"Thunderf00t" is a biochemist and the fact that people cite him as an expert in anything except biochemistry never ceases to amaze me.
Sorry, but inch thick steel does not peel back like a banana when you make a hole in it simply because there's a mere 1 ATM pressure differential. Nor does some supermassive shock travel like a brick wall hundreds of miles leading to instant repressurization. The behavior of rapidly progressing pressure waves is known as the shock tube problem. It's well studied physics, and with such a long length to diameter ratio and length to shock velocity ratio, "non-catastrophic" doesn't even begin to describe it. Yes, the wave travels very fast (several times faster than the speed of sound), but it does not carry a lot of force in these conditions, nor does it instantly raise the mass density to atmospheric over long distances, nor does "several times the speed of sound" equate to instant arrival a many hundreds of kilometers away. The same viscosity / wall friction limitations that apply to all tubes applies to Hyperloop.
As for the Mythbusters, DOT-111 railcars,like the Mythbusters used, are not designed to hold a vacuum. They're not even designed to hold positive pressures; they're designed to hold unpressurized liquids. They're given a small (7 bar) requirement to meet in new condition, but that's it. There is nothing in their design that is supposed to prevent pressure-related collapse when damaged. And it still took about half a second second to collapse across such a short length (the length of a tanker car).
Nobody in their right mind would ever engineer a vacuum pipeline that can catastrophically collapse along its length. It is in no way, shape or form some sort of fundamental property of vacuum lines, and only a person who has never worked in engineering would think so.
If "Thunderf00t" (Phil Mason) says something about biochemistry, listen to him. If he starts ranting about fields that he has no understanding of, close the window.
I'd rather teach them to keep their functions short and their function titles descriptive, so that the code comments itself. Nothing annoys me more than comments like:
for (i = 0; i < 3; i++)// Loop three times {
some_fn(); }
Comments should be about why, not what. What should be easily visible in your code on its own.
Object oriented is a good idea, so long as they have experience doing so (at least in school or at home). If not, just tell them to try to keep all of their functions down to less than X lines. Each with a very explicit name, to the point that the function name itself is practically a comment.
I'd also print out the following and have it near their desk:
---------- RULES FOR OPTIMIZATION:
1) Don't. 2) (Experts Only) Don't yet. ----------
I remember when I was starting out, being able to right "fast" code felt like the mark of a good programmer, and often rendered code unreadable and bug-prone by optimizing sections that had no business being optimized in the first place. It took time to learn that good programming is clear, easy to understand programming, with optimization done by first identifying a problem, profiling the code to see what's actually consuming cycles, and focusing on the low-hanging fruit therein.
Part of it also was that a lot of the "optimizations" aren't actually optimizations. For example, loop unrolling, and very often loop checks, the compiler does that for you, so I was just uglifying my code for no good reason and getting full of myself for "optimizing" when I was doing no such thing. My interest in people writing "fast" code however led to me reading Carmack and Abrash, which led to getting a better understanding of what actually helps vs. what's a waste of time, and where to focus your efforts.
Indeed. I have a password that I use for all of the diverse sites that I don't give a rat's arse about. What's someone going to do if they compromise it, make fake posts as me? Ooh, shudder.
I remain in disagreement that that is the best approach. It gives you needlessly large amounts of typing for little entropy. Acronym passwords are better - think of a sentence and a rule for turning it into a password (the simplest just being using the first letter or two letters of each word).
Sentences are easy to remember than four random words, the resultant passwords are shorter, and while the search space can certainly be reduced by statistical means, it's not nearly as much as with four random words. Aka, if the last letters the person typed in were "stapl", what do you think the next letter is going to be?
It's worth pointing out that XKCD's pretense that four random words are easy to memorize was based on them choosing four easy to memorize words. If I just have/usr/share/dict/words pull up random words for me, here's the first five passwords it comes up with:
Yeah, best of luck with that. By contrast, if I convert the previous sentence into an acronym password, I may get something like (depending on what rules I use):
Y,bolwt. Yebeofluwith yEbE0FlUw1tH.... etc. Choose your own rules. But you won't forget "Yeah, best of luck with that"
Everything in space is taken from "a long way away" relative to what we're used to in our everyday lives, as spacecraft move at speeds generally best measured in kilometers per second.
Hmm, I think I see the problem. You're expecting images that look like when they take photos of much larger bodies - for example, this also recent image, of Mimas. But Mimas is about 400 kilometers in diameter, while Pan is 35x23km. Pan is also in Saturn's A-ring, which makes it a dangerous place to approach (although I assume this was captured during a pass through the Encke Gap?). Let's see... these were taken from ~25000km away... so yeah, that'd have to be within the Encke gap.
It's incredibly smooth and uncratered because it's constantly accumulating fine-grained ring material. Think of it like a sand dune in space.
Also, people are generally used to images of the outer planets and their moons being poor quality (grainy, uneven lighting, often colorized poorly), but Cassini's imaging science subsystem is excellent. Really, everything about this spacecraft and mission has been superb, it's going to be such a shame to see it go. A very expensive mission, but worth every bit.
Winter potatoes do not grow in the winter. The plant dies off at the first frost. The potatoes remain intact underground, but there is no growth. They remain dormant. They couldn't grow even if the plant had died off because they can't extract water from ice (aka, frozen soil).
Perchlorates can form a liquid brine because they're even more dehydrating than the near-vacuum atmosphree. Being in contact with them doesn't give you water, it extracts water from you.
As for oxygen, shipping bacteria or something to produce it might be feasible,
You're talking terraforming. Not that even having photosynthetic bacteria survive on the surface of Mars is established; bacteria still need liquid water. Never mind that the surface of Mars is highly sterilizing.
This is significantly saltier than ketchup. It's crystalline - you pour it on like salt. It's basically like adding both salt and ketchup to your fries/chips. Something that a lot of Americans already do, no?
The concept is impossible. Water cannot exist in a liquid state in any Mars conditions (unless as previously stated concentrated by other factors, such as a strong perchlorate brine), and there is no oxygen for the roots to breathe (leaves make oxygen, but roots consume it, and die if it's not present in sufficient quantity).
Not sure whether this was meant seriously or in snark.
If actually meant seriously: potatoes, like all plants, exchange gas with air in the pore space at their roots in order to get oxygen. Said air is the same pressure as the outside air. Water vapour exchanges with it at the same rate as it would with air on the surface, with respect to partial pressures. And even if that wasn't the case, the mass of the soil would only add ~1-2 kPa pressure (on Earth, less on Mars due to the lower gravity).
That alone is enough reason to discount them, but beyond that, they don't state what simulant they used. There are two main Mars regolith simulants out there. JSC MARS-1 (most recent, MARS-1A) is ash from the Pu'u Nene cinder cone (simply dug up and sieved); and MMS, which is crushed Mojave desert rock. They only match Mars (very, very roughly) in terms of bulk composition, not at all in terms of hygroscopic and toxic compounds (MMS is somewhat hygroscopic, MARS-1A not at all). Mars perchlorates are not just hygroscopic, they're delequescent. And it's packed full of toxic compounds you generally don't find on Earth (outside of superfund sites, at least;) )
While The Martian was terrible, it is kind of amusing picturing other Matt Damon characters in that role;) Will Hunting, Private Ryan, Jason Bourne, Loki from Dogma...
No information anywhere specifying what pressure (Pa, mbar, psi, atm....) they're using in there, but I can tell you it's not a Marslike ~600Pa / 6mbar / 0.006 atm, because that's below the Armstrong limit, and water can't exist in a liquid phase at those pressures (the "liquid water flowing on Mars" was actually concentrated toxic deliquescent brine). I can also tell you that they're not using Marslike temperatures because it's not exactly a secret that potatoes don't sprout or survive in the winter.
Yeah, you can grow things in Mars regolith. If you first remove the toxic perchlorates. And the hexavalent chromium. And the general excess of arsenic. And on and on. Basically, if you take a highly polluted natural material and remediate the various pollutants from it, then add water, you can grow plants in it. Well golly gee, whoda thunk that?
This project is a stunt by a potato council. They're not growing potatoes in Mars regolith or anything similarly contaminated, they're growing them in soil taken from the Pampas de La Joya desert. Interviewed elsewhere:
The goal is to raise awareness of the incredible resilience of potatoes, and fund further research and farming in devastated areas across the globe where malnutrition and poverty are rife and climbing.
“How better to learn about climate change than by growing crops on a planet that died two billion years ago?” said Joel Ranck, CIP Head of Communications. “We need people to understand that if we can grow potatoes in extreme conditions like those on Mars, we can save lives on Earth.”
We've gotten some big chunks breaking off Dyrhólaey recently, including one that nearly took a tourist out with it. You know, you might have survived falling off the Azure Window, but you're not going to survive falling off Dyrhólaey.
Slashdot Mirror
"Thunderf00t" is a biochemist and the fact that people cite him as an expert in anything except biochemistry never ceases to amaze me.
Sorry, but inch thick steel does not peel back like a banana when you make a hole in it simply because there's a mere 1 ATM pressure differential. Nor does some supermassive shock travel like a brick wall hundreds of miles leading to instant repressurization. The behavior of rapidly progressing pressure waves is known as the shock tube problem. It's well studied physics, and with such a long length to diameter ratio and length to shock velocity ratio, "non-catastrophic" doesn't even begin to describe it. Yes, the wave travels very fast (several times faster than the speed of sound), but it does not carry a lot of force in these conditions, nor does it instantly raise the mass density to atmospheric over long distances, nor does "several times the speed of sound" equate to instant arrival a many hundreds of kilometers away. The same viscosity / wall friction limitations that apply to all tubes applies to Hyperloop.
As for the Mythbusters, DOT-111 railcars ,like the Mythbusters used, are not designed to hold a vacuum. They're not even designed to hold positive pressures; they're designed to hold unpressurized liquids. They're given a small (7 bar) requirement to meet in new condition, but that's it. There is nothing in their design that is supposed to prevent pressure-related collapse when damaged. And it still took about half a second second to collapse across such a short length (the length of a tanker car).
Nobody in their right mind would ever engineer a vacuum pipeline that can catastrophically collapse along its length. It is in no way, shape or form some sort of fundamental property of vacuum lines, and only a person who has never worked in engineering would think so.
If "Thunderf00t" (Phil Mason) says something about biochemistry, listen to him. If he starts ranting about fields that he has no understanding of, close the window.
I'd rather teach them to keep their functions short and their function titles descriptive, so that the code comments itself. Nothing annoys me more than comments like:
for (i = 0; i < 3; i++) // Loop three times
{
some_fn();
}
Comments should be about why, not what. What should be easily visible in your code on its own.
Object oriented is a good idea, so long as they have experience doing so (at least in school or at home). If not, just tell them to try to keep all of their functions down to less than X lines. Each with a very explicit name, to the point that the function name itself is practically a comment.
I'd also print out the following and have it near their desk:
----------
RULES FOR OPTIMIZATION:
1) Don't.
2) (Experts Only) Don't yet.
----------
I remember when I was starting out, being able to right "fast" code felt like the mark of a good programmer, and often rendered code unreadable and bug-prone by optimizing sections that had no business being optimized in the first place. It took time to learn that good programming is clear, easy to understand programming, with optimization done by first identifying a problem, profiling the code to see what's actually consuming cycles, and focusing on the low-hanging fruit therein.
Part of it also was that a lot of the "optimizations" aren't actually optimizations. For example, loop unrolling, and very often loop checks, the compiler does that for you, so I was just uglifying my code for no good reason and getting full of myself for "optimizing" when I was doing no such thing. My interest in people writing "fast" code however led to me reading Carmack and Abrash, which led to getting a better understanding of what actually helps vs. what's a waste of time, and where to focus your efforts.
I used /usr/share/dict/words. So you want a reduced set of words? Then you're getting reduced entropy.
Indeed. I have a password that I use for all of the diverse sites that I don't give a rat's arse about. What's someone going to do if they compromise it, make fake posts as me? Ooh, shudder.
I remain in disagreement that that is the best approach. It gives you needlessly large amounts of typing for little entropy. Acronym passwords are better - think of a sentence and a rule for turning it into a password (the simplest just being using the first letter or two letters of each word).
Sentences are easy to remember than four random words, the resultant passwords are shorter, and while the search space can certainly be reduced by statistical means, it's not nearly as much as with four random words. Aka, if the last letters the person typed in were "stapl", what do you think the next letter is going to be?
It's worth pointing out that XKCD's pretense that four random words are easy to memorize was based on them choosing four easy to memorize words. If I just have /usr/share/dict/words pull up random words for me, here's the first five passwords it comes up with:
cytopharynx Gasperoni gastroplasty revolutionising
reacidifying bosom-breathing sipers down-in-the-mouth
text-writer clubbed midfields Shuqualak
Malkite phthisiology BLM improbabilize
weaves Whiggamore unspirally Exod
Yeah, best of luck with that. By contrast, if I convert the previous sentence into an acronym password, I may get something like (depending on what rules I use):
Y,bolwt. .... etc. Choose your own rules. But you won't forget "Yeah, best of luck with that"
Yebeofluwith
yEbE0FlUw1tH
Everything in space is taken from "a long way away" relative to what we're used to in our everyday lives, as spacecraft move at speeds generally best measured in kilometers per second.
Hmm, I think I see the problem. You're expecting images that look like when they take photos of much larger bodies - for example, this also recent image, of Mimas. But Mimas is about 400 kilometers in diameter, while Pan is 35x23km. Pan is also in Saturn's A-ring, which makes it a dangerous place to approach (although I assume this was captured during a pass through the Encke Gap?). Let's see... these were taken from ~25000km away... so yeah, that'd have to be within the Encke gap.
It's incredibly smooth and uncratered because it's constantly accumulating fine-grained ring material. Think of it like a sand dune in space.
Also, people are generally used to images of the outer planets and their moons being poor quality (grainy, uneven lighting, often colorized poorly), but Cassini's imaging science subsystem is excellent. Really, everything about this spacecraft and mission has been superb, it's going to be such a shame to see it go. A very expensive mission, but worth every bit.
Winter potatoes do not grow in the winter. The plant dies off at the first frost. The potatoes remain intact underground, but there is no growth. They remain dormant. They couldn't grow even if the plant had died off because they can't extract water from ice (aka, frozen soil).
Perchlorates can form a liquid brine because they're even more dehydrating than the near-vacuum atmosphree. Being in contact with them doesn't give you water, it extracts water from you.
You're talking terraforming. Not that even having photosynthetic bacteria survive on the surface of Mars is established; bacteria still need liquid water. Never mind that the surface of Mars is highly sterilizing.
After 5 whats?
This is significantly saltier than ketchup. It's crystalline - you pour it on like salt. It's basically like adding both salt and ketchup to your fries/chips. Something that a lot of Americans already do, no?
The concept is impossible. Water cannot exist in a liquid state in any Mars conditions (unless as previously stated concentrated by other factors, such as a strong perchlorate brine), and there is no oxygen for the roots to breathe (leaves make oxygen, but roots consume it, and die if it's not present in sufficient quantity).
Not sure whether this was meant seriously or in snark.
If actually meant seriously: potatoes, like all plants, exchange gas with air in the pore space at their roots in order to get oxygen. Said air is the same pressure as the outside air. Water vapour exchanges with it at the same rate as it would with air on the surface, with respect to partial pressures. And even if that wasn't the case, the mass of the soil would only add ~1-2 kPa pressure (on Earth, less on Mars due to the lower gravity).
Not that far off. Puffins are a species of awk, which is in the same suborder (Lari) as gulls, terns, skuas and skimmers.
They are admittedly quite adorable. I have a parrot and their behavior reminds me a lot of parrots. They're also eaten here (puffins, not parrots).
I can just imagine the huge tomacco plantations on Mars... ;)
Here in Iceland a ketchup-flavoured salt is popular on fries (us)/chips (uk)
Mars One, seriously?
That alone is enough reason to discount them, but beyond that, they don't state what simulant they used. There are two main Mars regolith simulants out there. JSC MARS-1 (most recent, MARS-1A) is ash from the Pu'u Nene cinder cone (simply dug up and sieved); and MMS, which is crushed Mojave desert rock. They only match Mars (very, very roughly) in terms of bulk composition, not at all in terms of hygroscopic and toxic compounds (MMS is somewhat hygroscopic, MARS-1A not at all). Mars perchlorates are not just hygroscopic, they're delequescent. And it's packed full of toxic compounds you generally don't find on Earth (outside of superfund sites, at least ;) )
While The Martian was terrible, it is kind of amusing picturing other Matt Damon characters in that role ;) Will Hunting, Private Ryan, Jason Bourne, Loki from Dogma...
No information anywhere specifying what pressure (Pa, mbar, psi, atm....) they're using in there, but I can tell you it's not a Marslike ~600Pa / 6mbar / 0.006 atm, because that's below the Armstrong limit, and water can't exist in a liquid phase at those pressures (the "liquid water flowing on Mars" was actually concentrated toxic deliquescent brine). I can also tell you that they're not using Marslike temperatures because it's not exactly a secret that potatoes don't sprout or survive in the winter.
What a load of hype.
Oh, heck, from the look of it the thing's not even in space.
Yep, check out the timelapse mode on the livestream - there's clearly people walking by outside. For crying out loud...
Yeah, you can grow things in Mars regolith. If you first remove the toxic perchlorates. And the hexavalent chromium. And the general excess of arsenic. And on and on. Basically, if you take a highly polluted natural material and remediate the various pollutants from it, then add water, you can grow plants in it. Well golly gee, whoda thunk that?
This project is a stunt by a potato council. They're not growing potatoes in Mars regolith or anything similarly contaminated, they're growing them in soil taken from the Pampas de La Joya desert. Interviewed elsewhere:
We've gotten some big chunks breaking off Dyrhólaey recently, including one that nearly took a tourist out with it. You know, you might have survived falling off the Azure Window, but you're not going to survive falling off Dyrhólaey.
It wasn't even that impressive of an arch. We have sea arches far larger than that here in Iceland.
(( sound of a tumbleweed being blown across the desert by a flying car ))