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Gravity has arrived


Dogmaf

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I appologise if my need to know has outstripped your ability to explain.

English isn't my first language either.

I accept your apologies, no hard feelings, after all it was a funny mistake. :)

 

objects falling to earth under the influence of atmospheric pressure

If I have interpreted you correctly then you belive that the air pressure is holding us to Earth and air is sealed inside a exotic container around the Earth.

 

And you need to understand why this is wrong.

 

Is that correct so far ?

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If I have interpreted you correctly then you believe that the air pressure is holding us to Earth and air is sealed inside a exotic container around the Earth.

And you need to understand why this is wrong.

Is that correct so far ?

 

Thank you. Suspect rather than believe and I can't understand the 'need' of others to believe in something (gravity) that seems so difficult to understand that no one can explain it to me satisfactorilly without getting into even more exotic theorising. It seems more religious than scientific. Faith seems to be a more essential ingredient than understanding.

 

You know? I believe that religion was once the science of its day with the priests and prophets being the closed inner circle who understood whilst we unwashed masses were obliged to take their word for everything. Some of us are learning how to wash! I may even have a bath one day.

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okay, gravity isn't so simple, we don't know WHY it acts the way it does. or even how it acts, we just know that it does. now, i'm going to use the rubber sheet analogy but it should only be taken as an analogy since it is flawed but its close enough for a beginner.

 

say you have an infinite, frictionless rubber sheet(space-time) and a bowling ball and a golf ball(a planet and a rock). now the rubber sheet is taught and will deform slightly if you put a mass on it. (just imagine that the balls are pulled down it doesn't matter by what force but it acts on the mass, bigger mass = bigger downward force)

 

so you place your bowling ball on the rubber sheet it deforms a bit and its kinda steep near the ball but gradually gets less and less steep as you get further away. so, you could place the golf ball ANYWHERE on the sheet and it would start sliding towards the bowling ball (cos its going down hill). Or you could put some velocity on the golf ball when its near the bowling ball and it would have an orbit.

 

This is, very basically, how we think gravity works. to get it right you need a couple more dimensions and some other stuff that i don't know about since i don't study physics. It does actually get quite complicated when you try to put in the third spatial dimension, frame dragging, speed of propagation and all that jazz.

 

I don't know but somehow I preffered the apple falling from the tree. That was where this all began remember.

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yeah, the apple falling from the tree never happened. its just a story. newton worked out his theory by observing the moon and planets.

I knew that. But isn't that a major part of the problem. The whole question of gravity is now and always has been blurred, obfuscated, swamped in confusion, who in his right mind would insist on a comprehensible explanation? Well actually...................

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its only complicated before you learn it. same with calculus.

 

okay, i'm going to explain newtonian gravity to you and i'm going to to use equations. it'll show you how simple this can be.

 

The equation for gravitational field strength is

 

F(g)= (G*m(1)*m(2))/r^2

 

where,

 

F(g) = the gravitational force

G = Gravitational constant

m(1)= mass of object 1

m(2)= mass of object 2

r = distance between center of masses of the two objects

 

This equation states that the force of gravity is directly proportional to the masses of the objects(bigger mass, bigger force) and indirectly proportional to the distance (bigger distance, less force).

 

as you can see, at no point does an atmosphere come into the equation. it doesn't affect the force of gravity except by mass, it certainly isn't essential to the theory. for example, mercury has gravity and there is no atmosphere therefore the atmosphere cannot possibly be responsible for gravity. i can go even bigger if you want, galaxies are attracted to each other. this is over vast intergalactic distance of millions of light years. this couldn't be explained by and atmosphere.

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F(g)= (G*m(1)*m(2))/r^2

 

where,

 

F(g) = the gravitational force

G = Gravitational constant

m(1)= mass of object 1

m(2)= mass of object 2

r = distance between center of masses of the two objects

This has G on both sides of the equation so, whatever else it explains it can't explain G since G is assumed.

My problem is that in my time I understood many things, including calculus. I just never understood this, resurection, virgin birth etc.

Maybe it will be explained at the end of the world. Just before perusia.

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Thank you. Suspect rather than believe and I can't understand the 'need' of others to believe in something (gravity) that seems so difficult to understand that no one can explain it to me satisfactorilly without getting into even more exotic theorising.

OK, then I will try to explain the 'need' while insane_alien tries to explain gravity.

 

Lets make a thought experiment:

 

Take a large pressure camber, like a big room and shaped like a dice with a hook outside on the top. One man enters and when the pressure is equal inside and outside, he seals the hatch.

 

Will the man still be able to stand normal inside and will he notice any difference ?

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F(g)= (G*m(1)*m(2))/r^2

 

where,

 

F(g) = the gravitational force

G = Gravitational constant

m(1)= mass of object 1

m(2)= mass of object 2

r = distance between center of masses of the two objects

 

'The gravitational force' assumes the existance of gravity. This is not MY equation.

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OK, then I will try to explain the 'need' while insane_alien tries to explain gravity.

 

Lets make a thought experiment:

 

Take a large pressure camber, like a big room and shaped like a dice with a hook outside on the top. One man enters and when the pressure is equal inside and outside, he seals the hatch.

 

Will the man still be able to stand normal inside and will he notice any difference ?

 

Yes. I believe he will be able to stand and, over time he will exhaust the oxygen in the air and replace it with other components. Pressure may or may not decrease but it will not cease. If you elevate your chamber the pressure outside will decrease but the inside pressure will not be different due to elevation. Water, on the other hand, does rise when 'air' is exhausted. Where is gravity then?

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'The gravitational force' assumes the existance of gravity. This is not MY equation.

 

so your saying newtonian gravity is wrong? as in completely wrong? oh dear.

 

i wonder how we can launch so many rockets successfully then seeing as the designers base the calculations on that equation and that orbital mechanics relies on it for pretty much everything. i think the evidence is in its favour.

 

G does not appear on both sides it only apears on the RHS and is the gravitational constant the only thing on the left hand side is F which is the force caused by gravity.

 

Also, reality doesn't care if its your equation or not. if i put you in a space suit and kick you out a spaceship at 7.3km/s retrograde your going to fall.

 

Yes. I believe he will be able to stand and, over time he will exhaust the oxygen in the air and replace it with other components. Pressure may or may not decrease but it will not cease. If you elevate your chamber the pressure outside will decrease but the inside pressure will not be different due to elevation. Water, on the other hand, does rise when 'air' is exhausted. Where is gravity then?

 

water, evapourates when the pressure is lowered yes, but it is still affected by gravity. its the same thing as you picking up a stone and chucking it away. the molecules can tear free from the intermolecular forces due to the reduced pressure and follow ballistic trajectories until they hit something then they follow another ballistic trajectory and so on for every molecule.

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I'm sorry but unless I am sadly mistaken you are arguing that evidence is proof of existence. I put it to you that between the bible, new testament, Koran, book of Mormon, three thousand million christians, jews and muslims, countless saints, prophets, holy men and women, eye witness accounts, miracles, etc. etc. etc....... there is more evidence for the existence of the god of Abraham than there is for gravity.

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i wonder how we can launch so many rockets successfully then seeing as the designers base the calculations on that equation and that orbital mechanics relies on it for pretty much everything. i think the evidence is in its favour.

If you understand the principle of the self fulfilling prophecy you should understand the concept of the self fulfilling construct. Just because the construct supports the construct doesn't mean that the construct can be sustained. Equations are founded on observation and, if found to be unsatisfacory, are adjusted accordingly by such devices as 'constants' of which I believe G is such.

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if you count a bunch of books that have been bastardized over the millenia for political and sociological agendas as evidence then your still wrong.

 

what has the bible ever predicted? nothing. what has newtonian gravity allowed us to predict? only neptune and the orbits of every extraolar planet we've ever found. a couple of moons have also been predicted by newtonian gravity and shortly found using the derived coordinates.

it also allows us to determine what speed a rocket must achieve to end up at other planets or enter a certain type of orbit.

 

if its completely flase then it must be one hell of a coincidence don't you think.

 

oh and by your logic i can say that you don't exist. after all i only have evidence that you exist. that doesn't really mean you exist. and what about every prisoner in the world, we only have evidence that they done it. doesn't really mean that the crimes were ever commited.

 

THINK DAMMIT!

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I am sorry (again) if my desire to understand is greater than your ability to explain. I have found amongst religious types that if they can't answer the question they attack first the question then the questioner. I must admit you surprise me slightly.

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So if I can explain it to your satisfaction you will believe me. Is that what you are saying.

What a peculiar notion.

I don't think I have to defend anything actually. I'm just a stupid ignorant member of the great unwashed and huddled masses who depend on others to tell me what is what.

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truth seeker my ass. you ignore evidence. you dodge questions. you see that reality deviates from you own little world inside your head and you crawl deeper into your shell.

 

i just don't like seeing people do this. its depressing that people will ignore facts to avoid upsetting their world view. you may truely be a lost cause.

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