Why aren't plants black? 🌿

Why are plants green? Is there a reason plants evolved to be green, globally? What does it have to do with the color of the sunlight coming down through our atmosphere?
If you liked this video check out these:
Bandaids Glow when Opening?! | EVERYDAY MYSTERIES
• Bandaids Glow when Ope...
Why Hawaii's volcano is so UNUSUAL
• Why Hawaii's volcano i...
physicsgirl.org/
/ thephysicsgirl
/ thephysicsgirl
/ thephysicsgirl
Help us translate our videos! kzbin.info_cs_p...
Creator: Dianna Cowern
Editor: Jabril Ashe
Hamburger eater: Jabril Ashe
Colorful Planet Artist: Ashley Warner
Thanks to: Dan Walsh, Kyle Kitzmiller, Joe Hanson and Kyle Norby
Sources:
Black Nigrescens Plant:
www.thedangergarden.com/2013/0... With permission from Loree Bohl,
thedangergarden.com
Green Nigrescens Plant:
With permission from © Davis Landscape Architecture, London, UK www.davisla.com
Solar spectrum adapted from:
commons.wikimedia.org/wiki/Fi...
Chlorophyll spectrum adapted from:
www.austincc.edu/biocr/1406/la...
The Functional Significance of Black-Pigmented Leaves: Photosynthesis, Photoprotection and Productivity in Ophiopogon planiscapus ‘Nigrescens’
www.ncbi.nlm.nih.gov/pmc/arti...
Functional evolution of photochemical energy
transformations in oxygen-producing organisms
www.publish.csiro.au/FP/pdf/FP...
Evolutionary Competition Between Primitive Photosynthetic Systems: Existence of an early purple Earth?
adsabs.harvard.edu/abs/2006AAS...
A Compilation of Selected Data on Solar Radiation at Sea Level
www.dtic.mil/dtic/tr/fulltext/...
Green Light Drives CO2 Fixation Deep Within Leaves
pcp.oxfordjournals.org/content...
Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green
pcp.oxfordjournals.org/content...
msue.anr.msu.edu/news/green_li...
www.researchgate.net/publicat...
www.annualreviews.org/doi/abs/...
The sensitivity of the human eye to different colors
www.ecse.rpi.edu/~schubert/Li...
Music: APM

[@ProfessorPolitics]

I think Bill Nye has the best quote on the topic of evolution. It goes something like: "It's not survival of the fittest but survival of the good enough."

[@John_Ridley]

Survival of the "nothing better has come along to outcompete it yet." Actually, pretty much like scientific theory. A theory is what we have until someone comes up with a better one.

[@nineball039]

Stephen Jay Gould was more succinct: “We live now in the "Age of Bacteria." Our planet has always been in the "Age of Bacteria" ..."

[@bool.]

John Ridley there's no outcompeting to really do, though. If green chlorophyll is good enough to fully saturate the plant, then black would have no advantage.

[@lawrencedoliveiro9104]

If the dinosaurs were still around, they might outcompete us mammals.

[@John_Ridley]

Dinosaurs are still around, the little ones. They're flying around everywhere. Earth went through a period when large creatures couldn't survive because of lack of food after an asteroid strike. What is alive today evolved from the tiny creatures that survived 65 million years ago. At that time probably every type had an equal opportunity. If there were a niche for extremely large reptiles or birds or some cross between them, we'd have one now, but mammals outcompeted them along the way and the large creatures now are all mammals.

[@weshard1]

Interestingly, plants actually appear to be black in the dark.

[@keppycs]

Oh wow, you must be a genius

[@weshard1]

Thank you! I'm glad that people are beginning to recognise that.

[@DrunkenUFOPilot]

I am dialing the Nobel Prize nominating committee, to submit weshard1...

[@aliveithink6985]

But what if they are in the dark but with the lights on? What if I am blind? What if the plants are blind? #TheoryDebunked

[@zoltanszaszi2264]

In a groundbreaking discovery, I found that I can't even see plants if I cover my eyes with my hands. I'm still trying to find the best technological application of this marvelous scientific achievement.

[@ethanchien6803]

theory 1: too much green theory 2: let others have green theory 3: adapt to not having green theory 4: coincidence

[@industrialdonut7681]

excellent summary good sir

[@FcoMp]

I vote for theory 3.

[@patrickjoshuamanzo5420]

theory 5: Creator knows best.

[@solar0wind]

@@patrickjoshuamanzo5420 That's the lazy response for people who don't want to or can't figure out what's really going on.

[@patrickjoshuamanzo5420]

@@solar0wind i said that because I saw theory 4.

[@gabrielribeiro3166]

Diana: "It's like being served 3-5 hamburgers when you can only really fit one in your stomach" Me: Amateur... Also me: I should probably lose weight

[@firefish111]

OMG, shouldn't have eaten that extra burger... I'm gonna explode

[@Lucius_Chiaraviglio]

@@firefish111 How about an after-dinner mint?

[@firefish111]

@@Lucius_Chiaraviglio Well, that could make it worse...

[@coaltowking]

@@Lucius_Chiaraviglio it's just wafer thin.

[@aaronseet2738]

How does an obese plant look like?

[@phantomr277]

I thought it said "why aren't planets black"

[@physicsgirl]

That does make sense with the thumbnail. But not so much as a question

[@easyextreme31]

misleading thumbnail

[@usa1327]

yea not gonna lie, thats what i read aswell

[@gabejordan]

Phantom R but if you think about it, if plants were black, our planet would probably be black too, considering its green because plants are green

[@15sachin15]

Phantom R and I think she's gonna make whole video on this we all saw the pic of planet Earth and read the text below and our brain got fooled lol

[@marsamet128]

"The sun is a white dwarf"

[@JoakimfromAnka]

:D It's a yellow dwarf... that looks white... and emits mostly green light.

[@shiprasharma7479]

Yeah it is a yellow dwarf and approximately after 5billion years it will become a white dwarf after it goes through a whimper.

[@adityakhanna113]

Too early to say that?

[@marsamet128]

I know it's a yellow dwarf, and that it WILL be a white dwarf. It is not yet though.

[@shiprasharma7479]

Cool! even I said that👍

[@dinohall2595]

"You can't fit three to five hamburgers in your stomach." Me: Observe

[@MH-ms1dg]

in junior high i once ate three small white castle burgers, one after the other. the kid next to me was like o_o

[@somethingsinlife5600]

Evolution is always all about good enough and whatever works in this situation it's never about perfection.

[@joshuarandall6041]

Some Things In Life and perhaps perfection is irrelevant anyways because conditions will always change over time. Perhaps evolution had positioned itself to never fully overcommit for this reason. It's imperfect, which might be the true perfect.

[@chairwood]

@@joshuarandall6041 #deep

[@JCPRuckus]

The problem is we're using the wrong definition of "perfection" here. If having purple pigment was generally better than green, then most plants would be purple. Nature only cares about effeciency. Chlorophyll is probably just slightly more efficient to make while still absorbing more than enough energy from the sun. There's also a chance that reflecting the most plentiful light is a way to avoid sunburn. If you already get 3-5x as much light as you need, turning off the biggest bit first makes a lot of sense. And finally, the "color layers" theory is probably reversed. The reason that purple plants are less numerous is likely, again, that creating purple pigment is less efficient. So plants that can't get enough non-green light resort to using it. They're kind of the plant equivalent of scavengers, just light scavengers. So, yeah, "minimally functional and maximally efficient" is nature's definition of perfect. Whatever gets the job done with the least energy. Only humans think maximizing something no matter what the energy costs are is a good thing. "Work smarter, not harder" is basically the guiding principle of nature... Like, even at the base level of physics, and biology is just the physics of life.

[@Gariel2007]

Nature is an Engineer, not an Artist. Good enough is perfect, and perfect is a waste of resources that i don't have.

[@CaesarCassius]

LOL This proves yet again that evolution isn't science, only ignorant atheists are desperately believing in it at this stage #LOL #Trump2020

[@rebelbeammasterx8472]

Red sky and star, purple seas, and black plants.

[@Stan_Delone]

Gotta say, that sounds pretty metal.

[@ninjabluefyre3815]

RebelBeamMaster X84 AKA A planet I want to live on.

[@supersentaipepsi3736]

RebelBeamMaster X84 I would love to live on a planet like that.......if it's habitable to our chemistry.

[@sion8]

I think Krypton looked like that?

[@iniquumiudicium811]

I heard gliese 581c is desscribed similarly

[@roy4173]

The problem I have with the "good enough" hypothesis is that "good enough" works if you're not competing with other plants. The fact that our earth has been around for billions of years and at least a significant portion of that lifespan plants have also been in it suggests that if there was even one breed used a different pigment and it worked better, that species would proliferate more effectively and become more dominant over time as would other plants that might carry this mutation vis a vis convergent evolution. It couldn't have just been "good enough" but actually better than the rest because other pigments of plants do exist as shown in the video, and they are rare, not dominant. This, in turn, suggests that not only was green "good enough", but actually it conferred an advantage beyond what other colors carried, even if it wasn't the best at absorbing everything the sun provided. Evolution isn't the process of perfection. I think everyone understands that. So it means that everything we have living now is indeed "good enough" for survival and procreation. But we mustn't forget that this stuff that has been "good enough" to survive was also better than the stuff that hasn't, in particular, the stuff that had been competing for the same resources. The "good enough" hypothesis, when used to describe evolution, is best at explaining that while we see some pretty sophisticated stuff from biology, it isn't without its drawbacks or flaws. But we shouldn't thereby discredit its sophistication entirely either. Plants are green probably because green was the best color for what plants needed for survival.

[@LissandroBassani]

Indeed, as also maybe not only color-related issues, but also chemical, and temperature as stated so as to a more encompassing evolutionary solution that currently masks something not accounted for in the whole process.

[@Legominder]

I would say, absorbing blue and red light gives the most efficient multi junction solar cell with 2 absorptions. If the absorptions peaks are too close to each other, like blue and green, the benefit of adding the second absorption peak drops. So it's complexity (1 vs. 2 vs. >2 absorptions) vs. efficiency.

[@TheFifthEl]

It's weird to think about, but the sun would appear "white" no matter what colour it actually was, because our eyes evolved to see in an environment lit by it. So "all possible wavelengths our eyes can see" and "what the sun emits" are fundamentally linked.

[@ZevHoover]

TheFifthEl not true though. The sun emits plenty of light outside of the human visible spectrum, on both sides.

[@TheFifthEl]

@@ZevHoover That's not really the issue. Of course it emits wavelengths we cant see. The point is the blackbody radiation is centred at the wavelengths we can. Other stars look different because our eyes are calibrated to work with the sun. Under a bluer star we'd see more into the blue end because there's more light up there to use, and less at the red end.

[@ZevHoover]

TheFifthEl sure sure you are right and that’s definitely a cool way of looking at it. I just thought your last paragraph was a little misleading.

[@jimmybabovka]

So if we evolved around a star that we now perceive as blue, it would appear white, and our real life Sun would be red to us? Is that correct?

[@VoltisArt]

@@jimmybabovka That's the basic idea, yes. We'd probably see more into UV, as well, while IR would be farther out of the spectrum. (Some animals do see into UV, but most mammals don't.)

[@tibees]

Love this video, it's a question that I had been wondering although I guess the answer wasn't very conclusive.

[@wyllomygreene7700]

Tibees she hit the nail on the head tho, talking abt how evolution doesn't mean perfect, just good enough. It's not a satifying answer bc we're (wrongly) taught 'survival of the fittest'

[@ErikB605]

@@wyllomygreene7700 Survival of the fittest still stands. Just not survival of the fittest possible but survival of the fittest around.

[@EffySalcedo]

The joy of green 💚💚😁

[@nikhilnagaria2672]

Tibees!

[@jg1019]

@@wyllomygreene7700 how is survival of the fittest wrong? The reason every organism that is alive today is alive is because it's species was better fit for survival than all the ones that died off. Therefore every living organism right now is a part of the current fittest organisms. As circumstances change, many will become unfit and die off. Evolution is survival of the fittest.

[@mizuhonova]

A related question I've always wondered about. Why does our skin turn blacker (through melanin) when we get sun burned when the color black would cause even more sunlight to be absorbed?

[@rrozinak]

Yes, melanin actually absorbs more light. But that's good! It depends on where it gets absorbed. Melanin is in our skin to protect us from UV radiation. If UV radiation gets through your skin and hits your DNA it can damage it. This can lead to mutations and possibly skin cancer. But if your body shields your DNA with melanin, the UV radiation will get absorbed by melanin and your DNA will be protected in the shade. Sunburn happens when DNA is damaged and some of your skin cells die which creates inflamation. The more melanin you have, the less DNA gets damaged. That's how melanin actually protects you from getting sunburt.

[@mizuhonova]

Ohh, I see. That makes sense. Thanks for the reply!

[@cognitivedissonance7422]

roman does that mean dark skinned people have higher skin temperature than lighter skinned ones when standing around in the sun?

[@rrozinak]

It's not that simple. Heat is mostly absorbed in infrared spectrum and while melanin is good at absorbing visible and UV radiation, it can be different for infrared (I don't actually know that, I'm just speculating now). For example glass seems perfectly transparent in visible spectrum but it blocks all UV (glass would be "black" if our eyes could only see UV). So even though melanin is dark in visible spectrum it doesn't mean it absorbs infrared as well. Also the temperature of your skin depends on many variables like how fast is your metabolism and how efficient is your thermoregulation. But this is just my speculation, if you want to know more, you'll need to do some research. It's too complex for a KZbin comment. It would be interesting to do an experiment with a thermal camera and a crowd of black and white people.

[@cognitivedissonance7422]

roman thank you for the quick answer! Very interesting, I might just do that with some friends, lol. I also always wondered why all heaters are white. My physics prof once said it had to do with them being black in the infra red spectrum, so they radiate heat better? I dont precisely remember, any thoughts?

[@culwin]

So Superman's power comes from a green sun

[@typemoon4894]

>kryptonite is green

[@ZacPensol]

and spinach is green.... Popeye is a Kryptonian confirmed.

[@z-beeblebrox]

Wouldn't Popeye be like an anti-Kryptonian then?

[@ZacPensol]

Shh, don't think too much about it.

[@chervilious]

yeah it's anti-Kryptonian!

[@seska1245]

It’s adorable watching how excited you get about science. Love your vids :)

[@JustwatchingYouTube42]

Interesting, I had not thought about this before. I had a plant that I grew indoors in a medium-lit window, the plant had large light green leaves. I then moved the plant outdoors in the summer and the large light green leaves died off and the plant started growing small dark green leaves.

[@sinomirneja771]

Because otherwise they would never go back?

[@sinomirneja771]

BTW people This is a joke, don't go crazy.

[@Aristocratic13]

W

[@bikerusl]

nice

[@roryt4819]

Sinom Irneja I think you meant "would never work"

[@SkollTheWerewolf]

It would starve if we stopped giving them their welfare checks?

[@feynstein1004]

I think what actually happened was the purple halobacteria were a global phenomenon and hence cyanobacteria that harvested red and blue light were at an evolutionary advantage. The last theory also holds some merit. Evolution is not an engineering process. It's not about perfection. It's about being good enough to survive. And perhaps going green was more than enough for plants. Hence there was no significant advantage to going black.

[@guytheincognito4186]

Feynstein 100 Agreed. "It's not survival of The fittest but survival of The good enough" Bill Nye

[@paulsengupta971]

Where does Kermit fit in with this?

[@feynstein1004]

+Paul Sengupta I have no idea

[@vacri54]

Besides, once you go black, you never go back.

[@TheErudite21]

This is what I thought as well. Read it in a LiveScience article I believe... sounded pretty plausible, but apparently its one of the least popular theories?? :/ But I suppose its because youd then have to wonder, what happened to all the black/purple plants?... Maybe they went extinct with most other animals during the various extinction events?... idk...

[@christopherfassett9973]

I know I'm way late to this, but I own a number of planted aquariums. Red plants are some of the most challenging to grow because if you don't give them enough light they turn green. We usually say that the "red" in plants is essentially a tan that it uses to keep from getting burned because you have to saturate them consistently to keep them red. Having enough iron and CO² are also factors but by far the light intensity is the most important. I wonder how that would factor into those theories...

[@adrianmillard6598]

Thanks Physics Girl, this was really fun to watch and you looked like you were feeling positive and enjoying yourself.

[@hole1stdrillpresschannel]

First read ´why aren´t pants black?´... Don´t know... :-)

[@physicsgirl]

Well now I'm curious why denim is so commonly blue. To the Google!

[@tibimose823]

I read why aren't planets black and was expecting some astronomy

[@sayuas4293]

That's what I thought first and I was like wtf.

[@OzwaldHelin]

I thought it said "why aren't parents black?" :P

[@brokensilence6790]

+Tibi Mose Same here!

[@tortysoft]

I have wondered about this a lot. Two of the thoughts you offer sound good to me. First, the overheating trick - the plant can presumably - over time - alter the amount of light it reflects according to its needs. Then the other thought - that light reflected from leaves can be absorbed by other plants - I like that. We know that ground plants can be purple because that absorbs all the green - but the green has been let through by the plants above it. Co-operation in Nature ! That basically shows communication between life forms for mutual benefit.Yes. We should learn from that.

[@t-wrecks7481]

They're green so they contrast nicely with the blue of the ocean when you look at them from space. Mystery solved.

[@gallardosbull]

I just stumbled upon this Physics Girl and I'm in love! Lol. She does an amazing job at blending beauty, humor, and wit all at once. I think it's helpful that she keeps the segments contained to short entertaining videos that can easily be comprehended. I'm not a physicist who can back up the facts butI someone should get her a show!

[@VladSvoka]

What colour is sun? Easy: about 5780 K. EDIT: no, it is not 6500 K. 6500 is a daylight colour. It is sum of direct sun and ambient atmosphere light (aka sky). Air is much better in scattering blue light, this is why last component is mostly in blue spectre. This creates shift into hotter (more blue) areas, which gets us to 6500K.

[@GraveUypo]

daylight is defined as 6500k

[@VladSvoka]

***** well. That is designers construct. Just because color is called something, doesn't meat it has this color. For example rose, orange, chocolate or gold. Very few of those things actually have color named with them. 6500 K black body radiation is most definitely not what you see on Earth. Read Wikipedia. I bet it is nicely explained there en.m.wikipedia.org/wiki/Color_temperature

[@error.418]

On the page you linked it says 6500k for daylight...

[@VladSvoka]

***** try reading what exactly 6500K is

[@Khrayfish]

Not exactly true, as the sun isn't a perfect black-body.

[@Abdega]

OMG Physics Girl! You can’t just ask why they aren’t black!

[@thersten]

That's so fetch!

[@DeyvsonMoutinhoCaliman]

This green supremacist vegetation!

[@killemwifkindness]

Lol I see your ATLA reference

[@philippizza1]

@@killemwifkindness It's actually Mean Girls not ATLA

[@CartoonKidOLLY]

i love your enthusiasm across all your vids. This was was super interesting!

[@fedipoiana]

"is like being served three hamburger but you can fit only one in your stomach" Oh, you've never been so wrong...

[@jh4766]

you are a rare plant

[@KingsleyIII]

Because they're green.

[@solvillamichel760]

1because God don't want it to be black will be scared 2because they absorbe yellow and green most green not all the colors it Ll be black3black because if you see you are mixing all you have a horible black 3because clorophil is green the plants wher purple but clorophil make them green so they absorbe green.........5thats it 6 bye

[@solvillamichel760]

And that's funny good one! Now! I'll eat my cofe............... Aaaaah hot aaaaaaa aaaaaa Fire in my mouth no really water aaaaaa aaaaaaaaaaaaa hot hoooooooooooooooooooot! You Ll pay 1 0000000000 0000000000 0000000000 0000000000 0000000000 0000000000 00000000000 0000000000 0000000000 0dollars hot aaaa and you'll pay

[@ethanchou4906]

" Now! I'll eat my cofe " Covfefe.

[@raffimolero64]

totally not a circular argument

[@Andrei4436]

ROASTEEEED

[@faraxra]

Simple. God made plants green so they look good unlike black. *grabs popcorn*

[@keppycs]

OMFG HOW DARE YOU TO BE SO RACIST entertaining enough?

[@guitarheroprince123]

Dark memes are taking over the internet.

[@Foust.]

Farhan Do you really think the giant spaghetti monster would do that?

[@Triumvirate888]

Seems about as rational as any other hypothesis that's been offered. Saying that plants are green because of sunlight is like saying that sheep are white because of sunlight. Not all plants are green. Not all sheep are white.

[@hazelnut1013]

Farhan I wonder if Thats racist

[@hopesy12u4]

2:34 emo earth

[@mhvdm]

L M A O

[@rosymo0nn]

Rawr

[@Pining_for_the_fjords]

If the whole earth was Africa.

[@OrangeC7]

*It's not a **_phase,_** MOM.*

[@cosmo1494]

it liked black before it cooled .... ;)

[@skadidal]

The question blew my mind... Let alone the answers. Love your channel. Keep up the good work.

[@NendoNow]

I'm glad they didn't pin the microphone to her shirt, cause now it looks like she's holding the worlds smallest microphone. XD

[@physicsgirl]

"They" would be me.

[@sdmamitmahto]

Nendo Now I got it😂😂😂

[@NendoNow]

You made the right choice :D

[@typemoon4894]

Nendo Now The people she's talking to would need to talk into her shirt if it's pinned there.

[@Sniperson2002]

"Ummmm, My eyes are up here!"

[@MC-tk2qo]

Because they are absorbing a balanced amount of short wavelengths(blue), and long wavelengths(red), which reflect green. Green could be the vibrational equilibrium.

[@lorigulfnoldor2162]

As J.R.R.Tolkien once said, "It takes just a little imagination to imagine a Green Sun - but a whole lot of it to imagine a world where it would be a natural sight to behold."

[@korelly]

The colour most absorbed by chlorophylle is red. That's why the neon lamps advised to use in a greenhouse emit a pink light, which contains a bit more red than other colours. That is also why if you light up a leaf with some red light, if will appear dark brown or dark blue, almost black.

[@JoakimfromAnka]

Who the hell sees yellow whenever they accidentally look into the sun? It's a white blinding ball floating on a light blue canvas. Anyway great video.

[@physicsgirl]

Blinding, yes. But photos of the sun, sometimes with questionable filters and false-coloring, are often shown as orange, red, or yellow.

[@llumar100]

Physics Girl In the news and the blogs show us a sun with color like the volcano and we think the color is different to the White.

[@anushkakulkarni2238]

Planci Acanthaster mostly we are able seethe sun during sunsets and sunrise that time it is reddish or orange when it is very close to the horison , there light takes a longer path to to reach observers eye .the blue and violet colours are scattered than red ....so the light that reaches the observer is mostly red

[@anushkakulkarni2238]

Physics Girl I hope I'm right ....

[@JoakimfromAnka]

Well duh things can change when he sun is low but if you ask "what color is X" it's assumed to be about the most common circumstances. The default place of the sun is up in the sky not at the horizon. You might as well say the sun is green because that's what it would look like if you fill the atmosphere with sodium.

[@Hunar1997]

4:40 "purple theory that has nothing to do with hamburgers" .. and moments later in 5:15 humburgers again :D

[@ninjashuriken]

hunar omer Ikr

[@rogersledz6793]

Thank you so much for uploading this video. It is helping me get through the pandemic!

[@snehahazra22]

Actually, what I've learned from my biology book is that the photons which works best for photosynthesis is red and blue.Hence, plants absorb those and reflect away green

[@lizebrand]

But the question then remains why photosynthesis evolved to work best with red and blue light. True, here might be only one way for photosynthesis to work, which would be with those wavelengths of light. I don't know why that would be though, and it seems unlikely to me that scientists wouldn't have realized that there are no other possible variants of photosynthesis except for the red-blue type.

[@snehahazra22]

@@lizebrand because back in the anaerobic period of evolution, as green light is the most emitted wavelength from the sun the anaerobic microbes had evolved to utilize that wavelength for photosynthesis/chemosynthesis. This left the budding aerobes to evolve to adapt to availability of red and blue light in majority

[@eclectic505]

*GREEN IS NOT A CREATIVE COLOUR*

[@hermanlai6035]

.....

[@sahajsin7847]

woah.

[@tmpEngine]

what do you mean

[@Treethinking666]

It may not be creative, but it is my favorite color!

[@hermanlai6035]

dhmis

[@yeeyee2278]

As a graphic designer, I very much love that you scripted and filmed yourself acknowdging a graphical inaccuracy

[@bryan-zamanizulu-stone3911]

Diana, you're the best! Thanks so much for another amazing video!

[@DeyvsonMoutinhoCaliman]

I prefer the theory in which chlorophyll is just easier to come by. It's easy to make, works well enough, so that's it. You could make a video about why mammals are never green, since it should be expected that at least some would develop this color to be more stealthy in a forest.

[@amaytripathi4097]

*Or are they?* (Vsauce music starts)

[@JokelaTurbine]

Good thinking. The same question came in my mind 12 years ago, and I decided to study the topic more carefully. I even made experiments which supported my hypothesis. First, the Plants are basically just like any factory which produces something. They use Water, CO2 and sunlight to produce sugar and O2. So first we need to find what limits this production. In Ocean it surely isn't water, and it isn't sun light either. It's CO2 Notice that when a plant Takes CO2 from air and releases the O2 out, without wind, it would pretty soon be macroscopically surrounded by O2, and the average CO2 amount in air doesn't help anything. The Plant is out of supply of CO2. As this Wind stuffy happen's over the time, it's obvious that The Plants should be using the light which provides just enough energy for the process AND is longest present for the process. -> Blue/lila light is the first and last light of the day due to the Refraction. So basically the Plants are green because the Sky is Blue. But it's not that simple. Earth saves the heat of the day and radiates it back on the night. And plants use this "red" ligh too for the same reason. It's availability over time. Now, if this hypothesis is true, then providing more CO2 to plants should change their colour. And this actually is true, just look the grass after you have cut it. The part of grass closest to the ground is more yellow, because the humus supplies CO2, this means the average refleced wavelength might have gone from 550 nm to 580 nm. I have observations (fotos) from nature, where even trees change their colours to more yellow, if there is dying tree providing more CO2 in some windshade place in mountains. But the most interesting thing I did was the experiment with Sphagnum; I gave them pure CO2, (In a controlled setup) and here I could see how they changed their colour to yellow, and could visually obsorve that they were growing faster. Due to other interests, I didn't have the time to make ful scale study with accurate measurements. Bot what I found satisfied my own curiosity. The reason I chose Spaghnum is because it builds a structure, even though every single cell is fully functioning plant. This Structure gives the possibility to have a open structure and efficiently vented gas exchange; to deliver the gas and water directly where the plant can use it. The algen have the problem with difficult gas exchange, the O2 must get out of water, and CO2 must get in the water. btw. It's commonly known in Finnland that peat moss can change it's colours during the season, from red to yellow to green though the different coloured plants have given different names; en.wikipedia.org/wiki/Sphagnum#Taxonomy_and_phylogeny I personally am convinced that this colour is caused by the local CO2 supply, which can vary ie. because of water level changes etc.

[@Uyhn26]

This is fascinating. Thank you for sharing your theory and findings! :)

[@preternatural3231]

Love your videos ! This was really interesting

[@Alison0305]

This was posted ages ago, but I was researching this topic recently, and one of the theories had to do with efficiency and how useful certain colors are to the plant/ how much energy can be generated from a given color. Green just isn’t as efficient as other colors of light.

[@thokim84]

Color is a perception, wavelength is a physical measurement that corresponds to color and energy.

[@Gwyrddu]

If the predominant color the sun gives off is green, why is the sun classified as a yellow dwarf star?

[@stuartschaffner9744]

Gwyrddu , at 1:44, you can see a spectrum of the light the sun emits. We see that spectrum as white, because we evolved under that light. White is what we mean as “not colored”, I.e. average under the sun’s illumination.

[@Gwyrddu]

@@stuartschaffner9744 Right, but the sun is not called a white dwarf star, which is different type of star entirely. Either the group of G-type main sequence stars that the sun belongs to generally peaks in the yellow spectrum and the sun is just a bit of anomaly, or the term yellow dwarf is a misnomer. It's not like the name "green dwarf" was taken by any other group of stars either...

[@stuartschaffner9744]

Gwyrddu, the term “yellow dwarf” for the sun is not a scientific term. The sun is a G2V main-sequence star in its stable midlife phase. The term white dwarf may or may not be in current use either, but it refers to the old-age phase of most stars. Our sun will be a white dwarf in about 6 billion more years, after a brief phase as a red giant. Hope this helps.

[@TimpBizkit]

Because our eyes also perceive a mixture or "red" light and "green" light as "yellow" in addition to "yellow" itself. So you have a hybrid of 650 and 540 nano m light in addition to light around 580 nano m contributing to "yellow" as 580 triggers both red and green receptor cells in the eyes. Fun fact "magenta" does not have its own wavelength but is a hybrid colour.

[@diazinth]

@@stuartschaffner9744 I'm gonna guess that "brief phase" is not measured in seconds?

[@TooManyEditsProductions]

I’ve been learning about endosymiotic theory at my school, so I️ think it might have something to do with Cyanobacteria (it’s greenish) which would become chloroplasts, and then that would go with the sad theory - generally, plants didn’t need to do better when they survived well enough.

[@SteveKozma]

In order for plants to survive, they pull water from the roots and out the leaves (i.e. transpiration). That takes a lot of energy. It plants reflect green light, then they’re using the most amount of the sun’s light to help with turning water into vapor and carrying it several feet in the process. The reflection of the light might help somehow pull the water vapor out of the leaves. It’s just an idea and I’m sure someone has already thought of it somewhere else already, but came to mind halfway through the video.

[@michietn5391]

Hi PGrl; you missed one... chlorophyll is one of the pigmented molecules and its color happens to be associated with a metal, Mg. Metals have characteristic spectra, and their reflected light falls into quantized "spectral lines." See www.applet-magic.com/lifemolecules.htm , and then en.wikipedia.org/wiki/Emission_spectrum

[@heyimdanny100]

that's definitely true, but misses the point a little bit. Spectral lines apply for lone atoms, and things tend to get a bit wobbly and shifted around when you put an atom in a molecule. The energies of the orbitals on Mg (and thus the energies of the transitions, and thus the colour of the whole complex) depend on the environment in which the Mg finds itself, ie what ligands it has around it. So, by changing the ligands you can change the transitions and change the colours. So the question remains: why did nature choose these specific ligands to put around Mg, making it absorb in the red and the blue, when it could have done a bit of chemistry and shifted the absorption into the green?

[@TheNameOfJesus]

With a name like "Physics Girl" I thought I was going to get an atomic/quantum physics explanation as to why electron shells in the atoms of plants don't absorb green packets of photons.

[@temporaryaccount5698]

Because they're green

[@Lemonz1989]

I don't know if this is coincidence, but as an avid gardener, I've noticed that non-green plants, especially purple, dark red and black plants grow really slowly compared to most green ones. Red maple grows at least twice if not three times as slowly as a regular green maple tree.

[@letterbomb211]

I believe it's mostly to avoid over heat, a black metal sheet left in the sun rapidly reaches really high temperatures, such a strong light could dry a leaf in hours

[@curiousbit9228]

Just a line Of thought🤔: could it be Because blue light is the most scattered in the atmosphere. Which means at any given time on an average blue light photons are throughly distributed in the atmosphere So, during the time of genesis it was easy for blue light absorbing molecules to form than any other color. Assuming sky was blue back then*

[@spadaacca]

Did you say genesis? Go away!

[@rumsto1]

I love your videos, and I ask myself questions like these all the time. I appreciate you breaking down some potentially complicated subject matter into bite-size chunks (hamburger joke).

[@johnsperry3573]

Note that "green" light is several frequencies. A frequency that is absorbed for photo synthesis may not be the same as what is reflected. Plants change the color (frequency) and darkness of their leaves partly depending on exposure and intensity of light - darker when shadier, and lighter when high sun exposure. Different plants have different ranges of light that they are adapted to. There are other leaf pigments (orange, yellow) may be noticeable in in fall tree color.

[@kainpwnsu]

FYI, the photo of Great Salt Lake (at 6:32) is not stitched together from two photos. The lake is bisected by a train trellis, which has largely obstructed major water from tributaries at the north and south ends from mixing. So, the lake really does have two-tone water.

[@JustAnotherEngineer_]

Physics Girl; Now featuring Veritasium's attitude!

Also Jabrils

[@rkpetry]

6th theory: green light bounces around and so spreads its 'wealth' among all the leaves... 7th theory: plant genetics developed billions of years ago when red light was dominant... 8th theory: photosynthetic utilization of carbon-dioxide is just red-light-district efficient... 9th theory: growing in cold ground is far less efficient so plants would rather hibernate...

[@LtFoodstamp]

All light bounces around... but only if it's reflected and not absorbed. The green plants are reflecting the green light and not the red.

[@ashley3629]

6th and 7th theory seems relative to night vision goggles.

[@MrDerebail]

Very good topic physics girl... Great work. Didn't think of this...

[@emilygutknecht6098]

fun fact! red and blue light do different things for the plant. red light helps more with germination than blue light, while blue light is just more general.

[@baab4229]

I actually like the sad theory, because it's most likely to be true. There are many other examples of evolution not being perfect. Also, I think the word you could use is "hypothesis" because scientifically speaking theories are evidence-based explanations. If scientists don't know something but have a guess, it's a hypothesis.

[@alejandroloera5607]

The evolution not being perfect makes more sense to me. Why should it be perfect? It is awesome, though.

[@pugglehugs8032]

The Earth Is a Cylinder!!

[@dsp4392]

Exactly. Evolution doesn't lead to perfect things because there is no end goal to the universe, there's no metric to measure perfection against. Perfection is a purely human construct.

[@Kramlets]

With the sad theory if plant life is present on other planets we should expect to find it in different colours other than green.

[@WereWade]

that said, it makes me wonder about what the sad theory got right in it's inperfection. I love studies about light!

[@flightofthephoenix2072]

Hey Dianna, where did you film this? Looks like a botanical garden or something.

[@physicsgirl]

Yes, in Balboa Park!

[@pablooarmas]

Physics Girl I heard about it, it would be cool to go visit it

[@matthijndijkstra25]

Visited that a few months ago!

[@therealstubot]

You managed to film on a day that wasn't raining! How fortunate! I live north of Balboa park about 30 miles, and it's been downright wet this winter.

[@cixcell]

good time to film it after all the rain

[@felixvasin758]

you got me with your leading question. however because you taught me green is the peak of the spectrum emitted by the sun it makes sense to me that plants are green for protection from the most intense frequency emitted by the sun... made me think you could possibly search for life using different parameters. we can tell other suns' primary frequency so maybe, like your last question we don't have to look for biologics elsewhere that fit our homemade recipe.

[@ryanaraujo5102]

well, i was thinking about this, and i might be really wrong but, even the color that the sun emits the most being green, under our atmosphere, the light turns orange, even a bit red, during sunset, that apears to be the time where photosynthesis occurs the most (sunrise and sunset) (ithink this might have something to do with the saturations thing), so, plants being green, actually means they absorb all wavelengths most present in sunlight, and reflect the less present (because green is not so present in the orange/red spectrum). Im not sure if this makes any sense, but made me think about it!! great video!! thanks.

[@DrShaym]

Maybe plants prefer ultraviolet light, which is violet and thus falls on the opposite side of the color wheel, and reflecting green light somehow makes it better at absorbing violet light.

[@hurmzz]

Ultraviolet is not violet, it’s invisible. It is the “color” past violet, thats what the ultra stands for. The color wheel also is of no application here because color is in a band, its not circular, there is no red again after purple..

[@choppergamer]

Woaw,minute 5:17.....IS THAT Jabril from SEFD Science?daaamn.i learn new things every day

[@jenovaizquierdo]

Awesome video and you make the video fun and interesting to watch. You made me subscribe.

[@ericanderson1846]

excellent presentation. thx!

[@UniqueliAnimationsSN]

0:06 "its a white dwarf star" Me: Boi where did u learn that lie? His right about the color though

[@theothewise]

I loved this video!

[@rockroll7649]

Blue spectrum light is good for vegetative growth in plants. Red spectrum is good for flowering plants and plants that produce fruit, though blue spectrum is still needed for flowering plants too.

[@PupdudePwns]

5:30 I had the same idea when thinking about using cytosine in RNA when cytosine spontaneous deaminates into uracil (which is used in RNA instead of thymine).

[@AstusRush]

But actually the sun is dark grey with a bit of purple! The sun is emitting light but the better something is in emitting the less it reflects. The perfect emitter does not deflect any color at all but our sun is not a perfect emitter. the color the sun deflects is actual grey-ish but it deflects a bit more purple. So if the sun would not emit any light and one would point a giant flash light to the sun one could see a giant grey ball. So when taking about the color of the sun as we talk about the color of a leaf (that is the color that is deflected) the sun is dark grey.

[@Drakwdeanrer]

I dont what are you smoking but I want some.

[@AstusRush]

I learned about this from my physics professor. You can for example see on wikipedia "Black body" espacially the paragraph "Stars and planets" or google it

[@test4O4]

nah mate the sun is black

[@brendanstein88]

Robin Albers yeah mate and the earth is also the shape of a triangle

[@heyimdanny100]

nahhh dude that's a messed up way of thinking about it. the sun's colour comes from the combination of its emission and its reflection, just as with any other light source. Since it's emitting much more than it's reflecting, its colour's gonna come mostly from its emission (if you shine a green laser, that light is green because it's emitting loads of green light - what it's reflecting is basically negligible in comparison).

[@zeke1220]

Who the hell can only fit one hamburger in their stomach?!

[@gavinjenkins899]

plants.

[@dublb232]

Someone cute (and smart) enough to have 1.39 million followers...?

[@ra_alf9467]

The guy that isn't American

[@aaronseet2738]

those who are energy efficient.

[@dedge511]

Oh my! I'd love to know where you are! Those plants are amazing! 😍

[@stormrungaming]

Love your videos!

[@NewbyTon]

That's not true My plant started out green, but after a few months of neglect and not watering it, it just turned brown, then black

[@hopesy12u4]

I'm so glad we got green plants. Anything else is garish in comparison.

[@cpwm17]

john smith Then, perhaps, we may still experience the alternative color as we experience green now. What we experience as green is created in the brain but does not exist outside a brain.

[@spadaacca]

@@cpwm17 matrix

[@spadaacca]

@Audio Queen you go kween

[@Josh_Fredman]

A few years ago I came across the purple theory, and, in fact the way I remember it, I didn't even realize this was still not known for sure. I remember the explanation that plants are green today because the plants of long, long ago were mostly purple, because being purple gave them that little bit of an edge in terms of energy efficiency (since there's more green light). But then, in one of the mass extinctions (I don't remember which), the purple ones all died out, while the green ones didn't, so they took over, and haven't needed to turn purple because green is almost as good and outweighs the disadvantages of being a purple mutant plant.

[@hushhushbee1647]

We were also taught that the rate of photosynthesis is max for red and blue spectrum and it falls for green spectrum thats why they absorb red and blue part of light and reflect away the green part

[@John_Ridley]

There's more green light, but blue light is more energetic. What's the distribution of light at the surface when corrected for total photon energy?

[@3Dusers]

"because its a white dwarf star"

[@jameskubik8804]

I won't ever get enough of your videos

[@nandy9285]

10/10! The video was great too! 👌

[@navritkaur1902]

please make a video on the cause of refraction. its seems really simple, but its not. just try to think about the direct cause.please for the sake of physics. it will be awsome.

[@dylanhd1536]

Black leafs matter

[@saf5634]

Ego Hominum Don't do that stuff.

[@galadhremmin]

RACIST AND RUDE

[@rachelslur8729]

🖤🌿

[@hahahahaa5224]

🤣🤣🤣

[@spotlobac7694]

your funny.

[@George.Coleman]

Plants appear green to us because we see red blue and green light that mix together and make all colours of the rainbow. Plants absorb all the red end of the spectrum to retain heat and all the blue end of the spectrum for UV energy. Leaving green light to reflect the most, hence why they look green.

[@Gorlokki]

great video, ty

[@jmclean6648]

3-5 hamburgers sounds really good right now

[@C1TRU5]

Maybe green plants look better for the sake of spreading around, though it would also make animals more likely to eat them

[@C1TRU5]

Actually I kinda like me idea more now. The more appealing a plant is, the more likely it is for animals to eat it which in turn, those animals leave fertilizer in that area allowing plants in that area to grow more and be more appealing.

[@reallivebluescat]

They look better because they are green because that what we/animals are used to, not the other way around

[@Enjoy_my_1st_Amendment]

As an organic farmer this is very interesting and people don't understand the critical importance in a plants ability to photosynthesize. Literally everything you eat depends on it in one form or another. From a plant and vegetable to the steak that once ate pastures full of grass. It is all possible because a plant can turn light into energy. Amazing when you think about it. Fish also. That big one ate a smaller one that ate plankton that ate the algae which also converted sunlight to energy. Arguably if it wasn't for this unique process of photosynthesis life as we know it literally wouldn't exist.

[@killsnskills]

This has become my favorite channel you're the best

[@E27043]

4:25 WAAAA PLANT ABUSE!!!!!

[@seanm7445]

Why isn’t the sky purple?

[@fandyus4125]

Because it's blue.

[@fandyus4125]

No prob, glad I explained ;)

[@gabedarrett1301]

Sean M Because purple requires the red and blue cones in your eyes to be seen. Red light isn't as scattered as shorter wavelength light so only the blue makes it through

[@fudgelame]

More simply its blue because of refraction thru water and its vapor, which is blue.

[@HellFire178]

I didn't think I would need this video, I was wrong. Those theories are amazing

[@Phyto.]

You'll have to dig into the biochemistry and energetics of photosynthesis to explain why red and blue are the most "useful" from a photosynthetic POV.