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[–] 82 points 4 months ago (34 children)

We were taught blood was blue in school, not just once, in at least two grades. Not in the book mind you, but from the teachers' mouths.

The 7th grade science book did teach us gamma rays move faster than the speed of light, which is bullshit.

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  • [–] 51 points 4 months ago (13 children)

    Gamma rays do travel faster than light through some media, but obviously not faster than c, the speed of light in a vacuum.

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  • [–] 23 points 4 months ago (2 children)

    Well yeah, the media was that one kid's 7th grade science book

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  • [–] 7 points 4 months ago (9 children)

    Gamma rays are photons like light no? Is the speed in a medium related to its energy/frequency? Or am I misunderstanding something

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  • [–] 2 points 4 months ago

    That's correct, sort of. Individual photons travel always at c (they don't have mass, so they literally can't go slower), but when traveling through a transparent (for their frequency) medium they don't go through the atoms or around them—they would hit an atom (its electrons, really), get absorbed, and then re-emitted. The average speed of all the photons will be lower than c, and depends on the frequency, that's how we got rainbows. For most frequencies, including visible light, it goes slower the higher the frequency is, but gamma rays/x rays photons are so high energy that they don't interact with the electrons, but with the nuclei—that's why you want materials like lead or tungsten to block them—which are much smaller, resulting in fewer absorbing-emitting interactions and a higher average speed.

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  • [–] 3 points 4 months ago (7 children)

    Its because "speed" can refer to two different things in this context. Group velocity is the speed that your light waves can send a message it. This cannot move faster than light. Phase velocity on the other hand is the speed of the peaks of the wave. This can move faster but its not possible to send a signal through this.

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  • [–] 4 points 4 months ago (6 children)

    True, but this doesn't explain if gamma rays move faster than light in certain materials, right?

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  • [–] 2 points 4 months ago* (5 children)

    If you had a material with no light passing through it, then you shined a light through it, it would only move at the group velocity. The whole "faster than light" thing refers to the phase velocity, but you can't have a phase velocity if the light hasn't gotten there yet.

    Saying that gamma rays (or any light in general) moves faster than light is technically true but very misleading and relies heavily on when you define "speed" as.

    3Blue1Brown has a good video on why the phase velocity is different from the group velocity if you're interested in why. The faster than light phase velocity happens when the "phase kicks" are so delayed that the phase appears to move forward.

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  • [–] 1 point 4 months ago* (4 children)

    I must misunderstand, I wasn't thinking of the "group velocity" (or that "frequency" making light "faster than light"), but plain old slow speed of light!

    Like in water, light moves (as for data transfer) slower than in vacuum, right? There are materials that slow down light to a crawl (I read some theory some time ago about slowing down light to almost zero).

    So I thought that in some material, x-rays were faster than light, both being slower than c of course.

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  • [–] 1 point 4 months ago (1 child)

    c is the speed of light in a vacuum. It is impossible to send information faster than c. x-rays are also just light so everything I said before also applies to x-rays.

    I'm not very familiar with how light interacts with materials since it wasn't covered in the electromagnetism class that I took, so the next part might be wrong. The speed of light is calculated by looking at Maxwell's laws of electromagnetism and recognizing that it is the equation for a wave. The speed is then calculated as c = 1/sqrt(epsilon_0 * mu_0) where epsilon_0 and mu_0 are the vacuum permittivity and the vacuum permeability. Inside a material, I think the permittivity and permeability are different and thus the speed of light as determined by Maxwell's equations would be different. I know its not possible for the speed (group velocity) of light in a material to be faster than the speed of light in a vacuum because otherwise, you could send information faster than c, which is impossible.

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  • [–] 1 point 4 months ago

    Yeah we all know that (don't remember that function but if you say so, tje one I was taught was for sure simpler), but the question is not if light can be made to move slower (or over c) but if it moves slower than another electromagnetic radiation like x-rays in some specific material.

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  • [–] 16 points 4 months ago (6 children)

    The worst misinformation we got was that after erections (which functionally are made via blood flow) boys pee out the blood. Like Jesus fuck lady, what is wrong with your husband.

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  • [–] 6 points 4 months ago (1 child)

    That's definitely not about her husband, it's about scare tactics. The reason behind using scare tactics can be many, like religion, suppressed sexuality, what she was taught or even just not wanting to deal with her students doing stuff. It's absolutely not ok to say that no matter the reason though.

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  • [–] 1 point 4 months ago

    We got a lot of such lies, for instance on Marijuana, and everyone found out it was bullshit if they didn't already know, and it destroys the credibility of the authorities. Which in truth might be the most important message school could teach our kids heading into the 21st century, the government is dishonest. Everything is based on lies, and if it isn't they are trying to end that part of government.

    But they told us about cancer, it making you impotent and sterile, stupid and brain damage, all sorts of bullshit. Much based on studies where they spray pesticides on the plant then blame the plant for the pesticide effects. Thank the University of Missouri I think it is for a lot of that bullshit.

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  • [–] 15 points 4 months ago (3 children)

    Came here to say the same thing, for years I was believing my blood was blue before it hit oxygen....

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  • [–] 8 points 4 months ago (2 children)

    I was going to add the "hitting oxygen" is an important part of the blue blood myth back then.

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  • [–] 7 points 4 months ago* (7 children)

    Holy shit.

    As someone who does not possess the knowledge, is blood white? The deoxygenated channels?

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  • [–] 21 points 4 months ago* (1 child)

    Deoxygenated, venous blood is dark red. Oxygenated, arterial blood is bright red.

    I was taught the "blood is blue" myth also. My mom was livid, since her job involved drawing lots of blood, starting IVs etc.

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  • [–] 2 points 4 months ago

    I called bullshit from the start on that. If it was true, that blood turned red when it touched oxygen, then pulling blood from the vein in a needle would be blue. Teachers told me to shut up.

    It's such a stupid theory, knowing what we knew.

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  • [–] 37 points 4 months ago (2 children)

    We're still there, aunt Marge is just called Grok now.

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  • [–] 28 points 4 months ago (3 children)

    Now an LLM has parsed Aunt Marge's Facebook posts into it's knowledge bank and regurgitates it to everyone searching online for an answer.

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  • [–] 7 points 4 months ago (2 children)

    I'd prefer it if they actually worked that way

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  • [–] 1 point 4 months ago*

    It kinda does, but it's everyone's Facebook posts, and it's stored in a lossy way as a weighted graph rather than in a database, and it will sometimes traverse the graph down a different path depending on if venus is crowning a supercrescent moon.

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  • [–] 25 points 4 months ago (3 children)

    I had an argument with a teacher in middle school who shared the crap of, “If you swallow gum, it stays in your stomach for 7 years.” The kids told me I must be wrong, because the teacher said it so he must be right.

    I was so pissed that I came in the next day with three different sources saying that it was a myth. He quietly admitted the truth to me, but refused to tell the class.

    I get being frustrated with kids chewing gum in class, but if you have to lie to get them to follow rules, that’s a failure as a teacher. He was a science teacher, no less. If anybody should be open to a student pulling up sources for a claim, or to admitting they learned something new and they were wrong before, it should be a science teacher.

    Thanks, Mr H. Way to prove to me that even “cool” teachers care more about controlling kids than being truthful.

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  • [–] 10 points 4 months ago (1 child)

    He quietly admitted the truth to me, but refused to tell the class.

    98% of humanity, right there. Fuck I hate them.

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  • [–] 6 points 4 months ago*

    Yep, it was a lesson that cut deep. Which is why I won't let such stuff pass with my own students. One of my coworkers wanted to discourage a kid from using permanent markers and told him he'd give himself ink poisoning. The kid took it to heart and started saying he was allergic to tattoo ink. It was kind of funny at first, but he kept repeating it until it got concerning. I think he was starting to be scared of markers.

    I just told him the truth - he's probably not going to get sick, but permanent markers are hard to clean off of things, including skin, and that some of his peers might use them on things they aren't supposed to. He's a smart kid who just wants to understand things and will think through stuff he doesn't understand until they make sense to him, even if it means imagining an allergy to something he sees other people use just fine. It breaks my heart to think that's not the last time some adult will tell him a myth, but hopefully his natural desire to make sense of things will continue to develop into a first-rate bullshit alarm someday.

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  • [–] 25 points 4 months ago (1 child)

    Now you ask uncle Grok and carry his misinformation for 20 minutes, because your long-term memory doesn't exist anymore.

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  • [–] 22 points 4 months ago (7 children)

    My dad told me thunder is when clouds collide

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  • [–] 17 points 4 months ago (8 children)

    "Urine is sterile"

    "You can only fold paper 7 times"

    Etc.

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  • [–] 11 points 4 months ago (7 children)

    The paper thing is is testable! It’s not wrong. «You» can’t do it

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  • [–] -1 points 4 months ago* (5 children)

    DIN A4? Maybe

    DIN A1? I can do more than 7 times

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  • [–] 3 points 4 months ago (1 child)

    assume your hypothetical sheet of paper has thickness 1u; on fold iteration 1: thickness of the paper is doubled, 21u = 2u on fold iteration 2: thickness gets doubled again l, 22u = 4u

    this pattern continues for all subsequent iteration and by the seventh iteration the thickness of the paper is 2^7^ * 1u = 128u

    hence by the seventh iteration, assuming you have managed to reach this far, you will be trying to fold something that is 128 times thicker than your first fold.

    also whether it be DIN A4 or DIN A1 it doesnt matter, the ability to fold is dependent on the thickness of the paper, which is the same.

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  • [–] 16 points 4 months ago (1 child)

    And with AI and anti-science grifters, we’re back to that world!

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  • [–] 29 points 4 months ago (1 child)

    Nothing has really changed since then.

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  • [–] 14 points 4 months ago (5 children)

    We were led to believe we'd die if we ate a single apple seed until about 1995, when I observed my FIL eat an entire apple, core, seeds, and all, which obviously blew my mind.

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  • [–] 7 points 4 months ago (3 children)

    They will kill you, but you need to chew up a couple hundred.

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  • [–] 13 points 4 months ago (2 children)

    Tbf, some blood is blue, it just tends to be a few types of invertebrates that have that blood.

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  • [–] 13 points 4 months ago

    Now someone’s aunt marge in another country does it.

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  • [–] 12 points 4 months ago (1 child)

    As if now people are knowledgeable...

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    [–] 21 points 4 months ago

    Or, if you were lucky, you could look things up in your out of date encyclopedias.

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  • [–] 9 points 4 months ago* (1 child)

    I was taught that the white race was superior and that there was going to be a huge race war (one side of the family) and then Jesus was going to come back and murder everybody (other side).

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  • [–] 7 points 4 months ago

    My ex thought that night time just meant that the moon went in front of the sun. I have no idea how she managed to live to 30 years old before she learned about night time.

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  • [–] 6 points 4 months ago (1 child)

    Cousin asked my uncle how cows stood straight on the hills. He said one set of legs were shorter than the other s and sincerely believed that until going off to college lol

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  • [–] 11 points 4 months ago (1 child)

    You could go to your local library. I still do.

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  • [–] 5 points 4 months ago (2 children)

    I used the library. Because I didn't trust people or they didn't even attempt to answer. "I don't know, who cares."

    Even if I wanted to use the internet, when it started becoming popular, it used to be in the library. You'd have to reserve 30min to an hour timeslots beforehand. And then physically go back to the library at that specified time and use their computer to browse. Going to AltaVista.

    I used to Ask Jeeves.

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  • [–] 5 points 4 months ago

    My grandfather told me that grits were ground-up pig's knuckles. I was in my late 20s before I learned otherwise. Pop just didn't want to share his fucking grits, which is at least understandable.

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  • [–] 4 points 4 months ago

    Now you can go online and double down on your misinformation.

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  • [–] 3 points 4 months ago (1 child)

    "The eyeball is full of blackberry jam."

    ~ My grandfather, unironically, not remotely joking, actually completely serious.

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  • [–] 3 points 4 months ago

    Or you'd read an out of date Encyclopedia

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  • [–] 1 point 4 months ago

    I like the way Mary Jo and Bridget explained on a rifftrax video for 'Duties of a Secretary' - "Secretaries were the internet in heels."

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  • [–] 1 point 4 months ago

    This meme is older than Lemmy.

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