Is it wrong to ask, why something can't work?

[GTOM]

https://www.physicsforums.com/threads/vacuum-blimps.945086/#post-5981071

Yes, in this thread, i couldn't find an article to support my idea, but i think it is reasonable to expect details why is it bad.
For example, no we can't build a 100m tall mecha because square cube law. No we can't have Epstein drives anytime soon, because if you calculate with rocket equations, you get insane amont of energy density.

If i put lots of same-charged objects into a balloon, due to repulsive forces, they can expand the balloon at least a bit. I could also fix magnets to the ends of a spring, so they expand the spring because they repel each other. Generally i don't think, that a question: Could we substitute gas pressure with EM repulsive forces (so it can expand a balloon against atmospheric pressure) ? is the same meaningless category like How could i build a stargate in my garage?

Even if something is clearly impractical with all we have, it would be good to learn more about technical constraints limits etc.

I accept i had a bad question, but i could have come up with more specific questions if i had the chance. Meaningless discussions has to closed, but close a thread because of one poor question don't make someone more educated.

 

[Nugatory]

It's not wrong to start a "why doesn't this work" thread. Here's an example of one that went on for three pages: https://www.physicsforums.com/threads/exactly-why-ftlc-is-impossible-with-entangled-photons.944452/

However, we may lock the thread if the question isn't thought through enough to lead to a productive discussion.

 

[Borek]

Beware: "why it doesn't work" often borders "this is a perpetuum mobile idea and I don't get why it doesn't work" which will be shot down, as the rules don't allow discussions on perpetual motion.

 

[mfb]

Is it wrong to ask, why something can't work?

You didn't do that. You claimed it would work, that is completely different:

Theoretically its possible to expand their balloons electromagnetically.

Charging a balloon notably in air doesn't work - it would quickly accumulate the opposite charge from the air and collapse.
There is no magnet arrangement that generates an outwards force everywhere.

 

[anorlunda]

@GTOM ,

The best way to get questions answered is to just ask the question. The wrong way is to add stuff that is not part of the question, such as

Theoretically its possible to expand their balloons electromagnetically.
According to TV tropes, square cube law don't affect blimps so hard as helicopters, so while they would be slow, but they could be huge and reliable.

Neither one of those things were necessary as part of your question. Worse, the electromagnetic stuff is untrue. Also bad: using "TV tropes" as a source just irritates everyone here.

But you do need to give enough context to make the question specific. Overly general questions can't be answered either, and might get labelled "substandard". But that wasn't the case in your thread, the context was clear but the added stuff you put in spoiled the question.

 

[berkeman]

Theoretically its possible to expand their balloons electromagnetically.

This statement of yours in your original thread sent me immediately off into the weeds. I was trying to figure out what you might have been talking about, and I couldn't figure it out right away. That made me spend more minutes and brain cycles trying to figure out why I couldn't figure out what I couldn't figure out, and so on. I generally think your posts are very good, so that's another motivator for me to try to figure out why I didn't understand why I didn't understand what you are posting here... Ack.

Yes, in this thread, i couldn't find an article to support my idea, but i think it is reasonable to expect details why is it bad.

And that's the problem. When you are a valued member who usually is very technical and accurate, and you post like this with something unsupported, you send us off into the weeds wasting time trying to figure out what you are talking about. If you were a newbie with no track record, I wouldn't have spent more than a nanosecond on your post (well, other than Moderating it), but you have a strong track record here so I worked hard to try to figure out what you were talking about.

That's why it is so important to post links to what you are talking about. If you had a link to some electromagnetic repulsive dirigible structure, that would have been great. Seeing your follow-up posts about "well, maybe lots of charge and magnets might make it work" is difficult for me. I hope you understand.

 

[GTOM]

Well, thanks for the answers.

That's why it is so important to post links to what you are talking about. If you had a link to some electromagnetic repulsive dirigible structure, that would have been great. Seeing your follow-up posts about "well, maybe lots of charge and magnets might make it work" is difficult for me. I hope you understand.

If i could find articles about everything i wouldn't ask questions.

You didn't do that. You claimed it would work, that is completely different:

Charging a balloon notably in air doesn't work - it would quickly accumulate the opposite charge from the air and collapse.
There is no magnet arrangement that generates an outwards force everywhere.

IMHO theoretically isn't the same as practically, theoretically it sounds great to build a flexible road to the Moon. Ok, the charge escape problem is a very serious argument, why the idea wouldn't work in reality.
When i asked why it couldn't work i wanted to read exactly things like that.

@GTOM ,

The best way to get questions answered is to just ask the question. The wrong way is to add stuff that is not part of the question, such asNeither one of those things were necessary as part of your question. Worse, the electromagnetic stuff is untrue. Also bad: using "TV tropes" as a source just irritates everyone here.

But you do need to give enough context to make the question specific. Overly general questions can't be answered either, and might get labelled "substandard". But that wasn't the case in your thread, the context was clear but the added stuff you put in spoiled the question.

What is so wrong with TV Tropes? As far as i could see, sure it is popsci, but it writes down facts that are true.

 

[Vanadium 50]

You might want to reread answer #5.

 

[ZapperZ]

If i could find articles about everything i wouldn't ask questions.

Actually, you still would! Just because you have the article doesn't mean that (i) you understood what you read and (ii) you interpret it correctly. After all, students on here have textbooks! What could be a more complete document than that? Yet, they still ask questions about stuff they read in those textbooks.

So asking something out of an article that you read is exactly what is required here, because there has to be a valid source that the rest of us can check up on.

What is so wrong with TV Tropes? As far as i could see, sure it is popsci, but it writes down facts that are true.

So now you're questioning the PF policy. One would think after all these posts, and after being on here for that number of years, you would have noticed that (i) PF is not like any other forums and (ii) there is a higher demand for quality posts. This means that there has to be care and scrutiny given on the type of sources one uses as a reference. Using a popsci reference as a source, especially to counter an argument from an expert, is like using a Fox News talking head as a reference on issues of global warming against a climate expert.

I've said this here previously, and I'll say it again:

We try to enforce many things here on PF, and some of them to the dislike of many members. I’ve mentioned our insistence that members who wish to understand about stuff they read, heard, etc. must cite their sources clearly. This is a normal practice in science and engineering. We includes tons of citations in our papers, our funding proposals, our reports, etc. It is part of our standard operating procedure, making sure whoever reads it knows where the source of such-and-such information comes from. This is not a common practice for the general public. Newspapers very seldom provide such exact citations. Politicians are even worse – they seem to claim A causes B without even providing any justification, something we can’t do in science. Maybe, just maybe, if you learn how we arrive at our ideas in science, then you might set your acceptance level of what is valid to be higher, where you demand to know what is the evidence to support that A causes B? What is the nature of the source that support this? There is no reason to not demand valid supporting evidence even in dealing with political and social issues. Otherwise, it becomes just a matter of opinion or tastes without any rational justification. This is what science set as a standard, and this is why HOW we arrive at the conclusion we have is something important that you can learn from this forum.

Zz.

 

[russ_watters]

What probably triggered me most was hearing "theoretically possible" in an engineering forum. It's two levels below acceptable because usually (including in this case) it means 'nobody has proven to me that it is theoretically impossible yet, so I'm going to assume it is theoretically possible even though I don't actually know'.

Next level is something like a hollow sphere containing a vacuum. Theoretically possible it could be light enough for net lift? Sure. But since it requires a material many times stronger than any that exists, it is still "engineering impossible". And please: don't bring me the Wright Brothers. This isn't that. It is a much simpler issue, with a clear-cut constraint.

Please note though: vacuum balloons are not on our banned topics list. We can discuss them. But the threads need to be serious, with detailed proposals, including calculations -- they need to be engineering! Not handwaving.