Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gravity a result of procession of time?

  1. Feb 16, 2007 #1
    Ok First off Im a complete duffer to most of physics and the math necessary to describe the physics is beyond me right now (but im still learning!) I have done a search on what I thought were relevant terms and found many articles on different aspects but none that quite answer this question.

    From my understanding of physics at the quantum level (photons and electrons and other elementary particles) one of the numbers that consistently cause problems in equations dealing with same is the number for the mass of a particle usually designated m and measured I believe in Mev?

    It seems to me that, at least from what I have read so far, m doesnt cancel out like it is supposed to do in many of the equations dealing with electrons and photons.

    I also "know" that m is usually considered to be a result or an effect of Gravity. (this is where I get lost usually)

    Here is what I am wondering: Can Gravity be described as Moment of Inertia over a period of time? In other words Is the effect of gravity a result or an effect of each particles march through time?
     
  2. jcsd
  3. Feb 17, 2007 #2

    eV: electron volts: basically the charge of an electron times one volt. It is a measurement of energy. Usually mass could be in units of MeV/c^2, where mc^2 is the rest energy. Einstein said that mass is energy, thus in particle physics, typically energy and mass are 'interchangable' (loosely speaking)... the units are convienent nonetheless... E=mc^2, m=[eV/c^2].

    Rest mass (energy) of a particle is its energy when it is not moving relative to a given inertial reference frame.

    Mass is not a result of gravity.... Weight, in classical sense, is a 'result' of mass being under the influence of a gravitational field. That is why, for example, an astronaught can be 'weightless', yet he is not massless. Mass, again in the classical sense, does not change, especially because of gravity.

    Please reword your final question... I'm not sure what you are asking about.
     
    Last edited: Feb 17, 2007
  4. Feb 17, 2007 #3
    If by time you mean the action of matter upon other matter over a period of time (t), then yes, but the point is what is it that causes this attraction, with magnetic attraction and repulsion or electronic attraction or repulsion we have a particle the Electron, and a mediator particle, virtual photons; with gravity where is the graviton and Higg's Boson? Do they exist or is the attraction a fundamental part of the other forces interaction or something else like the "drag" of some field? or x?

    Mega is Millions: Mev is a short hand of Mev/c^2

    [tex] e=mc^2[/tex]

    energy=massxspeed of light squared so a simple rearrangement of the equation gives

    [tex] mass=\frac{energy}{c^2}[/tex]
     
    Last edited: Feb 17, 2007
  5. Feb 17, 2007 #4

    Gravity as defined as an external force that acts on all bodies generally
    is due as far as I understand it to the "fabric of space-time" GR tells us this and agrees with repeated experiments so far. (interesting to see what Gravity probe B results will be in April of this year by the way)

    But does it not take Time (t) to measure the amount of force exerted on a particle such as an electron? or how much force the electron exerts on its surroundings?

    What im asking I think is whether or not it is the progression of time itself that is responsible for an object having a Gravitational effect on its surroundings and vice versa? In other words Is Time granular? Is there a slice of Time from which we can not further subdivide it and still postulate the existence of a given particle of matter?
     
  6. Feb 17, 2007 #5
    Could you not as easily say that all the forces behaved in this way because of time, and therefore there are no need for electrons or photons or W bosons or gluons or quarks, it just is the action of time? This seems a little too much of an assumption to me, all the forces have there own mediator particle except at the moment gravity, we are looking for this particle at the moment and with CERNS collider coming on line in a little under a year we will finally be able to find out if gravity has the same sort of mediator and particles as the other forces or whether it is the result of something else such as a field theory, simply the result of the way matter interacts or is something even more mysterious x? Or heaven forbid some sort of ether:eek:
     
  7. Feb 17, 2007 #6
    I hope for Maxwells sake, and my sanity, that this is NOT the case. But if it were to be the case, does that mean that the underlying assumptions of SR are also not treated properly? that in fact Maxwells Demon must exist in some form?
     
  8. Feb 18, 2007 #7
    Gravity and Time

    Marlberg's question is extremely interesting. In my own words, "How much time is needed in order to see and predict the effect of gravity on matter?" That's like asking how many ordered pairs of x and y you need to come up with an equation to describe their relationship. The more pairs you have that support a specific pattern, the more confident you are that your equation is correct. So it's like watching the earth move around the sun, but what if you could only see this happening for a millisecond, or a picosecond? The earth would move in this time--although measuring it is not very practical--but could you measure the correct acceleration in that time? The correct acceleration being determined by the gravitational attraction between the earth and sun. hmmm........right now that can only be determined by extrapolating from the acceleration that we've measured. You could use dimensional analysis to go from seconds to picosenconds, but that wouldn't be the same as actually measuring it. GREAT question, Marlberg!
     
  9. Feb 18, 2007 #8

    jtbell

    User Avatar

    Staff: Mentor

    I'm sorry, I can't figure out what you're talking about here. Can you give a specific example?
     
  10. Feb 18, 2007 #9
    jtbell: m=mass As far as I know the mass in Mev of a particle is a number that is in the equations but that doesnt sit well at all because for whichever particle you are describing the theory and the experimental values never quite match up or they do match up but in matching they change j in some way that doesnt add up or it changes e or e changes m or in changing j,m,and e n is changed in some way that doesnt fit the model
     
  11. Feb 18, 2007 #10

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    What in the world..... ?

    As jt asked, can you give a specific example? You are explaining this via some handwaving, vague scenario. Point out a particular experiment, a particular theory, ....

    BTW, to be technically correct, a mass is in units of eV/c^2. You can get away with setting c=1 when you are in a setting among other physicists who get the "inside joke" and know what simplifications you are making. This isn't the case here.

    Zz.
     
  12. Feb 19, 2007 #11
    ZapperZ: I can only give the examples I am currently struggling to understand and those come from Feynman and are dealt with on a laymans terms (as I am yet a layman and not a student nor a graduate yet) using his diagrams for electrons and photons (and protons neutrons muons etc) The particular theory I am having trouble with is QED and how and where Gravity comes in to the picture in QED. I do not have the math available to me to be able to give you the questions without copying them out of the book and so of course not understanding them at all and perhaps this is where my answer really lies is in understanding the math necessary to be able to understand the physics. I am working on the math tho slowly and surely. Up to Analytical Geometry so far. Calculus Just over the horizon:smile:
     
  13. Feb 19, 2007 #12

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    1. There are no quantum field theory for gravity, at least, not within the accepted physics.

    2. QED is a description for electromagnetic interaction, so why are we using that for gravity?

    3. Marrying QED with gravity is one of the most horrendous and difficult task we have today, so why are you doing it?

    4. Don't you think that, as a "layman", you might want to learn how to walk first before attempting to run? It appears from your posts in this thread that you might still have not understood other basic physics issues (eg. gravity and moment of inertia).

    Zz.
     
  14. Feb 19, 2007 #13
    and My question returned to you is Why? It is not enough that you say there is not without proof that it does not exist. Absence of data does not mean abscence of being no more does Existence of data necessarily mean that the data and the theory agree.
    [/QUOTE]

    probably ignorance on my part, however, thinking outside the box(but within the framework of the scientific method) is it possible to treat gravity in the same way or a similar way that we did with QED?

    Why Not me? I like thinking about problems. I enjoy learning new things and I am not afraid to get down to what needs to be gotten down to to learn the answers. Truly if you do have a pedigree and you enjoy puzzles and games and finding the answer as any good scientist ought then you would not have asked this question.

    Yes and as I stated before I AM learning to crawl prior to walking. Learning the math so that I can learn to count the little arrows in an efficient manner. As to not understanding the other basic issues Im sure that I do not else why would I ask the questions :smile:


    One thing I do not do is attempt to not understand something. If Some half baked Idea comes into my pointy little noggin I research it until I either understand the Idea or its implications or I can determine that understanding the answer to the Idea or its implications is not relevant to my well being.

    Now back to topic, Someone please describe to me (even if its in a language I do not yet understand dont worry Ill work out the syntax eventually :smile: ) Whether or not Time is smooth or granular and whether or not gravity can be treated in the same manner that the other "forces" can be treated or if not WHY not?
     
  15. Feb 19, 2007 #14

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    I think in this case, it is sufficient to simply state the fact that there is no QFT of gravity (in the standard model). That's why thousands of people are trying to find one! The basic problem is that when we attempt to apply QFT to GR, then we get results that do not make sense. Basically, infinities appear, which we cannot get rid of to make the theory physically sensible (it is "nonrenormalizable")
    What do you mean by this?

    No, since QED is renormalizable; i.e. we can get rid of the infinites that appear in the theory.

    In your first post you say
    This may be why Zz asked you.
     
    Last edited: Feb 19, 2007
  16. Feb 19, 2007 #15
    He never alluded to the notion that it was physically 'absent' nor did he make any claims which require justification. The Standard Model of Physics does not currently contain a gravitational quantum field theory. There are many competing models of gravitational quantum fields, however, those exist indepedent of the standard model. Physics is an empirical science which uses the language of mathematics in cojunction with experimental observation to falsify current theoretical models. All QFT's of gravity have either been falsified or currently do not make predictions capable of falsifiability.

    You aren't necessarily 'thinking outside of the box' by suggesting a gravitational QFT as there exists many competing models which are very intricate and complicated both mathematically and conceptually. When you say 'treat gravity in the same way that we did with QED,' what does that refer to exactly?

    What does this mean exactly?


    Again, what?

    What mathematics level are you currently up to?

    How does time emerge as 'granular or smooth'? When you ask if we can 'treat gravity in the same manner as the other "forces",' what does this mean exactly?
     
    Last edited: Feb 19, 2007
  17. Feb 19, 2007 #16

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    If I get a $1 for every time I had to address this issue....

    I just don't have the patience, and I am way too tired to point out the ignorance in your reply. Instead, why don't you read what I've written already that addressed this very thing that you are "practicing":

    http://physicsandphysicists.blogspot.com/2006/10/imagination-without-knowledge-is.html
    http://physicsandphysicists.blogspot.com/2006/10/imagination-without-knowledge-is_18.html

    Zz.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?