Proxima Centauri, the closest star to Earth, is about 4 light-years away.
A light year is the distance light travels in one year.
Light can travel a distance equivalent to 7 and a half times around the Earth in one second, and it can travel to the Sun, which is 150 million kilometers away, in 8 minutes.
But, with that kind of light, we have to go not for an hour, not for a day, not for a month, not for a year, but for four years.
How far away is it? Still, this is the closest star, and most are vastly farther away.
(…)
Can you imagine? Imagine stars stretching hundreds of millions, even billions of light years across the vast expanse of the sky.
How vast is the universe? You might think it's incredibly large.
But you must realize that this universe is really much bigger than you think.
Space travel? Would humans, who live less than a hundred years, dare to embark on a journey spanning hundreds of millions of years?
Still, humans dream that dream.

--- pp.19~21

The atmosphere is a guesthouse for molecules.
In that inn, only one molecule can enter a room, regardless of type.
It does not consider the size or mass of the molecule.
Just as hotel rooms don't consider the guests' height or weight, neither do the inn rooms of the molecules.

However, not just anyone can enter the luxury hotel, which is a human inn.
You may need to have money and high social status.
There is discrimination in human inn rooms.
But the inn rooms of the molecules do not consider the class of origin.
Unlike human inns, there is no discrimination.
Nature is more fair than humans.

There are many things to learn from nature.

--- p.137

Newton, who observed that light travels in a straight line, reflects when it hits something, and refracts when it passes through glass or water, argued that light is a particle.
However, light goes around obstacles, and when two lights meet, they interfere, creating colors like a rainbow.
This phenomenon means that light is a wave.
And when Maxwell discovered that light is an electromagnetic wave, it became clear that light is a wave.
But light was not a being that easily revealed its identity.
When light shines on a metal, electrons are emitted from the metal.
This phenomenon is called the photoelectric effect.
Einstein successfully explained the photoelectric effect by hypothesizing that light is a particle.
For this achievement he received the Nobel Prize.
Light is clearly a wave because it diffracts, but it is also clearly a particle because it produces the photoelectric effect.
So then, is light a particle or a wave? (…)
Light is neither a wave nor a particle.
Light is not such a simple entity that it can be defined by anything.
Just as if you call the Tao the Tao, it is no longer the Tao (道可道 非常道, 名可名 非常名), if you call light a wave, it is no longer a wave, and if you call it a particle, it is no longer a particle.
A being that cannot even be named, that is light.

--- pp.156~158

Quantum superposition can be further extended and applied to the history of life.
No one knows whether I will be successful or unsuccessful in the future.
From a quantum mechanical perspective, my current self exists in a state of superposition of success and failure.
But as time goes by, either failure or success will become reality.
All futures are in quantum superposition.
As time passes, one of these superpositions will become reality.
If I were to be reincarnated tens of thousands of times, I might end up with half of me as a failure and half as a success.

We believe that truth exists objectively.
And I believe the truth is either O or X.
But the truth is not so clearly black and white.
The truth is rather overlapping and ambiguous.
Isn't this ambiguity the mystery of truth?
--- p.178

Both Newton and Einstein explain well why objects fall, but when it comes to light, the two theories are divided.
According to Newton's theory of gravity, light has no mass and is therefore not affected by gravity.
Light is not affected by gravity, so it is not affected by the Earth or the Sun.

But according to Einstein, since space is curved around a star, even massless light should be curved.
Einstein's claim was quite surprising, but British astronomer Eddington observed that light was actually bent by the sun's gravity.
It was the moment when it was proven that space was curved.
With this, Einstein's general theory of relativity was proven, and Einstein became world-famous overnight.

Curved space cannot be seen with the eye.
It can only be seen with the heart.
"Faith is the substance of things hoped for, the evidence of things not seen," wasn't it? The space we live in is curved, but we can't see that curve.
It is a logical conclusion, but one that can be verified experimentally.
The truth is not revealed, it is hidden.

--- pp.287~288