shine through a thousand kilometer Fresnel lens onto a thousand kilometer sail. With these numbers, it is claimed that one could send a thousand-ton vehicle with crew to our nearest star in 10 years!

What’s the catch? That 10-million-gigawatt laser. That power level is ten thousand times more than the power used on all the Earth today.

So, Forward revised the concept to more reasonable power levels. …

Oh, and here is the obligatory Wiki link.

[Ring]

Well, let’s see, from NASA we have the possibilities of wormholes and the Alcubierre’s "Warp Drive

Wormholes

First, collect a whole bunch of super-dense matter, such as matter from a neutron star. How much?- well enough to construct a ring the size of the Earth’s orbit around the Sun. Then build another ring where you want the other end of your wormhole. Next, just charge ‘em up to some incredible voltage, and spin them up to near the speed of light – both of them.

Alcubierre’s "Warp Drive

First, to create this effect, you’ll need a ring of negative energy wrapped around the ship, and lots of it too. It is still debated in physics whether negative energy can exist. Classical physics tends toward a “no,” while quantum physics leans to a “maybe, yes.” Second, you’ll need a way to control this effect to turn it on and off at will. This will be especially tricky since this warp effect is a separate effect from the ship. Third, all this assumes that this whole “warp” would indeed move faster than the speed of light. This is a big unknown. And fourth, if all the previous issues weren’t tough enough, these concepts evoke the same time-travel paradoxes as the wormhole concepts.

http://www.nasa.gov/centers/glenn/research/warp/ideachev.html

[Chronos]

Alas, hypothetical modes of hyperspeed or even light speed travel (for people anyway) are barely any more realistic than time travel at this point.

Scratch that statement: Hypothetical modes of hyperspeed travel are exactly as realistic as time travel. If you have any method which can be used to get you from point A to point B before a photon travelling through vacuum could get there, the same method could be used to travel into the past, and vice versa. Note that I am not qualifying “any method”, there. It could be hyperspace, it could be wormholes, it could be warp drive, it could be teleporting dragons. It doesn’t matter.

There are a number of theoretical methods to achieve faster-than-light travel (and hence time travel). They’re understood, in the sense that we can write down meaningful equations for them. But all of the known methods (and probably all methods, period, though I’m not entirely confident on that) rely on having exotic matter, which has negative mass (that’s the oversimplified version; the actual condition required is somewhat more mathematical). Unfortunately, there’s no evidence for the existance of negative mass, and no reason beyond wishful thinking to even think that it might exist.

This is like 18th Century people speculating on whether it’s possible to break the sound barrier when the fastest things available are racehorses and clipper ships.

No, it’s far worse than that. Even centuries ago, people knew of things which could break the sound barrier: Bullets and whips come to mind. The question then wasn’t whether it was theoretically possible for things to break the sound barrier; if there was a question at all, it was merely whether it would be practical to build something to break the sound barrier carrying a person. Note that there’s a huge difference between “possible” and “practical”.

This brings us back to the question of starships which are slower than light, but still very fast. There’s nothing inherent to the laws of physics which prohibits travelling at, say, .9c . It’s perfectly possible, for instance, to travel any distance you like at a constant acceleration of 1 g (fast enough to make a round-trip to nearby stars in a single lifetime), even just using chemical propulsion (you’d just need a ludicrous amount of fuel). This is a problem in the same category as previous generations speculating about supersonic travel: We know it’s theoretically possible; the question is just whether there’s any way to make it practical. If one’s measure of “practical” is generation starships, then sure, it’s doable, but the OP seems to want a bit more. As a rough answer, I’d say that in order to reach other stars in a single lifetime with a plausible amount of fuel, we’d probably need some way of converting most or all of the mass of our fuel to energy (fusion, at a fraction of a percent, isn’t efficient enough). This is not a completely insurmountable obstacle, the way that negative matter seems to be: I know of at least three methods within the known laws of physics to convert a significant fraction (half or more) of a mass into energy. I hasten to add that all three are far beyond the reach of our current technology, and we’ll probably reach the stars by slower means before we develop any of them. But it’s possible.

[alphaboi867]

@Q.E.D.

Oh, I don’t know about that. I wouldn’t rule out some form of suspended animation, like cryogenic storage. Granted, such a system would require an extremely high degree of reliability and would therefore be horrendously expensive, but it’s at least a possibility in theory. If such a system were workable, our astronaut(s) could return, although Earth would be practically unrecognizeable to them.

Embryo space colonization is a possiblity. Of course we’d need AI and robots capable of raising human children on their own.

[flex727]

@Chronos

I hasten to add that all three are far beyond the reach of our current technology, and we’ll probably reach the stars by slower means before we develop any of them. But it’s possible.

This reminds me of the stories where some folks set out to some nearby star on a very lengthy trip and when they arrive, 50 years later, they find other people already there. It seems that while they were in route, new technology was developed to dramatically reduce the travel time. Frankly, I can’t imagine this not happening.

[flex727]

@flex727

This reminds me of the stories where some folks set out to some nearby star on a very lengthy trip and when they arrive, 50 years later, they find other people already there. It seems that while they were in route, new technology was developed to dramatically reduce the travel time. Frankly, I can’t imagine this not happening.

“Far Centaurus,” a short story by A.E. van Vogt

and

Time for the Stars by Robert A. Heinlein

[Exapno_Mapcase]

@flex727

This reminds me of the stories where some folks set out to some nearby star on a very lengthy trip and when they arrive, 50 years later, they find other people already there. It seems that while they were in route, new technology was developed to dramatically reduce the travel time. Frankly, I can’t imagine this not happening.

I can.

Of course there can be a completely unexpected conceptual breakthrough at any time. Or there could be a completely unexpected mechanical breakthrough that would allow us to manipulate exotic materials.

But the point is that expecting these things to happen is merest wishful thinking. What our current physics tells us is that these things won’t happen. Quick travel to the stars is a plot device to get aliens or colonial empires into sf. It has been written out of science, so to speak.

Travel to the stars is still possible with several potential technologies. But it will require times longer than people’s lifetimes to accomplish. The universe is just that big and so are the energies required.

[Joshuawagner117]

Yes, as a matter of fact it is feasibly possible within the realms of current technology and physics to create a craft capable of interstellar travel, and, quite frankly, I don’t understand why we don’t just pool our resources into constructing such a craft at this point… what are we afraid of?? I know I’m probably gonna get a lot of flak from people but let’s be honest here, if we know we can do it, what’s honestly holding us back? To answer the question, yes, it’s possible. Look up “antimatter feuled alcubeirre drives” “graveteioelectromagnatistic energy feilds” “deuterium; aka: heavy water” and last but not least, a little thing I like to call" nuclear fussion" technology. And tell me we cannot construct t a craft capable of traveling to the stars…

[Mijin]

Well it took 9 years, but glad to hear that’s finally settled

[MrDibble]

@Joshuawagner117

Yes, as a matter of fact it is feasibly possible within the realms of current technology and physics to create […] “antimatter feuled alcubeirre drives”

Really? It’s “within the realms of current technology” to create matter with a negative density, now?

[Francis_Vaughan]

One assumes someone has seen the vague idea of the Alcubierre drive and mixed that up with the somewhat common misconception that antimatter has negative energy, and thus maybe negative mass, and somehow stumbled on from there to the idea that there is a viable warp drive just waiting to be built.

[AncientHumanoid]

What’s the fuss over fussion?

[Ethilrist]

@Joshuawagner117

I know I’m probably gonna get a lot of flak from people but let’s be honest here, if we know we can do it, what’s honestly holding us back?

So, you haven’t seen Jurassic Park. How awesome that you have that experience to look forward to. It’s an awesome movie, you should rent it.

Oh, and, yeah, it’s not that we haven’t bothered to build this drive. It’s that we haven’t been able to.

[bump]

@AncientHumanoid

What’s the fuss over fussion?

I’m guessing it’s powered by toddlers, and that’s why people are against it.

[Hermitian]

@Joshuawagner117

I know I’m probably gonna get a lot of flak from people but let’s be honest here, if we know we can do it, what’s honestly holding us back?

Before you prematurely build your antimatter drive and blast off toward the direction of space, maybe you should determine a good landing spot. I don’t think the list of planets that are earth-like enough to live on them is very long.

@Joshuawagner117

“graveteioelectromagnatistic energy feilds”

I definitely need to get one of those for Christmas.

[MrDibble]

I love that graveteioelectromagnatistic energy is a Googlewack!