What is Green: Definition and 306 Discussions

Green is the color between blue and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495–570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content.
During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers and the gentry, while red was reserved for the nobility. For this reason, the costume of the Mona Lisa by Leonardo da Vinci and the benches in the British House of Commons are green while those in the House of Lords are red. It also has a long historical tradition as the color of Ireland and of Gaelic culture. It is the historic color of Islam, representing the lush vegetation of Paradise. It was the color of the banner of Muhammad, and is found in the flags of nearly all Islamic countries.In surveys made in American, European, and Islamic countries, green is the color most commonly associated with nature, life, health, youth, spring, hope, and envy. In the European Union and the United States, green is also sometimes associated with toxicity and poor health, but in China and most of Asia, its associations are very positive, as the symbol of fertility and happiness. Because of its association with nature, it is the color of the environmental movement. Political groups advocating environmental protection and social justice describe themselves as part of the Green movement, some naming themselves Green parties. This has led to similar campaigns in advertising, as companies have sold green, or environmentally friendly, products. Green is also the traditional color of safety and permission; a green light means go ahead, a green card permits permanent residence in the United States.

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  1. kakaho345

    Finding free electron gas Green function in Fourier space

    As in title: Plugging in the definition is straight forward, I am too lazy to type, I will just quote the book Fetter 1971: Up to here everything is very straight forward, in particular, since we are working on free electron gas, ##E=\hbar \omega## However, I have no idea how to arrive...
  2. S

    B The green comet is just a weak smudge now

    I think I has observed it a few weeks ago (maybe it was something else), and it was long & bright, but now it's barely visible . (I'm using a 12X, 60mm binocular.)
  3. H

    I What is Brian Austin Green talking about here?

    Starting at about 15:15 in the video, he talks about a "fuel", related to a quantum field, that provides outward rush of space, and its virtually possible to use up. What is he talking about, anyone know? Sounds a little funny to me! Thanks.
  4. shivajikobardan

    “Light red” and “light green” background colors not working-CSS

    https://github.com/TheOdinProject/css-exercises/tree/main/foundations/02-class-id-selectors I’m doing this assignment of The Odin Project. But the two colors aren’t working. Here’s my code: index.html: <p class="odd">Number 1 - I'm a class!</p> <div ids="second">Number 2 - I'm one...
  5. Kalaton

    Green liquid that glows when electrocuted in 39 Clues

    Upon reading a book titled The 39 Clues, one of the main characters finds a vial of green liquid and holds it out into a thunderstorm to be struck by lightning to "charge" it. Once it's struck, it is now glowing, appearing as almost pure light and not even warm to the touch. I understand this...
  6. Algr

    Can Green Ammonia Be a Climate Fix?

    Wired has a new article that seems interesting. https://www.wired.com/story/can-green-ammonia-be-a-climate-fix/ The part about eliminating the use of methane in ammonia production sounds good to me. This could also be a good case of switchable demand - if the wind or solar power dips, the...
  7. SamRoss

    How can I get the RUN button in Visual Studio Code to turn GREEN again?

    I have been using Visual Studio Code for a couple months now and it has been fine. When I want to run some code, there is usually a little green triangle button in the top right corner that I can click on. A few days ago, that triangle turned white only for Python files (it is still green for...
  8. F

    Derivative of the deformation gradient w.r.t Cauchy green tensor

    What's the derivative of deformation gradient F w.r.t cauchy green tensor C, where C=F'F and ' denotes the transpose?
  9. louis_slicka

    Why is green light not useful for photosynthesis?

    Plant leaves only appear green because they absorb the red and blue wavelengths of light and reflect green away. Is there an intrinsic and innate reason for this that relates to the physics of light? Maybe green wavelengths are inefficient at storing energy in chemical bonds? Have plants simply...
  10. LCSphysicist

    Can Laplace Transforms be Applied to Finite Intervals?

    "Consider a string of length L that is connected at both ends to supports and is subjected to a load (external force per unit length) of f(x). Find the displcament u" https://i.stack.imgur.com/yVIDG.png We need to solve this: $$Tu_{xx} = f(x)$$ subject to $$u(0)=u(L)=0$$ But i don't understand...
  11. BWV

    Sodium Hydroxide + Iron Oxide: Green Tint Explained?

    Was spraying oven cleaner on a somewhat rusted grill and my son, who is taking AP chemistry, asked about the green color that appeared. googled sodium hydroxide + iron oxide and got this FeO + 4NaOH = Na₄FeO₃+ 2H₂O but can't find any info on Na₄FeO₃ - would this have a green tint, and is...
  12. MahdiI84

    I Obtain the Density of State using the Green function

    Hi everyone. Using the Green function, I want to obtain the density of states of a one-dimensional (linear) lattice. Depending on the problem conditions, we will have an iterative loop with 4,000 data for the energy component and a iteration loop with 2,000 data for the wave number component. In...
  13. J

    Removing green copper oxides with Electrolysis, chemicals, etc.

    I soaked the following school medallion in water with salt for 20 plus years in the attic and at that time I didn't know copper could corrode and make green oxides. I also didn't think about it much and just forgot about it. I brought it down just today. I read just a while ago that hot...
  14. Wrichik Basu

    Desktop PC not turning on, blinking green LED on motherboard

    Our Windows 7 32-bit desktop PC is fitted with an Asus P7H55-M LX motherboard. It was working fine till yesterday evening, but from this morning, it won't turn on. (By this, I mean that it is not even starting the boot; the fan on the processor won't run.) My first guess was the PSU. So I...
  15. C

    Odd evolutionary outcomes: green fur, body fat, anything else?

    I was watching a grey squirrel the other day who stood out amongst green leaves, and wondered whether there was a reason no mammals have evolved green fur (AFAIK?)? I'm aware there are a couple who allow green algae to grow in their fur (sloth and polar bears). I mean we have weird things like...
  16. A

    Looking for a Comprehensive Guide on Green Chemistry? Any Book Recommendations?

    I'm supposed to make a project on "Green Chemistry".so if you guys have any suggestions for a good book?
  17. H

    Method of image with Green function

    A conducting sphere of radius a is made up of 3 different shells, upper part a/2 z -a/2, the middle part -a/2 z a, the lower part -a z -a/2 where the center of the sphere is at the origin. The upper part V and the lower part has -V potentials, while the mid part is grounded. Find the...
  18. N

    What is salt that has a green colour?

    What are salt that have green colour?
  19. Rzbs

    A How Does the Two-Particle Green Function Relate to Hartree-Fock Theory?

    could anyone explain why in the page of book this figure is related to hartree-fock? I mean why if t1>t2 we have these possibilities? and why not particle propagate from x2t2 to x3t3 instead x3t3+?
  20. gmax137

    Remembering Guitar Hero Peter Green of Fleetwood Mac

  21. D

    Evaluate integral using Green Theorem

    I got stuck here, how to integrate e^(y^2), I searched but it's something like error function
  22. Superposed_Cat

    I Chance of x Red balls sharing a bucket with a Green ball

    If I have 237 buckets, and there are n green balls distributed randomly over those buckets, and I put 34 new red balls randomly in those 237 buckets, what is the formula for the probability that x green balls share a bucket with a red ball? Any help appreciated.
  23. jim mcnamara

    What Causes the Synchronized Movement of Fuzzy Green Glacier Mice?

    https://www.npr.org/2020/05/22/858800112/herd-like-movement-of-fuzzy-green-glacier-mice-baffles-scientists Check out the article - good photos. These moss balls, plants, are found with rarity in several glacier/ice fields world wide. This article is about researchers trying to understand how...
  24. Mounice

    Solving Potential of a Charge Outside a Sphere with Green Functions

    I was wondering if there is a way to deduce the solution of the potential of a charge outside a sphere given by the image method, though Green functions. Because of a Dirichlet condition (GD(R,r')=0), I know that a solution can be written as GD=Go+L, where ∇2L=0. But in order to approach this...
  25. vis viva

    Water, salt and a green Jello electret....

    I'm asking the question because I'm interested in learning more about how ionic compounds behave in and around electric fields. I'm not actually going to make the proposed electret. The color of the Jello is irrelevant, and Jello may not yield an everlasting electrect, so it's more about the...
  26. C

    B Exploring Color Mixing: Red & Green Chequer Pattern Spin Test

    If I paint a ball in red and green chequer pattern and with 50% coverage of each, then spin the ball then it looks white. If I make the pattern with smaller and smaller chequers, does it stay white and how small can the pattern be before it turns a different colour? Once the pattern is a...
  27. M

    Show that the given Green Function is the propagator of a certain Lagrangian

    My fundamental issue with this exercise is that I don't really know what it means to "show that X is a propagator".. Up until know I encountered only propagators of the from ##\langle 0\vert [\phi(x),\phi(y)] \vert 0\rangle##, which in the end is a transition amplitude and can be interpreted as...
  28. DaveC426913

    How does green screening technology handle secondary reflection of green?

    I get the basics of green screening. The processing software recognizes a small range of green and can substitute a different image where it occurs. Here's what I don't get: if a subject is standing in front of a green screen, they will have reflections of green. Notice that, in the...
  29. sergiokapone

    1D Green function for a charged layer

    I came across an example of a solution to finding the potential of a charged layer using the Green function (here, pdf). The standard algorithm for finding the Green function by boundary conditions for many problems is understandable: \begin{align*} G_\mathrm{Left} = Ax+ B \\ G_\mathrm{Right} =...
  30. J

    A Which operator corresponds to the Green function in QFT?

    The Feynman propagator: $$D_{F}(x,y) = <0|T\{\phi_{0}(x) \phi_{0}(y)\}|0> $$ is the Green's function of the operator (except maybe for a constant): $$ (\Box + m^2)$$ In other words: $$ (\Box + m^2) D_{F}(x,y) = - i \hbar \delta^{4}(x-y)$$ My question is: Which is the operator that...
  31. L

    The OVGF (outer valence Green Function) method

    Is there anyone here that know and understand the OVGF method who can help me? I have some doubts about it, and there is almost nothing about it in literature.
  32. J

    Why does PPG (photoplethysmography) Use Infrared and Green Both Light

    Hi Everyone, I'm doing research in Implanted Devices in Human Body (Sensors, Hearing Aid, Pacemaker) for my college course. I've started with FitBit that uses the PPG Principle. But I'm struggling to understand why the FitBit uses both Green and IR LED whereas the sensor at the receiving end is...
  33. S

    What kingdoms are blue-green, green & red algae?

    AIUI, there are these 3 types of algae, with blue-green algae being technically bacteria, green algae being plants, but what are red algae?
  34. J

    MHB There are z red marbles. How many green marbles are there?

    In a container, there are some blue, red and green marbles. There are twice as many blue marbles as red marbles, and there are 3 more green marbles than blue marbles. a) There are z red marbles. How many green marbles are there? my answer: z + 2z + 6z = 9zb) There are 19 green marbles in the...
  35. S

    Young's double slit experiment green laser

    Homework Statement If a green laser is (wavelength = 532nm) sent through two slits with a separation of 127 um, how wide (in total) would the 11 green dots formed be if they were projected onto a screen 1.25m away from the slits? Refer to this diagram sorry for bad quality...
  36. Willow Wanda

    Why do Christmas lights glow green near a Tesla coil?

    Homework Statement For a high school physics class, I chose to build a tesla coil for a real world application assignment. I was able to build it fairly easily and it turned out great. Before presenting to the class next week, I've been seeing its effect on different types of light bulbs and...
  37. V

    Where does the gene for green color come from?

    I was studying evolution and speciation and an example was given in my textbook. It said that there is a species of red beetles and through variation a green beetle is formed and then is naturally selected as red beetles are easily seen by crows and green are not. My question is where does the...
  38. H

    I Why does red food coloring look green when it dries?

    While experimenting with an idea for a demonstration in surface tension, I ran across something interesting. I placed a drop of red food coloring on a glass slide, and let it dry. Once dry, the residue was a light green in color, but when held up to let light pass through it, it looked red...
  39. M

    MHB Probability of 2 Green Marbles

    Gilligan has 16 green marbles, 50 blue marbles and 60 red marbles. What is the probability of randomly selecting 2 green marbles? What is the set up?
  40. Parker Hame

    Doppler Effect -- How fast would you need to go for a red light to appear green?

    I was driving the other day, and I was about to go past a green light when it turned yellow, so I sped up. I got past the light but but it got me wondering, how fast would you need to go for a red light to appear green due to the Doppler Effect. (Excuse me if this question doesn't belong in...
  41. C

    Why Doesn't White Light Appear Green Despite Human Eye Sensitivity?

    White light is usually stated as having a uniform spectrum (eg all frequencies at same intensity). However the human eye is more sensitive to green light than other colours. So why doesn't white light appear slightly green?
  42. Twigg

    A Green function issue: can bound. cond. be applied mode-wise?

    Hello, Before I begin, a lot of the math I try to describe in this post is stuff I worked out myself and have scribbled down. If something looks fishy or doesn't make sense, it could very well be totally wrong! Apologies for any confusions in advance. Consider a slab of linear isotropic...
  43. David K

    Ideal Windsheld Cleaner + Simple Green Ratio

    We are wondering if there is an ideal ratio of simple green + glass cleaner to get the bugs off & keep it streak-free. Thought there might be a chemist with the ideal ratio. We will experiment and let you know what happens.
  44. ORF

    I Why uranium glass glows green if it's under UV light?

    Hello Why the uranium glass glows green if it's under UV light? The most accurate thing I have found it's a brief history of uranium glass: somewhere it's said the more uranium oxide you put in the glass, the more intense will be the green light when exposed to UV light. Thank you for your...
  45. J

    Uses of Nuclear Fusion: Beyond a Green Energy Source

    I'm new to this so please correct me if I'm doing this wrong. I'm curious to know about what practical uses are there for nuclear fusion other than a green power source.? I've already seen a few readings and a video from a Michel fellow about how it works, and it's fascinating stuff I'm not much...
  46. G

    Projectile Motion: golf ball velocity to reach the green

    Homework Statement A golfer strikes a golf ball at an angle of 17 degrees above the horizontal. With what velocity must the ball be hit to reach the green which is a horizontal distance of 250 m from the golfer? It is at the same height as the tee. Homework Equations trig equations...
  47. ShayanJ

    A Green functions and n-point correlation functions

    Green functions are defined in mathematics as solutions of inhomogeneous differential equations with a dirac delta as the right hand side and are used for solving such equations with a generic right hand side. But in QFT, n-point correlation functions are also called Green functions. Why is...
  48. ShayanJ

    A Differential equations without Green functions

    Are there differential equations that, for some reason, don't have a Green function? Are there conditions for a DE to satisfy so that it can have a Green function? Thanks
  49. P

    A Are green lasers Left Circularly Polarized Light?

    I'm getting ready to do some testing, and need to decide which lasers to use . I need both left and right circularly polarized laser light . I was told that green diode lasers, the kind readily commercially available (usually around 200 - 500 mW.) , are LEFT CPL. 1. Is that usually true, and...
  50. Metals

    I Blue lights (LEDs) consume more power than red (and green)?

    Referring to LEDs as I'm not aware of any other "colour-producing" light, does blue light use more energy than red light? Planck's formula (E=hf) leads me to believe that blue light would drain a battery quicker than red, due to its higher frequency. Surely a device emitting blue light would...