Modding, Mission Design, and Coding > Help Wanted/Offering Help

Astronomy

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Banedon:
I've been slowly playing my way through the various user-made campaigns, and my impressions so far has been strongly positive - the amount of work that has gone into them is evident, and the campaigns are fun. Thanks for making them.

One major thing that irked me while playing is that the physics & astronomy that went into the campaigns are pretty bad. Yes, Freespace itself suspends physics; a real-life subspace drive would mean faster-than-light travel and bring to fore all manner of paradoxes. But we don't have to suspend everything, and some semi-arbitrary choices can be made believable. I have some expertise at physics & astronomy, so if anyone wants to check if their campaigns are plausible, feel free to ask. I can't guarantee everything I say will be completely accurate, but it should still be an improvement.

Examples of things I've noticed:

1) Capella supernova: this is not plausible (unfortunately it's also canon). That's because stars are way way way more massive than anything we can realistically affect. For example the Sun is 2x10^30 kg, while the Earth is only 6x10^24. We would need a million Earths to make something as big as the Sun, and there simply isn't enough material. A giant fleet of Sathanases probably still won't even reach the mass of the Earth. The Sun also outputs 10^26 J of energy every second. That's 10 billion times greater than the largest nuke ever detonated. There's no plausible way for us to cause the Sun or Capella to go supernova, unless we did something like collide another star with it (which is plausible, given enough time, using gravitational attraction).

Another thing is that Capella is ~2 solar masses, which is well below the threshold necessary to go supernova (~8 solar masses). However Capella is big enough to go nova, which is distinct from a supernova because it leads to the formation of a white dwarf as opposed to a black hole / neutron star. Left to its own devices, the order of magnitude of time taken for a star of Capella's size to go nova is several billion years.

2) Returning to Sol: the distance from Alpha Centauri, the nearest star to Earth, is 4.3 light years. This means that if Alpha Centauri is colonized, we should be able to send light-speed signals to Earth that arrive in 4.3 years. The return trip takes another 4.3 years, which means that communication is still possible without subspace drives - it just take 8.6 years to hear back from the other party. To actually visit Earth is harder, because real spaceships travel at much slower than light speed. The fastest ships in Freespace seem to move at ~100 m/s, at which point it'd take 12 million years for a ship to get from Alpha Centauri to Earth.

There's no easy way to solve this plot hole unfortunately, because we (2017 humans) have been communicating with light-speed signals for decades, and I imagine one of the first things people would do after the subspace node was destroyed will be to send light-speed signals back and forth. Not ideal but better than nothing.

3) Blue Planet (Wounded Prey): if I remember right, this was the mission in which you chase the Duke while your wingmen warp in to who-knows-where. One of them says he showed up 10 light years away. As with the analysis above, that's not believable. 10 light years is more than the distance from Earth to Alpha Centauri. It also means that the wingman would not be able to communicate, since any signals he sends takes 10 years to arrive. A more plausible distance is 1 astronomical unit, i.e. the distance between the Earth and the Sun, but even at this distance light takes 8 minutes to travel. Even more plausible is the distance between the Earth and the Moon - about 360,000 km. Light only takes one second to travel this distance, but for all intents and purposes, the wingman still won't be able to get to the Duke.

4) Ancient-Shivan War: I don't remember the exact mission but at one point a pilot comments that they're looking at ___ galaxy, and somewhere out there is their home. This is problematic because galaxies are big, and they are very far away. The Milky Way (our galaxy) is ~140,000 light years across, and contains some ~200 billion stars. If the Ancients are able to colonize the entire Milky Way, losing a single battle to the Shivans would be practically inconsequential, and they'd have plenty of time to build more ships, develop new technologies, etc. Another problem with this comment is that it implies the Ancient-Shivan War was an intergalactic war (as opposed to interstellar). The order of magnitude distance between galaxies is about 1 megaparsec, which is about 3 million light years. Travelling this distance would be formidably hard.

5) Finally, about technology: life on Earth has existed for over 3 billion years, and it's only in the past several hundred years that we've actually had firearms. If there is sentient life out there, they are not likely to be at a technologically comparable level. In other words, if we do go to war with an alien species, it's overwhelmingly likely that it would be like us vs. ants: one side wipes the other out without even trying. Unfortunately that doesn't allow for a good story but what to do :doubt:

If anyone has anything they want to check, feel free to ask!

Asteroth:
1 seems to make the assumption that Terrans are the ones causing the supernova (the repeated use of 'we' which could only imply humanity), and you seem to have forgotten that it wasn't us it was the Shivans that did it. We really haven't the slightest clue as to how they did it, which was part of the point, so it's silly to to attempt to dissect the possibility of the act when we don't know what the methods are. Nobody would argue that isn't well beyond any Terran method. And also Capella is below the threshold to supernova naturally, and I don't think anyone would describe Capella's supernova as "natural".

And 3 seems to completely forget that everyone has instantaneous FTL communication in Freespace. It's clearly used in nearly every mission so I'm not sure how you missed that one.

AdmiralRalwood:
Regarding point 2, Blue Planet actually references lightspeed communications between Sol and Alpha Centauri.

Aesaar:

--- Quote from: Banedon on December 13, 2017, 05:10:15 pm ---1) Capella supernova: this is not plausible (unfortunately it's also canon). That's because stars are way way way more massive than anything we can realistically affect. For example the Sun is 2x10^30 kg, while the Earth is only 6x10^24. We would need a million Earths to make something as big as the Sun, and there simply isn't enough material. A giant fleet of Sathanases probably still won't even reach the mass of the Earth. The Sun also outputs 10^26 J of energy every second. That's 10 billion times greater than the largest nuke ever detonated. There's no plausible way for us to cause the Sun or Capella to go supernova, unless we did something like collide another star with it (which is plausible, given enough time, using gravitational attraction).

Another thing is that Capella is ~2 solar masses, which is well below the threshold necessary to go supernova (~8 solar masses). However Capella is big enough to go nova, which is distinct from a supernova because it leads to the formation of a white dwarf as opposed to a black hole / neutron star. Left to its own devices, the order of magnitude of time taken for a star of Capella's size to go nova is several billion years.
--- End quote ---
Like Ralwood said, the Shivans did it, and the Shivans technologically outclass humanity by a considerable degree.



--- Quote ---5) Finally, about technology: life on Earth has existed for over 3 billion years, and it's only in the past several hundred years that we've actually had firearms. If there is sentient life out there, they are not likely to be at a technologically comparable level. In other words, if we do go to war with an alien species, it's overwhelmingly likely that it would be like us vs. ants: one side wipes the other out without even trying. Unfortunately that doesn't allow for a good story but what to do :doubt:

--- End quote ---
IDK, Freespace 2 and Blue Planet managed it.

Banedon:
There is no conceivable way the Shivans can cause a supernova either. It is just not believable. Just count how many Sathanas juggernauts will be needed to come to 1% of the mass of the Sun, or how much energy they must emit to come to 1% of the energy the Sun produces every second. To actually cause the Sun to go nova requires way way way more resources than the Shivans could conceivably field. To put in some numbers, assuming each Sathanas were a billion kilograms, it would still take ten billion billion billion Sathanas juggernauts to come to 1% of the Sun's mass. A fleet that size would have literally no trouble annihilating the GTVA (how many systems does the GTVA control anyway - less than 50?). At one Sathanas per second, it would also take billions upon billions of years to get all those Sathanases into the Capella system.

Also for comparison the Lucifer bombarding Vasuda Prime wiped out the surface, but did not blow the planet to pieces (something that would still have taken less energy than causing the Sun to go nova).

As for FTL communication - I'm under the impression that in the FS world, aside from intersystem jumps, communication occurs at light speed. Communication within a system at light speed is plausible. It takes several hours for light to reach Neptune, the outermost Solar System planet, which is short enough to make coordinating a fleet plausible.


--- Quote from: Aesaar ---IDK, Freespace 2 and Blue Planet managed it.
--- End quote ---
They also assumed three (four in Blue Planet's case) spacefaring races that were actually pretty close in technological capabilities. GTVA vs Shivans was nowhere near as imbalanced as humans vs. ants. Unfortunately in the humans vs. ants scenario there's just no story to tell, because everything would either be utterly futile or stupidly easy.

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