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The most expensive number in engineering

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Re: The most expensive number in engineering

#131

Post by thaumasiotes »

snowwrestler wrote: post #34

Grossly increasing the factor of safety is a subtle way that science fiction stories connote a feeling of very advanced technology. For example in the JJ Abrams movie Star Trek Into Darkness we see the Enterprise operating at depth in an ocean, then dramatically zooming away into space. Then later another ship falls from orbital height and plows through San Francisco without losing its hull shape. In Star Wars the Mi…

> The idea is: this advanced civilization has such command over physical technology, that they can effortlessly engineer unnecessary strength without losing any of their designed performance.

Are you sure the idea isn't just "we never thought about it"?

Old cars are sturdy and robust while new cars are extremely fragile and will total themselves at the drop of a hat. That's not because the 50s possessed ancient technology lost to the modern day. We put a lot of effort into designing our cars to destroy themselves under stress. We do that so that more of the energy of a crash, should it happen, will go into deforming the car (since that's easy now!) and less of it will go into deforming the passengers.

Re: The most expensive number in engineering

#132

Post by thaumasiotes »

codeflo wrote: post #44
snowwrestler wrote: post #34

Grossly increasing the factor of safety is a subtle way that science fiction stories connote a feeling of very advanced technology. For example in the JJ Abrams movie Star Trek Into Darkness we see the Enterprise operating at depth in an ocean, then dramatically zooming away into space. Then later another ship falls from orbital height and plows through San Francisco without losing its hull shape. In Star Wars the Mi…

About the Abrams movie: Too bad the same factor of safety wasn't applied to the buildings, where that should have been even cheaper. Your point is good though. Just like we're now starting to put wi-fi chips into absolutely anything just in case, why wouldn't an advanced civilization simply use their super strength nanoparticles for everything? Why go out of your way to use worse materials?

> why wouldn't an advanced civilization simply use their super strength nanoparticles for everything? Why go out of your way to use worse materials?

For the same reason we've spent decades making our cars structurally weaker?

Re: The most expensive number in engineering

#133

Post by lupire »

robbrown451 wrote: post #101
glitchc wrote: post #67

Earlier quoted context omitted.

Lucas himself has stated that although science fiction inspired him to create these stories, Star Wars is indeed not science fiction but rather science fantasy: https://scifi.stackexchange.com/questions/46481/did-george-l... Because all the stories are " a long, long time ago in a galaxy far, far away," it's not even clear if Luke and the gang are humans or some other species. Of course it's easy to think of them as…

True but Lucas doesn't have final say on classifying his movies. People who make things have an incentive to claim that their work is somehow special. I'd just say Star Wars is science fiction with lots of fantasy elements, as well as lots of influence from different genres (Earth-based war films, adventure serials, etc.) I see the fact that humans in Star Wars seem to be the "same species" as Homo sapiens to be simi…

Why isn't Lord of the Rings "science fiction" but Star Wars is? They both have technology unknown to us.

Re: The most expensive number in engineering

#134

Post by lupire »

UncleMeat wrote: post #103
glitchc wrote: post #49

Earlier quoted context omitted.

Seems disingenuous to lump a science fiction movie where the focus is future technologies to an action movie with exaggerated physics and lack of real damage. In action movies, bad guys die with one bullet while the hero finds his way to safety (and survives!) despite having 10 or more lethal bullet wounds. For the record, Star Wars is not science fiction nor has it ever been portrayed as such. It's very much an acti…

Three movies were referenced in the comment I responded to: Return of the Jedi, Star Trek: Into Darkness, and 2001: A Space Odyssey. Two of those movies are definitely not focused on future technologies. Many people call Star Wars "science fantasy", but I'm extremely confident that this is used less frequently than "science fiction" to describe it and I am absolutely confident that I'd be able to find marketing copy…

It's space fantasy or space western, not science fantasy.

Re: The most expensive number in engineering

#135

Post by thaumasiotes »

hypertele-Xii wrote: post #51
unethical_ban wrote: post #47

Earlier quoted context omitted.

Aren't all the major bridges in New York built with ridiculous safety factors? It's why these century old bridges built for carriages and small trucks in a city of a million, can deal with 2021? It's fascinating to me, and I feel like over-spec'ing certain chokepoints in infrastructure makes sense like this.

Then there's the factor that, in the times such a bridge was built, having it collapse would've been a larger catastrophy than today. Today, we can quickly fix things and build another. In the old times, that bridge might've been the only bridge making trade at all possible and it might've taken years to stack stones. An unnecessarily strong castle takes you more time and resources to build. A slightly too weak castl…

> An unnecessarily strong castle takes you more time and resources to build.

> A slightly too weak castle means you die, your family dies, and you lose all wealth and power.

You're really glossing over a lot of important concerns here. There are many, many ways to lose all your wealth and power, and lots of them might have been avoided if you'd had a few more spare resources.

Re: The most expensive number in engineering

#136

Post by snowwrestler »

thaumasiotes wrote: post #131
snowwrestler wrote: post #34

Grossly increasing the factor of safety is a subtle way that science fiction stories connote a feeling of very advanced technology. For example in the JJ Abrams movie Star Trek Into Darkness we see the Enterprise operating at depth in an ocean, then dramatically zooming away into space. Then later another ship falls from orbital height and plows through San Francisco without losing its hull shape. In Star Wars the Mi…

> The idea is: this advanced civilization has such command over physical technology, that they can effortlessly engineer unnecessary strength without losing any of their designed performance. Are you sure the idea isn't just "we never thought about it"? Old cars are sturdy and robust while new cars are extremely fragile and will total themselves at the drop of a hat. That's not because the 50s possessed ancient techn…

Old cars were not sturdier or more robust than new cars. That’s a myth. You can Google “crash test old car vs new” or something like that to see examples.

Re: The most expensive number in engineering

#137

Post by derbOac »

GCA10 wrote: post #46

I'm liking the Robert Norton chart about 2/3 of the way down, showing how safety factors need to be adjusted quite radically once we think about how reliable or rickety our estimates might actually be. Particular kudos to thinking harder about whether we've truly tested the actual environment where our product might be used. I wish social scientists would do the same in controlled studies of human behavior -- which a…

I agree completely regarding the social sciences. I think the devil is in the details, though, and to return to the original article, why 1.5 and not some other number? The author provides an answer, but the answer is only partially resolved.

I feel like some empirical study is needed, of how deviations from models occur in different fields, in a way that's applicable across fields. Maybe that's the same as the probabilistic analysis being discussed in the article, but what I have in mind is higher-level than what I understood that to be. I'm thinking of some meta-analytic survey across disciplines of what the safety factor would have needed to be to avoid various catastrophes of different sorts, or how much models are off in different areas. Maybe there is a field of study like this?

Re: The most expensive number in engineering

#138

Post by [deleted] »

londons_explore wrote: post #78
ghaff wrote: post #74

Earlier quoted context omitted.

It feels like you're picking numbers out of the air (or basing them on historical experience) either way. Unless you actually have historical data on certain types of problems--but then it seems like you're pretty much back to a safety/fudge factor.

But a large number of guestimated fudge factors all added up will approach the true value as long as there is no bias. The same does not apply for factors of safety - a 1.5 FoS is always between 0 and 50% too much.

[deleted]

Re: The most expensive number in engineering

#139

Post by snowwrestler »

glitchc wrote: post #67
ben_w wrote: post #58

Earlier quoted context omitted.

> For the record, Star Wars is not science fiction nor has it ever been portrayed as such. FWIW this is literally the first time I’ve encountered someone claiming that it isn’t science fiction. ( Soft SciFi, to be sure, but still: https://tvtropes.org/pmwiki/pmwiki.php/Main/MohsScaleOfScien... )

Lucas himself has stated that although science fiction inspired him to create these stories, Star Wars is indeed not science fiction but rather science fantasy: https://scifi.stackexchange.com/questions/46481/did-george-l... Because all the stories are " a long, long time ago in a galaxy far, far away," it's not even clear if Luke and the gang are humans or some other species. Of course it's easy to think of them as…

When Star Wars was released, it was understood to be science fiction. See this interview with Alec Guinness in 1977:

https://youtu.be/0qxcEBI1iKI

They both call it science fiction.

Lucas was wary of that label because science fiction had a (well-earned) reputation at that time as a ghetto of heavy-handed allegory with hammy acting and terrible special effects. Lucas was striving for more than that.

He was trying to create a modern myth, or modern fairy tale. But genres are defined by their conventions, and Lucas chose space opera conventions (space ships, lasers, aliens). Space opera is a subgenre of science fiction so Star Wars was considered science fiction.

J.R.R. Tolkien was like Lucas in that he also tried to create a modern fairy tale. But he chose wizards and dragons, so his stories became fantasy.

Re: The most expensive number in engineering

#140

Post by andi999 »

snowwrestler wrote: post #136
thaumasiotes wrote: post #131

Earlier quoted context omitted.

> The idea is: this advanced civilization has such command over physical technology, that they can effortlessly engineer unnecessary strength without losing any of their designed performance. Are you sure the idea isn't just "we never thought about it"? Old cars are sturdy and robust while new cars are extremely fragile and will total themselves at the drop of a hat. That's not because the 50s possessed ancient techn…

Old cars were not sturdier or more robust than new cars. That’s a myth. You can Google “crash test old car vs new” or something like that to see examples.

True. Old cars has real bumpers though.
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