this post was submitted on 26 Jun 2026
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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.
Gamma rays do travel faster than light through some media, but obviously not faster than c, the speed of light in a vacuum.
Well yeah, the media was that one kid's 7th grade science book
by my grade 7, i had already learned all about dalkon shield and iuds, silicone breast implants and their risks, rely tampons and toxic shock syndrome, roe v wade, aids and homosexuality......
that was just the sex ed units from the regular nightly news.
OK
Gamma rays are photons like light no? Is the speed in a medium related to its energy/frequency? Or am I misunderstanding something
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.
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.
True, but this doesn't explain if gamma rays move faster than light in certain materials, right?
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.
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.
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.
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.
I dunno about xrays, but it is true that light slows down in media and that particles can move faster than light in that medium, that's where Cherenkov radiation comes from! (Though I'm not sure if that also just slows down the particles or what)
Fascinating, thanks for the info!
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.
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.
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.
That's an odd one, since you'd think peeing or not peeing blood would be very easy to verify.
Wat
Ah, that's just omitting the details. She forgot about the circumstances of the situation, like, e.g., a super strong vacuum cleaner. /s
PSA: Go to the doctor if you're pissing blood.
Came here to say the same thing, for years I was believing my blood was blue before it hit oxygen....
I was going to add the "hitting oxygen" is an important part of the blue blood myth back then.
Which is really funny since your blood is already oxeygenated
Ah, but I think the "blue" blood you see is in your veins, which carry "spent" blood with low oxygen content. Those kinds of little truths are what make myths believable, too.
Holy shit.
As someone who does not possess the knowledge, is blood white? The deoxygenated channels?
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.
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.
It's actually green
🖖
That one guy in Carbon Creek is an outlier and should not be counted.
Plasma separated from red blood cells is sorta yellowish beige. At least in IV bags.
Blood separates into white, yeah. That's basically my understanding of (a type of) pus formation.
We still have pictures like this in books! It makes it hard to break the cycle.