# Realistic timeframes for interstellar travel and the development of antimatter propulsion

So in my setting, humanity has developed reliable sub-light travel using antimatter propulsion by the year 2247, and has slowly begun exploring and colonizing immediate interstellar space within a radius of about sixty light years. They have advanced biotech such as full prosthetic cyborg bodies and medical nanotechnology, and they have even created slightly superhuman artificial intelligences that, while not the dreaded apocalyptic superbrains predicted in our time, are smart enough to be of strategic value despite the hardware required to house them taking up the same space as a small warehouse.

Are all these technological advancements feasible within the next 200 years? Does it strain believability at all to suggest that in 200 years we'll have a functioning, thriving interstellar economy based on deep-space mining and colonization?

• Opinion based, but my answer would be yes, just advance AI and genetic hybrids a little bit. Jul 30 '16 at 14:37
• Two Hundred years ago, a smokeless candle was a great source of light, for reading, and London to Boston took 4 to six weeks. Information was no faster that the fastest horse. In another 200? Unknowable...
– Joe
Jul 31 '16 at 0:09
• Technology - yes. Interstellar economy - no, highly unlikely. Researches and presence and building in nearby stellar systems - yes, no problem. Antimatter and AI not needed - but not impossible, specially if u need them as plot devices. Aug 2 '16 at 10:47

Generally speaking you need to be able to get somewhere within a year to maintain some sort of direct trade with that place, so, as long as you can establish that you should be fine with a interstellar economy, but it'd be more like the silk road than the global trade that we're used to.

full bio-synthetic prosthetic bodies are fully possible by the end of the century. I'm in fact betting on it ^.^ The main issue is neural interaction which we are getting ever closer to figuring out with various prosthetics today.

AI is more a matter of algorithm than processing power. By the 2050s we will likely achieve the maximum processing power possible, but the whether or not we'll understand the brain and how it works enough to develop that level of AI is harder to say, but really, 200 years is more than enough time to brute force develop an AI, or building on what we've already developed with current AI, just letting them run would develop sufficiently advanced AI to what you're talking about. You're over estimating the size of facilities to house them though ^.^

The main bottlenecks with this possible development is solving the problems to build viable sublight interstellar spacecraft and the capacity to produce enough antimatter to power them. Unfortunately the two problems are interlinked.

In 2006, Gerald Smith estimated $250 million could produce 10 milligrams of positrons. in 1999, NASA gave a figure of$62.5 trillion per gram of antihydrogen

There are possible ways of bringing down the cost of antimatter, but unless a radical new technology can be devised to do this cheaply antimatter will put a brake on the energy and cost budgets for interstellar space travel.

it might be possible to use magnetic scoops to collect the antimatter that occurs naturally in the Van Allen belt of the Earth, and ultimately, the belts of gas giants, like Jupiter, hopefully at a lower cost per gram.

It is plausible to assume the biotech and AI's proposed by the mid-23rd century. Even making both more highly advanced than proposed.

To reach stars up to sixty light years, and within reasonable timeframes for a thriving interstellar economy, suggests 23rd century starships travel close to lightspeed. This will take vast amounts of antimatter to propel them. However, if the starships travel at lower velocities, less antimatter is needed to fuel them. The trouble with this is that round trip times soon push out to longer timescales.

For example, if the starships travel 0.5 c, as a matter of antimatter economy, then a trip to a star sixty light years gives a round trip time of 240 years. A starship launched in 2247 will return to its home base in 2487 plus however long it remained at its destination. This might apply to the limits of interstellar exploration rather than to an interstellar economy. Even journeys to nearby stars at 0.5 c, will have round trip times of decades. Not impossible or too prohibitive, but if it's factored into your future scenario then you can know what to expect.

With the most optimistic projections for increased, and cheaper too, antimatter production and the rapid development of interstellar space technology and vehicles by 2247 it is plausible we will see the beginnings of an era of interstellar exploration and an attendant interstellar economy.

However, it is plausible that the proposed biotech and AI's will exist by 2247, and might even more advanced than the OP suggests. This can be tweaked to meet the requirements of the future scenario.

Despite any arguments to the contrary, it's still your world and you're welcome to design whichever you want. These are only my projections. Besides knowing what other people's objections are can be basis for finding ways of overcoming them and building something that will do want you and be more plausible.

It is worth considering there might be a wild card factor that has greatly accelerated the drive to go into interstellar space. For example, the discovery of aliens with their own thriving interstellar economy that has expanded out to sixty to eighty light years, but this is located at a safe distance of several thousand light years. Humans will want to carve out their own sphere of influence in the galaxy before other sapients take it away from us.