3 Body Problem: What is a Syzygy and can it actually drag people into the sky? | Mini Science
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- เผยแพร่เมื่อ 13 เม.ย. 2024
- So that scene... I really needed to know if the gravity would be enough to pull them towards the stars.
There's a few ways you could work this out and without knowing the exact densities of the fictional stars we can't really know, it's all an approximation. But hopefully you learn some fun math today! - วิทยาศาสตร์และเทคโนโลยี
I also questioned the sygzgy, when the planet is free falling towards the three suns, it does not feel their gravity. Just like how we don't feel the gravity of the sun because we are free falling toward/orbiting the sun. We also don't feel the gravity from Sagittarius A because our solar system is orbiting it. I really think if there is Syzygy, the planet will quickly move to fall towards the three suns and therefore negate their gravitational effects.
It just occurred to me that if gravity from some other body is strong enough to pull things upward, you'd probably die of asphyxiation before it got strong enough to remove you from the ground. "Downward" gravity wouldn't be strong enough to maintain air pressure.
The book,does describe the air and atmosphere lifting off the planet too in the game.
I was thinking the exact same thing watching this scene. The atmosphere would've been long gone before they ever started to levitate regardless of the size of the aliens
What if the san ti are insects? The whole dehidration/hidration thing with the hive mind made me think they might be very tiny.
The biggest insect on hearth is around 115g, so 1.127N
This is a case of mass irrelevance, which means that if you're trying to compare the magnitude of the gravitational pull of the Earth and the Sun on the same object, the mass of that object itself is irrelevant to the result; its mass is eliminated from the equation when you are doing the comparison. An insect certainly receives a much smaller gravitational pull from the Earth than a person does, but it also receives a much smaller gravitational pull from the Sun than a person does, and the result is unchanged.
They are tardigrade/maggot like creatures.
@@monos70 that's my hypothesis. Is that what the books say they are?
Wouldn't star's pull be enough to tear apart a planet if it can pull objects up?
yes, that is what happened in the book, the planet got a new moon after that event
Not really. Yes, loose rubble or rocks would start floating off the surface same as you, but most of the matter the planet is made of is sticking together with a force larger than zero, while you stick to the surface with zero force if you consider gravity itself canceled out. You would float away long before the rock of the planetary crust begins to be torn apart from the rest of itself. Of course, a rotating planet is also pulled apart by centrifugal force, so the devil is in the details...
there's agradient where it would pull loose objects, but it would still be too weak to break molecular level forces
Your math didn't seem to account for the "free fall" of the planet. I think the scene would make more sense within the Roche limit of three stars while In the shade of a dimmer star.
Don't know if mentioned in the books but the tidal forces of the stars would warp the shape of the planet and the internal friction/heat would make it a volcanic nightmare.
It is! In the book it creates a moon around the planet
I keep thinking, if there is enough gravity to put the people up, wouldn't there be enough gravity to pull the entire planet up with them? Isn't that how gravity works? Why would gravity distinguish between people and dirt and rocks?
This is true. However when the gravitational pull is a sudden and massive change then it’s plausible to imagine loose material being pulled before the surface has a chance to respond.
The force of gravity moves at the speed of light so close objects feel the force first. The distance isn’t large though for this to really cause a delay however the surface is held together by more than gravity, there’s also the nuclear bonds which are stronger than gravity. So the effect on the planet is a gradual one as the new force ripples from one side to the other causing the side facing the star to start to bulge, it’s possible for that to be at a slower rate than the loose material rising from the surface.
One floating-off person to another: "You should have listened to me - if we built our base at the pole, we wouldn't be having this problem now!!!"
Thank you for finally debunking this!
Yeah what's hugely problematic is that the effect should have happened during the extreme heating event later on. Not by itself without glassing the crap out of the planet.
But if the three bodies were pulling on you with enough force, wouldn’t they also move the planet itself? So sure you’d go closer to the suns, but so would everything else. (If it didn’t, wouldn’t the near side of the planet be pulled apart and away from the far side of the planet.)
And just in the case of the video, I don’t think you can judge the distance and size of the other 2 bodies. Distance: they kinda just blend into one light source, and size: the perception would be based on distance. And none of that accounts for individual densities.)
Hi. Of course I can’t determine the actually distances. It’s an entirely fictional story but it is based on the Alpha Centauri system so using those stars as a base is reasonable.
And yes the near side of the planet is pulled apart, in the end it creates a moon around the planet.
The point is that the change in the gravity well is so sudden and drastic that loose surface objects start to fall immediately while the surface starts to bulge and break apart which takes longer due to the forces holding the solid rock together.
@@popculturescientist does the suddenness really have anything to do with it?
If the gravitational forces act proportion to mass, sure the sun(s) would pull on you at 700N. But wouldn’t they pull proportionally many orders of magnitude more on the planet? (Sure bulges, etc.)
But doesn’t the entire planet free fall at the same acceleration as you. You’d get sucked into the sun, sure, but so would the planet. You wouldn’t move relative to the ground, just the ground moving relative to the sun, right? No?
(Disregard the distance thing. That was responding to a specific clip you showed of the show that I think I took the wrong way. I wasn’t arguing with your centauri analogy.)
While I agree with your conclusion that people won't fall off of a planet (except in extreme circumstances), I don't think the logic you're using the arrive at that conclusion is sound.
The claim that the force from each body determines which way us people will accelerate is only correct if you assume that the planet and sun(s) are unmoving and fixed in space.
Imagine I'm in a room; I hold up a ball against the ceiling, and let go. Both the earth below me and the ceiling are fixed relative to each other, but the ball is free to move. Because the gravitational pull from the earth is stronger than the gravitational pull from the ceiling above the ball, the ball falls down.
However imagine I hold a ball up underneath a book, and let go of the ball and the book at the same time. Both the ball and the book are free to move (and so is the earth, technically, though it won't move very much). Both the ball and the book will fall down towards the earth at the same rate--the ball doesn't move relative to the book (at least not very much).
Additionally, you have to take into account the rotational velocity of the planet orbiting the star. The "centrifugal" force (from the rotating frame of reference) from the planet's orbital velocity counteracts the centripetal forces of gravity keeping it in orbit. This means that the net force exerted on both us people and the planet is going to come out to (nearly) zero in the rotational reference frame (ignoring the force of the planet's gravity).
I believe it would be possible for a star to pull people off a planet, if they get close enough such that the star's gravitational force at the center of the planet compared to the force at the surface of the planet (at the point closest to the star) is stronger than the gravitational force from the planet. I.e. the Roche limit you mentioned, which makes sense; if people and objects would start flying up into the sky, so would all the dirt resting on the ground, and so would the rocks beneath them, and maybe even the entire planet's crust (depending on its material properties).
(Another minor correction is that a syzygy won't happen at each full moon; it would take a lunar eclipse for that to happen.)
I appreciate you making an attempt to explain/solve this problem, on top of making a video about it. I love and want to encourage science education, and I don't want to come across as hostile or discourage you from it. At the same time I don't think the video is generally accurate. It's possible I'm wrong myself, but if so someone please correct me.
Firstly I appreciate your attempt at a correction however I think it’s important to understand both the process of learning and the stages of physics education.
I don’t ever claim that this is an entirely accurate analysis and I state that it is an as approximation. It’s a fun scene to use as a tool to teach some science but not an entire lecture and detailed mathematical .
I understand the drive for rigour, as I am a physicist I of course follow this in my work, but in science communication it is always a trade off between the pitch level. If you feel that my approximation is too simplistic that is your right, however in terms of understanding the basic principles of the gravitational pull between celestial bodies, I disagree with your assessment that this is ‘inaccurate’.
I’m happy for you to comment elaborating further for those who would want more detail but please do not assume that everyone would have the same level of background understanding.
Lastly, it is entirely correct to say that a Syzygy applies to both the full moon and new moon.
God this scene pissed me off so much. Like... it's supposed to be *science* fiction. Stars lining up do not turn into tractor beams ffs
It’s a chaotic three body system. Their positions constantly change and so does the gravitational well they form. A sudden change in gravitational pull is perfectly plausible to pull loose material from the surface while the ground starts to bulge before breaking apart. It is very much science fiction
With all due respect, you ascribe force to gravity which it doesn't have. The gravity of the Earth doesn't exert a force of 700 Newtons, that's the amount of force required to OVERCOME the gravitational pull of the Earth. Gravity isn't a force, it's a deformation of spacetime. That 700 Newtons refers to the amount of force that would need to be counteracted in order to begin to escape the Earth's gravity well.
Yes. I did explain that we would need to apply at least 700N to overcome the gravitational pull of the Earth.
It is entirely satisfactory to describe gravity as a force, it is defined as one of the four fundamental forces of nature.
Newtons laws are still used to describe the effects of gravity on a mass and this is taught in undergraduate physics courses around the world.
This is not the type of problem that requires general relativity to explain the effects on a person on the surface.
💁...
Some other things to consider.
It is actually named incorrectly. It is NOT a three-body system, but actually a 4 body system. 3 stars and a planet.
I guess 3 Body Problem just sounded better. Additionally, this doesn't happen in real life. There are only 2 possibilities. One is that one (or more) of the bodies gets ejected, or second possibility is that one or more of the bodies collides and becomes a singular gravitational well. That IS the way of chaotic three star systems do...
It is possible to have a stable 3 body system, but in practical terms, it is a simple 2 body system. You can have two smaller stars that are gravitationally holding hands and have a central gravitational point that they spin around each other, and then are bound by a much larger star that they jointly orbit. But really... Two gravitational points
But that isn't the description of this star system (and at least one planet). And I get the feeling that it is more of a "super-Earth" than actually sized same as our planet.
So from a science, physics, mathematics perspective, it is a false premise. It is a gimme for the sake of the story, like warpe engines, windstorms on Mars powerful enough to tip over a massive rocket, or space fighter ships that bank in space, or magic drug that enables folding of sparce.
I agree about the 4-body system and do think he chose 3body because it sounds better and represents the chaotic three body problem in physics.
And yes eventually one body will be consumed or flung out but when that will happen is entirely unpredictable.
As you said, it is possible to have a stable three body star system, that is what Alpha Centauri is.
I disagree with your assessment about it being a ‘gimmick’. The entire point of science fiction is to use imagination to envision worlds and technology beyond what we know and understand.
This is the very definition of science fiction. To ridicule it for not being accurate science means you are looking for a documentary and not science fiction.
That’s not really what the term means. The 3 bodies of a three body system need to be approximately similar in mass. So it’s the three suns, and doesn’t include the (presumably) much smaller planet.
For instance, we also like to think of our solar system as a two body system between the sun and the earth. But really it’s a stable two body system between the sun and Jupiter.
And if you want to get technical, it’s actually a 9 (or 10, poor Pluto) body system (again ignoring things like asteroids). Why then is it not chaotic? Well, in fact it IS. We just happen to be in a stable era that is lasting a few billion years.
well, the vr thing just used human avatars. the san ti are probably the size of a grain of rice if that helps the calculation make more sense. the implication is that they are small, and in the fan novel that the author approved of, they are tiny
I just don’t buy it. They make a fleet of spaceships, we know the size of the weapon they send ahead. I can’t see how they could build tools to that level while being tiny
@@popculturescientistAnts build much larger things than them, then at some point automatons will do it for them, just like for humans.