2300AD Realistic Near Star Map

[Rick]

I wish you'd just put the links up, Tom - it would make for easier scrolling and reading.

Even if you had a ramjet that worked on hydrogen rather than deuterium, you'd still need to accelerate it to around 1% of light speed before it could start working, which means having a secondary engine/fuel system, and that first 1% might be almost impossible to achieve without adding far too much mass, shielding, fuel, etc. Add to that the fuel needed to decelerate at the other end (you could just let inertia slow you down - but you would be in 0g and it might take centuries to slow right down) and manoeuvre.

 

[Anonymous]

and this has what to do with the near star map?

:?

 

[Tom Kalbfus]

I wish you'd just put the links up, Tom - it would make for easier scrolling and reading.

Even if you had a ramjet that worked on hydrogen rather than deuterium, you'd still need to accelerate it to around 1% of light speed before it could start working, which means having a secondary engine/fuel system, and that first 1% might be almost impossible to achieve without adding far too much mass, shielding, fuel, etc. Add to that the fuel needed to decelerate at the other end (you could just let inertia slow you down - but you would be in 0g and it might take centuries to slow right down) and manoeuvre.

Actually the secondary engine could be an antimatter engine, it uses stored anti-hydrogen and hydrogen to accelerate to 1% of the speed of light, using up its entire supply, while it goes from 1% of the speed of light to 99.999998% of the speed of light, it just uses hydrogen fusion, it then goes from 99.999998% of the speed of light to 1% of the speed of light and while its doing that it manufactures twice as much antihydrogen as it started out with, and it uses half of that antihydrogen to slow down from 1% of the speed of light to 0% of the speed of light and it retains the remaining antihydrogen to get back up to 1% of the speed of light. Now it takes more energy to make antihydrogen than the amount of energy that is released by that antihydrogen when combined with hydrogen, but the ship generates many times the energy required with its fusion reactions while its in transit. the amount of antihydrogen you need is about 0.5% of the hydrogen you'd need to release that same amount of energy in fusion reactions, so the mass of the antihydrogen is tiny by comparison. When an interstellar ramjet is constructed, the antimatter fuel it starts out with is figured as part of the construction cost, since antihydrogen costs a lot to make, you might double the price to about one billion credits for a 1000 ton ramjet, my guess is that a Bussard ramjet would have 20 to 40 staterooms, and it would need food storage for years of travel, it typically takes about 3.184 years of ship time and 4.823 years of proper time to travel 1 parsec assuming acceleration to mid point at 1 g a turn around and a 1 g slow down to the destination. Ship time is the time the crew and passengers experience while proper time is how much you advance the calendar to determine at what date the ship arrives. Using this calculator:
http://www.convertalot.com/relativistic_star_ship_calculator.html
The times for the following distances are as shown:
distance -- Ship Time ---- Proper time
2 pc ------- 4.172 years -- 8.233 years
3 pc ------- 4.817 years -- 11.557 years
4 pc ------- 5.298 years -- 14.852 years
5 pc ------- 5.682 years -- 18.135 years
6 pc ------- 6.002 years -- 21.410 years

 

[Tom Kalbfus]

and this has what to do with the near star map?

:?

If you don't have an FTL drive, then an interstellar ramjet is the way to go. It would take 7.716 years of ship time and 51.902 years of proper time to travel to the 50 light year radius with slow down at destination.
Also one potential FTL method is wormhole travel. Most realistic wormholes are created with both ends close together, and you can accelerate 1 end at 1 g over a distance of 50 light years for example, and it would take 7.716 ship years to get their and 51.902 years of proper time. the thing is the home end of the wormhole experiences only the ship years, that is those waiting on Earth, need only wait the 7.716 years for the ship carrying the wormhole to get their and then someone can step through the wormhole and arrive at the destination, or else the wormhole is expanded upon arrival so a spaceship can travel through it. the far end of the wormhole is 44.186 years in the future, of course no time paradoxes occur because the ship was accelerating away from Earth. Light traveling from Earth to that destination would take 50 years to get there, but since the far end of the wormhole is already 44.186 years in the future, one can send a broadcast to the far end, step through the wormhole and wait only 7.716 years for the signal to arrive. Of course if you send a broadcast back to Earth, the signal would take 50 years, but since the Earth end of the wormhole is 44.186 years in the past relative to the far end, one can step back through the wormhole and then have to wait 94.186 years for the signal to arrive. Wormholes are convenient so long as all of them are created on or near Earth and the outward bound ends of each wormhole are always accelerated outwards.

Accelerating them back towards Earth beyond a certain point creates a problem, because then, it becomes possible to send a signal through the wormhole and then broadcast it outside to arrive back at the outer end of the wormhole before it was sent, this in effect becomes a time machine. If you want time travel in your campaign, you need to set up rules for time travel. One way would be to just split the universe, each end of the wormhole is a separate timeline no longer connected to each other. Another way is just simply to make backwards time travel impossible using exploding wormholes, and finally you could just make changing the past impossible, but travel to it possible, that is you cannot change any events that are observed to have happened, but if events in the past are not know, the time traveller can still affect the outcome with his actions. I use the second possibility of split universes with my Triplanetary Wormhole. Both ends were once part of the same Universe until time travel through that wormhole became possible. You don't want too many wormholes of that sort, otherwise you have to create a separate universe for each wormhole, thus Triplanetary has only one.

 

[Reynard]

Pray for low berths.