: The distance from your thoughts to the starry sky (below)

"Using this point, it is possible to build an elevator on the equator whose height exceeds the synchronous orbit, and the two forces are balanced at the synchronous orbit."
　　 Hearing Li Ze's further explanation, Fang Ran saw him raise his hand and draw a picture. A slender rectangle extending beyond the outer circle was extended on the inner circle. The point where it intersects with the outer circle is marked as r0.
　　 subtly recalled the feeling of being dominated by physics.
　　 "In the part under the synchronous orbit, the radius becomes smaller, the gravity formula GMm/r2 is that the gravitational force is relatively large, and the centrifugal force formula mω2r is the centrifugal force is relatively large for the part beyond the synchronous orbit,"
　　 No, wait, I always feel that two familiar formulas have appeared...
　　Looking at Li Ze marking the slender rectangles on both sides of the outer ring in red and blue, indicating that they were ‘pulled’ by gravitational and centrifugal forces in two completely opposite directions.
　　, I’m really good, it’s worth installing, after all, you can cache and read aloud offline!
　　 Fang Ran, sweating in his heart, saw the opening he finally looked at himself:
　　 "Then, as long as the forces on these two parts are equal, the space elevator can stand in space without supporting force."
　　 After listening to these, Fang Ran felt astonished by the sudden realization.
　　 "The concept of space elevator was actually put forward very early, and the technical principles have been relatively perfect."
　　 Li Ze put away the projection, and the narrow top of the mountain returned to the warm light of the bonfire, while Klim saw Fang Ran smiling and added:
　　 "About a hundred years ago, Tsiolkovsky put forward this idea. The current jet rockets and graded rockets are all his ideas back then."
　　 more than a hundred years ago! ?
　　 had more profound feelings about the era before this time than the two of them. Fang Ran couldn’t believe that when he drove the carriage through the wheat fields,
　　 Someone has already proposed a space elevator, and it still makes him feel incredible today.
　　 "Why not build such a good thing?"
　　 Thinking of the series of advantages and meanings they both said just now, it seemed quite feasible to understand the principle, and then asked strangely.
　　 Knowing that he would definitely ask, Kerim and Rize looked at each other, as if they were communicating with someone to explain.
　　 "Because of the tensile strength of the material."
　　 In the end, Klim answered vocally. He recalled the relevant details he knew as much as possible, and said softly and helplessly:
　　 "At the same time, the balance of gravity and centrifugal force will produce a very huge tensile force. To meet the requirements of the space elevator, I remember that the specific tensile force per unit area needs to be greater than that of the material density multiplied by..."
　　 "Okay, just give an example."
　　 always felt that he was recalling a number that he did not understand the origin, and faced four people who were more knowledgeable than himself in the middle of the night.
　　 Fang Ran directly spoke silently without any fluctuations.
　　 "Haha, if you take the density of steel as an example, it would take about 4 million times the atmospheric pressure, that is, a steel cable with a thick thumb to hang 4000 tons of heavy objects,"
　　 "But the actual steel cable can only achieve one-thousandth of the degree, and its density is a bit too high."
　　 Hearing Fang Ran say this, Klim couldn't help but smile and give a direct example.
　　 "That is to say, it is also stuck on the material..."
　　 For such an answer, thinking of the problems I faced not long ago, it is always a difficult problem to develop new things and materials.
　　 "It's not completely stuck on the material. In fact, a material that can satisfy the space elevator has now been discovered,"
　　 Have discovered new materials?
　　 Surprised that he was not stuck on the material, Fang Ran looked at Klim unexpectedly and saw him smile and say a name.
　　 "Carbon nanotubes have excellent tensile strength, and the density is only one-sixth that of steel. They can be produced with the current technology in reality."
　　 "No, wait a minute, since I have discovered the material, I have never heard of it. Next, you must say that this material is not expensive or too expensive to produce..."
　　 was not happy too early, keenly aware of strange places, digging out relevant memories from the remaining high school knowledge,
　　 Fang Ran suspiciously looked at Klim and asked silently:
　　 "I remember that the synchronous orbit seems to be more than 36,000 kilometers, plus the section above, how much can that carbon nanotube produce?"
　　 "Half a meter."
　　 Fang Ran: "......"
　　嗬, good fellow, it's still a matter of rice...
　　 was simply choking silently, staring at Krim and unable to speak.
　　 It’s a good half,
　　 just burst into laughter, he clutched his stomach and looked up at the Milky Way above his head. For some reason, he couldn't help but laugh:
　　 "Half a meter...Puff, I drop the sky, half a meter is too ridiculous, hahahaha!!!"
　　 "I remember this was made by a laboratory in your China."
　　 Seeing him like this, Klim couldn't help but smile, and Li Ze also slightly laughed aside.
　　 "At least in terms of tons, it still gives me some hope..."
　　 I don’t know why I laughed so happily. Fang Ran wiped the corners of his eyes and looked at Li Ze and Klim. It turns out that this is what they both call ‘more realistic’.
　　 Half a meter is more than 36,000 kilometers, this difference is not a star and a half at all.
　　 But thinking about the deep-space navigation mentioned before, the light-speed engine that is not even theoretical, the half-meter that has been completed is indeed more realistic.
　　 When I think of the first step to enter the universe, the space exploration at close range is still a gap of half a meter to tens of thousands of kilometers.
　　 At this moment, looking up at the Milky Way,
　　 Only then did I really understand the distance of the starry sky above my head,
Even the solar system cannot travel, the Milky Way galaxy with hundreds of billions of stars, and the local galaxy group to which it belongs ~ EbookFREE.me~ and how far is the upper Virgo and Rania Kea supercluster.. ..
　　 But thinking of more than a hundred years ago, when there were no rockets, someone had already proposed the idea of ​​a space elevator.
　　 Suddenly felt that this distant seems not to be eternally out of reach.
　　 "Speaking of reality, it can be half a meter in length. If it is replaced by night combat technology, will it be possible to build a space elevator!?"
　　 As if suddenly thinking of something beyond reality, she asked with a slightly bright eyes when she mentioned this.
　　 "It's not that simple. Compared with reality, the level of night warfare is indeed higher, but most of the systems are partial to weapon and mechanical development, and there may not be related technologies.
　　As an elite technologist, Li Ze shook his head in answer, which was also the most important reason, looking at the Milky Way starry sky overhead.
　　 "And no one knows if night warfare technology flows into reality, whether it will be a space elevator."
　　 "That's it, eh! By the way, is there anything like a space elevator..."
　　 Following the sudden voice of the youth that seemed to understand, he curiously asked again.
　　In the midnight with rich fantasy colors, discussing the topic of science and technology and the starry sky,
　　 At the top of a narrow mountain like an island in the sky, three young people are sitting on a tree stump around a campfire, with the distant starry sky of the magnificent Milky Way above their heads. Their warm words have been going on for a long time at night.
　　 The figure jumped to the two birds next to the camera, and pecked the shutter to record...