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Thread: Can something be relative to itself?

  1. #1 Can something be relative to itself? 
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    Hello, I'm new to the forum, but I'd like to ask this here before introducing myself. For now, just know that I'm kind of a layman who doesn't have a lot of background in physics.

    Basically it's just the question on the topic. I talked with two people and one said that one object can be relative to itself while the other guy said that, if there is only one object, it is not relative to anything. What is you guys' verdict on this?

    I came up with this question because I kept thinking "If there was only one frame of reference, would relativity still apply?" And couldn't come up with an answer by myself.


    Also, one of them said that, for some millionths of a seconds after the Big Bang, the laws of physics did not exist. Does that mean that relativity itself was invalid at that time?

    I hope you guys can shed some light on me here.


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    Yes, Relativity would apply, considering the object "at rest."
    But an object cannot be relative to itself.

    Relativity is a model used to describe spacetime. As it is a model, it requires constant testing and verification in order to increase its accuracy.
    All the "laws of physics" did exist, clearly as everything is still here. We only need to improve the models we use in order to describe these things.


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    The best example of something which might be considered relative to itself is the speed of light. Although this speed is accordingly always constant in a vacuum, the rate at the surface of a large planet, for instance, is slower than higher up. How can this be? Well, time runs slower closer to the Earth's surface, therefore the distance traveled per unit of time would be faster for light higher up, when determined by a surface clock. So slower time means slower light. Light farther up would bypass light closer to the Earth since time is faster so more distance would be covered.

    To exagerate the point lets say on some very heavy planet light would travel X distance in one second near the surface, but farther up time would run twice as fast. So during the time on the surface that it took light to go distance X, further away from the planet lights distance might be traveling 2X distance while time would be measured as 2T. So to measure the change in the rate light is moving one could compare it to itself. Of course the speed per unit of time would not change but the clocks would be running at different rates, slower close to the ground.
    Last edited by forrest noble; April 2nd, 2013 at 08:04 PM.
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  5. #4  
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    Law of Physics although better term is" law of Nature" always exist but they have different applying conditions .
    Now true law broke if a law broke means it was not a true law and has dome inaccuracy
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    Quote Originally Posted by Rizols View Post
    Also, one of them said that, for some millionths of a seconds after the Big Bang, the laws of physics did not exist.
    Prior to that very small portion of a second (10-37) the laws of physics break down rather "didn't exist".
    But, since what we know, and thus what physics "works on" also didn't really "exist" at that time (i.e. there were no particles as exist today) then it's probably more accurate to say that the laws of physics were in formation.

    Does that mean that relativity itself was invalid at that time?
    Effectively, yes: This singularity signals the breakdown of general relativity. Wiki.
    "[Dywyddyr] makes a grumpy bastard like me seem like a happy go lucky scamp" - PhDemon
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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by forrest noble View Post
    The best example of something which might be considered relative to itself is the speed of light. Although this speed is accordingly always constant in a vacuum, the rate at the surface is slower than higher up. How can this be? Well, time runs slower closer to the Earth's surface, therefore the distance per unit of time would remain the same. So slower time means slower light. Light farther up would bypass light closer to the Earth since time is faster so more distance would be covered.

    To exagerate the point lets say on some very heavy planet light would travel X distance in one second near the surface, but farther up time would run twice as fast. So during the time on the surface that it took light to go distance X, further away from the planet lights distance would be traveling 2X distance while time would be measured as 2T. So to measure the change in the rate light is moving one could compare it to itself. Of course the speed for unit of time would not change
    That is potentially rather confusing. (for example, it isn't clear what "speed for unit of time" means; speed is independent of time, isn't it).

    The important point is that the person on the heavy planet and the person in space would measure the same speed of light. I suppose you can describe that as the sped of light being "relative to itself" it it might be better to explain it as "not relative to anything".
    ei incumbit probatio qui dicit, non qui negat
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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by Rizols View Post
    Basically it's just the question on the topic. I talked with two people and one said that one object can be relative to itself while the other guy said that, if there is only one object, it is not relative to anything. What is you guys' verdict on this?

    I came up with this question because I kept thinking "If there was only one frame of reference, would relativity still apply?" And couldn't come up with an answer by myself.
    "Relative to itself" doesn't really mean anything unless you say what is relative: position? height? size? velocity?

    If you are talking about relativity then the important thing is relative velocity. Something cannot be moving relative to itself (which is what one frame of reference means). So if there is only one object in the universe, then it is hard to see how the simple application of (special) relativity would apply.

    Although, if that object has mass, then general relativity would still apply as there would be gravity, which would affect light, at least.
    ei incumbit probatio qui dicit, non qui negat
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  9. #8  
    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by Dywyddyr View Post
    Prior to that very small portion of a second (10-37) the laws of physics break down rather "didn't exist".
    But, since what we know, and thus what physics "works on" also didn't really "exist" at that time (i.e. there were no particles as exist today) then it's probably more accurate to say that the laws of physics were in formation.
    I would say that the "laws of physics that we currently know break down or didn't exists. Presumably, at some point, we will have models that do describe what happened at that point (or that such a condition never existed).
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    ei incumbit probatio qui dicit, non qui negat
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    Quoting myself from another thread by the same member with pretty much the same question- Consider it cross referencing...
    Quote Originally Posted by Neverfly View Post
    Quote Originally Posted by Rizols View Post
    Hi. I often see that it's an accepted consensus that the laws of physics break down at a singularity (or Big Bang).
    But does that mean that relativity itself crumbles as well?

    Sorry for asking so straight.
    What it means is that the theories are models to describe reality. We cannot see any reality directly, so we must model reality and try to make these models as accurate as possible.
    When it comes to the interior of a Black Hole, the conditions are so extreme that these models are still unable to fully describe what the properties are and what goes on.

    If we had a more accurate and detailed model, that covered such extreme conditions, then that model would not "break down" or stretch into infinities. Currently, we lack the information needed to build such a model.
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by forrest noble View Post
    The best example of something which might be considered relative to itself is the speed of light. Although this speed is accordingly always constant in a vacuum, the rate at the surface is slower than higher up. How can this be? Well, time runs slower closer to the Earth's surface, therefore the distance per unit of time would remain the same. So slower time means slower light. Light farther up would bypass light closer to the Earth since time is faster so more distance would be covered.

    To exagerate the point lets say on some very heavy planet light would travel X distance in one second near the surface, but farther up time would run twice as fast. So during the time on the surface that it took light to go distance X, further away from the planet lights distance would be traveling 2X distance while time would be measured as 2T. So to measure the change in the rate light is moving one could compare it to itself. Of course the speed for unit of time would not change
    That is potentially rather confusing. (for example, it isn't clear what "speed for unit of time" means; speed is independent of time, isn't it).

    The important point is that the person on the heavy planet and the person in space would measure the same speed of light. I suppose you can describe that as the sped of light being "relative to itself" it it might be better to explain it as "not relative to anything".
    The meaning of my point is that light on the surface of the planet would travel a shorter distance per unit of time than light farther away from the planet, when using the same surface clock. Of course each in their own time frame would measure light at the same speed, each using their own clocks. By comparing light to itself you could measure the increased distance per unit of time that light travels when away from a heavy planet, and thereby could calculate the difference in the rate of time -- concluding that time moves at a faster rate away from the surface.
    Last edited by forrest noble; April 2nd, 2013 at 08:05 PM.
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  12. #11  
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    Rate of Time Spending change at different locations as gravity and other forces make effect on "Motion of Objects"
    I will walk fast on a cement fursh
    When I would walk on wet sand , a force would slow my speed
    Similarly in complex case, Gravity make effects on motion and make time spending rate low
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