3
$\begingroup$

The structure of this website makes it every difficult to speak to people on the other side of a set of moderation buttons, leading to confusion and infuriation. This is one such situation where peer-reviewed science in a frame challenge was unilaterally declared "a low quality post."

Apparently, this is considered a low quality post. The poster was asking about "nebulas slowing down space ships." I pointed out that you can use your relative velocity with the interstellar medium (which nebulas are very much made of!) and even linked to a peer-reviewed paper exploring the concept. For my effort someone said it's low quality and deleted it without comment or explanation.

Is actual science low quality? Is peer reviewed science low quality? Are frame challenges low quality?

I can't help but assume the moderator, in their haste, either didn't bother to read the post, or look at the paper, or perhaps simply did not understand, and therefore dismissed it as "junk science," despite the direct relevance to the question I was trying to answer.

I can't help but think some transparency would help.

$\endgroup$
10
  • $\begingroup$ I think that there is no real answer to this question. Three separate answers have been deleted, not just yours. As I see it, nobody can specify a mechanism by which speed would be limited, besides the thrust required to get to the speed. Nebula just aren't dense enough to matter. $\endgroup$
    – Robert Rapplean
    Jul 14 at 23:15
  • 1
    $\begingroup$ Firstly, that would be the question's problem, not the answer's, and the question is still there. For two, the interstellar medium absolutely does matter as has been fleshed out by the paper I linked and I explained in layman's terms. For three, it absolutely would matter at relativistic speeds, though I am not qualified to look at pressures from relativistic plasma. $\endgroup$
    – cthon
    Jul 14 at 23:30
  • 2
    $\begingroup$ @cthon To explain a bit : Answers should answer the question, even if only partially. If a question has no answer, no answer would effectively answer the question. So questions and answers are more interconnected than at first glance :). $\endgroup$
    – Tortliena
    Jul 14 at 23:42
  • 1
    $\begingroup$ If the question has no real answer, why would you delete multiple answers, and keep the question? That's contradictory. Nevertheless, drag does matter, at the relativistic limit for any space ship at all, and at far lower speeds if you're using plasma magnet brakes or plasma magnet windmills. I feel like a lot of people are out of their depth and it would be best if discussion was open for correction instead of what I've seen, which is blatant dismissal. $\endgroup$
    – cthon
    Jul 14 at 23:47
  • $\begingroup$ Answering an unanswerable question is the answer's problem. I think you're missing something. Try this: If you compressed all of the mass in a chunk of nebula, 1 meter x 1 meter x 1 light-year into a 1m x 1m sheet, it would be .03mm thick. Does that help? $\endgroup$
    – Robert Rapplean
    Jul 15 at 0:07
  • $\begingroup$ @cthon Two things : First, that's assuming there's no answer to the question. In that I'm much more reserved than Robert : nobody truly knows since there's no contradiction which rejects every answer without resorting to our partial knowledge. Then, if indeed there was no answer, sometimes the query is closed as story-based ("build something that meets your story needs"), or opinion-based (my favored choice : "There's no valid answer, therefore every answer is equal in their 'failure'"). Still, you do have to answer the question; if you can't, you can instead comment about why you couldn't. $\endgroup$
    – Tortliena
    Jul 15 at 0:14
  • $\begingroup$ Speaking of which, I cannot answer this query since I don't have access to the deleted answer(s). I'll wait a kind +10k rep soul to pass and provide a screenshot of them :). $\endgroup$
    – Tortliena
    Jul 15 at 0:16
  • $\begingroup$ The solar wind exerts a pressure on something 'static' (unmoving with respect to the sun) of roughly 1-6 nano pascals. The formula for ram pressure from the solar wind is P=mass_proton*particle_density(particles/cm^3)*velocity squared. The densest nebulae are up to 10,000 times as dense as the solar wind, and we're considering a space ship that is likely going faster than 400 km/s. In such a dense nebula, with a ship going at 1% the speed of light, the pressure is 150327.76 nanopascals. The pressure scales with the square of pressure. $\endgroup$
    – cthon
    Jul 15 at 1:02
  • $\begingroup$ In that case one need only solve what speed (squared) gives a pressure times the frontal area of the ship (for a given nebula!) equals it's thrust. Instead of going down that path I wanted to say you can accelerate in it, but because people don't really understand this, and made assumptions, here we are. $\endgroup$
    – cthon
    Jul 15 at 1:03
  • $\begingroup$ In relativistic cases, where gamma = 1/(sqrt(1-(v^2/c^2))), you multiply the mass of the particle by that gamma. As that trends toward infinity as v approaches c, you need to account for this if you're going near the speed of light, which is likely to be of use for a ship going through space, and could easily set a 'speed limit'. $\endgroup$
    – cthon
    Jul 15 at 1:14

1 Answer 1

Reset to default
3
$\begingroup$

@L.Dutch hasn't explained anything to me and I don't claim to read @L.Dutch's mind.

But I do know the deleted answer wasn't a valid frame challenge.

From A proposal for helping users understand frame challenges we read,

Formally: I propose that frame challenges are an acceptable way to answer any question posted to this site. As a definition: a frame challenge is any assertion that challenges the premise or underpinnings of a question.

I propose that an acceptable frame challenge must fundamentally express the idea:

What you're asking for won't work because of X, but you could alternatively consider Y

I'm not looking to impose a specific form (syntax, format, etc.) as much as I'm proposing a philosophy. (A) A frame challenge must of necessity contain an explanation of why the respondent believes answering the question as proposed by the OP isn't useful, relevant, or meaningful. However, (B) A frame challenge need not offer an alternative solution.

In your deleted answer you never challenge the frame. You identify no issue that you consider wrong with the premise of the question.

In fact, at best, what you propose (cool as it is... and it is cool...) is really nothing more than an aspect of the requested graph. At worst it falls into the same category as the comment made by @Vesper and my response to it:

The real question here is, what are the means of the ship to dump excess energy while travelling through the nebula. At the very least you're looking at a constant heat flow from the front of the ship, together with it getting damaged by individual particles, and the former would melt the ship way faster than the latter. – Vesper

@Vesper That's a method of extending the maximum velocity of the ship, but it's not a requirement for the graph. I've no doubt there are a great many things that could be done to extend max-v. I doubt the quesiton could reasonably account for them all. This is meant to be a starting point to help worldbuilders understand the consequences of increased particle density - not to help design a ship to get through any arbitrary particle density. – JBH

The "frame challenge" doesn't challenge any premise and, though not obligatory, offers no alternative to achieve the goal of the quesiton — which is a graph helping worldbuilders understand the consequences of nebula particle density on space ships. All it does is point out a cool way to increase maximum velocity.

Were Stack Exchange a discussion forum, or arbitrary brainstorming questions permitted, then the deleted answer would have been an amazing answer — to another, similar question.

Consequently, I must support @L.Dutch's decision to delete the answer.

$\endgroup$
13
  • $\begingroup$ If I made another answer that spat out the answer, "solve for pressure given a frontal area, speed, and density of a nebula" (P=density*velocity^2), and how low that is for nonrelativistic speeds for a ship without a big magnetic field, could I then add the other point? $\endgroup$
    – cthon
    Jul 15 at 2:23
  • 1
    $\begingroup$ I also have to comment that the way SE works is extremely stilted and janky. Instead of "hey uh, put in X" I had to leap through hoops to get anything out of this, and had I not, readers would not have been exposed to what I brought up at all. Would it not have been much better to say "hey, make sure you point out why you're suggesting this?" $\endgroup$
    – cthon
    Jul 15 at 2:26
  • 1
    $\begingroup$ Also, with this technology, you always make more thrust than ram pressure slows you, which does obviate the need for some graph. At any rate, the answer comes down to "if you have a known thrust and frontal area, and have a given density of the nebula in question, solve for speed" for conventional rockets. I suppose you could graph velocity from 0 to c and note where thrust equals drag (and then gamma makes it shoot up to infinity...), but that's beside the point that you don't really need such a graph with a q-drive or plasmadyne! $\endgroup$
    – cthon
    Jul 15 at 2:34
  • 1
    $\begingroup$ @cthon Comment #1: it wouldn't solve the problem. What I'd recommend is that you ask a new question, "What methods could a space ship use to improve their max-V in a nebula?" and then answer your own question. While I wouldn't be surprised that people might think it's too opinion-based, I think it falls into the finite list of things exception. Comment #2: All I can do is shrug. SE's owned by a third party who controls 95% of the rules. It's one of those, "don't like it? go somewhere else." things - they've even said that (in a way). $\endgroup$
    – JBH
    Jul 15 at 2:38
  • 1
    $\begingroup$ I feel like I'm having a stroke here. You can absolutely graph how drag force goes up with the square of velocity through the gas (well, plasma) and then slap a gamma on there for relativistic correction - but that's not useful. To make a useful graph where one input leads to one output, you'd need to have a fixed, known density, one fixed known frontal area, and one fixed, known thrust to match. "I can give you a function instead of a magical all-useful graph" is probably a better frame challenge. But as I said, you don't need it if you give your ship a q-drive, lol. $\endgroup$
    – cthon
    Jul 15 at 2:40
  • 1
    $\begingroup$ @cthon Comment #3: that's only true of a civilization posesses the technology and it fails to meet the point of providing the graph. We get regular questions about ships travelling through nebulae. Many authors think the average nebula is thick as ketchup. They're frustrated because their expectations don't match actual science - insofar as we understand it. The graph is a means of helping people get over the expectation problem so they can ask more useful questions. From that point of view, your suggestion doesn't improve the graph. $\endgroup$
    – JBH
    Jul 15 at 2:40
  • 1
    $\begingroup$ There is no one graph to rule them all here, there are too many parameters - but it is effectively ketchup thick if you're going fast enough. Here, SPACE RED OCTOBER. I'm feeling lazy so the frontal area is a rectangle of it's beam and draught, so 276 square meters. I'll give it the thrust of Starship's first stage, 89 Meganewtons. Without relativistic adjustment, the most drag I see at light speed is 415 newtons, which is far less than 89 million. Let me figure out how to add a relativistic gamma to the proton mass. $\endgroup$
    – cthon
    Jul 15 at 2:47
  • 4
    $\begingroup$ @cthon You're falling into a common trap. I'm looking for a simplification to help overcome a common worldbuilding problem. You're trying to crowbar all of known science into the solution (and not wanting to let go of your cool idea). I'm an electrical engineer, we live in the frontier of simplification. It's like asking for s snipet of VHDL or Verilog code and being told it's impossible because all the nasty calculus of transistors isn't being considered. The entire premise is false because a simplification is the request - and yes, it can be done. $\endgroup$
    – JBH
    Jul 15 at 2:52
  • 1
    $\begingroup$ 99.9999999999% light speed results in 30 meganewtons. Put this into Wolfram Alpha to check:[ (1.672621911×10^-24 grams * (1/(sqrt(1-(((0.9999999999 * speedoflight))^2/speedoflight^2))))/second) * (10000/cm^3) * ((0.9999999999 * speed of light))^2 * 276 square meters ] So, no, it will never matter, but at least we know. In this case, do I Frame Challenge with "I've basically proven it will never matter like you think," or do I have to make a new question and leave this just hanging? $\endgroup$
    – cthon
    Jul 15 at 2:58
  • 1
    $\begingroup$ This felt like such a good teachable opportunity, but rigid rules like we're robots has made this so clunky, and if the question just hangs unanswered how will a random person coming by from a search engine learn this? $\endgroup$
    – cthon
    Jul 15 at 2:59
  • $\begingroup$ Actually, let me correct myself. A sufficiently large ship could run into this problem, but we're talking about something that would dwarf a heighliner. $\endgroup$
    – cthon
    Jul 15 at 3:05
  • 4
    $\begingroup$ @cthon Rigid rules be Stack Exchange. You have options, if it's not your cup of tea... but you're having a bit of trouble letting this go. The question doesn't accept an application of technology other than thrust and 10m of titanium hull. $\endgroup$
    – JBH
    Jul 15 at 3:18
  • 1
    $\begingroup$ I overlooked how big your ship is! At rather sane speeds (10% light speed) without relativistic corrections, you get 11.8 kilonewtons of drag. [(1.672621911×10^-24 grams) * (10000/cm^3) * ((0.1 * speed of light))^2 * 0.785398 square kilometers] Replace (0.1 * speed of light) with a variable and graph from 0 to c. But I would recommend relativistic corrections, since it's a simple term. $\endgroup$
    – cthon
    Jul 15 at 3:24

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .