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Thread: Is gravity 100% efficient?

  1. #1 Is gravity 100% efficient? 
    Forum Freshman √-1human's Avatar
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    I have learnt that nothing in the universe is 100% efficient, so is gravity 100% efficient.If not then should't the orbits really differ?Black holes should have more pull truly than we observe?So there will be many differences, no?Or is it now taken as not a 100% efficient force?


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    I don't understand your question. It's like asking if the sun shines 100% efficient. The answer is both yes and no.

    It's 100% efficient because that's the output it has, why would it be less than it is?

    Or you may be confused with the volume of the mass of gravity we are on. If you propose we reduce the volume to 0, and ask if the gravity is greater then, you are correct, in that case it's not efficient now. But for the rest, i doubt i understand your point.


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  4. #3  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by √-1human View Post
    I have learnt that nothing in the universe is 100% efficient
    Where did you learn this?
    The saying is properly only applied to systems and processes.

    so is gravity 100% efficient
    It's a meaningless question, efficiency is defined as: Useful work per quantity of energy, mechanical advantage over ideal mechanical advantage.
    Or, more simply: output/ input.
    What "input" is there with gravity? What "output"?
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  5. #4  
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    Quote Originally Posted by √-1human View Post
    I have learnt that nothing in the universe is 100% efficient, so is gravity 100% efficient.If not then should't the orbits really differ?Black holes should have more pull truly than we observe?So there will be many differences, no?Or is it now taken as not a 100% efficient force?
    Gravity is 100% efficient because everything falls down but nothing ever falls up.
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  6. #5  
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    Perhaps the term efficent should be replaced with perfect for the sake of discussion. If so I would interject that nothing is perfect, as an observer. If gravity where perfect we would most likely be at one with the sun? Our galaxy would be a black hole. Perhaps the math is perfect, but , I do recall hearing learned minds referring to the universe as being caotic.
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  8. #7  
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    Quote Originally Posted by keeseguy View Post
    I do recall hearing learned minds referring to the universe as being caotic.<br>
    probably referring to the science of chaos. a much different subject.

    Chaos theory - Wikipedia, the free encyclopedia
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  9. #8  
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    Quote Originally Posted by keeseguy View Post
    Perhaps the term efficent should be replaced with perfect for the sake of discussion.
    How would that help?

    If so I would interject that nothing is perfect, as an observer.
    Is it not?
    The Sun, for example, seems to be a perfect Sun to me.
    To dispute that you'd have to specify exactly what "perfection" is and how it applies (if it even should) to the Sun.

    If gravity where perfect we would most likely be at one with the sun?
    What?

    Our galaxy would be a black hole.
    Double what?

    Perhaps the math is perfect, but , I do recall hearing learned minds referring to the universe as being caotic.
    Um, and you don't think that being "perfect" should include chaos? Why not?
    Since "this" universe is the only example we have, how would you decide what a "perfect" universe "should" be?
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  10. #9  
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    Does evolution favor that which is closer to perfect? So our sun should be the dominant star type in the universe, is that the case? Perfection is a value that no individual can judge, but only by it's ability to dominant completely that around it. I can only say, from observation, that the effects of gravity cause interactions that make it less then efficient, or perfect.
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  11. #10  
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    The answer to your two questions is No. As for the rest this is physics, philosophy is down the hall.
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  12. #11  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by keeseguy View Post
    Does evolution favor that which is closer to perfect?
    Again you're left with the problem of defining "perfect" in the context of the question.
    But the short answer is: "No. Not even close to true".

    So our sun should be the dominant star type in the universe, is that the case?
    Why should it?
    On what do you base this claim?

    Perfection is a value that no individual can judge
    Oh great.
    You suggest that instead of "efficient" we use "perfect" and THEN claim that we can't judge "perfect". How exactly does that substitution therefore help in the orginal question?

    but only by it's ability to dominant completely that around it.
    Why?

    I can only say, from observation, that the effects of gravity cause interactions that make it less then efficient, or perfect.
    Then you're either using the words "efficient" and "perfect" incorrectly or you're simply making it up.
    Could you explain exactly how gravity fails to be "perfect"?
    Please list the "observations" that support this.
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  13. #12  
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    Quote Originally Posted by Dywyddyr View Post
    Could you explain exactly how gravity fails to be "perfect"?
    Please list the "observations" that support this.
    he already said that if gravity was perfect the earth would collide with the sun. (a few posts up). of course that makes no sense at all.

    here is the logic: if gravity was perfect the earth would collide with the sun. since earth has not collided with sun, gravity is not perfect. QED
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    Quote Originally Posted by Chucknorium View Post
    Quote Originally Posted by Dywyddyr View Post
    Could you explain exactly how gravity fails to be "perfect"?
    Please list the "observations" that support this.
    he already said that if gravity was perfect the earth would collide with the sun. (a few posts up). of course that makes no sense at all.
    Maybe I should have asked "Why is that implied if gravity is "perfect"?".
    Oh wait, I more or less did in post #8.

    Although that's not a"how" since it's unsupported.
    How about "If gravity was perfect there'd be free bacon sandwiches ready made in the kitchen every morning. They're not, so gravity is imperfect".
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  15. #14  
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    The one example that I could not forgive on this matter is, 1 micro second before the big bang what happened to gravity?
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  16. #15  
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    Meaningless question. Before the Big Bang there was no time (or gravity).
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  17. #16  
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    Quote Originally Posted by keeseguy View Post
    The one example that I could not forgive on this matter is, 1 micro second before the big bang what happened to gravity?
    you do understand that BB Theory starts after the BB ? very, very soon after the BB. but after the BB. not before.
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  18. #17  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by keeseguy View Post
    The one example that I could not forgive on this matter is, 1 micro second before the big bang what happened to gravity?
    Oh good.
    I'm especially glad to see that you have avoided answering any of my questions and decided to change the subject.

    Always a sure sign of someone who doesn't have the first clue what he's talking about.
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  19. #18  
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    I didn't really profess to know what I am talking about. I assumed that since we were considering 100% efficiency that was close to being perfect...my bad. I know I have no idea what perfection is. My statement pertaining to which was better, only replied to your statement that our star was a perfect sun in your opinion. I only wanted to propose that evolution on most scales favors the most fit.
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  20. #19  
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    Quote Originally Posted by keeseguy View Post
    I didn't really profess to know what I am talking about.
    So you were simply making statements at random?
    Out of boredom?
    A keyboard equivalent of Tourette's?

    I assumed that since we were considering 100% efficiency that was close to being perfect...my bad.
    And you STILL haven't explained how "100% efficient" means "perfect".
    Or how "perfect gravity" would pull the Earth into it. (Or any of your other claims).

    I know I have no idea what perfection is. My statement pertaining to which was better, only replied to your statement that our star was a perfect sun in your opinion.
    And yet you thought it reasonable to bring "perfection" into the conversation anyway... (And, on top of that, to replace a meaningful term - efficiency - with what you subsequently admit is neither measurable nor definable. Not very useful, was it?)
    As for me stating that the Sun appears to be a "perfect Sun", maybe you've forgotten that I made that statement in reply to YOUR claim that "If so I would interject that nothing is perfect, as an observer. "

    I only wanted to propose that evolution on most scales favors the most fit.
    And the point here is... what, exactly?
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  21. #20  
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by keeseguy View Post
    I didn't really profess to know what I am talking about.
    So you were simply making statements at random?
    Out of boredom?
    A keyboard equivalent of Tourette's?
    Haha, i´m cracking up. But a lot of people seem to suffer from Keyboard Tourette´s, please consider donating to our relief fund for K-T victims. May their time they wasted on crap be remembered.

    I assumed that since we were considering 100% efficiency that was close to being perfect...my bad.
    And you STILL haven't explained how "100% efficient" means "perfect".
    Or how "perfect gravity" would pull the Earth into it. (Or any of your other claims).
    You could actually try and calculate it, however even if gravity on earth is multiplied by a factor of 50 (say this happens to the gravity on earth, and the effect of orbital bodies), we would not crash into the sun. We could however at first get a slight ellipse around the sun, generate more speed of orbit, and then slowly reach a different orbit. Which is probably further away from the sun, and at a greater speed. To crash into the sun with this kind of thinking, we would almost need infinite gravity, so our ellipse is actually through the sun itself.

    Any astrophysicist may correct me on this, as i am just guessing here and calculating with regular mechanics.
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  22. #21  
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    One could consider the emission of gravitational radiation with the concomitant decay of binary system orbits as a less than 100% efficiency in the thermodynamic sense.
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    There are no paradoxes in relativity, just people's misunderstandings of it.
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  23. #22  
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    This is the second thread today where I have felt constrained to mention that in science the terminology is very tightly defined. If one then enters a discussion using everyday meanings of the words one will almost certainly arrive at a seriously flawed conclusion, or will formulate essentially meaningless questions.

    I think it would be more helpful if we pointed out the fault is in the process rather than in the individual. Do you think we could try that in future?
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  24. #23  
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    [QUOTE=Zwolver;549279

    You could actually try and calculate it, however even if gravity on earth is multiplied by a factor of 50 (say this happens to the gravity on earth, and the effect of orbital bodies), we would not crash into the sun. We could however at first get a slight ellipse around the sun, generate more speed of orbit, and then slowly reach a different orbit. Which is probably further away from the sun, and at a greater speed. To crash into the sun with this kind of thinking, we would almost need infinite gravity, so our ellipse is actually through the sun itself.

    Any astrophysicist may correct me on this, as i am just guessing here and calculating with regular mechanics.[/QUOTE]

    If you mean a 50x increase of the Sun's gravitational pull on the Earth, then you are going to get quite an eccentric ellipse, assuming that we start with the Earth's present orbital distance and speed.

    All you need is the vis-Viva equation:



    r would be the Earth's present orbital radius, and v its present orbital speed. M would be the mass of of the Sun. By increasing G by a factor of 50 and solving for a, we would get the new semi-major axis of Earth's orbit. The Semi-major axis is equal to the average orbital distance. So we get an orbit with a aphelion equal to the Earth's present orbital distance and and a nearer average distance. Plugging in the numbers, we get a new average distance of 75.15 million kilometers with aphelion of 149.6 million. This puts the new perihelion at ~1.5 million km or a bit over twice the Sun's radius. The new orbit would also be 18.34 days long.

    These are rough estimates since the Earth's present orbit is already an slight ellipse and thus its orbital distance and velocity varies a bit. Thus the answer would vary depending on where in its orbit the Earth was when the change in gravity was applied.
    Last edited by Janus; April 7th, 2014 at 01:05 PM.
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  25. #24  
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    Many folks type faster than they think.
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  26. #25  
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    Thanks Janus. Interesting formula, Why would mass and gravity be separate? And what is with the 2/x - 1/x thing.. I don't understand why that's there..
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  27. #26  
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    Quote Originally Posted by Zwolver View Post
    Thanks Janus. Interesting formula, Why would mass and gravity be separate? And what is with the 2/x - 1/x thing.. I don't understand why that's there..
    g=gravity, the local gravitational field. This depends on the mass of the object in question.

    G=the gravitational constant. This is the constant which allows one to calculate the above.

    As for the rest, have a look here:
    Vis-viva equation - Wikipedia, the free encyclopedia
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  28. #27  
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    Quote Originally Posted by Zwolver View Post
    Thanks Janus. And what is with the 2/x - 1/x thing.. I don't understand why that's there..
    It's basically a modification of orbital velocity for circular orbits:



    With circular orbits this remains constant, but with elliptical ones, it doesn't; the orbital speed varies with the planet's distance from the sun.

    The total energy(kinetic + gravity potential) does remain constant and is equal to



    Here M would be the mass of the Sun and m the mass of the planet.

    It also works out that



    Where a is the average orbital distance of the elliptical orbit.

    Thus











    Which gives you the orbital speed of the planet in an elliptical orbit with an semi-major axis of a when it is a distance of r from the Sun. ( note that when r=a, it reduces to the original circular orbit form.)
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