No one knows the answer, and perhaps humans will never know the answer. Because we live in a limited world, all kinds of things we encounter are limited and concrete.

Is our universe infinitely large? No one knows the answer, and perhaps humans will never know the answer.

Because we live in a limited world, all kinds of things we encounter are limited and specific. So, once something infinite appears before us, we will appear overwhelmed.

Because infinite things are often abstract, abstract things are difficult to understand in a popular way, and even difficult to imagine.

is like the "infinite size" in mathematical concept. There is no largest number in mathematics. Assuming that the largest number is X, then X+1 is definitely larger than X. This is undoubtedly a contradiction, so X does not exist.

In fact, the concept of infinite has been plaguing humans for thousands of years, and until today, humans have not fully figured out the concept of infinite.

Don’t underestimate the wisdom of the ancients. In fact, more than two thousand years ago, the ancient mathematician Niu discovered the special nature of pi π and found that π seems to be different from ordinary numbers. It is an infinite non-cyclic novel. No matter how you calculate it, you cannot calculate the last digit of π because it does not have the last digit. The discovery of

has troubled mathematicians. Humans once refused such "unreasonable" numbers because "infinity" will bring a lot of trouble and many paradoxes that people cannot explain.

The most famous ones are Achilles and turtle. I believe many people have heard of it, let me briefly talk about it.

Suppose you are racing against a turtle, and your speed is 10 times that of a turtle. You first let the turtle 100 meters, that is, count the turtle 100 meters in front of you, and then start at the same time.

When the turtle runs 100 meters, you run 100 meters, which is the starting point of the turtle. When the turtle runs 1 meter, you run 10 meters, which is where the turtle runs 10 meters before. When the turtle runs 0.1 meters, you run 1 meter...

You can find that you will always be at the distance you ran before the turtle, and it seems that you will never catch up with the turtle, and the turtle will always lead you.

But in reality we all know that it is impossible that something can happen, you will soon catch up and surpass the turtle. This seemingly inconsistent phenomenon is the paradox of "Achilles and the turtle".

This paradox can be seen everywhere in our daily life. Just like when we applaud, if the distance between the hands that applaud is 1 meter at the beginning, the distance between the hands must first be close to 0.5 meters, and then 0.25 meters...

There are endless ways to applaud, which means that the distance between the hands is limited, but it requires endless steps.

Also, if a stick that is one meter long is divided infinitely, what will you get in the end? Or is there nothing left? If there is nothing, then how can you get a one-meter-long stick by turning the whole process over and "nothing"?

This means that if you split infinitely, you must end up with something.

Now we can better understand the concept of infinite using concepts such as calculus. There are concepts such as Planck length and Planck time to let us understand that nothing can be divided infinitely, and there is the smallest unit of length: Planck length. Any unit smaller than Planck's length makes no sense.

But people always feel something is missing, for example, why does Planck length exist? Why can't Planck's length be divided?