Gravity Works Like This

Discussion in 'Physics & Math' started by Farsight, Feb 25, 2014.

  1. Farsight Registered Senior Member

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    The thing about physics is that once you understand one thing, it’s easy to understand the next. A while back I was explaining that time travel is science fiction because clocks "clock up" motion. Once you understand that, it’s easy to understand that the speed of light is not constant. There no actual time flowing in an optical clock. It goes slower when it's lower because light goes slower when it's lower, just like Einstein said. Then once you understand that, it’s easy to understand gravity. You’ll be familiar with the bowling-ball analogy. The Earth is likened to a bowling ball in a rubber sheet, like this:

    [​IMG]
    GNUFDL image by Johnstone, see wikipedia

    You probably know already that one problem with this picture is that the Earth looks like it’s being pulled down by gravity. It’s no good using gravity to explain gravity, that’s circular. But the picture isn’t totally wrong. Imagine you’ve placed a whole lot of parallel-mirror light-clocks in an equatorial slice through the Earth and the surrounding space. When you plot all the clock rates, your plot resembles the rubber-sheet picture because clocks go slower when they’re lower. Then the curvature you can see relates to Riemann curvature which relates to curved spacetime. And yes, you measured those clock rates, so yes, it’s a curvature in your metric. But it’s important to remember that the curvature is just a curvature in your plot of clock rates, and those clocks measured the motion of light through space. So what the rubber-sheet analogy is really depicting, is the varying speed of light.

    It’s also important to note that the clocks nearer the Earth don’t run slower because your plot is curved. In other words, they don’t run slower because spacetime is curved. Spacetime is an abstract mathematical space, and it is static. It’s the plot, the map, and the map is not the territory. Spacetime is not what space is. The clocks run slower when they’re lower because the space down there is different. That’s because a concentration of energy in the guise of the matter of the Earth “conditions” the surrounding space, the effect of this diminishing with distance. Einstein talked about this in his 1920 Leyden Address, where he also talked about inhomogeneous space. That’s the physical reality that underlies curved spacetime. And like I was saying in the speed of light thread, he didn’t say light curves because spacetime is curved. He said light curves because the speed of light varies with position.

    I don’t know if you know, but there’s another couple of problems with the rubber-sheet picture. One is that it depicts tension instead of pressure. Einstein’s stress-energy tensor has an energy-pressure diagonal, and to envisage pressure you need to step up from a rubber sheet to three-dimensional space. Imagine it’s like some gin-clear ghostly elastic jelly, then you insert a hypodermic needle and inject more jelly to represent the mass-energy of the Earth. The surrounding jelly is pressed outwards rather than being pulled inwards. The other problem is that the Earth is spherical, which really muddies the water when we’re talking about Einstein’s inhomogeneous space. To get past that, we need to zoom in a little, like this:

    [​IMG]
    Image credit: NASA (I removed the moon and added the lattice lines)

    The height of each square relates to your clock rates. Remember they’re light-clocks, so the height of each square relates to the speed of light at that position. And because the speed of light varies from top to bottom, a beam of light going across the picture will curve like a car veers when it encounters mud at the side of the road. Like this:

    [​IMG]

    Hence Professor Ned Wright’s Deflection and Delay of Light wherein "the delay experienced by light passing a massive object is responsible for the deflection of the light”. That’s easy to understand. And of course, once you understand why light curves, it’s easy to understand why matter falls down. There’s only one other thing you need to know about, and that’s the wave nature of matter. You can make an electron along with a positron out of light waves in pair production. And you can diffract an electron. Plus in atomic orbitals electrons exist as standing waves. So just think of an electron as light going round and round. Then you can simplify it to light going round a square path. Try drawing it, like this:

    [​IMG]

    Now imagine it’s in a gravitational field. The vertical parts of the path are still vertical, but the horizontal parts bend down a little. So the electron falls down. Like this:

    [​IMG]

    In essence the reducing speed of light is transformed into the downward motion of the electron. You can diffract protons and neutrons too, so the same principle applies to matter in general. From this you can even understand why the general-relativity deflection of light is twice the Newtonian deflection of matter. It’s because for matter, only the horizontals bend down. Yes, it’s pretty simple really. But as for why this isn’t common knowledge, I don’t know. It should have been common knowledge for about three hundred years, because in Opticks queries 20 and 21 Newton said this:

    "Doth not this aethereal medium in passing out of water, glass, crystal, and other compact and dense bodies in empty spaces, grow denser and denser by degrees, and by that means refract the rays of light not in a point, but by bending them gradually in curve lines? ...Is not this medium much rarer within the dense bodies of the Sun, stars, planets and comets, than in the empty celestial space between them? And in passing from them to great distances, doth it not grow denser and denser perpetually, and thereby cause the gravity of those great bodies towards one another, and of their parts towards the bodies; every body endeavouring to go from the denser parts of the medium towards the rarer?"

    That’s Newton telling you why light curves, and it's pretty much what Einstein said. And in Opticks query 30 Newton said "Are not gross bodies and light convertible into one another?" So I imagine he had an idea about why matter falls down. I hope that now you do too. Understand time, then the speed of light, and then gravity is easy. And so it goes. It's like pulling a thread with Einstein's name on it, and out comes a string of pearls.

    Oh, and one of them is called black holes.
     
  2. Russ_Watters Valued Senior Member

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    Can you show or describe a real experiment that demonstrates your hypothesis and shows the mainstream theory does not work?
     
  3. Farsight Registered Senior Member

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    Huh? Russ, I'm not some my-theory guy. I root for relativity. This is mainstream theory, explained properly, in line with Einstein. What you think is "mainstream theory" is a popscience parody of the real thing. You know that Einstein overturned his own constant-speed-of-light postulate. You know he said light curves because the speed of light varies with position. Don't you? You know about the wave nature of matter. Don't you? Why do you think light curves? Because the abstract mathematical space called spacetime is curved? Russ, that's wrong. That's a cargo-cult tautology for kids. Here, have a read of http://arxiv.org/abs/physics/0204044:

    "There exists some confusion, as evidenced in the literature, regarding the nature of the gravitational field in Einstein's General Theory of Relativity. It is argued here the this confusion is a result of a change in interpretation of the gravitational field. Einstein identified the existence of gravity with the inertial motion of accelerating bodies (i.e. bodies in free-fall) whereas contemporary physicists identify the existence of gravity with space-time curvature (i.e. tidal forces). The interpretation of gravity as a curvature in space-time is an interpretation Einstein did not agree with."

    As regards "real experiment", see Clifford M Will's The Confrontation between General Relativity and Experiment. Oh, and pay special attention to page 6 where he tells you that special relativity wasn't accepted by mainstream physicists until the late 1920s. And while we're on a roll have a look at the History of general relativity on wiki. See this bit:

    "Kip Thorne identifies the "golden age of general relativity" as the period roughly from 1960 to 1975 during which the study of general relativity,[18] which had previously been regarded as something of a curiosity, entered the mainstream of theoretical physics. During this period, many of the concepts and terms which continue to inspire the imagination of gravitation researchers and the general public were introduced, including black holes and 'gravitational singularity'".

    It ain't what you thought Russ. So wise up.
     
  4. Uncle Pythagoras Banned

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    Einstein's maths can be reversed to get 3D geometry. The flat space picture is due to the maths being backwards. Instead of using the outside of a sphere, and expansion, you move the maths to the inside of the Universe, and contraction. The red shift is then taken from a different observation point in the other direction. The bending of spacetime becomes points, and points become locations. It's 3D, very easy.
     
  5. origin Howdy Valued Senior Member

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    You know, of course that this is meaningless.
     
  6. Uncle Pythagoras Banned

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    All maths can be reversed to get the same result. It's points moving inwards not a bending of anything. You move points in, you get a red shift from the contraction, and not inflation. It's relative to you.
     
  7. Russ_Watters Valued Senior Member

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    Yeah, Farsight, I know: you root for Einstein, bla, bla, bla. You have explicitly claimed that the current mainstream understanding of Einstein, GR and of reality is wrong. So my request still stands: where is your experimental support? If the scientific mainstream is wrong, there should be plenty of experimental evidence of that.
     
  8. Farsight Registered Senior Member

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    In the NIST optical clocks and GPS clock adjustment and the Shapiro delay. They support what Einstein said: the speed of light varies with position. Even a child can see this, because even a child can see that there isn't some river of time passing inside a clock. Why can't you?
     
  9. Russ_Watters Valued Senior Member

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    2,656
    GPS clocks don't measure the speed of light, they simply record the passage of time and are adjusted for differing rates in accordance with it. We discussed (you posted) the equation in the black hole thread and it doesn't say anything about a variable speed of light (it is here, in case you forgot: http://en.wikipedia.org/wiki/Gravitational_time_dilation#Outside_a_non-rotating_sphere ). Further, you claimed that the modern interpretation is wrong, yet give modern experiments done based on the modern interpretation as support. So the best you can really claim for yourself here is that your view makes no predictions that differ from the mainstream view and thus provides no added value.

    But again: if that wasn't the correct equation, then post the correct one!
    I'm sure most children recognize that as a strawman, even before learning what a "strawman" is: no one has ever claimed here or anywhere else that there is a river inside a clock.
     
  10. Farsight Registered Senior Member

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    It is hopeless. You explain what clocks do, but the shutters are down and there's nobody home.

    Naysayer ramblings. The equation relates one t to another, and the second is defined using the motion of light.

    Ah but "GPS clocks... simply record the passage of time". Hey open up that clock, see all that time passing in there! Yes? No? Knock on wood!
     
  11. James R Just this guy, you know? Administrator

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    Farsight:

    I don't understand this part:

    If the light is going across the square horizontally, how does a vertical difference in the speed of light affect it? Why does it curve downwards? Shouldn't the speed of the light be constant as it travels horizontally, and only change if it's already moving vertically?
     
  12. Farsight Registered Senior Member

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    "The height of each square relates to your clock rates. Remember they’re light-clocks, so the height of each square relates to the speed of light at that position".

    Maybe I should have said the vertical size of each rectangle. Where you see a short rectangle the coordinate speed of light is lower. Where you see a tall rectangle the coordinate speed of light is higher.

    "And because the speed of light varies from top to bottom, a beam of light going across the picture will curve like a car veers when it encounters mud at the side of the road".

    Maybe an analogy will help. Imagine you're travelling straight across a body of water in a motorboat. But when you plot your course with GPS positioning you realise your path is curved rather than dead straight. You scratch your head wondering if your rudder isn't right. Or if there's a wind. Or a current. You eventually work out that it was none of these things. Instead it was because the water was saltier and so denser on one side than the other. It was inhomogeneous, and therefore your path through it was curved. The water wasn't curved. For your next experiment you place little toy motor boats in various locations, and work out that they go fractionally slower where the water is saltier/denser.

    Light takes many paths. So a vertical gradient in the speed of light alters its horizontal path. See above and see Ned Wright's deflection and delay of light:

    "In a very real sense, the delay experienced by light passing a massive object is responsible for the deflection of the light. The figure below shows a bundle of rays passing the Sun at various distances. The rays are always perpendicular to the wavefronts which mark the set of points with constant travel time from the star. In order to bend the light toward the star one needs to delay the wavefront near the star:

    [​IMG]

    Another way to delay the wavefronts of light is to send the light through glass, as in a lens or a prism. The deflection and delay of light caused by massive objects is called gravitational lensing".
     
  13. Russ_Watters Valued Senior Member

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    So you recognize/admit that the equation doesn't take into account/describe the different speeds of light? If you recognize that a variable speed of light assumption doesn't impact the calculations, how can you still think the assumption has value?

    Again: the time dilation equation you yourself posted uses a constant speed of light. What you claim is contrary to your own source! You know your source doesn't support you and you know your assumption has no practical value, but you believe it anyway. Crazy.

    It doesn't matter how many times you assert/explain your crackpot views - and yes, I DO - understand your crackpot beliefs, they won't ever stop being wrong.
     
  14. Farsight Registered Senior Member

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    Russ, take it to the speed of light thread. The second is defined as the duration of 9,192,631,770 periods of radiation. You wait for 9,192,631,770 light waves to pass you by and then you say that's a second. You work out your t in seconds. When t isn't the same as t' at another place, one second isn't the same as another. Because the coordinate speed of light at one place isn't the same as at another. And this coordinate speed of light varies even in the room you're in. Because it's more than just the coordinate speed of light. It's the speed of light. And an optical clock goes slower when it's lower because light goes slower when it's lower, just like Einstein said.

    Now read the OP above and comment upon it with relevant observations or issues, and your total sincerity. If you will not, I will put you on ignore.
     
  15. Russ_Watters Valued Senior Member

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    2,656
    All of that is fine except for the fact that you are using the coordinate speed of light (then stepping on your own tongue with the bolded mishmash), whereas the equation uses the proper speed of light. Since you apparently know this (since you brought it up), clearly this is intentional deception by you: your main claim here is wrong AND YOU KNOW IT.

    Or to put it another way: we are agreed that the coordinate speed of light is not constant. By bringing it up, this means that you know that the proper speed of light IS constant and you've been purposely conflating them the entire time.
    Translation: "stop busting my trolling, I don't like it and can't successfully keep trolling if you won't fall for my tricks (waaaaa)."

    Not happening. Your trolling is all about pulling people down your rabbit hole of twisted logic - instead of discussing what matters: math and experiments - and I won't follow. I'll just keep pointing out the big picture errors:
    -You have no math to support your claim (the math you post contradicts you)
    -You have no evidence to support your claim.
     
  16. Farsight Registered Senior Member

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    My main claim here is not wrong. Light curves and matter falls down because the speed of light varies with position. That's what Einstein said. That's what the evidence says.

    And you've said nothing other than nay nay nay. You're a naysayer who cannot put together a counterargument. The NIST optical clocks can be simplified to this gif:

    [​IMG]

    The speed of light varies with position. And for all your feather-spitting and tearful outrage, you have given us nothing at all.
     
  17. Beer w/Straw Transcendental Ignorance! Registered Senior Member

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  18. wellwisher Valued Senior Member

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    The simplest explanation for gravity is connected to the observation that in our universe, mass will net convert back to energy, via fusion, instead of energy net converting to mass through energy condensation into mass. Most of the star light has a connection to mass burn. This trend of mass burn to energy shows the direction of lower potential which is in the direction of energy.

    This observation also implies, that mass, which cannot move at the speed of light (per special relativity) is nevertheless able to head back to the C reference, when mass converts to energy. Since there is net mass to energy in our universe, this also suggest the C reference is at the lower potential, or else mass burn would be endothermic and energy condensation into mass would be exothermic.

    Since the net trend in our universe is mass heading toward the lower potential of the C reference of energy, then mass acted upon by gravity should be just another way to move mass in the general direction the C reference. If this premise was true, gravity should be reflected by the local space-time reference changing in such a way as to head all the mass in the vector direction of the speed of light reference (gravity should cause space-time reference to contract) in the direction of C reference limit.
     
  19. James R Just this guy, you know? Administrator

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    Farsight:

    I see. You weren't really talking about a single ray of light of negligible width, but rather a light wave, with wavefronts like those shown in the animation above.

    I don't have a problem with this explanation of the deflection of light. It does, however, assume that space is flat and that the speed of light therefore varies. A different way to look at things is that space is curved and the speed of light remains constant.

    It's really just two ways of looking at the same effect.

    For example, in the animation above, we can explain the apparent slowing of the wavefronts that pass closer to the sun as due to their having to their not travelling in the two dimensions of the screen any more, but dipping "down" perpendicularly to the plane of the computer screen then up again, as they pass near the sun. The dip is greater for the waves passing nearer to the sun than it is for waves passing further away. The added component of the light's velocity perpendicular to the plane of the screen accounts for its apparent slowing in the plane of the screen. Adding up the components, the light still has its usual, constant speed.

    This is a somewhat flawed, 3-dimensional analogy of what actually happens, of course. Because, in fact, that bending of the light perpendicularly to the plane of the screen doesn't really happen in that particular direction at all. The bending actually happens in the 4 dimensional spacetime around the sun, which is such that there's actually more space near the sun than there would be if spacetime was flat there. Light takes longer to travel through the space near the sun than it would if the spacetime there wasn't curved, and that accounts for the apparent slowing of the light (the Shapiro delay).

    The common ball-on-a-trampoline picture of curved spacetime near the sun or the Earth, which appears as your very first diagram in the opening post of this thread, gives an easy way to picture what is going on with the curvature, although it does that at the expense of dropping a spatial dimension from the picture.
     
  20. James R Just this guy, you know? Administrator

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    This is the simplest explanation for gravity, is it? I have a few questions:

    How does mass convert back to energy via fusion, exactly?
    What kind of energy does the mass convert into?
    What is energy condensation into mass?
    What is mass burn?
    What is the startlight's connection to mass burn, exactly?
    Why is there a trend of mass burn to energy?
    What does it mean for energy to have a direction?
    What kind of potential are you talking about here?
    What does it mean for potential to have a direction?

    I hope you can help me with these questions. Your simplest explanation for gravity is quite opaque to me as things stand.

    What do you mean?
    What kind of energy does the mass convert into?

    What does it mean to say that "there is net mass to energy in our universe"?
    What kind of potential are you talking about here?
    What is this "C reference", and why does it have a potential?
    What does it mean for mass burn to be endothermic or exothermic?

    What does it mean to say that gravity is a way to "move mass in the general direction the C reference"?
    How can "the C reference" have a direction?
    Or do you just mean that mass speeds up as it falls?

    What's a local space-time reference?
    What's the speed of light reference?
    What do you mean by the vector direction of the speed of light reference?
    What does it mean for the space-time reference to contract?
    What is the "C reference limit"?
    Why is it a limit?
     

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