23
votes
Accepted
How stable would a rogue star system be?
It could certainly be stable; it's possible for a star to be ejected from a galaxy and still have other objects be gravitationally bound to it. Observations of the hypervelocity star HE 0437-5439 ...
- 99.6k
21
votes
How can we meet aliens in an underpopulated galaxy?
How about this:
The milky way is absolutely teeming with life, most of it confined to super earths, so the few dozens or so instances intelligent life emerged they didn't manage to leave their ...
- 3,487
20
votes
Space-ships and stations...made from cast-iron?
It's Not.
There's your answer. Not with cast iron.
Here's a good visual (and auditory) reason why
The above is a YouTube video from one of my favorite channels - Cutting Edge Engineering - an ...
- 16.7k
18
votes
How can we meet aliens in an underpopulated galaxy?
Frame Challenge: They can be way more advanced than us but not in ways that matter.
They will be vastly technologically superior to us if they can travel between the stars.
This axiom is not ...
- 87.1k
14
votes
Space-ships and stations...made from cast-iron?
As has been pointed out, thermo-mechanical fatigue of cast iron will be a large problem. Merely rotating such a vessel in sunlight will cause differential cooling and heating that will cause stresses ...
- 52.7k
12
votes
Accepted
Space-ships and stations...made from cast-iron?
Cast iron can be made of the same atoms as steel. Something like blackheart malleable cast iron can have good properties. But it will not be as good as rolled steel. Something that is cast into a ...
- 5,866
9
votes
Spacecraft Design of a Cold-Blooded Humanoid Race
On Earth, the range of environmental conditions is quite narrow; most places where you’d find cold-blooded animals, the range of temperatures is perhaps 20 Kelvins. In that context, human ...
- 4,624
8
votes
Accepted
Amount of antimatter needed to propel large spacecraft?
I don't think you can mark a answer to be correct if it uses classical mechanics, but whatever. $\frac{1}{2}mv^2$ definitely does not work at these speeds anymore, plus there is a factor missing.
...
- 1,087
6
votes
How can we meet aliens in an underpopulated galaxy?
Desperation
You could have an alien race about the same technology as the Solarisians ("Earthlings" from the Solar system, working title).
The aliens were desperate to get out of their star ...
- 34.1k
5
votes
Accepted
Communication between a stationary observer and a spaceship traveling at near lightspeed
Bob and Alice start in the same place with synchronized clocks. Alice is flying away from Bob towards Planet X at $v=.9998c$. Assign Alice time $\tau$, assign Bob time $t$. Bob sends a message to ...
- 2,781
5
votes
Communication between a stationary observer and a spaceship traveling at near lightspeed
They can send signal and they will not receive them at the same time. Light speed is always c no matter the relative motion.
What they will observe is relativistic Doppler effect:
The relativistic ...
- 273k
4
votes
Accepted
Spacecraft Design of a Cold-Blooded Humanoid Race
Anabiosis would be easier to implement
Most cold-blooded creatures, likely including your species, are able to hibernate during cold seasons, with their body temperature going below zero Celsius. ...
- 5,262
4
votes
Accepted
Would a star's spectroscopy be stable enough on approach to use it as a navigational reference from a great distance?
Let's start with what we know about stellar evolution. Stars coalesce from a mass of gas, mostly Hydrogen, with some Helium and other trace elements, and begin to fuse Hydrogen to Helium. As they ...
- 52.7k
4
votes
How can we meet aliens in an underpopulated galaxy?
While this is a bit of a “hypothetical” question, I will still endeavor to answer it.
One method of ensuring you avoid super technologically advanced aliens is to limit the technology development ...
- 1,221
4
votes
Space-ships and stations...made from cast-iron?
Metallic (M-Type) asteroids are predominately made up of Nickel / Iron. Which happens to be a quite passable alloy for spaceship hulls.
Tough and versatile, nickel What are the properties of nickel ...
- 5,470
4
votes
How can we meet aliens in an underpopulated galaxy?
Neighbors from within our solar system
this may depend a little on how alien they can be, since we haven't managed to find them yet. it also means their technology can't be that similar to ours unless ...
- 261
3
votes
Accepted
The late-victorian nuclear-thruster
Wondering if perhaps for your specific situation a more primitive approach but still using nuclear tech to achieve the result.
Decaying nuclear material is used with a Thermocouple to produce ...
- 5,470
3
votes
The late-victorian nuclear-thruster
It rather stretches belief that a late Victorian engineer would have a launch vehicle that could stick a nuclear rocket into space (without Cavorite, of course). Jules Verne's 'From Earth to the Moon' ...
- 5,866
3
votes
Space-ships and stations...made from cast-iron?
Large vessels with thick walls made of cast iron will be very heavy. You could make them very small and/or paper thin walls, but that would go against your steampunk aesthetic.
When you look at what ...
- 479
3
votes
Amount of antimatter needed to propel large spacecraft?
Two problems:
250 tons of cargo, not 250 tons of ship. I'd be more inclined to believe 1000 tons of ship including cargo.
Somehow, your calculations were wrong... I got 61,250 kg of matter from ...
- 52.7k
2
votes
How stable would a rogue star system be?
Should be fine
Your safest bet for causing a rogue star would be a galactic collision event in which all the stars that pass through the equilibrium point of the 2 galaxies will shoot off in a more or ...
- 87.1k
2
votes
Accepted
How can we meet aliens in an underpopulated galaxy?
Unwilling visitors
Aliens do not have the technology for interstellar travel, but nature is an unforgiving female dog.
The poor bastards were evicted from their stellar system when another star came ...
- 134k
2
votes
The late-victorian nuclear-thruster
You're looking at throwing something behind you at extreme velocity. The Falcon rocket throws exhaust out at around 4 km/s in order to provide thrust. Here are a few options, plus or minus a little ...
- 13.9k
1
vote
How can we meet aliens in an underpopulated galaxy?
Singularity is the great filter
Alien life is extremely common, as are alien ruins, but most life that reaches a certain point, a few hundred years in advance of humanity, tends to leave. There are ...
- 37.4k
1
vote
How can we meet aliens in an underpopulated galaxy?
We are the one of the closest planets with an Oxygen/Water Vapor Atmosphere
We are not that far away from being able to detect elements in a planets atmosphere and if you reverse directions, we might ...
- 79
1
vote
How can we meet aliens in an underpopulated galaxy?
What's wrong with wormholes?
You state that wormholes and other methods of FTL travel cause paradoxes. But, AFAIK, for wormholes that is only the case if the two mouths of a wormhole are in each other'...
- 1,384
1
vote
How can we meet aliens in an underpopulated galaxy?
Generational Ark Ships
Humans already have the level of technology to travel between stars, it's just they haven't had the motivation to do so as yet but if Earth was to become uninhabitable, they ...
- 45.3k
1
vote
How can we meet aliens in an underpopulated galaxy?
Sounds like you want something equivalent to the Alderson Drive.
This is a form of jump-drive described by Larry Niven and Jerry Pournelle in Mote in God's Eye. The odd part about it is that it uses a ...
- 13.9k
1
vote
How can we meet aliens in an underpopulated galaxy?
Have them travel to us from so far away that they evolve to be on a comparable technological level en route. I guess for this to be feasible though they'd have to have some quirky "natural space-...
- 11
1
vote
Would a star's spectroscopy be stable enough on approach to use it as a navigational reference from a great distance?
Stars have predictable life cycles, shifting their core up the periodic table. That doesn't mean that they won't receive input from outside, or that their aging can't be disrupted by gravitational ...
- 13.9k
Only top scored, non community-wiki answers of a minimum length are eligible