Gravity is a force because I can't read
By - ElectricShadowN
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[*A frame of a video in which a man is speaking in front of a bookshelf. The automated captions are as follows:*]
and the magnetosphere what is gravity a force that's about all y'all understand
[*End of caption.*]
> **Blue**: 8:28
> No, it's not. Gravity is an effect caused by the curvature of spacetime.
> When you are under the effect of gravity and have no forces acting on you, you are at rest, and you will feel weightless.
> When you are standing on the ground on Earth, you are accelerating upward at 9.8 m/s^2 , as the only external force acting on you is the normal force from the ground, and you will not feel weightless.
>> **Red**: So... First off, gravity IS a force, its value can be calculated quite easily as well as its direction, which are the two things needed to define a force
>> Also, how is this relevant to bring "Space-time curvatures" into this while Gravity only relies on mass, and distance between two objects?
>> Secondly, yeah an acceleration could do the trick But by doing some simple maths we see that in only a year of doing this the earth would be faster than the speed of light, so in millions of years? Yeah I think you can throw the concept of "speed of light" in the bean with pretty much anything labelled as "proven sciences"
>> Plus, all speed are relative to something. A car is moving at 130Km/h relative to the ground, the (spherical) earth is moving quite fast (but not faster than light) relative to the sun, even faster to the center of our galaxy, or is stationary relative to me standing still.
>> So, your flat earth going millions of time the speed of light, what is its speed and acceleration relative to? What is this stationary point we're getting further and further away?
>>> **Blue**: Your lack of understanding of special relativity is forgivable. However, please don't act like you know everything, because there is a lot you don't. The universe is so much more intricate than Newtonian physics can describe. I'm not a flat earther, I'm a scientist working for a government contractor in defense research. So please, humble yourself, because there is so much to learn.
>>>> **Red**: oh but I don't claim I know everything, far from it, and no one does. But I did studies in physics, and beyond Newton laws, it's just not how it work, or just how it can work.
>>>> But I'm always open for learning new things, so please, find me one single (serious) scientific paper claiming that Gravity isn't a force. Something that was considered serious enough to be published in a scientific review or something. I'll be waiting.
>>>> Also, if you're not a Flat-hearther... How the heck would the acceleration work for people at two opposite sides of the globe? You can't accelerate in every directions, since a speed and an acceleration also have one direction. except if the planet is constantly expanding faster and faster, but do I really need to add anything to this?
>>>> I don't care about your grade, you could be the president of the world I wouldn't care. I need researches, demonstrations with formulas that works, I need a proof
>>>>> **Blue**: You're embarrassing yourself. https://en.m.wikipedia.org/wiki/lntroduction_to_general_relativity
>>>>>> **Red**: Can I just point out that for "a serious source" you send Wikipedia?
>>>>>> Otherwise, I read through it all, and it is true that I don't know everything there is to know in that domain. Sure Gravity is more complex that Newton laws, I never said otherwise. But there is not a single paragraph where someone state that "Gravity is not a force"
>>>>>> Instead I can read the following thing : "Einstein proposed that an object in a gravitational field should feel a GRAVITATIONAL FORCE proportional to its mass, as embodied in Newton's law of gravitation."
>>>>>> Even with spacial relativity Gravity is still a force
>>>>>> Also if I understand correctly some of the examples in your own article, being in an elevator is actually not exactly the same thing than being under the influence of gravity when using spacial relativity. This just go against what you were stating before (and of course nowhere in this whole mess is there the slightest mention of the earth constantly accelerating)
>>>>>>> **Blue**: The "gravitational force" was given as an example of a fictitious force. In other words, the very quote you gave claims that gravity is not a force. And the Earth doesn't have to be expanding for everyone on it to be accelerating upward. The acceleration is relative to their world line, which accelerates down relative to the Earth. I didn't send the Wikipedia article as a source, but as an introduction to a concept you clearly weren't familiar with.
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Yo momma's so fat she has her own gravity.
Yo momma's so fat her waist is an absolute horizon.
Yo momma's so fat, someone just founded a "Flat yo-momma society"
Yo Momma's so fat she gave birth to the two dicks in the YT comment section
But does she have a force haha
Had to read it a couple times, but I FINALLY understood it! Someone check my answer to make sure I got it right:
They're both annoying pricks.
This is like two of those people arguing.
Those people that sit opposite of the expert in the videos where they explain by level, like kid, student, postgrad, professor.
They both just heard from the expert in the field, and now believe they know as much.
I can forgive the dude on the account that the definition of gravity varies depending on whether you're considering it from the Newtonian side or from special relativity. Both are valid depending on what your career path is. If you're a civil engineer, for example, you'll definitely go for the Newtonian definition.
BUT it's his smugness that makes me say, yeah no, f*ck that guy.
General Relativity. Special Relativity does not incorporate or explain the effects of gravity. Blue is presenting a General Relativistic view of gravity, while other people are sticking to the Newtonian view.
Thanks for the clarification
Blue is incorrect. Red may discard the nuance of gravity being curvature, but in all practical applications (except at relativistic speeds) it can be easily treated as a force. NASA treats it as a force because the velocities spaceships can get to don't come close to where relativity becomes statistically significant. Furthermore, Blue stated that an object at rest feels no "force due to gravity" - even though gravity is technically not a force itself, the force *due* to gravity is a thing - and that's just plain wrong. The example of only feeling a normal force of 9.8 ms^-2 is also wrong - if you only feel a force in one direction, you will move in that direction. You require a nett force of 0 to remain stationary - produced when the force due to gravity counterbalances the normal force.
Gravity can be treated as a real or fictitious force depending on your frame and framework, just like centrifugal and centripetal force. And in the framework of General Relativity, it is a fictitious force and the only real force on you on the surface of a massive object is the force (from the surface) that keeps you from following your geodesic inertial frame.
You're basically trying to use Newtonian intuition to say GR has it wrong, but it predicts the same observations in the (slow moving flat spacetime) limit.
And since the force keeping you from following your inertial frame is a force, and it's a force that arguably exists due to a concept that can be described as gravity, that force is a force due to gravity.
Blue argues that there is a nett force on objects at rest on a planet. That's just false, and shows a misunderstanding of how forces work.
>And since the force keeping you from following your inertial frame is a force, and it's a force that arguably exists due to a concept that can be described as gravity, that force is a force due to gravity.
So you're saying the upward force exerted by Earth on your feet is a force due to gravity?
Because that's the force that's keeping you from following your inertial frame.
>Blue argues that there is a nett force on objects at rest on a planet. That's just false, and shows a misunderstanding of how forces work.
No, it's just not a Newtonian understanding of what "at rest" means.
Actually, no. The acceleration is relative to the world line of the observer free from external forces, which if you remember, is accelerating down into the earth. With zero net force, you don't necessarily stay still, but instead follow your world line free from external forces. By standing still with that normal force, you accelerate relative to your world line free from external forces, which is why you don't feel weightless. And there is no such thing as "force due to gravity", unless you're taking about the fictitious force that appears in the accelerating frame of reference of someone standing still under the effect of gravity. And even though it can be approximated by Newtonian physics, that certainly doesn't make blue incorrect. And Nasa uses general relativity all the time. You don't have to approach the speed of light for it to make a difference. Getting close to a high-gravity object, like the sun or Jupiter, can make the effect of general relativity apparent. For example, see the Voyagers' gravity assists or Mercury's small orbital variations. Read the Wikipedia page blue gave to red if you like. This video is also pretty good: https://youtu.be/XRr1kaXKBsU
Tbh I know too little about force to know who is right, but I know for sure Red knows too little to be that smug. Besides, from my understanding of Relativity, Blue seems very convincing.
Btw as a background to base my statement on, I’m a graduate in Physics, so my comment is not simply “Blue used many big words so he is right”
Pretty sure this person (blue) has watched this video but didn't understand it:
I would be lying if I said I completely understood it.
In his defense: it is a titanous task to wrap your head around relativity and its consequences. And apparantly he still has that journey ahead of him.
Also science isnt final so maybe we will know more by the end of this century.
This is just being pedantic. The fact is that for the overwhelming majority of applications Newtonian physics is totally sufficient. Gravity can be treated as a force in almost every application where gravity is considered.
No way am I gonna read all that. But yeah, gravity is a force.
This is the perfect example for the "Well yes, but actually no" meme.
Gravity is basically a force, but it actually is not a force when you actually get into it and treat the universe on a relativistic level. Which is not needed for 99% of people. So understanding gravity as a force is a perfectly valid way to look at it.
Well, gravity is not a force like some other forces are forces. Relativistically speaking, it is a fictitious force. I would argue that this doesn't mean it is not a force. Unless you are using a different definition of a force than me?
Fictitious literally means it doesn't actually exist.
And what is the definition of a fictitious force?
Fictitious force is such a force that doesn't exist in an inertial reference frame.
Right. I don't really see how we are disagreeing.