Notices
Results 1 to 21 of 21

Thread: A question on Gravity

  1. #1 A question on Gravity 
    Forum Freshman
    Join Date
    Jul 2007
    Posts
    5
    Does anyone believe that since gravity is the weakest of the four forces that control the universe does anyone else believe that gravity is leaking into our universe from another universes brane or that it could possible be leaking out


    Reply With Quote  
     

  2.  
     

  3. #2  
    Suspended
    Join Date
    Sep 2006
    Posts
    967
    Is it possible that such short questions are considered spam?

    You know that neutrinoes oftenly pass by matter without hitting it, and when it does hit, it only transforms a raw momentum? If gravity is not neutrinoes, but also have this property, then it could be strong, just not that efficient.

    Gravity is an additive force, and that means that the more matter, the stronger acceleration it is exposed to. This increase mass through relativity, and hence it must be outer. Else matter would release alot more energy then its own weight when it transforms to energy. Example:

    The mass becomes energy, energy has no gravity hence the gravity becomes energy. But the mass can be callibrated by the equation:
    F = ma. Even though the gravity field contains the potential to increase the mass substantially, had it been part of a bigger mass. But none of that potential was transformed to energy.

    It seems quite clear to me that the gravity force is outer and comes from Big Bang that is currently located 15 billion years away in all directions.
    But it is to me it sounds clear, does it seem clear to you?


    Reply With Quote  
     

  4. #3  
    Forum Freshman
    Join Date
    Jun 2007
    Location
    Toledo, OH
    Posts
    68
    string theory eh? im still havin trouble believing in string theory. but if it were true, i think gravity would be leaking out.
    "Life is what happens to you while you're busy making other plans." - John Lennon
    Reply With Quote  
     

  5. #4  
    Forum Professor
    Join Date
    Oct 2006
    Posts
    1,595
    Assuming this is a real question, Gravity as we now understand it is an attraction to matter with regards to its total mass. Anyway you observe it gravity should not be leaking away from mass, whether in our universe or a suggested other. The attraction, could happen if other universe do exist and close enough to have a effect. Frankly if an expansion is on going and your not in the Big Bang Theory camp, you could justify an expansion pull from other universe.

    Energy or that from our Electromagnetic Energy Chart, could be another issue. Since these energies travel at C speed in all direction from a source, that energy would have at some point exit what ever the limits of our universe is. Likewise if other universe exist that could reach ours over time.

    Just a thought....
    Reply With Quote  
     

  6. #5  
    Forum Professor leohopkins's Avatar
    Join Date
    Dec 2006
    Location
    Dulwich, London, England
    Posts
    1,417
    Id have to say that this is something which I believe.

    Incidentaly, does anyone know what happened to megabrain ?? Havnt seen any posts of his for a while.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

    www.leohopkins.com
    Reply With Quote  
     

  7. #6  
    Forum Professor
    Join Date
    Oct 2006
    Posts
    1,595
    Quote Originally Posted by leohopkins
    Id have to say that this is something which I believe.

    Incidentaly, does anyone know what happened to megabrain ?? Havnt seen any posts of his for a while.
    MB has been ill, some sort of Kidney problem which apparently is draining his strength. He pops up every once in awhile.

    In my opinion, I started with "as is understood today" and admit am very skeptical of the theory, nearly in total. Gravity even in attracting must be pulling in all directions, which if nothing there could extend to infinity, but I think in logical terms and have trouble with this notion.
    Reply With Quote  
     

  8. #7 orbits and attraction 
    Forum Freshman Ozolnyex's Avatar
    Join Date
    Jul 2007
    Location
    Latvia
    Posts
    84
    Do You think Orbital and attractional are the same sort of gravity?
    Ozolnyex
    Reply With Quote  
     

  9. #8 Re: orbits and attraction 
    Forum Professor
    Join Date
    Oct 2006
    Posts
    1,595
    Quote Originally Posted by Ozolnyex
    Do You think Orbital and attractional are the same sort of gravity?
    Objects in orbit seems to be directly related to velocity/speed of the object. Certainly in our solar system, as each unit regardless of density or mass revolves slower with distance and faster in closeness to the gravity source, our sun. However is asking if gravity caused that speed, most would probably say no.

    In the formation of a star, if as some suggest is a rolling spinning process, then the debris of things later becoming planets would have been spinning as well. What may have been trillions of debris objects in formation most should have lost speed falling into the sun in the first trillion or so years from lack or lost speed, or ability to repel gravity.

    opinion and the way i read it...
    Reply With Quote  
     

  10. #9 Re: orbits and attraction 
    Suspended
    Join Date
    Apr 2007
    Location
    Pennsylvania
    Posts
    8,795
    Quote Originally Posted by Ozolnyex
    Do You think Orbital and attractional are the same sort of gravity?
    There is only one kind of gravity. The force between the sun and planets is what keeps the planets in orbit and determines the orbital speed.

    Kepler figured out that the planets trace out equal areas in equal amounts of time. Newton explained Kepler's laws in terms of the gravitational attraction.

    Look up Kepler's laws of planetary motion.
    Reply With Quote  
     

  11. #10 LHC experiment 
    Forum Freshman
    Join Date
    Jul 2007
    Location
    Israel
    Posts
    6
    I think that LHC experiment will show whether another dimensions are exist,and consequently whether the gravitational force is leaked to another dimensions
    Reply With Quote  
     

  12. #11 orbital vs attractional grvity 
    Forum Freshman Ozolnyex's Avatar
    Join Date
    Jul 2007
    Location
    Latvia
    Posts
    84
    I am sure that when the object is in orbit it just follows curved space path did by the planet and it has nothing in common with gravity, it's just followin the easiest way not loosing energy. It is obvious to me even if contemporary phisics says different.

    Attraction begins when approaching surface. And this gravitational attraction is the cause of pressure made by the space. It is curved along the planet, but on the surface if the planet or star is relatively big, we have real flat circles on the surface. And that difference causes pushing matter down, curved space tends to flatten. I see these things caused only by curvation of space.

    What You think?
    Ozolnyex
    Reply With Quote  
     

  13. #12  
    Forum Freshman
    Join Date
    Jul 2007
    Location
    Israel
    Posts
    6
    I think you right,it is relativistic discription of gravity
    Reply With Quote  
     

  14. #13 Re: orbital vs attractional grvity 
    Suspended
    Join Date
    Apr 2007
    Location
    Pennsylvania
    Posts
    8,795
    Quote Originally Posted by Ozolnyex
    I am sure that when the object is in orbit it just follows curved space path did by the planet and it has nothing in common with gravity, it's just followin the easiest way not loosing energy. It is obvious to me even if contemporary phisics says different.
    Newton's great achievement was to unite physics with astronomy by proving they are the same force. So it looks like you want to turn the clock back on science 3 or 4 hundred years.
    Reply With Quote  
     

  15. #14  
    Suspended
    Join Date
    Sep 2006
    Posts
    967
    You definitely have a point there harold. Gravity should be somewhat uniform, else the planets wouldn't have different orbits (I've read his proof of the gravity declining with distance and the planet affecting force analysis)
    Reply With Quote  
     

  16. #15  
    Forum Sophomore
    Join Date
    Oct 2006
    Posts
    107
    The simplest way of understanding orbital mechanics on a quazi-newtonian non-mathematical standpoint might be this:

    "Orbit" and "Falling" are the same thing. the only difference is the forward speed involved.

    If the surface of a planet/sun is roughly spherical within a 5% error for elipsoid.
    You start with an object 200km high. And release it.

    It falls straight down accelerating toward the surface (centre) of the planet.
    It eventually collides with the surface. which stops the object from moving toward the centre, however there is still an attraction toward the centre. In an odd way you could consider the Surface (Ground) to be accelerating the object away from the centre at exactly the same force that gravity is attracting the object toward the centre of the planet. Also the mass of the object, now firmly touching the planet, is actually added to the planets overall mass.


    In orbit you are just traveling 'forwards' in relation to the gravitational pull, so that by the time you have 'decended' by 200km, the curvature of the planet's spherical shape has taken the surface away from where you are. Thus you are falling down and always 'missing' the planet because of your sideways velocity.

    Kind of like dropping a parachutist out of a plane.

    If you have a target to hit (say an X drawn on the ground) and you drop the parachutist off at the moment that you pass over the X, the parachute will miss the target because the speed of the aircraft means that you are overhead that location only for a moment. Assuming no forward velocity is lost on the way down (which is the case in space since there is no wind resistance) the point of impact with the surface of the planet could be very accuratley predicted by Newtonian Physics. (and will be in the direction the plane was going.)

    Now just replace that scenario but make the entire earth (centre of gravity and surface) the size of the X. Drop the parachutist, and he falls down toward the centre, however he misses the X. Imagine the X is where all gravity is pulling from and he missed the X. What happens now? no momentum loss because the parachutist is a vacuum. Only gravity changes the direction of Velocity as the parachitist has no engines. and no drag anymore due to the vacuum. He always falls "Toward" the X, but his motion forward means he always misses the target and always falls 'too far forward' of the X. In some circumstances, he would never hit the X, ever. With enough forward speed he would always "Circle" the X, as the gravity is trying to pull him to it, but his forward velocity from the airplane drop will never dissipate (due to no air resistance). He's now in an orbit, and will never in all time hit that X.

    The moon is attracted to earth's gravity (falling toward earth) but is moving fast enough so that it never hits the ground. (infact it never really even comes significantly closer to earth at any point)


    An Eliptical Orbit (some sattelites for instance) gets faster as the object gets closer to earth.

    This is because it is 'falling' 'downhill'.

    As it does so it gains momentum, but inertia resists any direction change so the object continues to fall faster. At some point the object gains so much speed that the 'falling' is outpaced by the horizontal speed, and so the object starts to increase the distance from the surface of the planet, since the direction it is taking is a flatter line in comparison to the surface of the planet's curvature, thus the 'altitude' if you will, increases.

    This is akin to falling 'uphill' and the forward speed starts to decrease. Enough time later the object is moving forward slower, (the gravity pulls the same, so the fall is just as fast) and the curvature of momentum is less than the curvature of the planet's surface, and so the object again decreases altitude. 'falling down' and picking up energy to start the cycle over again. From the perspective of occupants of such a vehicle, Gravity would always appear to be in Freefall. 0 G, no acceleration against inertia.

    Standing on the Ground, the Ground itself 'accelerates' you against the natural inertia of Gravity's power which naturally tends toward a freefall trajectory (based around the centre of gravity.) If you could fall through the surface of Earth as if it wasn't there (hypothetical and impossible in reality) you would tend toward a highly illiptical orbit, completley underground, and centred on the centre of mass of the planet. Instead the Ground prevents motion, and the Inertia of the Gravitational Freefall is converted into apparent G force, equal to the gravity of the planet.

    Gravity also seems to be slowly weakened the further you go in a very graduated way. For instance, it should make sense that to track a larger circle you would need to go faster assuming the 'acceleration toward centre of gravity' is the same at the higher (and longer) path. However we know this is not the case. For instance Mars's path around the sun is much larger than Earth's. And yet Mars is moving slower through space.

    If you have an object such as a satellite and want to move it from a 200km circular orbit to a 38000km high circular orbit (ie geostationary). not only will you go from an orbit which circles the planet in 90 minutes (at 200km) to one which circles the same planet in 24 hours (at geostationary altitude of the high 30k's km). but the actual forward motion is also slowing. Now you need to accelerate twice to get there (add motion to boost into an eliptical orbit then more to increase speed at the 'top' of the orbit so that the path to the 'bottom' doesn't decend.)

    But after accelerating (adding motion via a rocket in the direction of travel) you will be Higher but slower (track across the ground).
    Reply With Quote  
     

  17. #16 Re: orbital vs attractional grvity 
    Forum Freshman Ozolnyex's Avatar
    Join Date
    Jul 2007
    Location
    Latvia
    Posts
    84
    [/quote] Newton's great achievement was to unite physics with astronomy by proving they are the same force. So it looks like you want to turn the clock back on science 3 or 4 hundred years.[/quote]

    Astronomy and physics the force is the same, no doubt. But if anybody believes the space is curved around the planets, then one should agree that orbit is not a gravity and not a force that keeps the object near, the object is just moving free along its curved path, and to give him another direction the energy is necesary.
    Ozolnyex
    Reply With Quote  
     

  18. #17  
    Forum Sophomore
    Join Date
    Oct 2006
    Posts
    107
    It is true that both discriptions of Gravity seem to work in their fields. Certainly the Curve of space-time is a more useful discription in Relativistic situations, but also, the Apollo missions used Newton, and that got them some very accurate and useful (fuel-wise inexpensive) trajectories. I also find the Newtonian version of gravity is easier to explain why we experience "Forces" on the ground, and is more intuitive than Relativity.
    Reply With Quote  
     

  19. #18 orbits 
    Forum Freshman Ozolnyex's Avatar
    Join Date
    Jul 2007
    Location
    Latvia
    Posts
    84
    If anybody believes that the space is curved around planets and stars then one should agree that orbiting is just following curved space path.

    Gravitational attraction is another thing. The essence of gravity is unknown, gravitons?, gravity wawes? or something else, no device has registered something like this. Maybe it's the same thing - curvation, but acts differently when approaching surface.

    We have curved space around the planet, but we have flat circles on the surface.

    The surface of infinitely large sphere is flat. There should be something about it concerning attraction or pushing down.

    Odd thing, but if it had to be a force of attraction, objects with bigger mass should assimilate more of this forse and G would be more than 9,8 for them. G is equal for any falling objects, unfortunatelly
    Ozolnyex
    Reply With Quote  
     

  20. #19  
    Suspended
    Join Date
    Apr 2007
    Location
    Pennsylvania
    Posts
    8,795
    Befory you study Einstein and the general theory of relativity you need to learn about Kepler and Newton.

    I don't claim to fully understand general relativity, and I don't think there are a whole lot of people who do. What I do know is that at speeds much less than c, the equations for relativity reduce to the same as Newton's laws of gravitation. This is called the correspondence prnciple. So if you can explain planetary motion by curved spacetime, then you can also explain an apple falling from a tree by curved spacetime.
    Reply With Quote  
     

  21. #20  
    Forum Sophomore
    Join Date
    Oct 2006
    Posts
    107
    While I am sure that a falling apple, the G-force of standing on the ground, and Planetary orbits (along with photons, black holes and so on) are calculatable and discribable in Relitivistic terms, the fact remains that Newton is both more intuitive (Simpler) and accurate enough to discribe events at velocities for which the human mind is more capable of. And by that I mean the kind of human mind which is comfortable processing "Aircraft" and "Spacecraft" speeds. Once this is achieved and an understanding of the idea of orbits is achieved, Newton seems to sit quite well for it's purpose.

    After all, if it's good enough to get you to the moon in 1969 - 1972, you can pretty well discribe it as a proven concept.

    Now the issue is that it stops working at very high speeds, or in unusual circumstances like Black Holes. Nor is it able to deal with the nature of light. However it is a very friendly model as far as I can see, and if NASA freely use the principal for spacecraft navigation, as they do, then as an "Enthusiast" rather than a scientist, I am quite happy with my mind's model of Newton, as it seems to be fairly self evident once you remove a few misconceptions about how space and inertia works. Certainly my discription is oversimplified for my own brain model, but it has been tempered with my own research, and use of the Orbiter Simulator. (and perhaps through my long-ago Flying lessons and experience with modified G-forces due to acceleration)

    In all, the main concept is the idea that Gravity which makes you feel Heavy standing on planet earth, and Gravity which makes the moon stay in orbit around the earth is the same thing.

    Afterall if we are trying to figure out for ourselves how orbits and such things work, we are doing it for our own good, Thus the importance is how your brain can get around something (ie internal model of concept). I'm assuming that this is the case here because Im not seeing large amounts of equasions populating this thread, so can only assume it's not a scientific verifiable and mathematically correct discription of gravity and motion, but rather a fairly basic "Concept" mind-model of the topic instead.

    So without launching you into space, I'd suggest that diagrams, and perhaps even the freeware Orbiter Simulator and playing around with it's Orbital Trajectory MFD and adding and taking away speed through propelling oneself prograde and retrograde for a while to see what happens to the orbit is a great way to get a fairly clear brain-model of the topic. Of course discussions like this are also interesting because it forces you to try to put your brain model into words, then see if it comes up short.
    Reply With Quote  
     

  22. #21 Suns & black holes & atoms 
    Forum Freshman
    Join Date
    Aug 2007
    Location
    China
    Posts
    5
    So maybe the spinning suns and black holes and all are somekind of vortexes, depressions on the sheet of reality, appearing in this "dimension" to our intelligence as spinning masses throwing light around. Holes in the black paper. Spinning. Falling through time.
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •