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Thread: Speed of Light

  1. #1 Speed of Light 
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    I just thought of proposing this analogy, with my current understanding I can't make any sense of it so here goes.

    Consider this, a man at an airshow is watching a plane break the sound barrier. He see's the plane go over his head but doesn't hear it because it is travelling faster than the speed the sound can travel at.

    Similarly a man in space is watching a spaceship that ''breaks the light barrier'', just because he can't visually see it doesn't mean it can't go faster...? Why do we assume that if we can't see it, that it must be travelling through time. Can the sound in the first example be analogous with time in the second?

    This sounds rather stupid even for me but I just want a few people to think about it. I'm well aware of all the paradox's so lets not stray from the point.

    Barry


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  3. #2  
    Forum Senior miomaz's Avatar
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    the way I explain lightspeed might help you:

    take a paper and fold it. Voila, the highest speed of an object.
    Try overfolding the paper - impossible. It is a interresting way to picture the speedbarrier, a good example which helped a few people I know understanding.


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  4. #3 Re: Speed of Light 
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    Quote Originally Posted by Barry Flannery
    I just thought of proposing this analogy, with my current understanding I can't make any sense of it so here goes.

    Consider this, a man at an airshow is watching a plane break the sound barrier. He see's the plane go over his head but doesn't hear it because it is travelling faster than the speed the sound can travel at.

    Similarly a man in space is watching a spaceship that ''breaks the light barrier'', just because he can't visually see it doesn't mean it can't go faster...? Why do we assume that if we can't see it, that it must be travelling through time. Can the sound in the first example be analogous with time in the second?

    This sounds rather stupid even for me but I just want a few people to think about it. I'm well aware of all the paradox's so lets not stray from the point.

    Barry
    The problem is that the light speed barrier has nothing to do with our not being able to see it, or any assumption about it going back in time.

    One reason that the speed of light is a barrier for material objects is that the amount of energy it takes to increase an object's speed approaches infinity as the object's speed approaches light speed.
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  5. #4  
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    Correct me if I'm wrong , but you can hear the sound from an object moving faster than sound away from you. That's because sound travels at the same speed regardless of how fast the thing the emits it is going.

    The man should be able to hear the plane.

    This goes to how waves are different from objects. If I have a 60 mph throwing arm, and I'm driving in a car at 60 mph and throw it behind me, the ball will be going 0 mph. But, waves don't work like that. If I emitted a wave behind me, it would just become weaker. It wouldn't change speed, just carry less force.
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  6. #5 Re: Speed of Light 
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    Quote Originally Posted by Barry Flannery
    I just thought of proposing this analogy, with my current understanding I can't make any sense of it so here goes.

    Consider this, a man at an airshow is watching a plane break the sound barrier. He see's the plane go over his head but doesn't hear it because it is travelling faster than the speed the sound can travel at.

    Similarly a man in space is watching a spaceship that ''breaks the light barrier'', just because he can't visually see it doesn't mean it can't go faster...? Why do we assume that if we can't see it, that it must be travelling through time. Can the sound in the first example be analogous with time in the second?

    This sounds rather stupid even for me but I just want a few people to think about it. I'm well aware of all the paradox's so lets not stray from the point.

    Barry
    Well you eventually hear the sound, so I guess not.

    Have you seen the Star Trek: TNG episode where Picard does an old manevouere where he jumps the Enterprise D to warp and then to the enemy ship it looks as though there are two Enterprises.
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  7. #6 Re: Speed of Light 
    The Doctor Quantime's Avatar
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    Quote Originally Posted by Janus
    Quote Originally Posted by Barry Flannery
    I just thought of proposing this analogy, with my current understanding I can't make any sense of it so here goes.

    Consider this, a man at an airshow is watching a plane break the sound barrier. He see's the plane go over his head but doesn't hear it because it is travelling faster than the speed the sound can travel at.

    Similarly a man in space is watching a spaceship that ''breaks the light barrier'', just because he can't visually see it doesn't mean it can't go faster...? Why do we assume that if we can't see it, that it must be travelling through time. Can the sound in the first example be analogous with time in the second?

    This sounds rather stupid even for me but I just want a few people to think about it. I'm well aware of all the paradox's so lets not stray from the point.

    Barry
    The problem is that the light speed barrier has nothing to do with our not being able to see it, or any assumption about it going back in time.

    One reason that the speed of light is a barrier for material objects is that the amount of energy it takes to increase an object's speed approaches infinity as the object's speed approaches light speed.
    You know, all these 'impossibilities' wasn't thought of by Einstein at all, it was other people after him who intropolated Quantum Mechanics into relativity. Thats why I never listen to half of it, and thats why its called relativity and not quantity, because its based on one person observations over another.
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  8. #7  
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    I was just going to add what some people have already pointed out. You do hear the plane just not as its passing over you. It gets to you at the speed of sound which, I am just guessing here is like 800 mph?

    So if you turn E=mc^2 into Sqrt(E/m)=c would that be infinity I don't think so but then again I really don't have a strong foundation on all the modern physics equations. I am probably most definitely wrong in some way. I will be here waiting for someone to correct me.
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  9. #8  
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    Quote Originally Posted by GenerationE
    So if you turn E=mc^2 into Sqrt(E/m)=c would that be infinity I don't think so but then again I really don't have a strong foundation on all the modern physics equations. I am probably most definitely wrong in some way. I will be here waiting for someone to correct me.
    E=mc² refers to just the energy equivalence of the rest mass. If you want to find the total energy of the object, including the energy due to its velocity you use.

    E= mc²/sqrt(1-v²/c²)

    v is the velocity.

    Note that as v gets closer to being equal to c, then E gets closer to infinity.
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  10. #9  
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    Thank you its much nicer to see a mathmatical representation of a concept. I knew that I had to be wrong.
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  11. #10  
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    It is only a theory that Faster than light is impossible but
    there is no mathamatical, empirical, mechanical, or observational evidence to support physical matter travelling faster than light.

    Since our best efforts so far are in the order of 1/10,000 of the speed of light is it worth worrying about?
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  12. #11  
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    Quote Originally Posted by Megabrain
    It is only a theory that Faster than light is impossible but
    there is no mathamatical, empirical, mechanical, or observational evidence to support physical matter travelling faster than light.

    Since our best efforts so far are in the order of 1/10,000 of the speed of light is it worth worrying about?
    Yeah erm, the LHC can accelerate protons up to near light speed (and with a lot of energy, granted but nowhere NEAR an infinate amount !) so if it can accelerate one atmoic particle with that much energy then you should be able to accelerate a few trillion of them no problem, surely.
    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.

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  13. #12  
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    Err no,

    Acceleration in these particle accelerators is done to single (or small groups) of protons ie it has a positive charge. It is the differential charge which produces the acceleration. A group of atoms has a net charge of zero and would therefore require far more energy per 'particle'

    If you could just scale this one up they would have done it years ago it is only possible on small groups of sub-atomic particles with the present kit.
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  14. #13  
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    What about the speed of mind is in front of the light !
    Solomon Grundy
    In 1944, this creature rose from the swamp, with tremendous strength and some dormant memories that for example allowed him to speak English, but not knowing what he was, and not remembering Cyrus Gold or his fate. Wandering throughout the swamp, he encountered two escaped criminals, killed them, and took their clothes. When they asked him his name, he simply muttered that he had been born on Monday. Reminded of an old nursery rhyme about a man born on Monday, the thugs named the creature "Solomon Grundy".
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