Over the years, I learned some animation skills using Blender. It is an awesome opensource software. You can make incredibly good 3D animations in Blender. I also learned Python. Well, only some part of it. Now combining these two, I invested some time to create animations on two subjects that always attract me. One is the advent of Artificial Intelligence, with its great potential. The other one is the space, animations about space object and travel in the space.
I am regularly uploading my animation videos to my Youtube Channel: The Alien World … and you can watch the AI videos from the links below.
Summary :: Is the sky we see in the night, real ? Does it really exist or is it just our imagination ? The answer is simple. The sky that we see, is unreal. It exists only in our mind, in our imagination. It is not real. It never was. Not convinced ? Okay, please find out the truth in this article.
Reading Time :: 10 minutes.
We have an amazing sky around us, filled with beautiful stars. Who did not look up in the night & count the stars ever in his childhood ? We live with the stars. Stars are believed to be eternal and immortal compared to the very small lifespan of humans. We placed the stars in our religious thoughts, we have even imagined many figures around the stars, we named the constellations, we made horoscopes based on the stars. Is it all just absurd & imaginary ? No. Each of the stars very much exists in reality, or did exist sometime in the past. But the view that we see from Earth is still unreal. It is merely an illusion or imagination. Sounds contradictory, right ? No problem, we will get into the details in a moment.
What is reality ? We assume that what we see is real. Seeing something is the single-most important criteria that defines reality (or pseudo-reality) for us. And light is the means by which an object becomes visible to our eyes. Hence, in the discussion of reality, light plays one very important role.
You have probably learned this in school physics. A recap first. Light travels at a very high speed. In just one second, light can travel around the globe… not just once, but 7 times. In fact light has the highest possible speed we know in our known universe. Still it takes more than 8 minutes to reach us from Sun. And in fact this is just a short distance compared to the gigantic size of the universe where we have all other stars. The distance between these stars is so huge that even light takes hundreds or thousands of years to reach us from the stars. These distances are unimaginably high. That is why we measure such distances in a special unit called light-year. One light-year is the distance traveled by light in one year i.e. 365 days running 24×7. Do you know how far is that ? It is approximately 9,460,730,472,581 kilometers !
And then, we do not have even a single star within one light-year distance from us (except of course Sun). The closest star from Earth is Alpha Centauri which is at a distance of 4.4 light-years. The brightest star in our sky is Sirius which is at a distance of 8.6 light-years from us while the North Star or Polaris is approximately 400 light-years away. And these are just few nearby stars. Many stars are at a much greater distance – hundreds, and thousands, and millions of light-years away from us.
What this means is, the light that we see today from a star, had started its journey from the star several years ago. May be that particular star does not even exist today, or its position in the sky has already changed. What we see is not today’s reality. It is yesterday’s reality. Today we are seeing where that star was some years ago. This “some years” may be 5 years, may be 500 years or may be 5 million years… it depends on how far away the star is. Our school books have already taught us all these.
So the star is real. We are just seeing it late. We can compare this with the “Live” broadcast of a cricket or football match. We know the broadcast is not really “Live”. There is a 5-10 minutes delay kept for editing purpose. But it does not matter much. We ignore that small delay and enjoy the match as “Live”. Same is the case for a star. The only difference is, here the delay is not just few minutes or few hours, it is in years. Still, that is kind of a reality – a reality of the past. We see the historical star, not today’s star.
That is only true as long as we are considering a particular star. The situation would dramatically change if we consider many stars together as we see in the night sky. Why ?
In ancient times, people used to believe that the stars are fixed on a celestial globe, all at an equal distance from us, and these stars do not move. The scientific techniques available during that time was insufficient to measure the true nature of stars. They did not even have a telescope. But today we know that the stars are not at a fixed distance from us. Some stars are near to us, some are far away. Moreover, nothing is standstill there. Everything is moving in this universe with respect to each other. Every star is running.
Let us consider the two stars as shown below. One star is 100 light-years away from us. It is moving from left to right along the white dotted line. The other star, on the right hand side, is 200 light-years away from us. It is moving along a path shown in yellow dotted line. The picture shows how exactly they appear in the sky today. We will find out if this picture is real or not.
Star A and Star B in the sky as we see them from Earth
Star-A : Light takes 100 years to come from this star. That means, whatever we are seeing today, is 100 years old. We are looking at the past. This is 2019. So we are seeing where the star was in the year 1919 (position A-2). Today it has moved further into position A-3. We will be able to see that position only 100 years later. What we see today is its position in 1919.
True position of Star A in the year 1819, 1919 & 2019
If we go back 100 years further in the history, in the year 1819, this star must have been somewhere near position A-1 as shown in the above picture. It has moved from A-1 (year 1819) to A-2 (year 1919), then A-2 to A-3 (year 2019) along that white dotted line.
True position of Star B in the year 1819, 1919 & 2019
Star-B : Since this star is 200 light-years away, it takes 200 years for the light to travel through this distance and reach our eyes. Hence, we are lagging behind by 200 years in this case. The current position that we see for this star, is its true position back in 1819 i.e. 200 years ago (position B-1). It was in the position B-2 in 1919. Today it has actually moved into position B-3 which we will be able to see only in future.
Now check what the position A-2 and position B-1 means together. Position A-2 is the first star’s true position in the year 1919. But position B-1 is the second star’s true position in the year 1819. These two lights are reaching together to our eyes today, in the year 2019. So we are seeing the history, but we are seeing a different history for each of them. Part of it is from the year 1819 while the other part is from the year 1919. These two different historical pictures get superimposed in the sky and we see a joint picture that has no meaning. These stars were never in these relative positions ever in their life.
Let us strengthen our understanding from a different perspective now.
True positions of Star-A and Star-B in the year 1819
True positions of Star-A and Star-B in the year 1919
True positions of Star-A and Star-B in the year 2019
Look at the above pictures carefully. The first picture shows the true positions of the stars in the year 1819 and the second picture shows the same for the year 1919. The third picture shows their current position (i.e. in 2019), which anyway we will be able to see only in the future, at two different times.
Now check the below picture.
How Star-A and Star-B appear in the sky today
This is how these two stars appear in the sky today. Does it match with any of their relative positions in the past history ? No. They were never in these positions relative to each other, as we see them in the sky today. A-2 is the true position of Star-A in 1919 while B-1 is that of Star-B in 1819. What do they mean together ? Simply, nothing! This means, what we see in the sky, is completely unreal. It is not true, and it was never true, never real any time in the history as well.
That’s it. In a nutshell, every star brings to us a piece of their history. But each star is at a different distance, and as a result, each star brings a different piece from their history. We see these different pieces together and our eyes make a jigsaw puzzle to develop an unreal, imaginative picture of hundreds of stars in the night sky. We just discussed about two stars above, and saw that their relative positions are unreal. Now think about those hundreds or thousands of stars – everything of which is unreal. The entire scene we perceive from the night sky, is unreal, purely imaginative.
But whatever it is, we still cherish their beauty. We get amazed looking at the endless stars making a super-natural collage in the backdrop of our dark sky, every night. Each part of it is real, but the collective picture is very much unreal, immaterial.
Immaterialism is a concept first used by George Berkeley in the 18th century. He argued that whatever we see in the real world, is imaginative… i.e. they exist only in our mind. He extended this concept to most material objects like table, chairs, trees etc. It was mostly a philosophical discussion, as it tries to disprove the very reality we are living in. Whether we accept that or not, there is no doubt that the sky we see everyday, is not real. We build the concept of reality through our vision. But our vision can be mischievous, as we just saw in this article.
Thanks for reading!
I cordially welcome your comments if you have to say anything on this write up.
Summary :: Have you ever wondered what is the resolution of the screen over our head up all time throughout the year ? One day, this idea hit my mind and I tried to actually calculate the resolution of the sky that we see. The result is very interesting. Find out more about this in this writing.
Reading Time :: 10 minutes.
There is a giant screen above our head, the biggest & the brightest amphitheater around us, built by the nature. It is the brightest in the day, and it is also the darkest in the night, unless the street lights mess up with the natural panorama of the beautiful stars all over the sky. There is hardly anyone there who did not ever look up into the sky in a solo night, did not get mesmerized in its beauty and did not ponder upon the questions like who are we… where did we come from… what is the meaning of this universe…
Well, I am just like that common man who has always been a fan of the night sky. How the stars, uncountable in number, twinkle restlessly, how they tell us the story about the immortality of time, how the deepest silence rein all over the sky in a moonless night – have always attracted me like anything. I have been looking up into the sky every evening. On one such day, the idea came to my mind about the resolution of this scene.
Let us consider some facts and do little bit of calculation. Our eyes are made of very precious nerves and very delicate mechanisms that enable us to see the beauty of this world around us. Still, there are some limitations or boundaries in our eyes. No, it is not the dark spot I am talking about, which you must have read in the school books. I am talking about the maximum and minimum limits to which our eyes can stretch themselves for vision. One such limitation is the smallest size our eyes can see. We know that we cannot see tiny elements… for example, we cannot see electrons, protons or viruses. But what is the smallest size that we can actually see ?
Honestly, there is no ‘smallest size’ in absolute terms. What matters is the angle made by the object in our eyes. If we just imagine two rays coming from two extreme points of an object (let us consider the Sun in this case), the rays make an angle when they meet our eyes. Check the diagram below. For the Sun, this angle is approximately half a degree. A smaller object in the sky, will make a smaller angle when we see them. But there is a limitation there. An object must make an angle of half minute or more in order to be distinctively visible by our eyes. Here minute is not a measurement of time, one minute is 1/60-th part of one degree. It is a measurement of angle, very tiny angle.
Angular size of the Sun is 0.5 degrees approximately
If the two points are such that they make an angle less than half minute, our eyes cannot distinguish them as separate points. They will appear as one single point in our eyes (if at all visible). This is the case with the most perfect eye in the world, although on an average, we all have lesser resolving power in our eyes. But let us assume here that we all have perfect eyes and hence all of us can distinguish a half minute angle. This is the boundary value we will use in order to calculate the resolution of the sky.
Before that, let us understand this part of the math little better.
We said, the angle made by an object must be at least half minute. But we did not specify the actual size of the object. Why ? Because the actual size does not matter. If we draw a half minute angle from our eyes, taking any one eye as the vertex of a triangle, and extend the angle further, the two lines will move apart from each other as we extend them. The distance between the two lines will increase if we go far & far. This means, the actual object may be of any size, but it can make a small angle in our eyes if the object is far away from us. This is why we do not take the actual distance between two points on an object, instead, we take their angular distance i.e. the angle they make in our eyes. If their angular distance is half minute or more, they appear as two distinct points to us. We see in the above figure that the Sun makes an angle of half degree in our eyes. A half minute angle will be 1 of 60 parts of it.
Now… what is a resolution ? You probably already know that, but here is a quick recap.
Comparison of screen sizes 720p vs. 1080p vs. 4K
A resolution means, how many ‘dots’ are present on a screen. A dot is the tiny unit on the screen that emits a single light beam & represents one pixel of the image on the screen. Our smart phones typically has 720p or 1080p resolution. That means, the mobile screen has got 720 or 1080 dots (or pixels) along its width (the shorter dimension). Here ‘p’ stands for pixels and we assume the mobile is held in portrait mode. Based on the aspect ratio of the screen, there will be a fixed number of dots (or pixels) along its height too. The most common aspect ratio is 1.778. Using that, the number of dots (or pixels) along the height will be 1280 for a 720p display and 1920 for a 1080p display. Thus, we can imagine the mobile screen as a matrix of 1280 by 720 pixels. This is called HD (High Definition) screen. The larger screen of 1920 by 1080 pixels is known as Full HD (FHD).
With that much knowledge in our kitty, let’s now try to figure out the resolution of the biggest & the brightest screen of all times.
We can imagine the sky as a hemisphere. Two distinct dots on this hemisphere can be imagined as two distinct stars. If these two stars make an angle less than half minute, they will appear as one single star. Hence let us assume the sky is full of such stars which is barely just distinct in our eyes. How many such stars do we need in order to fill the entire sky ?
If the radius of our imaginary hemisphere is R, then the two distinct stars making a half minute angle in our eyes, will be separated by an aerial distance of Rθ where θ = 0.5 minute angle expressed in the radian system (1 radian = 57.3 degrees approximately). Each star will have to maintain this distance in all directions, hence each star can be imagined to occupy a circle of diameter Rθ (or radius Rθ/2).
The sky is imagined as a hemisphere here. Total surface area of one hemisphere is 2πR². So the number of dots (stars in this case) required to fill the entire sky is given by:
2πR² / π(Rθ/2)² = 8/θ² = 378,179,292. If we put any more stars there, they will get superimposed on some existing stars and won’t be visible distinctively in our eyes.
From this result, we can conclude that the sky has got a total of 378,179,292 pixels as visible in our eyes. Wow, that’s whooopping 378 megapixel screen over there! To express this pixel set in our common resolution format of width by height, we must first transform this hemisphere-shaped sky into a rectangular plane, much like how the map of our round-shaped Earth is usually drawn on a rectangular paper.
Maintaining the commonly used aspect-ratio of 1.778, we can see that,
378,179,292 = approximately 25930 (width) × 14584 (height) in landscape mode.
Taking the wider dimension, we see that the screen has a resolution of 25930 pixels. In binary mathematics, 1024 is taken as 1K. For example, a 4K television has nearly 4 × 1024 or 4096 pixels along its width (somewhat less than that due to commercial reasons). So dividing 25930 by 1024 we get approximately 25K. Yes, that’s the number we were looking for. We can say that the celestial hemisphere above our head, known as sky, is a perfect screen of 25K resolution. None of the planetariums in the world has gone up to that level yet. Maximum resolution we can see in a planetarium projector, is 8K. And that looks quite good. But with advent of new technology, we will one day see 25K screen as well. I have no doubt about it.
One point needs to be noted here. When I say the resolution of the sky, I mean the sky as we observe. The sky itself is not 25K, in fact no matter has any finite limit up to which you can divide it or partition it to count its units. We are talking about the resolution at which our eyes see the sky. If we replace the sky with an artificial screen, and it has better resolution than 25K, our eyes wont be able to catch the difference. So the maximum resolution at which we see the sky, stands at 25K.
But is the sky real ? Whatever we see in the night sky, does that really exist or is it just our perception and imagination ? Have you ever heard about immaterialism that questions the validity of the reality itself ? Stay tuned for my next article on this blog.
Thanks for reading!
I cordially welcome your comments if you have to say anything on this write up.
Planet of Love 