23 OCT 2013 by ideonexus
Proof that Objects Fall at the Same Rate
Salv.
But, even without further experiment, it is possible to prove clearly, by means of a short and conclusive argument, that a heavier body does not move more rapidly than a lighter one provided both bodies are of the same material and in short such as those mentioned by Aristotle. But tell me, Simplicio, whether you admit that each falling body acquires a definite speed fixed by nature, a velocity which cannot be increased or diminished except by the use of force [violenza] or resistance.... 1 
notes
notesGalileo's proof is based completely on a thought-experiment, no observation necessary.
20 JUN 2012 by ideonexus
Newton on the Power of Gravity
As he sat alone in a garden, he [Isaac Newton in 1666, age 24] fell into a speculation on the power of gravity; that as this power is not found sensibly diminished at the remotest distance from the centre of the earth to which we can rise, neither at the tops of the loftiest buildings, nor even on the summits of the highest mountains, it appeared to him reasonable to conclude that this power must extend much further than was usually thought: why not as high as the moon? said he to himself; an... 1 notes
notesWondering if it extended up to the moon.
08 JUN 2012 by ideonexus
Fear of Comets
When the movement of the comets is considered and we reflect on the laws of gravity, it will be readily perceived that their approach to Earth might there cause the most woeful events, bring back the deluge, or make it perish in a deluge of fire, shatter it into small dust, or at least turn it from its orbit, drive away its Moon, or, still worse, the Earth itself outside the orbit of Saturn, and inflict upon us a winter several centuries long, which neither men nor animals would be able to be... 1 notes
notesLambert considers the gravity of the comet and how it might throw the Earth out past Saturn.
16 MAY 2012 by ideonexus
Simple Laws Produce Complex Phenomena
But the most impressive fact is that gravity is simple. It is simple to state the principles completely and not have left any vagueness for anybody to change the ideas of the law. It is simple, and therefore it is beautiful. It is simple in its pattern. I do not mean it is simple in its action—the motions of the various planets and the perturbations of one on the other can be quite complicated to work out, and to follow how all those stars in a globular cluster move is quite beyond our abil... 1 notes
notesGravity is simple and elegant, but it produces immensely complex interactions of objects in the Universe.
29 MAR 2012 by ideonexus
Gravity is an Extremely Feeble Force
...imagine holding an electron in your left hand and another electron in your right hand and bringing
these two identical electrically charged particles close together. Their mutual gravitational attraction will favor their getting closer
while their electromagnetic repulsion will try to drive them apart. Which is stronger? There is no contest: The electromagnetic
repulsion is about a million billion billion billion billion (10 to the 42th) times stronger! If your right bicep represents the s...
1 In comparison to the other forces holding the Universe together.
29 MAR 2012 by ideonexus
Gravity Travels at the Speed of Light
Here's the rub. In Newton's theory of gravity, one body exerts a gravitational pull on another with a strength determined solely by
the mass of the objects involved and the magnitude of their separation. The strength has nothing to do with how long the objects
have been in each other's presence. This means that if their mass or their separation should change, the objects will, according to
Newton, immediately feel a change in their mutual gravitational attraction. For instance, Newton's theor... 1 notes
notesAccording to Einstein, overturning Newton.
16 FEB 2012 by ideonexus
Copernicus on Gravity
I myself consider that gravity is merely a certain natural inclination with which parts are imbued by the architect of all things for gathering themselves together into a unity and completeness by assembling into the form of a globe. It is easy to believe that the Sun, Moon and other luminaries among the wandering stars have this tendency also, so that by its agency they retain the rounded shape in which they reveal themselves, but nevertheless go round their orbits in various ways. If then t... 1 notes
notesHe correctly surmises that the force pulls heavenly objects into spheres.
08 FEB 2012 by ideonexus
The Earliest Account of Newton and the Apple
In the year 1666 he retired again from Cambridge... to his mother in Lincolnshire & whilst he was musing in a garden it came into his thought that the power of gravity (wch brought an apple from the tree to the ground) was not limited to a certain distance from the earth but that this power must extend much farther than was usually thought. Why not as high as the moon said he to himself & if so that must influence her motion & perhaps retain her in her orbit, whereupon he fell a c... 1 notes
notesIncludes the fact that he extended the force pulling the apple to the ground up to the moon.
31 JAN 2012 by ideonexus
The Beauty of Newton's Hypothesis
Newton supposed that the case of the planet was similar to that of [a ball spun around on the end of an elastic string]; that it was always pulled in the direction of the sun, and that this attraction or pulling of the sun produced the revolution of the planet, in the same way that the traction or pulling of the elastic string produces the revolution of the ball. What there is between the sun and the planet that makes each of them pull the other, Newton did not know; nobody knows to this day;...Folksonomies: gravity hypothesis
Folksonomies: gravity hypothesis
1 notes
notesIs that it worked, produced measurable results and predictions, and it didn't matter that what gravity is remained a mystery.
01 JAN 2012 by ideonexus
Sports on Phobos
Because of their small sizes, Phobos and Deimos have very low gravitational
accelerations. Their gravities do not pull very hard. The pull on Phobos is only
about one one-thousandth of that on Earth. If you can perform a standing high
jump of two or three feet on Earth, you could perform a standing high jump of
half a mile on Phobos. It would not take many such jumps to circumnavigate
Phobos. They would be graceful, slow, arcing leaps, taking many minutes to reach
the high point of the self-p... 1 notes
notesHow the low gravity and tiny size of Mars' moon would affect the game.
