The first comment makes the most sense, it is just saying boxes are an an additive map. The third comment is hopefully half joking, and the one that is more cry-worthy.
I was at coxswain in high school, and at the handful of high school level competitions we went to I've never seen anything that bad. Although to be fair, I don't think any of the ones we went to were on a river that narrow, and some boats did veer a lot, but even the races close to the shore avoided the ground. For the the boat with a cox, the coxswain is fully responsible for what happens to the boat. The only mild issues I had was finding out the hard way where we could go outside of the channel markers to avoid normal boat traffic on the river we used to practice on, but a soft sandbar is easy to get out of. Also, the sculls, where each rower has two oars, there is usually no coxswain and the foremost rower is in charge and needs to keep looking over their back or use a mirror to see where they are going, and that can be considerably more difficult without some experience.
XKCD has been updating the comic "live" and the site xkcd1446.com has all the previous comics. It now reflects the questions about whether it worked or not that was stated at the end of the live feed announcements. It is mildly annoying that the live feed had talking admins like clockwork for most of the hour, but then only a minute long status update with actual info, followed by a silent feed of the control room. Not that I would want my idle conversations with coworkers broadcast on the internet...
Regardless, it was a great accomplishment even if there turns out to be more problems.
I wish I could afford cutters with that many inserts...
You can see chips coming off with a purple to blue color, meaning they are reaching temperatures of over 300 C. Once upon a time, I saw an offline video showing high end machining of some high temperature metal (like some kind of Inconel). It was a material that had big problems with work hardening, where strain causes the material to harden, so if you cut too slowly with the mill it will strengthen the material in front of the cutter faster than it cuts it away, wrecking havoc on the cutter. The solution is to cut very aggressively, producing red to yellow hot chips. Online videos of similar things were not as impressive as the one I saw offline, although I haven't looked too hard recently. It is one thing one a grinder makes hot dust, but another when a cutting edge going at near highway speeds is producing large, glowing chips.
Is the white one even decreasing the brightness at all? If that is just frosted glass, or even so thin white coating, it is just softening the light when you look right at it by diffusing it, but otherwise not really dimming it much.
TV and movies do erroneously show a defibrillator as being used for someone flatlining. But in situations where a defibrillator is appropriate, I've heard, from both CPR instructors and someone I know who's had to use an AED, that the reaction can be quite quick sometimes. It doesn't work every time, but they warned to not be surprised if the person starts waking and moving around in the short time before resuming chest compressions. Of course they probably won't be in great shape and still need a doctor immediately.
People have a bad habit of not distinguishing between pescetarian and vegetarian, especially since the former didn't have a good, well know label more than a decade or two ago, and because of various religions declaring fish not to count as meat.
The audio/CC for the video doesn't work where I am at the moment. While there are some possibly legit complaints about modern processed meat, I do see a few too many reactions that amount to more baseless disgust. What is especially sad is when it comes from chefs that complain about the scrap meats and bones being used in some processed goods, but still use stocks and offal made from the same animal parts.
The sodium+water reaction is pretty common in high school chemistry classes, and I've been around some larger examples when they actually have a pond near by. The LN2 rocket and various dry ice bombs I've seen at quite a few demonstrations too, when probably those are ones likely to be frowned upon by administration.
The pumpkin one can be done with alcohol instead. I wouldn't do the acetylene version myself, as there have been a few too many incidences with acetylene in a confined space suddenly exploding a lot more than expected. Some people I knew had setups (not pumpkins though) that worked fine several times, then got knocked on their butt and were lucky no shrapnel was involved.
The microwave oven transformer mod is a fun one that comes up some outreach demonstrations, and is essentially just doing what a primitive arc welding unit will do. In fact, you can build a primitive arc welder with a few more cheep parts.
If you get a chance to take an intro physics course at a university of go to an outreach program, there might be a chance to see this in person. A smaller version is pretty common with two glass tubes, one with a ball bearing and the other a feather, and the air can be pumped out of them.
Either I strongly disagree with his interpretation of what relativity is saying, or he said it very poorly. While a key part of general relativity is that the effects of gravity and acceleration are indistinguishable from a closed box, it doesn't change that objects will still fall toward the Earth.
I think most, if not all, of those animations were just lifted from Wikipedia/Wikimedia. In which case you could just link to their Animations of machinery category, where some people have put some serious effort in creating illustrations of how various things work. At least then you can get links to actual articles on it, as opposed to just a couple single-line bad summaries.
This line of reasoning doesn't work though. Try applying it to the Monty Hall problem:
You pick one of three doors on a game show, trying to find the one of the three with a prize. The game show host then always opens one door that does not have the prize, and asks if you want to switch your choice to the door you didn't choose and he didn't open.
You can demonstrate by straightforward experiments that by switching you have a 2/3 chance of winning, while not switching gives you a 1/3 chance of winning. If you simply ordered the doors by the order they were revealed, you would say that the two remaining doors each have a 50-50 chance of having the prize, and there is no reason to switch. Except both probability reasoning similar to what gives 1/3 for the problem in the story above, and simply trying it out experimentally show it is not 50-50.
The key in both cases is that what you are told gives you information. In the Monty Hall problem, the host always opens a losing door: in the case your first pick was right, it doesn't change anything by switching, but if you were wrong with your first pick, it guarantees your second pick will be right. By saying that one of two child is a boy, you've already said they can't both be girls, but didn't say which of the two kids is a boy.
The genotype vs. phenotype example I previously gave might seem more clear (to me at least). You have two carrier parents (each with a dominant and recessive gene). You look at the offspring, and can see which ones are double recessive, because they express the recessive trait. You grab one that is not expressing the recessive gene, what are the chances of it being a carrier versus double dominant? That is the same as saying you know one of the genes is dominant because it shows the dominant phenotype, but there is still a 2/3 chance of it being a carrier versus a 1/3 chance of it having no recessive genes at all. You can't say "Gene #1 is the one I know is dominant" and "Gene #2 is the one I don't know" because you don't know which of the two you actually know (e.g. if they both were dominant, you couldn't point to one and say that was Gene #1).
In other words, if you were told of two kids: Pat and Chris, and told one, but not which one, is a male, you would say the first child in your order is the first one revealed, a male one. If you found out both Pat and Chris were boys, which one was the one you were labeling as the "first child?" You can't say if you were referring to Pat or Chris in that case, so your original labeling was not referring to a specific child.
Confidence intervals with the binomial distribution has some issues, but ignoring that and using the crude Wald confidence interval, lets look at your numbers and see what are the chances you missed 50% and above by luck (plus-minus errors below are approx 1 sigma):
Run 1: 13/31 -> 42+/-9% -> about 16% chance you got below half by luck Run 2: 12/29 -> 41+/-9% -> about the same Run 3: 10/27 -> 37+/-9% -> about 8% chance you got below half by luck Run 4: 8/21 -> 38+/-11% -> about 15% chance getting below half by luck Combined: 43/108 -> 39.8+/-4.7% -> less than a 2.5% chance of it originally being half or above, i.e. a 95% confidence interval would exclude one half but include one third.
If you think the problem is your runs were too short, try the link I give several comments down (not in response to a person, just the the story). You can easily do runs of a million or more. For example, if I do three runs, the percentages I get for males are: 33.36%, 33.29%, and 33.30%.
"because the known boy is the first known, reading left from right."
Why? What if they were listed by age and you knew the older one? The younger one? The key point to the question is it doesn't specify which boy you know, or that you even know a specific one. If someone said "I have two kids, and Bobby is such a handful" you can't say the "first" or "second" is Bobby in any order without more information.
Regardless, it was a great accomplishment even if there turns out to be more problems.
You can see chips coming off with a purple to blue color, meaning they are reaching temperatures of over 300 C. Once upon a time, I saw an offline video showing high end machining of some high temperature metal (like some kind of Inconel). It was a material that had big problems with work hardening, where strain causes the material to harden, so if you cut too slowly with the mill it will strengthen the material in front of the cutter faster than it cuts it away, wrecking havoc on the cutter. The solution is to cut very aggressively, producing red to yellow hot chips. Online videos of similar things were not as impressive as the one I saw offline, although I haven't looked too hard recently. It is one thing one a grinder makes hot dust, but another when a cutting edge going at near highway speeds is producing large, glowing chips.
The pumpkin one can be done with alcohol instead. I wouldn't do the acetylene version myself, as there have been a few too many incidences with acetylene in a confined space suddenly exploding a lot more than expected. Some people I knew had setups (not pumpkins though) that worked fine several times, then got knocked on their butt and were lucky no shrapnel was involved.
The microwave oven transformer mod is a fun one that comes up some outreach demonstrations, and is essentially just doing what a primitive arc welding unit will do. In fact, you can build a primitive arc welder with a few more cheep parts.
Either I strongly disagree with his interpretation of what relativity is saying, or he said it very poorly. While a key part of general relativity is that the effects of gravity and acceleration are indistinguishable from a closed box, it doesn't change that objects will still fall toward the Earth.
You pick one of three doors on a game show, trying to find the one of the three with a prize. The game show host then always opens one door that does not have the prize, and asks if you want to switch your choice to the door you didn't choose and he didn't open.
You can demonstrate by straightforward experiments that by switching you have a 2/3 chance of winning, while not switching gives you a 1/3 chance of winning. If you simply ordered the doors by the order they were revealed, you would say that the two remaining doors each have a 50-50 chance of having the prize, and there is no reason to switch. Except both probability reasoning similar to what gives 1/3 for the problem in the story above, and simply trying it out experimentally show it is not 50-50.
The key in both cases is that what you are told gives you information. In the Monty Hall problem, the host always opens a losing door: in the case your first pick was right, it doesn't change anything by switching, but if you were wrong with your first pick, it guarantees your second pick will be right. By saying that one of two child is a boy, you've already said they can't both be girls, but didn't say which of the two kids is a boy.
The genotype vs. phenotype example I previously gave might seem more clear (to me at least). You have two carrier parents (each with a dominant and recessive gene). You look at the offspring, and can see which ones are double recessive, because they express the recessive trait. You grab one that is not expressing the recessive gene, what are the chances of it being a carrier versus double dominant? That is the same as saying you know one of the genes is dominant because it shows the dominant phenotype, but there is still a 2/3 chance of it being a carrier versus a 1/3 chance of it having no recessive genes at all. You can't say "Gene #1 is the one I know is dominant" and "Gene #2 is the one I don't know" because you don't know which of the two you actually know (e.g. if they both were dominant, you couldn't point to one and say that was Gene #1).
In other words, if you were told of two kids: Pat and Chris, and told one, but not which one, is a male, you would say the first child in your order is the first one revealed, a male one. If you found out both Pat and Chris were boys, which one was the one you were labeling as the "first child?" You can't say if you were referring to Pat or Chris in that case, so your original labeling was not referring to a specific child.
Run 1: 13/31 -> 42+/-9% -> about 16% chance you got below half by luck
Run 2: 12/29 -> 41+/-9% -> about the same
Run 3: 10/27 -> 37+/-9% -> about 8% chance you got below half by luck
Run 4: 8/21 -> 38+/-11% -> about 15% chance getting below half by luck
Combined: 43/108 -> 39.8+/-4.7% -> less than a 2.5% chance of it originally being half or above, i.e. a 95% confidence interval would exclude one half but include one third.
If you think the problem is your runs were too short, try the link I give several comments down (not in response to a person, just the the story). You can easily do runs of a million or more. For example, if I do three runs, the percentages I get for males are: 33.36%, 33.29%, and 33.30%.
Why? What if they were listed by age and you knew the older one? The younger one? The key point to the question is it doesn't specify which boy you know, or that you even know a specific one. If someone said "I have two kids, and Bobby is such a handful" you can't say the "first" or "second" is Bobby in any order without more information.