On earth, in India darkness is equally proportionate to light. But space is mostly darkness. Space doesn't have its own light. I want to know whether the blue colour found on earth is found in space? And also the clouds on earth, are they only found surrounding earth or found elsewhere in space?
https://medium.com/the-infinite-universe/olbers-paradox-why-the-night-sky-is-so-dark-b7b39487e8f8
We can see 2 dimensions of every 3 dimensional object. Our eyes and the way light behaves with them shows us 2 dimensions only. Is it possible that some acquatic species or bird or insect or reptile or animal can see all 3 dimensions simultaneously? If i see all three dimensions simultaneously, would i hop, fly, be slow or fast?
Maybe because we live in the Yin side of Yin Yang system. The dominance is darkness. When we are in the Yang side of Yin Yang system, the dominance is brightness.
Why is the sky blue: In space light travels in a straight line. You will only see sun light as coming directly from the sun to your eye. There is no light coming to you from any other direction. That is to say the sun looks very bright but the sky around it looks dark. To see sunlight coming from a direction other than directly from the sun, something must change the direction of the light. When you look up at the blue sky you are seeing sun light that has scattered off of the molecules in the air causing the light to change direction so that some of the scattered light happens to travel towards your eye. The reason it is blue is because of the size of the air molecules. They are very much smaller than the wavelength of the light. In that case scattering is more efficient the closer the particle size is to the wavelength of light. Blue light has a shorter wavelength, and so it scatters more. Note that it doesn’t all immediately scatter. There’s a small probability of scattering in each bit of atmosphere, and most of the light keeps going straight. That’s why you see bright sky everywhere and it doesn’t all just scatter in the first bit and the rest of the sky would be dark. That is also why the sun still appears bright. Only a small part of the light scatters. That is also why the sky isn’t blue at night. The same thing happens with starlight or moonlight, but a small fraction of an already weak light scattering towards you is not readily discernible. The wavelength doesn’t just determine how much of the light scatters, but also at how large of an angle. Blue scatters not just more but also much more at larger angles. This is why the sky is bluer further away from the sun and whiter towards the sun. Higher scattering of blue is also why the sky is red at sunset and sun rise. With the sun low in the sky you are looking at the sun through a lot more atmosphere. More of the blue has scattered away before the light reaches you, but the red, scattering less, penetrates further. Also it tends to scatter at smaller angles so the sky looks redder nearer the sun and less so off at large angles. Note that the blue is not completely gone, it is just comparatively less. Looking well away from the sunset the sky is still blue but darker than in the day time.
In contrast, in clouds light scatters off of water droplets which are much larger than the wavelength of light. In that case the scattering is much less dependent on the wavelength and so all the wavelengths scatter about the same. So clouds look white. Also, the amount of light scattered per distance travelled is much greater, so it doesn’t take too much thickness to prevent a large fraction of the light from getting through. So clouds look white on the sunny side where you see the scattering and dark on the far side where you only see light that has managed to penetrate the cloud. At sunset, the clouds equally scatter all the wavelengths of light that reach them and that light continues on to you. However the path through the atmosphere both before reaching the cloud and after preferentially scatters blue, so the clouds look orange or red, but that isn’t anything the clouds are doing.
RE two vs three dimensions: yes, animals do have adaptations to judge distance, such as … humans! That’s the main benefit of having to forward facing eyes. We use parallax to judge distance. Animals with eyes more on the sides of their heads (most birds other than birds of prey, to a lesser degree horses, etc) see a larger slice of the world, but over the parts that are only covered by one eye they miss out on the extra tool of parallax to judge distance. You are probably aware of this ability if you have ever had to walk around with one eye covered. You have trouble avoiding obstacles.
Even without parallax we have a lot of information revealing distance. First is focus. Your eyes adjust focus so the conjugate image is formed on the retina. Over a range of distance your brain knows how far something is by how much it has to focus the eyes. More subtly, the brain maps out depth by constantly varying the focus. The distance where this is useful depends on the size of the aperture. The pupil of your eye is much smaller than the distance between your eyes, so parallax works out to longer distances than focus. Even with one eye your brain is still using parallax to map out the third dimension. our head an eyes are constantly moving. That creates continuous small changes in our perspective. The brain uses the parallax caused by the movement to map the world in 3D. Beyond simple measurement of distance we also use experience and expectation. We know things further away look smaller, so we perceive perspective to gauge distance. for example how an artist uses converging lines to convince us a scene has depth.
Taken all together we very much perceive the world in 3D. Nowhere is this clearer than watching a professional basketball player drain practice shots from all over the court. Our ability to judge distance is brilliant.
There is more complete information regarding depth in the phase of the light reaching our eye. Focus and parallax are samples of that information, but a more complete record of the phase front can be stored in a hologram. Shining a laser through the hologram then reproduces the original phase front and as near as we can tell the original scene is reproduced with all its 3D info. White light holograms are a little less perfect, but generally work pretty well.
Light scattering is proven concept? Or a theoretical concept ? Why just blue and not any other wavelength? Thank you for this information @Mike Albert
Yes, very well understood long long ago and put to good use in various technology such as measuring wind velocity by measuring the Doppler shift of the back scatter. There are many types of scattering, but for the molecular scattering that makes the sky blue see the Wikipedia article on Rayleigh scattering. For scattering from larger particles see Mie scattering.
One more thought: in your last question you asked “proven” or “theoretical”. There are two big problems with that question.
First, in everyday language “theory” means supposition. However, in science “theory“ means almost the exact opposite. Something that has reached the level of Theory is very well grounded and supported by evidence. See the Wikipedia article on “scientific theory”. Something that is proposed but not yet well tested is called a hypothesis.
Second, scientists tend not to think of things as “proven”. Proven suggests a finality and completeness, an immutable fact. Even if a theory completely describes all currently known data there is always the possibility that in our ever expanding understanding the next piece of data may break the existing theory. Scientist love that. Those discrepancies at the edge of what is currently understood have been the motivation for most of the great advances in science over the centuries. And, so, you will find a million scientific papers testing at the boundary of what is already understood, everyone of them done in the hopes of finding a discrepancy that will break a currently well established theory. Nothing is ever proven. To the scientist, the current theory is known to adequately explain all available observations. But we sincerely hope that won’t remain true. Finding where the theory breaks is where we learn.
Thank you so much @Mike Albert. Its feels great to experience your repies which you have spared time and patience to type in here. Yes , science is beautiful. No matter whichever route any scientist takes, it proves him right . But he can be contradicted by another theory. Nature is just so intelligent. Glad to meet you.
Our body is:
Good conductor of electricity which we cannot tolerate.
Good conductor of heat which burns our skin.
Good reflector of sunlight which is sensitive for our eyes.
So,huge amount of electricity, temperature and light are intolerable to our body.
Also,
We cannot witstand huge amount of force.
We are not faster than light or leopard.
So, huge amount of force and speed are intolerance to our body.
We can't see the sun directly due to intensity of illumination, but every other color of the spectrum is easy to be seen when they remain as individual colours in the plants. We can tolerate the flame of a candle, then what's wrong with the sun? We are viewing the sun on a blue space. We can tolerate this saturated blue light. We can clearly see the clouds but the sun is like peeling onion. As if i am not allowed to see the sun nor the onion.
In the evening the sunsets are beautiful with no onion effect.
Never seen a candle in blue space . Never seen a candle scatter blue. Infact the flame contains an innermost blue layer.
Never seen a fireball in any other colour background like light pink...
Since there is virtually nothing in space to scatter or re-radiate the light to our eye, we see no part of the light and the sky appears to be black.
https://www.livescience.com/why-does-space-look-black.html#:~:text=Because%20space%20is%20a%20near,the%20eyes%2C%20they%20see%20black.
I marvel at the way the light from the planets and the stars from outside our solar system travel far enough for us to see them on Earth, although it takes so long for the light to get here and the actual star may not still be casting its light by the time that we admire it in our time:
https://www.pbs.org/seeinginthedark/astronomy-topics/light-as-a-cosmic-time-machine.html
Nothing like a starry night!
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