"But this time, I'm writing to you not to boast about my achievements, but rather to swallow that money (strikethrough)... but there's something I need your help with."

Seeing this sentence.

Xu Yun immediately became interested and read on seriously.

"During the previous research on gravity, I summarized and optimized some of Galileo's ideas."

"Some were solved smoothly, but others encountered problems, to put it bluntly, very serious problems."

"Fat Fish, you should know, Galileo believed that there is no absolute reference frame in the world, only relative ones."

"Therefore, it is impossible to measure the velocity of this system through experiments within an inertial system."

"But in my view, time and space are two independent concepts, having no connection with each other, each possessing absoluteness."

"I believe space is absolute, by its nature, it remains independent and unaffected by external objects, always the same and immobile."

"To validate this hypothesis, I conducted a wood bucket experiment; the specific illustration is as follows..."

"Logically, this experiment seems fine, but later I further researched the dispersion phenomenon you first experienced."

"Well, how should I put it? I discovered the nature of light... seems to be far more complex than I originally imagined..."

"Fat Fish, I remember you said you were an assistant at the Netherlands Leiden University College of Natural Sciences; thus, I wrote this letter with intense doubt and anticipation."

"If you receive this letter and can solve my doubts, please reply to me as soon as possible..."

The letter ends here.

At the bottom right corner is a name:

Isaac Newton.

......

After setting down the letter.

Xu Yun gently rubbed his nose, his chest rising and falling a few times, exhaling a heavy breath.

In the 21st century.

Some marketing accounts often hang this statement on their lips:

"Newton's theory is wrong, and it was overturned by Einstein long ago!"

Some videos explain this with vivid detail, and due to physics being a distinctly barriered discipline, some people don't fully understand the intricacies and believe it in a muddled manner.

So what is the actual situation?

The truth is this:

Newton proposed many theories in his lifetime; among them, one was half right, one entirely wrong.

The remaining theories and their system are alive and well, genuinely forming the cornerstone of our macroscopic world.

Let's talk about the half-right theory first.

This theory is the light particle theory that Little Niu insisted upon.

At the time, Little Niu gathered a lot of evidence through his research to support the particle theory of light, thus promoting it, becoming the representative figure of the particle theory in that era.

This matter truly has nothing much to say; before 1909, no one knew about the wave-particle duality of light.

After all, back then, no one would have imagined such an oddity in light, possessing the dual character of behavior that was beyond the syllabus.

Just like someone whose gender can't be determined entered the male restroom and audibly tinkled in front of other males, then went to the female restroom and did the same audibly.

Thus, the males said this person is male, the females said this person is female, both parties believed what they saw with their own eyes could not be wrong.

So what was the outcome?

Eventually, the school had a hospital conduct an examination, discovering the person's gender was Hideyoshi, where do you go for redress now?

Thus, Little Niu's speculation on the particle theory can only be considered a limitation of the times, many Bosses overturned their positions later on.

As for the completely wrong theory...

It is the absolute space-time view proposed by Little Niu.

Little Niu put forward this idea in "Mathematical Principles of Natural Philosophy," wherein he depicted an absolute space-time view:

Velocity is a function of time, space and time are mutually independent, existing as uninterrupted time flow and spatial expansion.

In other words.

He believed that time and space exist independently, separated from the movement of bodies.

For this, he conducted the experiment, which was also mentioned in the letter, the wood bucket experiment.

This experiment is actually quite simple; even Xian Weiren can easily complete it:

Firstly.

Use a long, soft hanging rope to lift a bucket of water, twisting the rope into a braided pattern.

If you hold the hanging rope, keeping the braided rope from unraveling, then the bucket and the water within are relatively static; the water surface is flat.

But suddenly releasing it, the braid begins to relax.

The hanging rope begins to rotate, and the bucket rotates with the rope.

At first, the water in the bucket doesn't rotate, only the bucket rotates, the bucket and water rotate relatively.

But slowly.

The water is taken by the bucket and begins to rotate.

Finally, both the water and bucket rotate alike.

At this point, the water and bucket are relatively static, not rotating.

Yet the water's surface presents a concave shape, lower at the center, higher at the edges of the bucket.

To be sure.

The operation is simple, but the thought is quite ingenious:

Firstly... or call it thought 1, we can calculate the angular velocity Ω of the water's rotation from the shape of the water's surface.

Thought 2, we observed an objective experimental phenomenon:

At the start.

The relative motion of the water in the bucket is maximal, yet it shows no tendency to leave the rotation axis.

The water neither shifts to the edge nor rises, but maintains a plane, so its circular motion hasn't truly begun.

From point 2, we derive three things:

3. This reference frame is not the bucket.

4. This reference frame is not the water itself.

5. Within this system, there are only the water, the bucket, and space.

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