Interstellar travel and Galactic travel This is the last one in the series of ‘space’ stuff for now. It rounds it off very nicely by looking at the possibilities of flying off to another star to find a planet like ours (or rather a solar system like ours) or even flying off to another galaxy. This is into science fiction really. It is beyond known technologies of today and might not be feasible the next hundreds of years.
Galaxies are even further away: Andromeda: 2,5 million LY RX J1241-11: 650 million LY Cassiopeia: 2,5 million LY
... and might not be possible within the next hundreds of years
Is that to say it is impossible? I am not venturing into anything that says ‘impossible’. That is impossible to me. But let us be honest about it. There must be a quantum leap in technology and in methods for making this possible. We are not even close to it today. So let us get into the facts. Distances Let us look at just three examples in terms of stellar systems where we might find a planet like ours, where life either exists or can exist: Tau Ceti: 11,8 LY (light years) away. 5 planets, 2 in the habitable zone. Gliese 581: 20,3 LY, 581d a planet in the habitable zone Gliese 667C, 22 LY, 5 in the habitable zone These are all in our own galaxy, the Milky Way. Although it sounds like just around the corner, it is not.
Unless we can accelerate a space ship up to something close to speed of light, we cannot get beyond our own galaxy.
If we take into account a start-stop time of a spaceship and a rather fast speed of 50% of the speed of light, we will look at a return trip of at least 30-40 years just to the next star. That is into the next generation of space travellers! There is no way of avoiding this fact. The one’s leaving Earth will (most of them at least) all be dead before the ship returns to Earth and those onboard will be the next generation. Even if take into account that we do not age as fast the faster we travel (Einstein, look it up), we cannot become immortal. The average life time is still a factor we cannot escape. All of this leaves us with two choices for interstellar and inter-galactic travel: Technology which can go faster than light/use time-warp things OR plan for a multi-generational trip into the unknown.
The next is inspired by Wikipedia. Should we do ‘flying saucers’ first: Rockets: Typically a rocket will need fuel to fly. And a rocket will run out of fuel at some time, so anyone flying will have to plan on meeting up with a ‘petro-station’ in space. That is a problem in all this. Ion engine. Wonderful concept. Via electricity heating up a gas (xenon is a good gas) and shoot the ion out the read end. That propels the ship. It is working in the lab and it is possible to scale it up. The thing is: there is a need to produce a massive amount of electricity in the space ship. Plasma engines. In essence a nuclear reactor where the waste products are shot out. That propels the space ship. It is possible to achieve 15% of speed of light. But it might take a few hundred years to get it accelerated to that. Nuclear pulse. This is one I like. We put a steel plate at the end of the space ship. Then we drop nuclear bombs out and when they explode, they will propel the ship. It is a bit dramatic, but it will work. We just need to be careful that the steel plate does not rupture as we will be in big trouble then. Anti-matter rocket: we produce anti-matter and store it (how?) and then we chuck matter and anti-matter into the jet engine as fuel and off we go. Great. Except how do we store anti-matter and how do we produce it in quantity? Solar sail: huge sail and when solar particles hit it, it will propel the ship. Insofar as it is in a vacuum in space, the power of a particle will nearly all be used for a forward motion – no friction in space.
This is a direct quote from Wkipedia: I am not sure I fully get it, but here it is: “In physics, the Alcubierre drive is based on an argument, within the framework of general relativity and without the introduction of wormholes, that it is possible to modify a spacetime in a way that allows a spaceship to travel with an arbitrarily large speed by a local expansion of spacetime behind the spaceship and an opposite contraction in front of it. Nevertheless, this concept would require the spaceship to incorporate a region of exotic matter, or hypothetical concept of negative mass”
cannot really go home, can we? We might not have enough fuel to go somewhere else? That will really be a bad hair-day.
The last is the classic one: Wormholes! It is postulated that it is possible to connect two points via a ’funnel’ thing. It is based on Einstein’s theories, but it will involve negative mass, which might not be physically possible.
This is the mechanical side of it. I think the real challenge will be something else.
The two points can be different universes, meters apart, different points in the known universe and whatever we feel like. Insofar as it is based on the folding of spacetime, there should be no limits. The part-conclusion is: Science fiction for now. Also because – after all – there cannot be speed faster than speed of light. None of the above concepts violates this law. Flying off to the stars and coming back is a bit off target for now. That means we can only turn to the other good concept: the Generation Ship. The generation ship is a realisation that we cannot go to the stars and come back in our own life time. We can start it off with some propulsion known today (see above) and then just leave it to the future generations onboard the star ship. There are a few problems with this concept: Where to go: We might identify a star somewhere with a planet like ours. That might be the target. But what if, when we get there, it is not so? Maybe the planet is a gas planet without a surface? Then we
Fuel. Somehow we need to store enough fuel to go where we want to. But if we need to fly for some hundreds or thousands of years, it could be quite a lot. If something breaks. That can really ruin the trip. We might not be able to fix it so we are sort of stranded somewhere.
We might be able to find a set of people, all fired up for a trip into the unknown. But who says their children or grand-children also would like to fly off to somewhere? Maybe they would like to go to school on Earth and so on? How many people should we start with to ensure the gene pool is stable? What if we start with a million people? But hey, what if they really like to have kids and have 10 kids per couple? They could out-grow the space ship in a few generations. Boredom. What if the kids two or three or four generations down are bored as the only thing to do is to just fly and look forward to land on a planet – maybe – some day? The space ship has to be a fully functioning society
and fully self-sustainable. It has to be a space world which can fly. It has to be Earth-like all of it. What if they decide to go home to Earth after some generations? Or have a mutiny? Or a civil war? What type of government will they choose? It is a fascinating scenario insofar as what we really look at is a totally fresh start on humanity. And we really don’t know what will happen. But maybe they will take the human race to a totally different world and be happy. “””””””””””””””””””””””” Contributors "Bussard Interstellar Ramjet Engine" by NASA - http://nix.ksc. nasa.gov/info?id=MSFC-9906399&orgid=11. Licensed under Public Domain via Commons – "Ion Engine Test Firing - GPN-2000-000482" by NASA - Great Images in NASA Description. Licensed under Public Domain via Commons "Hubble Ultra Deep Field part d" by NASA, ESA, S. Beckwith (STScI) and the HUDF Team - http:// hubblesite.org/newscenter/archive/releases/2004/07/ image/d/Centered on UDF 8026. Licensed under Public Domain via Commons – "Lorentzian Wormhole" by Kes47 (?) - File:LorentzianWormhole.jpg. Licensed under CC BY-SA 3.0 via Commons -