F = G(m1m2)/r²

EdFred said:
Happy Birthday Sir Isaac.
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So much more elegant than:
b3f14edb49fd763ec19df7dcf1ff087e.png
 
perhaps i should drop my apple at lunch before i eat it?
 
smigaldi said:
Ah but will it fall according to Newtonian theories of gravitation or Einsteinian?
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It will fall according to Newtonian theories. It will follow the shortest path through curved space-time according to Einsteinian.:D
 
Perhaps Newton was right after all...

From Scientific American:

Was Newton right and Einstein wrong? It seems that unzipping the fabric of spacetime and harking back to 19th-century notions of time could lead to a theory of quantum gravity.
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tonycondon said:
and will the difference be detectable??
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Sam D said:
Perhaps Newton was right after all...

From Scientific American:
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It really depends on the context of the measurement. Einsteins equations simplify down to Newton's in the context used here on Earth (for the most part- GPS has a correction because the satellite clocks are in a different inertial reference than we are). The Scientific American article is talking about high energies. Within the solar system, Einstein's equations work well. The SciAm article is new to me and very interesting.
 
true. i timed my fall with the time honored 1 mississippi 2 mississippi method of timing. with your accent though we would get different answers to the same question.
 
smigaldi said:
Ah but will it fall according to Newtonian theories of gravitation or Einsteinian?
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Newton's straightforward math applies for objective observations.
Einstein's hocus pocus math applies for subjective observations.

Ex:
Apple falls = consistent measurements = Newton at work.
Trip down stairs (takes forever to arrive at the ground) or fall off a motorcycle (sub microsecond range to go from sitting up to blamo) = no consistency = Einstein at work.


Gravity sucks however would you be prepared if gravity were to suddenly reverse itsself?
 
My theory is that gravity isn't an attractive force...
 
angular momentum troy. and thats just the way it was meant to be. maybe nascar is on to something and turning left in circles is natural
 
tonycondon said:
angular momentum troy. and thats just the way it was meant to be. maybe nascar is on to something and turning left in circles is natural
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Is there anything (other than Venus) in the solar system that rotates retrograde? Venus spins backwards on its axis, but orbits normally.
 
i think that either uranus or neptune is tilted 90 degrees to typical N-S orientation?
 
TangoWhiskey said:
"Why do the planets all orbit the sun in a counter-clockwise direction?"
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Of course, if our major dominant civilizations had developed on the Southern Hemisphere, our maps and globes would be upside-down, and all the planets would be orbiting clockwise.
-harry
 
And who decided which way is galactically "up"? Is it because early astronomists were on the European continent? We could just as easily have looked at the universe with the Sun's south pole as its north pole, and then Australia would have been at the top of the globe with the planets orbiting clockwise around the Sun.

EDIT: Ha! Harry was thinking the same thing as me...
 
Also, the sun itself rotates like earth does, and I am sure that imparted a nudge of which way the accretion disk started to spin.
 
EdFred said:
Also, the sun itself rotates like earth does, and I am sure that imparted a nudge of which way the accretion disk started to spin.
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The explanation I've carried in the back of my brain was that this whole solar system started out as a giant rotating gas cloud. So the Sun rotates in the same direction as the planets revolve, because that's the direction that everything was rotating in the beginning.
-harry
 
mantakos said:
The explanation I've carried in the back of my brain was that this whole solar system started out as a giant rotating gas cloud. So the Sun rotates in the same direction as the planets revolve, because that's the direction that everything was rotating in the beginning.
-harry
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Sun isn't a first generation star, unsure how much of the original star was left to maintain any rotation.
 
EdFred said:
Sun isn't a first generation star, unsure how much of the original star was left to maintain any rotation.
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I interpret that as meaning that the metallicity of the Sun suggests that it was made up of "stuff" that was formed in an earlier star, but that there's no suggestion that this earlier star was part of our solar system, merely that the raw materials that formed the gas cloud that was to become our solar system were, at some earlier point, produced by some long-since extinct stars.
-harry
 
No, it's how all the heavy elements formed the rest of the planets.
 
In the beginning, there was wikipedia:
http://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System
The formation and evolution of the Solar System is estimated to have begun 4.55 to 4.56 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the centre, forming the Sun, while the rest flattened into a protoplanetary disc out of which the planets, moons, asteroids, and other small Solar System bodies formed...
...
Until a few decades ago, the conventional view was that the Sun formed in relative isolation, but studies of ancient meteorites reveal traces of short-lived isotopes such as iron-60 which only form in exploding, short-lived stars. This indicates that one or more supernovae occurred near the Sun while it was forming...
​
-harry
 
EdFred said:
Sun isn't a first generation star
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The Sun is a second or third generation (Population 1) star. It's not a first generation star.

unsure how much of the original star was left to maintain any rotation.
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None in relation to the hydrogen and heavier elements that created the Sun or other stars.

The short simple version:
The Sun is not made of an old start that relit or anything like that. The older stars (Population 2 and 3) created the heavier elements as they used their hydrogen fuel then eventually blew off their outer layer or went supernova blowing their heavier elements into interstellar space over lots of light years thus the original rotation is nonexistent. The debris eventually created gravity and pressure bound nebula which collapsed and created completely new stars from scratch. As the mass increased locally near a new star over time, random moving mass directions eventually damped out and established a rotation direction for the star itself and it's planetary disk. Once everything starts spinning the same direction, most of the time, anything else entering the area tends to be pushed in the same direction.
Of course there are always likely to be the variations with planets in retrograde orbits, tilted planet axis due to whatever and maybe a new nearby star that encouraged rotation of a new forming star nearby in a given direction. Those situations are probably far less common that everything rotating the same direction though.

Based on the planets being found around other stars lately, they're determining that planetary disk orientation from one star to another is very random and not generic for the galaxy. Our own solar system is significantly tilted to the galactic plane.
 
EdFred said:
Also, the sun itself rotates like earth does, and I am sure that imparted a nudge of which way the accretion disk started to spin.
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Um...actually, it's the other way round. The accretion disk imparted the spin to the Sun as it collapsed.
 
JeffDG said:
Um...actually, it's the other way round. The accretion disk imparted the spin to the Sun as it collapsed.
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In your scenario, why was the accretion disk spinning, but the Sun not already spinning?

My understanding is that the entire system was already rotating, though the rate of that rotation certainly increases as the moment reduces, per conservation of angular momentum.
-harry
 
The USPTO has granted Boris Volfson, an inventor in Huntington IN, US Patent 6,960,975: Space vehicle propelled by the pressure of inflationary vacuum state. According to National Geographic News, the patent is a design for an antigravity space vehicle:
Volfson's craft is theoretically powered by a superconductor shield that changes the space-time continuum in such a way that it defies gravity. The design effectively creates a perpetual-motion machine, which physicists consider an impossible device.​
 
mantakos said:
In your scenario, why was the accretion disk spinning, but the Sun not already spinning?

My understanding is that the entire system was already rotating, though the rate of that rotation certainly increases as the moment reduces, per conservation of angular momentum.
-harry
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Because the accretion disk existed before the Sun did. The Sun formed from the accretion disk. Any slight motion would be accelerated as the nebula contracted from tens-of-light-years down to the solar system we see today, especially for the Sun itself, which took several light-years worth of gas/dust and compressed it into a ball of the Sun's current size, while maintaining angular momentum.
 
mantakos said:
So the Sun formed from a rotating gas cloud, but it wasn't rotating itself?
-harry
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Think conservation of energy. The rotating mass accumulates at the center where the star eventually forms. It doesn't stop moving for no reason just because it gets to the center.
 
I'm more interested in what the apple will fall in rather than how it falls! I want to know if I can eat it afterwords. :D
 
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