Gravity???

[newtonian]

igorsboss- Thank you. <br /><br />Actually, our universe obeys very precise laws and has properties which are fine tuned to allow stars, and life, etc., to exist.<br /><br />So I wouldn't say it just is. Rather I would see this as evidence of intelligent design and creation.l<br /><br />Clearly the laws and properties involving gravity and inertia are involved, in turn, with the fine tuning of the expansion of our universe to close to omega=1, i.e. close to the critical point. i.e. between eternal expansion and collapse.<br /><br />It is tipped ever so slightly (as a fraction in the origin of expansion) towards eternal expansion, with indications that some form of invisible energy is causing our universe to be stretched out, as Isaiah 40:22 describes. [God is stretching out our universe like a fine gauze- Hebrew: thin cloth, also crumbling from the primitive root derivation]<br /><br />To me it is awesome.

 

[Maddad]

kmarinas86<br />I'm still waiting for myballs to stop spinning backwards after reading that post of yours. The strangest part is that I think I understand what I thought you meant you thought you said. I think. Maybe.<br /><br />Yeah, I would expect a person to weigh measurably more at the poles than at the equator.

 

[nacnud]

<font color="yellow">So I wouldn't say it just is. Rather I would see this as evidence of intelligent design and creation.</font><br /><br />Yeah and if there were slightly differences we wouldn't be here disusing them, but I suspect something might be, and would probably use the same arguments of 'but it just works out so nicely'. I'm sorry but I just can't see the argument being valid, why leap to this fantastically complicated intelligent design conclusion.<br />

 

[igorsboss]

Knowledge is not self-sustaining! Knowledge dies without education.<br />The question remains valid, even it has been asked for centuries, so long as each time the question is asked, a new mind is asking it.

 

[siarad]

Weren't the Greeks using something like Roman numerals. If so the Indian/Arab numerals we now use may never have happened. <br />Nine pin bowling was banned so 10 pin came into use in the USA.<br />Playing of drums were banned so now we have steel bands.<br />Sometimes banning brings new thought where previously was stagnation.

 

[jschaef5]

Force of gravity = (gravity constant * mass of object one * mass of object two) / radius^2<br /><br />So actually the force of gravity on the bowling ball is different then that of a feather because it has less mass. But how do you then calculate the acceleration due to gravity, like how do we come up with the 9.80665 m / s^2? <div class="Discussion_UserSignature"> </div>

 

[igorsboss]

Please consult my earlier post, with timestamp 09/03/04 03:20 AM. I'll derive it more completely this time.<br /><br />Let G = universal gravitational constant<br />and Me = Gravitational mass of Earth<br />and me = Inertial mass of Earth<br />and M = gravitational mass of object<br />and m = inertial mass of object<br />and r = radius between the centers of mass of the Earth and the object.<br /><br />The magnitude of the force due to gravity on the object, which is also the magnitude of the force due to gravity on the Earth, f, is given by: f=G*Me*M/r*r.<br /><br />Since in general f=ma, then a=f/m. If we ignore all other forces, such as friction, we can solve for acceleration.<br /><br />The acceleration of the object due to Earth, a, is a=f/m, and the acceleration of the Earth due to the object, ae, is ae=f/me, towards each other's center of mass.<br /><br />Since inertial and gravitational mass are emperically equivalent, Me=me and M=m, precicely. Hence inertial mass and gravitational mass cancel out. (BTW - this is a deep mystery.)<br /><br />So a=G*Me/r*r and ae=G*M/r*r.<br /><br />Since Me is much much larger than M, a is much much larger than ae. That is to say that the Earth hardly accelerates at all, so little that it appears stationary within measurement error.<br /><br />So, although a bowling ball and feather would accelerate the same, the bowling ball would reach the Earth's suface in less time than the feather would, because the bowling ball moves the Earth more than the feather does.<br /><br />...Except in the case where they are dropped next to each other at precicely the same time!!! In this case, the acceleration of the Earth due to the bowling ball will cause the Earth to accelerate towards the feather in exactly the same way that the Earth accelerates toward the bowling ball! The Earth's motion cancels completely!<br /><br />So Gallileo was precicely correct, a bowling ball and a feather, dropped at the same time from the same height, ignoring all forces except

 

[igorsboss]

Note that in the expression <font color="yellow">a=G*Me/r*r</font>there is no mention of the mass of the object.<br /><br />Hence, approximately, g=G*Me/r*r=9.81 (m*s-2) where r is the radius of sea level.<br /><br />Given (from the CRC handbook, 77th edition)<br />G=6.67259(85) E-11 (m^3*kg^-1*s^2)<br />Me=5.9742E24 (kg)<br />r=6371000 (m)<br /><br />We may calculate: <br />g=9.821087 (m*s-2)

 

[siarad]

That's simple. Just roll a coin down a slope & time it's transit. You know the length of travel from zero speed so calculate the acceleration. S = ut + 1/2ma^2<br />The Universal constant of gravity was measured here in the UK by holding a plumb bob close to a mountain, then going to it's opposite side & measuring the angular difference w.r.t a star. The Scot, I think, spent 2 years trying to find a conical mountain so he could calculate it's mass. In so doing he invented contour lines we use in so many ways.

 

[Maddad]

jschaef5<br />"<font color="yellow">Force of gravity = (gravity constant * mass of object one * mass of object two) / radius^2 So actually the force of gravity on the bowling ball is different then that of a feather because it has less mass. But how do you then calculate the acceleration due to gravity, like how do we come up with the 9.80665 m / s^2?</font><br />The acceleration between the bowling ball and Earth is the same as between the feather and the Earth. While the gravitational force on the bowling ball is a thousand times that of the feather, the bowling ball also masses a thousand times as much as the feather. A thousand times larger force pushing a thousand times larger mass means the acceleration is remains constant.<br /><br />In the English system that constant is 32 feet per second per second. In the metric system it is 9.8 meters per second per second. I'll use ten meters for round numbers.<br /><br />In a vacuum in the first second an object falls five meters, half of ten meters. It's half because it started out that second at no speed at all, zero, and finished the second at 10 meters per second.<br /><br />At the end of two seconds the object will have fallen 20 meters. We square the number of seconds, two, to get four, and take half of that times 10 to get our 20 meters. Note that while the object fell five meters in the first second, it fell 15 meters in the next second.<br /><br />igorsboss<br />"<font color="yellow">So, although a bowling ball and feather would accelerate the same, the bowling ball would reach the Earth's suface in less time than the feather would, because the bowling ball moves the Earth more than the feather does.</font><br />Maybe not. The mass of the Earth, with the feather, and the bowling ball is the same as the mass of the Earth, with the bowling ball, and the feather.

 

[jschaef5]

Thanks for clearing that up for me igorsboss. <img src="/images/icons/smile.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[newtonian]

nacnud - That's OK if you reject the conclusion. However, gravity is fine-tuned with the other forces of physics to make stars and life possible. <br /><br />So then, what explanation for this do you consider valid?<br /><br />I certainly do not consider "it just is" to be a valid scientific explanation of cause and effect as to what caused gravity to have its specific properties so necessary for stars and life to exist.<br /><br />Are you familiar with Isaac Newton's demonstration of the design requires a designer argument in reference to our solar system and its orbits?<br /><br />The math involved in the physics of our universe is both precise and awe-inspiring to me. And over my head (both meanings).<br /><br />Where did this math in our universe, e.g. the precise ratios, come from if not from a Mathematician?

 

[nacnud]

Where did this math in our universe, e.g. the precise ratios, come from if not from a Mathematician?<br /><br />I don't know, my feeling is that complexity in this case the mathmatics inherent in the universe is an emergent behavior of the universe. The problem is its probably impossibe to predict.

 

[igorsboss]

<font color="yellow">igorsboss:"So, although a bowling ball and feather would accelerate the same, the bowling ball would reach the Earth's suface in less time than the feather would, because the bowling ball moves the Earth more than the feather does."<br /><br />maddad:Maybe not. The mass of the Earth, with the feather, and the bowling ball is the same as the mass of the Earth, with the bowling ball, and the feather. <br /></font><br /><br />No, I think I'm still correct...<img src="/images/icons/smile.gif" /><br /><br />Things accelerate towards bowling balls faster than things accelerate towards feathers, because the bowling ball warps space more than a feather does.<br /><br />Of course, I'm sure we both realize that this is far too small an effect to measure.

 

[igorsboss]

<font color="yellow">I certainly do not consider "it just is" to be a valid scientific explanation of cause and effect...</font><br /><br />Oh! No! You misunderstood me!<br /><br />Saying "it just is" isn't meant to be an explanation at all!<br /><br />It's an OBSERVATION!<br /><br />Maybe someone, someday, might come up with an explanation. However, the presence or lack of an explanation has NOTHING to do with empirical facts!

 

[Maddad]

igorsboss<br />There is a line of reasoning that makes us both wrong. Ultimately the bowling ball would accelerate more than the feather, but for a slightly different reason and at even a lesser difference than our already undetectable difference.<br /><br />The mass of the three objects together, the Earth, the bowling ball, and the feather, is a constant. The acceleration (space-time warpage) will be proportional to the <strong><em>product</em></strong> of the two masses. So far my contention has been that the <strong><em>sum</em></strong> of the masses is the same since the feather and the bowling ball both exist in both examples, but this is subtly different from the product of the two masses.<br /><br />When two pairs of numbers add up to the same value, you get a larger number when you multiply two numbers that are closer together than when you multiply two numbers that have a larger variance. For instance, if the first pair of numbers is 9 and 11, the product is 99. If in a second pair the two numbers are 8 and 12, then the variance is greater even though the two still add up to 20. The product of these two numbers however has dropped to 96.<br /><br />For this reason the bowling ball will accelerate faster than the feather. The Earth, bowling ball, and feather still are a constant, but the <strong><em>product</em></strong> of the Earth and the feather times the bowling ball will be more than product of the Earth and the bowling ball times the feather.

 

[siarad]

Thanks for the site. So it was a sort of decimal system. They certainly achieved a lot using it.

 

[igorsboss]

<font color="yellow">The acceleration (space-time warpage) will be proportional to the product of the two masses.</font><br /><br />Nope! The FORCE is proportional to the product of the masses, not the acceleration.<br /><br />The acceleration of object A is proportional to the gravitational mass of object B.<br /><br />(and inversely proportional to the square of the distance between A and B)

 

[igorsboss]

This is silly...<br /><br />If the bowling ball and the feather fall simultaneously, the direction of the gravitational attraction betwen the bowling ball and the feather will be horizontal, hence this force will have no effect on vertical motion.

 

[Maddad]

Do the math.

 

[igorsboss]

I did the math! Now I'll interpret it for you. Again.<br /><br />Every object accelerates towards a bowling ball in the same way, be it a feather, the Earth, or the Earth plus a feather.<br /><br />Every object accelerates towards a feather in the same way, be it a bowling ball, the Earth, or the Earth plus a bowling ball.<br /><br />Every object accelerates towards the Earth in the same way, be it a bowling ball, a feather, or a bowling ball plus a feather.<br /><br />Why? Because the inertial mass of the falling object cancels the gravitational mass of the object.<br /><br />Since the Earth has more gravitational mass than a bowling ball, and a bowling ball has more gravitational mass than a feather, things accelerate faster towards Earth than a bowling ball, and faster towards a bowling ball than a feather.

 

[Maddad]

*Sigh* You did the logic, not the math. We're going around in circles here, so I'm done. I'll let others figure it out for themselves. You and I have said all we appear that we are going to say.

 

[newtonian]

Igorsboss - Sorry I misunderstood you. <br /><br />However, the origin of gravity should be by cause and effect - agreed? The lack of empirical facts aside, this scientific principle would logically apply. <br /><br />Also, the specific properties of gravity, such as its mathematical ratio with the other forces of physics, should also have a cause. <br /><br />And, to fully understand gravity shouldn't we be trying to determine how it was originally caused and how it continues to operate in a causal manner - i.e. by cause and effect?

 

[newtonian]

nacnud- Yes, an emergent behavior. Math emerged and is inherent in our universe.<br /><br />Impossible to predict? Well, one would have to first determine how this property came about.<br /><br />Compare genetics and human birth. Now that we know more we can predict certain emergent properties or traits.<br /><br />However, it is not just by chance - there is informational coding in DNA and RNA and epigenetic coding (such as the recent discovery of methyl links on introns (not actually Junk DNA) and also methyl and acetyl links on histones in the chromatin, or outside the DNA, hence dubbed epigenetic coding).<br /><br />Likewise the birth of our universe shows properties or traits comparably as unlikely as the genetic traits allowing us to live and our brains to contemplate all of this.<br /><br />This all involves math.<br /><br />Now, there are many other forms of math inherent in our universe -such as e=mc^2. Scientists merely discover this math, these formulas. They already operate in our universe..<br />Now, how could such precise math, linked with law and order, become inherent in our universe so it emerged to be as it is if not by a Mathematician?<br /><br />I think you will agree that we do not fully appreciate the gravity of the matter!<br />

 

[igorsboss]

<font color="yellow">...should...would...should...shouldn't</font><br /><br />Another deep, deep sigh.<br /><br />Gravity happens. Why? I don't know. Neither does anyone else. Yet.<br /><br />And ya know, that's just fine. Where would we be without the mystery?<br /><br />If and when we finally figure it out, you might become right, perhaps, or maybe not.<br /><br /><font color="yellow">the origin of gravity should be by cause and effect - agreed?</font><br /><br />No, I don't agree. Neither do I disagree. I continue to observe, listen to my peers, and think for myself.<br />