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Fun Fact Thread! (previously fun fact for the day, not limited to 1 per day anymore.)


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On 8/23/2022 at 2:14 PM, Maria Sirona said:

That's beautiful. What is that red glow near the poles? Methinks it's aurorae

Correct, they are aurorae that would fit the Earth many times over, very impressive. The bigger riddle though is what that 'double rim' on the right side of the planet is. Nobody really seems to know, initially it was even thought it might have been some sensor alignment problem, but that doesn't seem to be the case, it has shown up in several images and it seems to really be there. I think it has been suggested that it's a thin layer of Hydrogen, however, that shouldn't be there in such high quantities, and that doesn't explain why it's only seen on 1 side of the planet. It's the old story again, you lob something up there to find answers, and all you get are more questions :)

 

 

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I'm sure many of you have come across this question a few times, it's an old one but made more widely known in recent years due to the fact that it is supposedly a question asked when applying for a job at SpaceX:

"You walk 1 km South, you then walk 1 km East, and then 1 km North again, and you end up at the same spot as where you started. Where are you?"

The press then typically gives the answer (You're at the North pole) and tells us the purpose of this question is to test creative thinking.

I hereby pose that anyone who answers this question with "I'm at the North pole" has failed the creative thinking test, and should therefor not get the job. Why? Because there are an infinite number of points on a globe that are a valid answer to this question, and all but one of them are nowhere near the North pole. Think about that for a moment before reading on, can you come up with the other locations that are a valid answer?

The full, correct answer to this question is: You're either at the North pole, OR you are 1 + 1/(n*2*pi) km North of the South pole, for any positive integer 'n'.

Let's take n = 1, so you're approximately 1159 meter North of the South pole. You walk South for 1 km, ending up 159 meter North of the South pole. You now walk 1 km due East, what happens? You will be walking in a circle around the South pole, always keeping a distance of 159 meter to it. The circumference of that circle is of course 2*pi*r, which is exactly 1 km, so after walking that distance, you end up at the same spot as where you started walking East. Finally you walk 1 km North, ending up at the same spot where you started.

For n > 1 the effect is the same, except while walking East, you walk n full circles around the South pole instead of a single circle. So by far the most likely answer (with p = (inf-1)/inf ≈ 1) is that you are between 1000 and 1160 meter of the South pole, just about as far away from the North pole as is possible!

 

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22 hours ago, Beamer said:

I'm sure many of you have come across this question a few times, it's an old one but made more widely known in recent years due to the fact that it is supposedly a question asked when applying for a job at SpaceX:

"You walk 1 km South, you then walk 1 km East, and then 1 km North again, and you end up at the same spot as where you started. Where are you?"

The press then typically gives the answer (You're at the North pole) and tells us the purpose of this question is to test creative thinking.

I hereby pose that anyone who answers this question with "I'm at the North pole" has failed the creative thinking test, and should therefor not get the job. Why? Because there are an infinite number of points on a globe that are a valid answer to this question, and all but one of them are nowhere near the North pole. Think about that for a moment before reading on, can you come up with the other locations that are a valid answer?

The full, correct answer to this question is: You're either at the North pole, OR you are 1 + 1/(n*2*pi) km North of the South pole, for any positive integer 'n'.

Let's take n = 1, so you're approximately 1159 meter North of the South pole. You walk South for 1 km, ending up 159 meter North of the South pole. You now walk 1 km due East, what happens? You will be walking in a circle around the South pole, always keeping a distance of 159 meter to it. The circumference of that circle is of course 2*pi*r, which is exactly 1 km, so after walking that distance, you end up at the same spot as where you started walking East. Finally you walk 1 km North, ending up at the same spot where you started.

For n > 1 the effect is the same, except while walking East, you walk n full circles around the South pole instead of a single circle. So by far the most likely answer (with p = (inf-1)/inf ≈ 1) is that you are between 1000 and 1160 meter of the South pole, just about as far away from the North pole as is possible!

 

After a good night sleep I recalled something from a long time ago. See I originally heard this riddle from my father when my age still measured in the single digits (that was some 4 decades ago), which is one of the reasons it caught my eye when it popped up again recently. My dad was a scientist himself (chemist) and always supported my curiosity for the various sciences, so he often came up with riddles like this to tickle my growing brain.

The original riddle as he posed it to me way back then was a variation on the above, going something like: "A bear walks 1 km South, ...<etc>... and ends up at the same place as where he started. What colour was the bear?"

The answer of course is white, since it has to be a bear living near the poles. But polar bears only live at the North pole, not the South pole. So in the original version as I heard it, you had to figure out that the location was a pole, and that there was a bear there, so it had to be the North pole. By changing the riddle to not be about a bear, the infinite number of solutions around the South pole was created. Maybe this is why the press (at least as far as I've seen) never comes up with the full correct answer. Perhaps along the way someone changed the wording of the riddle (removing the reference to the bear) without realizing this would change the valid answers. It's like a game of science-riddle-telephone.

Edit: to keep things simple, let's not get into the fact that polar bears are actually black skinned and the whiteness we see is just the effect of the light on their transparent hairs, that's another fun fact altogether :D )

 

Edited by Beamer
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The whole polar bears are black thing is just people trying to appear superior by knowing something. The skin may be black but their fur is clearly white. Sure there is a reason why their fur is white but that is true of everything.

Supporting xkcd

rayleigh_scattering_2x.png

 

 

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4 minutes ago, tomf said:

The whole polar bears are black thing is just people trying to appear superior by knowing something. The skin may be black but their fur is clearly white. Sure there is a reason why their fur is white but that is true of everything.

Supporting xkcd

rayleigh_scattering_2x.png

 

 

https://xkcd.com/1818/

I'm pretty sure a Polar bears fur is white because it has no color is the fur.

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47 minutes ago, tomf said:

The whole polar bears are black thing is just people trying to appear superior by knowing something. The skin may be black but their fur is clearly white. Sure there is a reason why their fur is white but that is true of everything.

Supporting xkcd

rayleigh_scattering_2x.png

 

 

Knowing some things is what pub quizzes are all about. Yes, I really did get the question what colour a polar bear's skin is in a pub trivia :)

However knowing that it isn't white probably also means that you know about the truly interesting part, that their hairs have evolved to be the natural equivalent of glass fiber in order to conduct as much sunlight to their skin as possible, which then  of course means that black is the ideal colour for the skin to be, as it absorbs the most of that light.

Isn't stuff like that what this whole thread is about?

 

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While we're talking about light and colours, here's one from my field of work I've always found amusing.

First a bit of background: Glass is transparent because it transmits pretty much all the visible light at every wavelength equally. All over the visible spectrum, it lets through 95% or so. However, it doesn't stop at the edge of the visible spectrum either. It's equally transparent quite far into the infrared. This means that it's transparent to thermal radiation as well as visible light. From the perspective of a "ray" of heat, it doesn't matter if your window is open or closed, heat passes through regardless.

Now, this is obviously not good for building energy management. We'd like our windows to insulate against the cold. Or the heat, depending on your climate. To help energy efficiency, modern windows are coated with a transparent coating that blocks thermal radiation - that is, infrared light.

And that's the cool part: what do you call a substance that blocks radiation in only a certain part of the visual spectrum? Coloured!

Essentially, modern windows are painted in a colour we can't see. It's totally unlike other colours, because our eyes can't perceive it, but it can be measured. Some animals can probably see it too.

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1 hour ago, Codraroll said:

While we're talking about light and colours, here's one from my field of work I've always found amusing.

First a bit of background: Glass is transparent because it transmits pretty much all the visible light at every wavelength equally. All over the visible spectrum, it lets through 95% or so. However, it doesn't stop at the edge of the visible spectrum either. It's equally transparent quite far into the infrared. This means that it's transparent to thermal radiation as well as visible light. From the perspective of a "ray" of heat, it doesn't matter if your window is open or closed, heat passes through regardless.

Now, this is obviously not good for building energy management. We'd like our windows to insulate against the cold. Or the heat, depending on your climate. To help energy efficiency, modern windows are coated with a transparent coating that blocks thermal radiation - that is, infrared light.

And that's the cool part: what do you call a substance that blocks radiation in only a certain part of the visual spectrum? Coloured!

Essentially, modern windows are painted in a colour we can't see. It's totally unlike other colours, because our eyes can't perceive it, but it can be measured. Some animals can probably see it too.

I’m guessing low-light surveillance cameras or night vision goggles could pick it up? Assuming it’s not overwhelmed by other colours? And how far up the ultraviolet is glass transparent?

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2 hours ago, Codraroll said:

Essentially, modern windows are painted in a colour we can't see. It's totally unlike other colours, because our eyes can't perceive it, but it can be measured. Some animals can probably see it too

That's a really cool way of looking at it /describing what is going on! 

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9 hours ago, StrandedonEarth said:

I’m guessing low-light surveillance cameras or night vision goggles could pick it up? Assuming it’s not overwhelmed by other colours? And how far up the ultraviolet is glass transparent?

Low light is just the ability to see at very low light levels, for IR the windows would be non transparent like if painted over. Glass naturally blocks UV light

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10 hours ago, StrandedonEarth said:

And how far up the ultraviolet is glass transparent?

Quite a bit if it's not coated, which is why items left in your window sill will be bleached by the sun. You don't get that degradation just from visible light.

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1 hour ago, Codraroll said:

Quite a bit if it's not coated, which is why items left in your window sill will be bleached by the sun. You don't get that degradation just from visible light.

Did not know, I believed glass blocked UV light, you can not use standard glass in solarium lamps. 

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Now on to something completely unrelated, two things about Finland!

1. We have an ages-old traditional food called the Karelian Pie, (karjalanpiirakka) which consists of a thin rye dough surrounding a lump of rice porridge. In a country that is way too cold to grow rice and is far from where rice is grown.

2. There is an actual proper word in finnish for LGBTQIA+ people, that being "sateenkaari-ihminen". It literally means "rainbow human/person".

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18 hours ago, Codraroll said:

While we're talking about light and colours, here's one from my field of work I've always found amusing.

First a bit of background: Glass is transparent because it transmits pretty much all the visible light at every wavelength equally. All over the visible spectrum, it lets through 95% or so. However, it doesn't stop at the edge of the visible spectrum either. It's equally transparent quite far into the infrared. This means that it's transparent to thermal radiation as well as visible light. From the perspective of a "ray" of heat, it doesn't matter if your window is open or closed, heat passes through regardless.

Now, this is obviously not good for building energy management. We'd like our windows to insulate against the cold. Or the heat, depending on your climate. To help energy efficiency, modern windows are coated with a transparent coating that blocks thermal radiation - that is, infrared light.

And that's the cool part: what do you call a substance that blocks radiation in only a certain part of the visual spectrum? Coloured!

Essentially, modern windows are painted in a colour we can't see. It's totally unlike other colours, because our eyes can't perceive it, but it can be measured. Some animals can probably see it too.

So basically, what are windows for us would be sunglasses for the JWST?

 

5 hours ago, magnemoe said:

Did not know, I believed glass blocked UV light, you can not use standard glass in solarium lamps. 

I once saw a docu where they examined the facial skin of long time professional drivers. All of them had significantly more UV damage to the skin on the left side of their face (which were in the sun most of the time), to the point where you could clearly see the difference with the naked eye. What I got from that was basically that glass filters the 'good' UV (UVB, needed for vitamine D production) but lets through the 'bad' UV (which causes DNA degradation, skin cancers, etc). Mind you this was from back in the 90s and specifically looked at the glass used in car/truck windows, maybe glass coating tech has progressed since then to reduce this problem.

 

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Monarchy is one of the few things that can travel faster than light. The system is set up so that the reign of one monarch officially begins instantly when their predecessor dies. There can never not be a monarch.

If Queen Elizabeth had died in a hoverboard accident on Mars instead of in Scotland, the news would take 30 minutes or so to reach Charles on Earth, even if he was watching the livestream of her fatal attempt at doing a 1080 over the mouth of a sandworm on fire, due to light speed delay. However, from his point of view, his regency would have begun 30 minutes before he watched the spectacular crash.

Of course, things get a little complicated as soon as you start considering third-party observers to verify the timing of the transition of power, but with the monarch and the heir apparent as two fixed points in time and space, it works out quite well between the two, at least.

Edited by Codraroll
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11 hours ago, Codraroll said:

Monarchy is one of the few things that can travel faster than light. The system is set up so that the reign of one monarch officially begins instantly when their predecessor dies. There can never not be a monarch.

If Queen Elizabeth had died in a hoverboard accident on Mars instead of in Scotland, the news would take 30 minutes or so to reach Charles on Earth, even if he was watching the livestream of her fatal attempt at doing a 1080 over the mouth of a sandworm on fire, due to light speed delay. However, from his point of view, his regency would have begun 30 minutes before he watched the spectacular crash.

Of course, things get a little complicated as soon as you start considering third-party observers to verify the timing of the transition of power, but with the monarch and the heir apparent as two fixed points in time and space, it works out quite well between the two, at least.

Not true. In actuality because they didn’t know for 30 minutes, Queen Elizabeth’s reign would continue after her death for 30 minutes.

A system can spout all of the regulatory stuff it wants but in reality, the Queen was still the monarch inside everyone’s head on Earth and every institution on Earth and therefore she was for those 30 minutes until the news arrived; the technicalities only exist on paper.

Can something on paper be called “faster than light”?

Edited by SunlitZelkova
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“Nothing travels faster than the speed of light with the possible exception of bad news, which obeys its own special laws. The Hingefreel people of Arkintoofle Minor did try to build spaceships that were powered by bad news but they didn't work particularly well and were so extremely unwelcome whenever they arrived anywhere that there wasn't really any point in being there.” ― Douglas Adams, Mostly Harmless

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6 hours ago, SunlitZelkova said:

Not true. In actuality because they didn’t know for 30 minutes, Queen Elizabeth’s reign would continue after her death for 30 minutes.

A system can spout all of the regulatory stuff it wants but in reality, the Queen was still the monarch inside everyone’s head on Earth and every institution on Earth and therefore she was for those 30 minutes until the news arrived; the technicalities only exist on paper.

Can something on paper be called “faster than light”?

Those 30 minutes would be a gap in the monarchy; time when the previous monarch was dead but the new one unaware of it. And monarchy does not allow for gaps. 

Hence, when Charles sees it happening, he will learn he has already been monarch for 30 minutes. Or in other words, the exact start of his reign would be impossible for him to experience. It can only be learned about after the fact.

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