Some problems with light speed barrier.

Discussion in 'Physics & Math' started by RawThinkTank, May 2, 2004.


Do you belive in light speed barrier ?

  1. Yes

  2. No

  3. Its an alien conspiracy to stop us claiming their space.

  4. It will be broken just like Sound barrier.

Multiple votes are allowed.
  1. RawThinkTank Banned Banned

    At speed of light why wont there be any more acceleration , meaning : Why there wont be any further opposite reaction on a space ship that is thrusting matter in opposite direction at an enormous rate in order to gain more speed. Is it as if god wont allow it ?

    Even if the time there stops, why wont the space ship people feel the speeding up ?

    Admitted that mass will increase, but at what location on each atom of the space ship will these new mass appear ? Or how will the ship understand that it has reached the light barrier ; will actually say so by becoming alive ?
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  3. Pete It's not rocket surgery Registered Senior Member

    Hi RawThinkTank,
    Your question suggests that you haven't got a handle on the light speed limit.
    Perhaps you should read up on it. You could start here: PhysicsGuy FTL FAQ
    In particular, Chapter 7: The First Problem: The Light Speed Barrier

    The speed of like isn't like a wall that you can approach - it's like a will-o-the-wisp that never get's any closer.

    In a way, all speeds are the same... they are all equally far from the speed of light.

    Imagine you were in a spaceship, somewhere deep in intergalactic space, and you detected another spaceship approaching at a hundred thousand miles an second.
    Can you tell if you are stopped and they are moving, or the other way around, or if both of you are moving? How? Does it matter?
    Last edited: May 2, 2004
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  5. 2inquisitive The Devil is in the details Registered Senior Member

    Apply the same logic and questions to a ship detected at two hundred thousand miles
    a second.
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  7. Nasor Valued Senior Member

    You will begin to receive ‘diminishing returns’ from throwing matter out in the opposite direction as you approach the speed of light. The relativistic mass of your space ship will increase with its velocity, so when you get very close to the speed of light the mass of your ship will be so great that any amount of fuel burned will have only a tiny effect on your velocity. As you approach the speed of light, the amount of energy needed to accelerate the ship approached infinity.

    This isn’t just some arbitrary rule that physicists made up; it’s an inevitable result of the laws of physics. The phenomenon of mass increasing with velocity has been experimentally verified, so it isn’t just conjecture.
  8. beta Registered Senior Member

    Lets say I'm observing a rocket accelerating constantly ( constant acceleration from the perspective of the rocket).
    I will start to notice that as it nears the speed of light, the rocket seems to have less acceleration. I concluded from this observation that the rocket must have greater inertia as it approaches light speed in order to explain what I observe as a reducing acceleration. I know that the rocket is trying to maintain its constant acceleration, so I make the conclusion that its mass has increased.
    But the actual mass does not increase.
  9. 2inquisitive The Devil is in the details Registered Senior Member

    "This isn’t just some arbitrary rule that physicists made up; it’s an inevitable result of the laws of physics. The phenomenon of mass increasing with velocity has been experimentally verified, so it isn’t just conjecture."

    Stating that mass increase with velocity has been experimentally verified requires
    a strong leap of faith. The only way it has been inferred is by observing particles
    accelerated by EM radiation. Thie cut & paste and article explains it better than I:
    "The well-verified relation of apparent mass increase with velocity is derived from a direct approach utilizing concepts of finiteness of the transmitting velocity of force (TVF), effective action, and the coupled effect of the of the TVF for two EM fields. A more appropriate interpretation of the Lorentz factor is developed, whereby when a particle is moving at a speed v under an EM field, it is the effective action on the particle which is effected, and not the mass of the particle itself. Since the only way to measure the mass of such particles is by measuring the impact of the action of EM fields upon their trajectories, the concept of mass increase with velocity is inherently protected against refutation in all such experiments to date, while the experiments themselves provide no test or verification of the theory of mass increase with velocity"
    Last edited: May 3, 2004
  10. Paul T Registered Senior Member

    Firstly, the above site was written by a crackpot and therefore beware about its content.

    Secondly, about mass increases with velocity is actually related to relativistic mass, which is energy. Not all modern physicists use the concept of relativistic mass. However, we can still find many books describing about special relativity use such concept. There are many physical phenomena that are best described using mass concept, as they seem to be more intuitive.

    Earlier version of particle accelerator called cyclotron suffers a serious drawback because there is a limit for energy level it could reach. There is something called cyclotron frequency which is equal to qB/2<FONT FACE=symbol>p</FONT>m. When particle get too fast relative to the speed of light, such frequency decreases. The change is best explained by special relativity as the result of mass change.
  11. 2inquisitive The Devil is in the details Registered Senior Member

    "When particle get too fast relative to the speed of light, such frequency decreases."

    So, if we were on that particle, we would see external light that approached
    from the rear as tremendously red shifted and light that approached us from
    the front as tremendously blue sifted. If we emit light in both directions from
    our particle, will we observe the same shifts?
  12. crazymikey Open-minded Scientist Registered Senior Member

    I wouldn't say it's an alien conspiracy, even though you know how strongly I feel about aliens

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    I think the belief that the speed of light is constant for all observer is a self-imposed barrier brought upon by our paucity of comprehension. Much similar to our previous accepted notions on the sound barrier.

    There is little to no evidence for the postulates of relativity, which sound quite absurd to me, other than some particle tests which can be hardly be construed as empirical proof for Einstein's theory.

    1. At c mass is infinite
    2. At c time stops

    I think Einstein assumed from the observable universe, that the speed of light is the fastest, and hence assumed it to be a point of infinity. A rather simplified and naive assumption.

    This is however wrong:

    1. Laser Pulses have been sent 200-300 times faster than the speed of light.
    2. Spacetimes moves faster than the speed of light
    3. Quantum entanglement travels infinitely faster than the speed of light
    4. Gravity may act faster than the speed of light(the jupiter light bending experiment does not measure the speed of gravity)

    I am sure, if Einstein knew about the above, he would have set a higher limit for speed. It's like travelling in a car that goes at 50 mph for all your life, and then concluding, that no car can travel faster than 50 mph.

    Sorry Einstein, as much as I like you, I think you were being silly with that one.
  13. 2inquisitive The Devil is in the details Registered Senior Member

    Also, the energy level limit you speak of in early cyclotrons was solved by using
    frequency modulation. Syncho-cyclotrons removed the earlier limit in maximum energy thought to be due
    to relativistic mass increase.
  14. John Connellan Valued Senior Member

    The FTL things u mention above will of course, not have infinite mass at or above c because they do not have rest mass! Also u haven't disproved the theory that time stops at 'c' so we will continue to believe them!
    Now Im not sure exactly all of what Einstein said or believed, but one thing he definitely believed is that information cannot travel faster than light. This was something he claimed after the EPR paradox showed that 'things' can sometimes travel faster than 'c'.
  15. crazymikey Open-minded Scientist Registered Senior Member

    Actually light can have rest-mass. What I am contending here, is that Einstein believed the speed of light to be constant for all observers and that all information travel at the speed of light or slower. This is clearly proven wrong now.

    To be honest, there is little empirical evidence to suggest, that mass will become infinite and time will stop at "c" this itself is enough reason not to accept the postulates of relativity as absolute. You can only disprove something that is proven.

    Now how this applies to interstellar travel

    1. To simply exceed "c" and incur no significant effects of relativity
    2. To use quantum entangelment to send and recieve information faster than "c"
    3. To warp spacetime to travel faster than "c"

    I think "c" is just like the sound barrier. It's not an absolute limit.
    Last edited: May 4, 2004
  16. mhobbs_bbt Mike Hobbs Registered Senior Member

    crazymikey :

    I tend to agree with you about relativity. It's a theory that has been accepted by those in science with the biggest voice. It has never been proven and there seem to be some very large holes in the logical arguments.

    From your posting :

    1. To exceed the speed of light, you would need to be able to exert a force at the tail end of the object. Whatever you use to exert this force would have to be travelling faster than the speed of light to exert any force at all. So you need to find something else that's already travelling faster than the speed of light to accelerate the original object !! I agree it should be possible, it's finding something that travels faster than c to use as the force that's the problem ? ... unless you could set off an explosion on the object itself ?

    2. Quantum entanglement. Hmmm. Don't shoes always come in pairs with 'left' & 'right' spin ??

    3. So far, I've seen no evidence that space / time can be warped in any way whatsoever. Nice theory for books & films, but no place in science ? other than to discuss VERY unlikely theories and keep scientists in a job ???

    I guess that these theories have to be voiced in an attempt to push science forward. The real problem is the people, no names mentioned, who make a career out of pushing these theories as fact and those that worship those people as some sort of super-intelligence. Something that can't be disproved isn't necessarily fact.

    I would guess that the 'real' world isn't quite as interesting. There's probably an endless Universe and only one real time. I would also guess that the basic problem with all of these theories is that light isn't really absolutely constant ?? I've seen at least one 'scientific' test that suggests not. Strangely enough, it was used to prove that the theory of relativity is correct !!!!
  17. blackholesun Registered Senior Member

    Really what CAN be proven? Everything is just a theory. Relativity explains what we have observed better than anything else so far.

    Um....yeah. What's your point? And yet without you scientist have demonstrated entanglement many times over and have even used it recently in quantum secured data transmission.

    I've seen evidence....gravitational lensing....a well understood phenomenon. Also all the evidence we have for black holes.

    Well without those theories you speak of we wouldn't have GPS, computers (that you used to post this message btw) and any number of technology that have come from accepted physics theory. There needs to be some logic in your thinking instead of dismissing things you really don't understand yet. I myself don't understand it all but I'm learning and I gladly listen to those who know this stuff MUCH better than I do.

    So why do you sould like you're condemning that theory then? Just because you don't agree with relativity you dismiss it? At least there are people in the world trying to understand the universe. You are just dismissing those persons.

    Edit: I toned it down. I sounded too much like a jerk.
    Last edited: May 4, 2004
  18. crazymikey Open-minded Scientist Registered Senior Member

    No, not necessarily. You can accelerate to the speed of light.

    Quantum entanglement is being used for quantum computers, and theoretically it could be used for quantum transportation and information transmission at near infinite speed.

    No, spacetime can be warped, because it is also composed of matter. This is shown by the gravitational lensing effect and black holes. However, warping spacetime, would involve creating intense gravitational fields as powerful as black holes, for which you would need energy in the order of planks constant. Warping spacetime directly means travelling faster than the speed of light. You are effectively warping the space between you and the destination, bringing the destination to you. This is not fringe science; it is theoretically possible.

    I agree with you, this universe probably is endless, but I don't think time exists, it is an only an imagination of spacetime. The theory of the speed of light barrier is only a theory, albeit, an inherently flawed theory. We should not accept it as an absolute, which is unfortunately what some pseudoscientis do, and then use it as a justifcation for their warped notions of ET civilizations visiting us.
  19. John Connellan Valued Senior Member

    Well no, it can't since it can never come to rest!

    There is plenty of evidence of particles obeying the equation:

    m<sub>r</sub> = m<sub>0</sub>/1 - v<sup>2</sup>/c

    Which implies that mass approaches infinity at c
  20. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

    Why not? Doesn't the speed of light slow down when it's trying to get out of stars? Or that is just the frequency? Because light certainly can lose energy, eh?

    How can mass be infinite? And wouldn't that "infinite" mass be just relative to an external observer rather then the true mass of the object?

    Maybe the speed of light is the limit speed before reaching the hyperspace speed?

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    (such as in Star Trek

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  21. PhysMachine MALLEUS SCIENTIARUM Registered Senior Member

    Actually, no you can't. That's part of the point: it would take an infinite amount of energy to get that fast, since your mass would diverge to infinity as you came close to the speed of light.

    As blackholesun so aptly pointed out, physical theories are constrained to being empirical observations and explainations of them. We lack basic axioms to work with, so we cannot prove things from these axioms, unlike mathematics. Physics is not an axiomatic science, so the only real test of a legitimate theory is falsifiability (read Karl Popper for more). Basically, a theory is only legitimate if it's accuracy can be tested, and furthermore if said tests repeat the predictions of the experiment. There is no such thing as a "true" theory, there are only theories that are not false up to a degree of experimental inaccuracy. Classical mechanics is a "false" theory in the sense that it doesn't work for all domains, but for a car traveling on a highway at 60 mph, it's a perfectly accurate theory.

    Also, there is ample evidence for the theory of relativity, making it so far unfalsified:

    * Special relativity is derived from Maxwell's equations, so therefore all the evidence that supports classical electromagnetism indirectly supports special relativity.

    * Special relativity accurately accounts for the meson decay in the atmosphere.

    * General relativity accounts for the rotation of Mercury's orbit, giving a correct value which Newtonian gravitation could not.

    * In 1919 gravitational lensing, a consequence of general relativity, was observed during a solar eclipse when the Hyades star cluster should have been behind the sun, but was visible.

    * There's plenty of accuracy in the black hole observations.

    * There is the observation of electromagnetic red shift.

    * As has already been stated, there are a huge number of applications of special relativity that wouldn't work if the theory were incorrect.

    Unless somebody comes along with a theory that accurately predicts everything general and special relativity predicts and accounts for phenomena that we have yet to observe that relativity cannot handle, relativity will continue to be the standard theory of gravity.
  22. John Connellan Valued Senior Member


    Just the frequency!

    Actually infinite is really the wrong term because I believe the universe to be finite but I mean infinite in that it will eventually encompass all the masas of the universe

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    No, as I have explained in another recent thread, Relativity is not just about the observer, instead most of the effects are actually real
  23. 2inquisitive The Devil is in the details Registered Senior Member

    "I've seen evidence....gravitational lensing....a well understood phenomenon. Also all the evidence we have for black holes"

    Gravitational lensing and black holes are evidence gravity affects light. Light is bent
    when passing through the gravitational lens, there is nothing to suggest time is also
    affected. A black hole shows light can be bent and when the gravity is intense enough,
    the escape velocity of light can be exceeded. Theory states time is also affected, but
    as of yet, that has not been proven. Also, a gravitational field can generate its own
    gravity, suggesting gravity can interact with itself. If the 'speed of gravity' is c, how
    can gravity escape a black hole? For any particle to move faster than light, it would
    seem a force that moves FTL would be necessary. Gravity possibly could be such a
    force. Despite all attemps to measure the speed of gravity, none have been conclusive. Unless science finds a way to acquire information faster than light, the
    true speed of gravity cannot be known. Eugeney Podkletnov has demonstrated a force
    that remains unexplained by current physics. Not true anti-gravity, but a focused
    force that can pass through walls of any composition to transmit a repulsive force to
    material of any composition on the other side of the wall, much like gravity passes
    through a concrete floor to attract objects on the other side. If the true nature of
    gravity is ever understood, then we will know IF we can manipulate it, much as we
    now know how to manipulate the EM force. Could gravity possibly be focused into
    a coherent beam like a laser? Could we use such a beam in space to provide movement, so we could 'fall' to a destination?

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