What is Hair: Definition and 133 Discussions

Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals.
The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types, and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha-keratin.
Attitudes towards different forms of hair, such as hairstyles and hair removal, vary widely across different cultures and historical periods, but it is often used to indicate a person's personal beliefs or social position, such as their age, sex, or religion.

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  1. lk0306

    Do these substances emit formaldehyde gas when heated?

    Hey there, Trying to confirm whether or not these substances emit formaldehyde gas when subject to heat of hair straightener and hairdryers. Both were ingredients in a keratin treatment i used at home and i had a crazy reaction (irritated skin, eyes, hair, nose and lungs) in the process of...
  2. S

    I Laser and hair - scattering or destructive interference?

    There is a video, where the author shows the interference of laser beam on a strand of human’s hair: I bought a laser pointer and reproduced this experiment. Indeed, when a single hair is placed on the way of the laser beam, I see the “scattering” picture (a series of points with intervals of...
  3. kma

    Can wet hair cause an electric shock if it gets into outlet/power cord

    Hi I have a very random question I would like to ask. Say if someone just got out the shower and either plugged something into the wall, or plugged a high voltage power cord into a device. In the process of doing so a small clump or strand of their wet hair manages to get into the socket or the...
  4. atyy

    A Calmet & Hsu: Quantum hair and black hole information

    https://www.bbc.com/news/science-environment-60708711 Scientists claim hairy black holes explain Hawking paradox https://arxiv.org/abs/2112.05171 Quantum Hair and Black Hole Information Xavier Calmet, Stephen D.H. Hsu It has been shown that the quantum state of the graviton field outside a...
  5. PainterGuy

    Medical Curly hair gene, straight hair gene

    Hi, One of my cousins had a baby almost six months ago. The baby's father has straight hair and mother has very curly hair. After almost six months, the baby's hair started looking somewhat wavy. By "wavy" I mean a little curly. Out of curiosity, I wanted to see which gene is dominant - curly...
  6. L

    Hair Depilation? (with hair removers like Nair)

    Are hair removals like Nair safe and do they in anyway increase future regrowth of hair? If they are rather abrasive can it be diluted enough to practically wash itself away with sweat? Would hate to chemical burn myself, but back hair is otherwise hard to address. Shaving is near impossible...
  7. jim mcnamara

    Hair Freezing Contest: Chilling Photos From A Unique Event

    https://www.atlasobscura.com/articles/what-is-a-hair-freezing-contest I do not know where to post this, exactly. Photos are interesting...
  8. G

    Automatic Hair Comb Question

    Hey guys! I've got an OTF comb (a.k.a. "out the front," where the plastic hair comb "blade" ejects straight out from the handle) that is held in the closed position with 1 lb, 12 ounces of magnetic force. I.e, upon measuring it takes 1 lb, 12 oz. of finger pressure against the comb switch to...
  9. DaveC426913

    Halloween: Gluing things to facial hair

    Googling the title will get you a million hits on how to glue a fake beard on. I have a real beard and want to glue stuff to it. My first attempts are not viable. Need suggestions. OK, here's the concept: "Mandusa" My moustache is about 1" long and my beard is only about 3/4". I started with...
  10. T

    Low level hand held lazer therapy for hair works?

    Hi, does low level hand held laser therapy work for stimulating the hair follicles, scalp and improve your hair’s appearance with a couple of fifteen minute sessions per week? if yes how much do they cost?
  11. S

    Changing the Air Temperature with a hair dryer

    Hi, so I found this on another old "AP" High School Finals Exam. I think I may be super lost. Because the only way that I can think about is KE = 3/2kT. And then that the difference of the Kinetic Energy of the air Particles is the Q supplied by the heater inside the air dryer. So ## \frac...
  12. A

    MHB HELP How to calculate wage for assistants at hair salon?

    Hello! So I'm not sure if this is the right forum or thread to ask this question but I really need help figuring out a formula in a work context. Please help if you are able! My mother owns a hair salon where the stylists share the help of several assistants. There are 4 stylists and 4...
  13. P

    A cure for gray hair is on the way?

    I saw this news article (here is the article about it in a medical journal) and began to wonder if the cure for gray hair is on the way. Those immunotherapy drugs can restore hair color on healthy people?, And what about the safety? It is dangerous to healthy people more than to cancer...
  14. spareine

    Electrostatic levitation of hair

    If a person with long thin hair touches a Van de Graaff generator, his hair will begin to levitate by electrostatic repulsion. The body is a conductor. Hair is an isolator, so the charge cannot flow through the shaft from root to end. To me it is unclear whether the hair is charged...
  15. D

    Can Sleeping with Wet Hair Cause Insanity? The Truth Revealed!

    I always bath before I sleep and sometimes my short hair not so dry... is there a basis that one can go insane if one sleeps with wet hair? how?
  16. J

    Does body hair really grow back thicker each time you shave?

    Does body hair really grow back thicker each time you shave it? I hope this is just a myth. It's gotten me worried about shaving my facial hair too much.
  17. E

    B Help with Physics lab idea (creative)

    Hiya! In school we have tha task to create our own phy lab. I am going to investigate the width of a hair using wave diffraction (a laser maybe?). Does anyone have any creative ideas on how to develop the lab to make it more uniqe and interesting. E.g measuring from different distances. Or...
  18. NaukowiecGirl

    Uses for laser light in measuring hair width

    I have a question that I feel I cannot find enough on. We just did a practical in Physics class where we used a laser light shined on a single hair strand in order to create a diffraction pattern and use formulae to determine the hair's width. Because of Babinet's principle, the hair managed to...
  19. dlgoff

    Why Fathers Get Gray Hair

    In my case anyway, this does:
  20. Efast

    Why do our bodies stay neutral after combing our hair?

    **This is more a general understanding question rather than a homework question** 1. Homework Statement So when you comb your hair trillions of electrons get transferred from your hair to your comb. So when trillions of electrons go missing how is your body able to maintain a neutral charge...
  21. E

    Hair/wire laser diffraction interference pattern

    Hair/wire laser diffraction interference pattern - does it follow single-slit or double-slit? for single-slit interference, the equation nλ = d (y/D), (d is the width of the single-slit, y is the distance between central BRIGHT fringe to the nth DARK fringe, D is the distance from slit to...
  22. haael

    A Do black holes lose hair in finite time?

    OK, so it's time to start a new thread. I heard many times that there exists only one black hole solution for a given mass and angular momentum, but I know already that this is not true. We all know that if we throw something into an existing black hole, its event horizon starts to ripple. So...
  23. M

    Can a hair dryer burn? Thermodynamic considerations....

    Hi all, I actually work in physics (quantum physics) but my thermodynamics knowledge is a bit lacking these days. The following problem has had me puzzled for quite a long time. Basically, if I point the hot air coming out of a hairdryer at a target, will that target's temperature ever go...
  24. K

    Soft Hair on Black Holes

    Soft Hair on Black Holes Stephen W. Hawking, Malcolm J. Perry, Andrew Strominger (Submitted on 5 Jan 2016) It has recently been shown that BMS supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These...
  25. Monsterboy

    Humans Lost Body Hair: What Happened & Why?

    Humans lost body hair in order to lose heat more efficiently according to this article. http://www.independent.co.uk/news/science/why-humans-lost-their-body-hair-to-stop-their-brains-from-overheating-as-we-evolved-8498623.html So , some humans moved out of Africa and into the cold regions of...
  26. J

    Hair & Nutrition: Retaining More Nutrition with More or Less Hair?

    When would I retain more nutrition in my body - when I have more hair or less hair?
  27. D

    Airflow and hair dryer efficiency

    Homework Statement Can the power efficiency of the domestic hair dryer be improved by reducing the heat energy and increasing airflow? Homework EquationsThe Attempt at a Solution
  28. A

    Hair Loss cause and treatment

    I want to know more about hair loss issue. The basic idea to stop hair loss by knowing the main cause of hair loss. Also provide some valid hair loss treatment available in the market
  29. Y

    Hair dryer thermal energy

    Homework Statement A hair dryer consists of a coil that warms air and a fan that blows the warm air out. The coil generates thermal energy at a rate of 600 W. Take the density of the air to be 1.25 Kg/m^3 and its specific heat capacity to be 990J/Kgk. The dryer takes air from a room at 20C and...
  30. Larry Pendarvis

    Can a maximal charged black hole have "flavor" or weak hair?

    Consider a Maximal (negatively) charged black hole. Can it have "flavor" or weak charge? Suppose a muon collided with that hole. Would an electron be emitted? What if electron neutrinos collided with that black hole; would electron neutrinos more likely be emitted as Hawking Radiation...
  31. Spinnor

    Can't comb hair on a 2-sphere. On a Calabi Yau manifold?

    Does it make sense to ask if we can "comb the hair" on a Calabi yau manifold? Hope this is the right place for this question. Thanks for any help!
  32. H

    Hair in between two glass plates. Decreasing the distance between the maxima

    Homework Statement A thin hair is placed between two microscope slides. When laser light is shined down onto the slides, periodic intensity maxima are seen to span the slides. Which of the following changes will decrease the distance between the maxima? I. Decrease the wavelength of the laser...
  33. gfd43tg

    Air Flow through a hair dryer

    Homework Statement A hair dryer is basically a duct in which a few layers of electric resistors are placed. A small fan pulls the air in and forces it to flow over the resistors where it is heated. Air enters a 900-W hair dryer at 100 kPa and 25° C, and leaves at 50° C. The cross-sectional area...
  34. Medicol

    Cause of gray hair and actual ageing

    I have learned that a catalase increase may help feed peroxide and reduce gray hair but on the other hand human ageing states that its heme-Fe increases automatically overtime. These two "facts" really confuses me. Could you help me explain this ? Thank you.
  35. M

    Medical Oily skin, foliculits and hair loss

    Hi, I have a very oily skin especially in the face and hair. I think the oil causes acnes or something called foliculit. Foliculits and oil started at the end of the secondary schools which corresponds to puberty. I used a tablet it was good for me. It dried my skin against oil but it dried...
  36. A

    Measuring Hair Thickness (Young slits)

    Homework Statement Hi, We're doing an experiment of measuring the thickness of a hair using a laser. So we took a hair, and a laser, and shot it through the hair, to receive the following pattern on the wall. The image of what we received (after red filter applied) on the wall is...
  37. Monique

    Plantur 39 - to stop menopausal hair loss?

    Marketed to stop menopausal hair loss, has it been shown to be effective? http://www.plantur39.ca/en/
  38. A

    Cochlear hair cell & sounds

    Hi, I've been studying the cochlea, and how the hair cells (IHCs) receive sound, and some amplify it (OHCs) ; and am trying to get an idea of the density profile of hair cells acting as a spatial filter. The smallest discrimination in frequency that is positional (not temporal) coded...
  39. qspeechc

    How difficult is cutting hair?

    Hi Everyone. The place I have been going to for the past 8 or 10 years to cut my hair closed down, so I went to the barber's around the corner. Now for as long as I can remember I've always had the same haircut: a number 4 clipper (or whatever the attachment is called) on the electric shaver...
  40. N

    Thin Film Interference Problem: A hair is placed at the edge .

    Thin Film Interference Problem: A hair is placed at the edge... Homework Statement Thin Film Interference Problem: A hair is placed at the edge between two 10.0 cm glass plates of n= 1.52. Light of 400 nm wavelength shines on the glass and an interference pattern is formed. If the...
  41. Anna Blanksch

    Hair growing on the body to different lengths

    The hair on my head grows longer and longer while other hairs, like arm hair, only grow to a much shorter length. Why do certain hairs on the body grow only to certain lengths? How do the cells know when to stop? Thank you! →
  42. Fernando Revilla

    MHB Hair Canada's question at Yahoo Answers (Constant series)

    Here is the question: Here is a link to the question: Math: Is a_n = c diverging or converging? - Yahoo! Answers I have posted a link there to this topic so the OP can find my response.
  43. J

    Function of an Ionic hair dryer.

    I recently heard of these ionic hair dryers. 1. what do they create ions of? how? if it is of hydrogen how does that not become hydrogen peroxide when it comes in contact with the water on hair? there is a new one with a digital reading how can it determine how many ions it produces? they have...
  44. K

    Medical My hair is turning gray and feels like straw

    I am a 25 year old male and my hair is starting to turn gray at a rapid pace and it feels like straw. When I was in my teens, my hair was jet-black and very smooth and shiny, now it looks and feels completely different. Is this unusual for someone my age?
  45. T

    Cutting Long Hair: Is It Really Worth It?

    Girls, girls, girls. Come and give me your thoughts girls. Ponder for a moment on a hypothetical scenario in which you find yourself in a happy relationship. However, you're about to attend a yearlong study abroad program at school in a tropical country, and you're not looking forward to...
  46. P

    I'm young and my hair is thinning

    I'm 16 years old male, and I noticed last year that my hair was thinning. I do not know if it's because of my dry scalp or because of the shampoo I'm using. Is it normal to have thinning hair at this age?Can I regrow my lost hair? Also, how can I get rid of my dry, itchy scalp? Thank you.
  47. M

    Medical Body and head hair differ, why?

    Why does head and body hair differ? Doesn't monkeys have the same type of hair on their head and the rest of their body?
  48. S

    Speed distance and not a lot of hair left

    Homework Statement a balls inital velocity is 72 km/ph and falls 100 meters with gravity @ 10 meters per second and i need to work out the time it takes to fall to ground. i was given s=ut+0.5*gt^2 Homework Equations s=ut+0.5gt^2 v^2=u^2+2as t=(v-u)/aThe Attempt at a Solution v2=u2+2as v=squr...
  49. M

    Is it possible for a long hair to having heavy weight?

    http://www.odditycentral.com/pics/tran-van-hay-the-man-with-the-worlds-longest-hair-dies-at-79.html The man is reported to have the longest hair in the world, they claimed that his hair was measured at 6.8 meters long but never been measured officially. But what I'm skeptical about this was...