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OT: breaking the speed of light

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  • OT: breaking the speed of light

    I was thinking today about the speed of light and how it is supposed to be unbreakable for anything with mass..

    However I came up with this scenerio and wonder if it is possible...

    I have managed to invent a gun that can fire projectiles at 250 000km/s..I have also invented a train that travels at 150 000km/s...

    Now whilst the train is travelling at top speed I fire the gun in the direction the train is travelling....Now relative to me on the train the projectile is now travelling at 250 000km/s BUT relative to an observer who is watching the train go past he sees the projectile travelling at 350 000km/s and in fact is going faster than the speed of light..

    Does that sound correct???
    Precision takes time.

  • #2
    In a word NO!
    ...lew...

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    • #3
      No. The speed of light is the same for all observers in all frames of reference because of time dilation.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Originally posted by Ringer
        BUT relative to an observer who is watching the train go past he sees the projectile travelling at 350 000km/s and in fact is going faster than the speed of light..

        Does that sound correct???
        he won't see it moving faster than the speed of light because the light only moves at the speed of light. it doesn't matter if the object could go past him at 1 billion km/s.

        andy b.
        The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

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        • #5
          Originally posted by Evan
          No. The speed of light is the same for all observers in all frames of reference because of time dilation.


          And length contraction...

          Ringer, pick up a copy of Einstein's "relativity". You should be able to find a translated copy for cheap at most book stores. I found a copy for 3 bucks a few years ago. Well worth a couple of bucks since it's not a text book. (i.e. its a great place to start learning about relativity because its written for the layman)


          p.s. So to an observer on the ground, the length of the train (and therefore the path of the bullet) appears shorter. At the same time, the amount of time that the observer on the train measures is going to be slower than the time measured by the observer on the ground. This means that if, in one second (by the clock that the observer on the train uses) the bullet moves 250,000 km, it will take about 1.2 seconds for the bullet to travel that far according to the observer on the ground. (That was assuming the train was moving at 150,000 km). Thus the velocity measured by the observer on the ground is actually about 208,000 km/s - disregarding the observed contraction in length. When the contraction is figured in, the velocity drops to 216,506 km ... which works out to a velocity of 180,000 km/s. Now - you say well 180,000 km/s plus 150,000 km/s is still greater than the speed of light. But we only consider the time and length changes due to the speed of the train, not the speed of the bullet. Since the bullet is moving faster than the train, you can see that the effect will be even more pronounced.

          If you actually plot the effects of velocity on time it draws to infinity while the length goes to zero. And, of course, 0/(infinity) is pretty slow

          p.p.s

          t = t' / [sq rt (1-v^2/c^2)] and x = x' [sq rt (1-v^2/c^2)]
          Last edited by Fasttrack; 02-24-2008, 01:14 AM.

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          • #6
            Evan is partially correct. But time dialatation does not pertain to the energy required to change the speed that the object is travelling. Only to the amount of time that passes on the object relative to the passage of time on another object. However, the time dialation equations are very similar to the energy equations to determine the answer to relativistic questions.

            The real problem is the amount of energy required to increase the speed. To accelerate an object, with mass, to the speed of light requires an infinite amount of energy. If you were to graph the amount of energy required, for an object's acceleration, it would look like a hyperbola. Once you reach about 70 to 90 percent (I am going from memory here.), the speed of light, the amount of energy required to accelerate faster becomes an exponential number....eventually ending at infinity. So, the reality is that if you were travelling at 196,100 miles per second and fired an object that normally travels at 500 miles per second (when you are not moving) it would only be travelling at slightly over 196,100 miles per second.

            Bear in mind, there is no known location in the universe where nothing is moving. Relative to the Earth's rotation, I am travelling at about 1000 mph just sitting here typing this reply. Then you have to factor in the speed the Earth moves around the sun, the speed the sun moves around the galaxy, the speed the galaxy is moving. But, the speed the galaxy is moving could only (theoretically) be determined by having an object that is completely static otherwise it's speed is relative to that of another object. So, the speed of the galaxy relative to a static location is completely unknown.

            In theory, to travel at or beyond the speed of light requires either creating a mini-universe where your ship is stationary and moving that universe within our universe. (Avagadros (not spelled correctly) warp drive.) Another possibility is to create a "worm hole" between your source and destination point and use that for travel. The third possibility is to "pull" the "fabric" of the universe towards your ship and ride it's wave as you release it. Imagine sitting on a gigatic rubber band, reaching out a mile away, pulling that part next to you, moving foward onto the pulled part, then allowing it to snap back into it's normal position. These are the theories that I can think of off the top of my head. I am sure that there are more. Oh, yeah, the warp drive theory is not only a Star Trek fabrication...it is a real theory.

            Regards,

            Brian
            There are only 10 types of people in the world: Those who understand binary and those who don't.

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            • #7
              Oh Brian brings up an interesting point:

              According to Einstein, the idea of increasing mass with increasing velocity should be disregarded because it posses some difficulties in determining "what" mass is and what to reference off of. Distance and time can be referenced off of light.

              The energy argument, however, is used often in two places:
              1) popular science (nova, science channel, etc)
              2) high energy physics (i.e. particle physics) since it does require more energy to increase velocity. For instance, the particle acelerator at Fermi lab is in the TeV range. At 1 TeV a large hadron - i.e. proton - should be able to obtain a velocity of 13841114 km/s!! Of course, the proton only achieves a velocity of .99999 the speed of light.



              (incidently, the time dialation and length contraction is the correct answer to the problem of the bullet being shot on a really fast vehicle. The energy argument is an implicit solution - its actually derived from the change in observed velocity at high "actual" velocity. From that, a change in mass can be determined, but it all starts with the lorentz transforms.)
              Last edited by Fasttrack; 02-24-2008, 01:27 AM.

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              • #8
                is this the same arguement as taking a spaceship close to the speed of light and then shining flashlight off the front end of it? (it dont work)


                Rif, i tripped over your reply and read as much as i should in my current cond.

                I like what i read and will check it out in the monyadda...

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                • #9
                  Originally posted by Fasttrack
                  Oh Brian brings up an interesting point:

                  According to Einstein, the idea of increasing mass with increasing velocity should be disregarded because it posses some difficulties in determining "what" mass is and what to reference off of. Distance and time can be referenced off of light.

                  The energy argument, however, is used often in two places:
                  1) popular science (nova, science channel, etc)
                  2) high energy physics (i.e. particle physics) since it does require more energy to increase velocity. For instance, the particle acelerator at Fermi lab is in the TeV range. At 1 TeV a large hadron - i.e. proton - should be able to obtain a velocity of 13841114 km/s!! Of course, the proton only achieves a velocity of .99999 the speed of light.



                  (incidently, the time dialation and length contraction is the correct answer to the problem of the bullet being shot on a really fast vehicle. The energy argument is an implicit solution - its actually derived from the change in observed velocity at high "actual" velocity. From that, a change in mass can be determined, but it all starts with the lorentz transforms.)
                  You also brought up another interesting point about the "length contraction." As the velocity, of an object, increases it's length, in the direction of travel, becomes shorter. A person, travelling at close to the speed of light, would look like a pancake if they were able to be observed by someone who is relatively stationary.

                  The increase in mass is the true reason for the increase in energy required for acceleration to higher speeds. As an object increases in speed, it's mass increases.

                  I don't understand your claim that time dilation is the correct answer. Time dilation only pertains to the passage of time on a moving object relative to that of a stationary object. Time dilation is the reason why some high speed elementary particles can be detected from the Earth. Some particles only have a life span of thousanths or even millionths of a second. Yet, they travel for long distances (i.e. Thousands of miles above the surface of the Earth to the surface of the Earth.) and survive for a longer period of time (as observed by us). This is due to time dilation. For the elemetary particle it is only surviving for it's normal time period....relative to itself. But, relative to us, it is surviving a lot longer. Time dilation has also been proven by atomic clocks...one stationary and one in motion.

                  Regards,

                  Brian
                  There are only 10 types of people in the world: Those who understand binary and those who don't.

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                  • #10
                    Originally posted by A.K. Boomer
                    is this the same arguement as taking a spaceship close to the speed of light and then shining flashlight off the front end of it? (it dont work)


                    Rif, i tripped over your reply and read as much as i should in my current cond.

                    I like what i read and will check it out in the monyadda...

                    The example you mention happens only because light only travels at the speed of light. Light can never travel faster or slower that the speed of light. So, a beam of light shining off of the front of a fast moving spaceship will still only travel at the speed of light relative to a stationary observer.

                    There have been claims, however, of the speed of light being manipulated in the laboratory. Given the descriptions of how they have accomplished this, it sometimes makes me wonder if it is really the speed of light being manipulated or how the medium the light is travelling through reacts to the experiment.

                    There is a possibility, however, that the speed of light may change depending upon the proximity to a gravitational field.

                    Regards,

                    Brian
                    There are only 10 types of people in the world: Those who understand binary and those who don't.

                    Comment


                    • #11
                      If that were possible then it would be possible to hear the shot before it was made. Time doesn't work like that.

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                      • #12
                        I've never forgot a Disney cartoon from when I was a kid that had Goofy standing there with a stopwatch as a beam of light bounced around the room on mirrors. Yep! 186,000 miles per second! But I wondered ever since who in the hell clocked it anyway?

                        Fast forward to the kids coming home from school one day talking about the speed of light and I decided it was time to do some digging and find out. Turns out an astronomer named Herod had it figured out 500 years ago when most of earth's population still thought it was flat.

                        What he was doing was watching a moon disappear behind Mars. At one point in the year it took 12 hours longer for the moon to re-appear than at the other. The difference of course is the amount of time it takes light to cross the dia of the earths orbit.

                        Still amazes me.

                        SP

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                        • #13
                          But would you use old iron or a new Asian import to build the train and gun?

                          Glenn

                          (Just trying to tie all of todays threads together.)

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                          • #14
                            You also brought up another interesting point about the "length contraction." As the velocity, of an object, increases it's length, in the direction of travel, becomes shorter. A person, travelling at close to the speed of light, would look like a pancake if they were able to be observed by someone who is relatively stationary.
                            The Fitzgerald Contraction is not observable by any observer in any frame of reference. There are a number of misconceptions that have been spread even by the popular science press and teachers who really don't know any better. For instance, it is frequently said that the speed of light is constant. No, only the speed of light in a vacuum is constant. Light slows down when interacting with matter. The denser the matter the slower it goes.

                            Light does interact with gravity. Gravitational lensing of distant quasars and galaxies are proof of that. However, if it slows down is not measurable because gravity also affects any observer and his equipment who tries to measure it. Time slows down in a gravity well but again it cannot be observed. There seems to be some sort of shielding effect built into the rules that prevents paradoxes from occuring or being observed. They may exist but if they do they can never be seen.
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                            • #15
                              It has already been done.
                              In the 1960's Lucas came out with their first alternator to be fitted to a motorcycle.
                              Amongst the first to use this was the BSA [ Bits stuck anywhere ] C11G and I was fortunate enough or unfortunate enough to own one of these fine ? machines.

                              The total output of these first alternators was 45 watts or wot's??
                              30 watts were used by the headlight, 5 watts were used by the tail light, 10 watts were used by the stop light and 8 watts by the ignition coil, the rest that was left over was used to charge the battery by the latest in electronic technology of the day, the selinium rectifier.

                              So 30 + 5 + 10 + 8 = 53 watts required by the system before charging the battery.

                              Now granted you don't go riding about all day with the rear brake on, not that it would have made much difference so deducting 10 watts for the stop light we now have a total night load of 43 watts less losses to charge the battery.

                              The result of this amazing amount of homework by the engineers at the Joseph Lucas, Prince of Darkness chapter was that at night even given the speed of light is 186,000 miles per second it was perfectly possible to run over your main beam.

                              It cannot be proved but I think this phenomenon was discovered a lot earlier by J M Barrie who used this information to write about Peter loosing his shadow in Peter Pan.

                              .
                              .

                              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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