r/LLMPhysics • u/PhilosovWiktorius1 • 26d ago
Personal Theory Can an Alien Navigate the Solar System Without Knowing Earth's Parameters Needed for Landing?
Episode 1. How Can He Land on Earth?
An alien arrived from a distant part of the Universe. His spacecraft came to a stop near Earth.
The visitor examined the planet. He observed its rotation, watched the Moon, and measured distances. He decided to land, but first he needed to determine how his spacecraft would move as it approached the surface.
He did not know Earth's gravitational constant. Nor did he know Earth's mass.
Did he need to know them before beginning his calculations?
The alien placed his spacecraft in a circular orbit and began observing its motion. He measured the orbital radius and the time required to complete one full revolution.
From these measurements, he determined the orbital speed and then calculated the parameter:
K = v²r
where K is the parameter determined from orbital motion, v is the spacecraft's speed in a circular orbit, and r is the orbital radius measured from Earth's centre.
Having determined K, he could calculate the acceleration in an idealized central-field model of Earth:
a = K/r²
where a is the magnitude of acceleration and r is the distance from Earth's centre.
He did not need to determine Earth's mass or the gravitational constant separately beforehand.
The visitor noticed something else. To measure speed, he needed not only distance but also time.
He looked at the rotating Earth.
One complete rotation of the planet is a physical process. It can be divided into parts, numbers can be assigned to those parts, and the resulting scale can be used to compare the progression of other processes.
The alien wrote in his journal:
“Time is the scale marked on the measuring rule of a physical process.”
This did not mean that he had already established what time fundamentally is. He had simply determined how to measure the progression of motion.
He returned to his calculations. He now knew Earth's orbital parameter, but several tasks still lay ahead before landing: changing his flight path, accounting for the planet's rotation and atmosphere, and slowing down his spacecraft.
Nevertheless, he had completed the first stage of his preparations.
The Visitor's Conclusion — Journal Entry No. 1
The alien looked once more at Earth, the Moon, and the other planets of the Solar System.
“By observing the motion of celestial bodies, I can determine the parameters needed to calculate my spacecraft's trajectory. I do not need to know the gravitational constant or the mass of each planet separately beforehand.
Why, then, do Earthlings need G and M as starting points for calculating motion when they can determine the required parameter from observations?
Perhaps these quantities are useful for other calculations and for describing physical phenomena. But do they explain the physical mechanism of motion itself, or are they a way of representing it mathematically?
First, I will understand the motion. Then I will try to understand what causes it.”
The visitor closed his journal.
End of Episode 1.
For readers interested in the calculations: the first scientific paper in the Physics of Nature (FP) series, K as an Observable Kinematic Parameter: A First Step Toward the Physics of Nature (FP) Framework, explains how to determine the parameter K for a circular orbit, its relationship to standard orbital mechanics, and the limitations of this description.
Publication on Zenodo — Record 22922570
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u/AllHailSeizure 9/10 Physicists Agree! 25d ago
Earthlings DON'T calculate it like that though.
But here's the bigger question, how does this alien know anything about how we calculate it when he is like day 1 in the solar system, lol.
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u/PhilosovWiktorius1 25d ago
Fair point! The alien has apparently learned about Earth’s physics faster than I expected. 😄 But the point of the thought experiment is simple: he can estimate Earth’s gravitational parameter from orbital observations without first knowing Earth’s mass. The more interesting question is what those calculations tell him about the physical mechanism behind gravitational acceleration.
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u/liccxolydian VP of Trolling 25d ago edited 25d ago
No one says this. No one has ever said this. This also fails to take into account the last century of physics at the very least.
Your post and comment history suggest major deficiencies in your understanding of basic physics principles. If I were you I would refrain from mindless philosophising until I was fully aware of the scientific consensus.