So.. we don't know what causes gravity?

[coldcreation]

Richard P. Feynman, certainly one of the most prominent characters in the history of 20th century science, tells us with due reason that “All we have done is to describe how the earth moves around the sun, but we have not said what makes it go. Newton made no hypotheses about this: he was satisfied to find what it did without getting into the machinery of it. No one has since given any machinery.” We use mathematics to describe nature without knowing what mechanism is operating, though many have been suggested. Feynman continues, “No machinery has ever been invented that “explains” gravity without also predicting some other phenomenon that does not exist.”(1994 pp. 107-109)

 

The cosmological constant (lambda), certainly an intrinsic feature of the gravitational interaction, has led to a great deal confusion since its introduction into the framework of GR.

 

Traditionally, the cosmological constant has almost exclusively been regarded and treated as a repulsive force (or pressure) that counteracts the attractive force of Newtonian gravitation, where lambda is in a sense the opposite of gravity. However, closer examination of the problem reveals that this concept cannot be accepted. A change in our perception of lambda is required when interpreted in the context of gravitation as a curved spacetime phenomenon.

 

It is quite possible (and in fact essential) that in order to understand the operational mechanism involved in the gravitational interaction, we need first to understand lambda.

 

Coldcreation

[Cryogenic]

Gravity is .95% the speed of light. All planetary bodies are magnetic. The earth has 6 times more gravity than the moon, because the earth contains a solid core surrounded by a circulating liquid core. Gravitational pull is greatest at a planetary bodies core. An atmospheric outer shell or planet earth's exosphere, acts as a blanket/insulator which confines and amplifies a planetary bodies magnetism.

 

We slingshot space a probes travels by utilizing a planets magnetism and/or gravitational pull.

 

Thank You,

 

David Adams

[C1ay]

All planetary bodies are magnetic.

You must have overlooked Venus, it is completely non-magnetic.

 

We slingshot space a probes travels by utilizing a planets magnetism and/or gravitational pull.

I'm not aware of any probes that used a magnetic assist vs a gravitational assist. Could you tell us which ones the were since most spacecraft try to minimize the use of ferrous material to reduce weight.

[Cryogenic]

I surely will,...although first you'll need to move my thread from 'Strange Claims' back to 'Science Projects'...then we'll talk slingshot. Unless of course you can explain strange claims. ;)

[Cryogenic]

Interplanetary space probes often make use of the "gravitational slingshot" effect to propel them to high velocities. For example, Voyager 2 performed a close flyby of Saturn on the 27th of August in 1981, which had the effect of slinging it toward its flyby of Uranus

on the 30th of January in 1986.

 

Since gravity is a conservative force, it may seem strange that an object can achieve a net gain in speed due to a close encounter with a large gravitating mass. We might imagine that the speed it gains while approaching the planet would be lost when receeding from the planet. However, this is not the case, as we can see from simple consideration of the kinetic energy and momentum, which shows how a planet can transfer kinetic

energy to the spacecraft.

 

In 1993 Magellon discovered the Beta and Atla regions of Venus are volcanic with both high topography and high gravity. Venus has an iron core, although it's thick atmosphere is mostly carbon dioxide and may be a factor in the planets over-all weak magnetic field, at least in comparison to earth. The gravity on Venus is 91% of the gravity on Earth. A 100-pound person would weigh 91 pounds on Venus. If the iron core is no great size or significance, it may also play a factor. It's relevance to the sun may also play a part, in that no significant gravitational pull is required to continue on it's orbital pathway. My guess would be the mass of it's inner iron core. Less than earth, but still over 5 times greater than the moon.

 

Nowthen how about we get DAGAFEED moved to 'Science Projects'? It's only fair, and it's only strange to the uninformed. :hihi:

[Qfwfq]

Since gravity is a conservative force, it may seem strange that an object can achieve a net gain in speed due to a close encounter with a large gravitating mass. We might imagine that the speed it gains while approaching the planet would be lost when receeding from the planet.

It is perfectly so in the planet's rest frame but not so for an observer that isn't moving along with the planet. There is nothing odd about the slingshot effect.

[Tormod]

The slingshot effect is basic science, although it is a very interesting lesson in orbital mechanics and gravity.

 

http://www.dur.ac.uk/bob.johnson/SL/

[Tormod]

We slingshot space a probes travels by utilizing a planets magnetism and/or gravitational pull.

 

Actually, the slingshot effect means that the spacecraft gets a boost from the kinetic energy of the planet's near-circular orbit around the Sun. This energy is infitesimal for the planet, but huge for the spacecraft. There is no mystical trickery involved.

 

Gravity assist primer:

http://saturn.jpl.nasa.gov/mission/gravity-assist-primer.cfm

 

Ask the expert - Scientific American

http://www.sciam.com/askexpert_question.cfm?articleID=0001B3B9-8D66-1C72-9EB7809EC588F2D7&catID=3&topicID=2