Stephen Hawking and Kip S. Thorne, two giants of modern physics.
Dr. Thorne made a bet on whether the object Cygnus X-1 was a black hole or not.
A black hole is a celestial body with extremely strong gravity, with all of its mass concentrated at its center.
It sucks in any material with its strong gravity.
Even the light.
In fact, until then, black holes had never been discovered.
Then you might wonder, how on earth did we know that black holes exist and how did we go out to find them?
This is where we can feel the greatness of scientific theory.
According to Einstein's theory of relativity, there should be a black hole somewhere in the universe.
But unfortunately, even Einstein denied the existence of black holes.
Even Einstein, who was considered the greatest genius in human history, seemed to have difficulty accepting the possibility that a single point with a volume of 0 and a density of infinity could exist in the universe.
For the Earth to become a black hole, its volume would have to be compressed to the size of our fingernail.
It has to be done, but in fact, I can't really imagine it right now either.
The mysteries of the universe seem to constantly test the limits of human imagination.
--- p.57~58

In fact, isn't Earth's presence in this vast universe too weak for aliens to invade? If Earth were to leave some kind of trace, like emitting radio waves into space, aliens wouldn't be tempted to invade, saying, "I'm tempted by that planet."
But no matter how long you take it, the history of sending radio waves from Earth into space is only about 120 years.
Then, even if we take the broadest possible view, we can only detect Earth's radio waves from neighboring planets within a radius of 120 light years, and we can think about going there and taking a look.
But the radius of our galaxy alone is over 50,000 light years.
Imagine a speck of dust 120 light years across, inside a disk 50,000 light years across.
What presence could there be on our Earth?
--- p94

Believe it or not, time travel into the future is still possible today.
Strictly speaking, if you travel a long distance by plane and come back, you will look younger than someone who stays still.
It may be a very small difference that people cannot feel.
It is even possible to scientifically calculate how far into the future we have actually gone.
This is because of the ‘principle of constancy of the speed of light’, which states that the speed of light is always the same.
To put it simply, for the speed of light to be the same for both a stationary object and a rapidly moving object, time must pass that much slower for the moving object.
Take a look at the following picture.
The distance that light travels up and down once for a person sitting inside a moving train is shorter than the distance that light travels back and forth for a person standing still outside the train.
But the speed of light is the same for both people, and the speed of light is the distance traveled by light divided by the time it takes, so when a person standing on the ground outside the train sees the light traveling back and forth inside a moving train, the time it takes appears to be longer.
The fact that time passes more slowly for a moving object is a clear fact that we can easily understand simply by knowing that the speed of light is constant.
GPS satellites, which send information to actual car navigation systems, orbit at a high speed of 14,000 kilometers per hour, and due to the effects of special relativity, time slows down by about 7.2 microseconds per day compared to the ground.
--- p.132~133

In the movie Avatar (2009), the reason humans invade the planet Pandora is to obtain a superconducting material called 'Unobtanium'.
If you put the English words for unobtenium apart, it is U'n + obtain + ium', which literally means 'a substance that cannot be obtained'.
Superconductors are so precious that they are obsessed with them to the point of committing the sin of slaughtering the Na'vi, the planet's masters.
So what would happen if humans could freely use superconductors in everyday environments?
The ability to deliver electricity without resistance will make energy available to all of humanity more abundant than it is today.
And it will also help solve the climate crisis by reducing the use of fossil fuels during the development process.
By using the Meissner Effect, which perfectly repels external magnetic fields, more efficient means of transportation will be available that can levitate and move without frictional resistance with the ground.
It could also dramatically reduce the heat generated by electrical resistance in all electronic devices.
Quantum computers using superconductors could operate at room temperature and pressure, potentially creating enormous ripple effects.
Frankly speaking, it is difficult for anyone to imagine what kind of changes await humanity.
--- p.221~222

When our body is exposed to radiation, the cells that make up our body are destroyed.
It breaks the weak strings that connect nucleic acids, such as DNA and RNA, which are essential biomolecules for life.
It disrupts the base sequence of the chromosome.
That's why it's also called 'ionizing radiation'.
Especially in the elderly, who have weak cell regeneration ability, abnormal or mutated cells, or cancer cells, can proliferate very quickly, which can lead to blood cancer or leukemia.
Brain tumors or thyroid cancer may also appear.
If you are exposed to a high dose of radiation, exceeding several hundred sieverts, your skin will immediately burn as if you were being burned.
And it will lead to death.
--- p.265

Of course.
Research on the stability of the solar system began in Newton's time.
Because classical mechanics made it possible to calculate the movement of celestial bodies.
When scientists discover a previously unknown tool, they immediately want to apply it and test it on everything around them.
So, when we looked at the movement of celestial bodies using classical mechanics, we calculated that the structure of the solar system is not stable.
The current structure, in which the planets rotate and revolve around the sun and each orbits the sun, could collapse at any time.
In fact, considering the level of astronomical observation technology and computational capabilities at the time, it would be difficult to expect accurate research results.
The important thing is that even with modern scientific technology that has advanced to a considerable degree, it is impossible to confirm whether the structure of the solar system will remain stable in the future.

--- p.313~314