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Thread: Why can't we go faster the speed of light?

  1. #1 Why can't we go faster the speed of light? 
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    Why can't we go faster the speed of light?
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    Stop trolling.
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  3. #3  
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    Quote Originally Posted by AlexG View Post
    Stop trolling.
    What do you mean? I just want to know about this
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    How detailed an answer do you want? It can range anywhere from " That's the way our universe is put together" to an entire treatise on Special Relativity.
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    Space and time are related to each in such a way that if you could go faster than the speed of light we could travel backwards in time. This would cause lots of issues like being able to kill your grandfather etc.
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    Quote Originally Posted by johnzxcv View Post
    Why can't we go faster the speed of light?
    To go faster requires doing work on an object. The more work done the more energy the particle has. As the speed approaches the speed of light the energy of the object approaches infinity. To actually go the speed of light requires an infinite amount of energy and that's impossible.

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    Why can no particles move faster than the speed of light?

    To accelerate an ordinary particle, such as an electron or proton, to the speed of light would require an infinite amount of energy, and to make it go faster than the speed of light would require an imaginary amount of energy (and imaginary momentum). Since we have no supply of infinite energy or of imaginary energy, we cannot accelerate an ordinary particle to a speed faster than light. However, we can conceive the existence of hypothetical extraordinary particles, called tachyons, that always move at a speed faster than light and never slow down (to decelerate a tachyon to a speed below the speed of light would require an infinite amount of energy—the speed of light is a barrier for the deceleration of tachyons just as it is a barrier for the acceleration of ordinary particles). There are various physical problems with the tachyon idea. One problem is the resulting instability of the vacuum. Tachyons can have positive as well as negative energies, and that means that small thermal or quantum fluctuations can spontaneously create tachyons of negative energy, with a concomitant explosive release of positive energy throughout the entire universe—obviously, this is not happening. Direct experimental searches for tachyons have found no tachyons at all.
    Last edited by Physicist; 08-11-2014 at 02:17 PM.
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    Quote Originally Posted by Physicist View Post
    To go faster requires doing work on an object. The more work done the more energy the particle has. As the speed approaches the speed of light the energy of the object approaches infinity. To actually go the speed of light requires an infinite amount of energy and that's impossible.

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    When an object is moving , It doesn't incease it's own rest mass, the only things happen is it has more energy in it,Right?
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    Quote Originally Posted by johnzxcv View Post
    When an object is moving , It doesn't incease it's own rest mass, the only things happen is it has more energy in it,Right?
    In the frame of reference in which the object is moving, the object has greater momentum, greater energy, but the expression remains the same. But in the frame of reference that is moving with the object, everything is the same as if the object were at rest.
    A tensor equation that is valid in any coordinate system is valid in every coordinate system.
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  9. #9  
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    Quote Originally Posted by johnzxcv View Post
    Why can't we go faster the speed of light?
    One need not invoke infinite energy to answer this question. One can simply apply the principle that all inertial frames of reference are equivalent. In particular, the speed of light in a vacuum is the same for all inertial frames of reference. Thus, no matter how fast one is travelling relative to some frame of reference, one never gets any closer to the speed of light in a vacuum.
    A tensor equation that is valid in any coordinate system is valid in every coordinate system.
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    First, assume 2 round inertial objects at rest wrt each other. They start out of the same frame. Object B begins a steady acceleration wrt A using A (or the starting inertial frame) as the reference for motion. If B could attain the rate of c wrt A (it cannot), a mathematical anomaly then exists, which physicists do not like because reality seems to have none. At a relative c, the entire universe (including A) contracts to plane figure at B's own location. IOWs, B holds the cosmos to contract to nothing, or said another way, B would exist everywhere in the known cosmos along its propagation path AT ONCE per B. The everyday cosmos (including) A would hold B to travel at the rate of c indefinitely, and if B's clock could be read, it would never tick as it goes. If a body could travel at c (it cannot), then as it's propagation path shrinks to a point, and so its reasonable to assume it would collide with other bodies in its path, cosmos wide.

    However, as has been stated, the energy required to accelerate a body to a relative c, is infinite. Since the universe is considered a closed unbounded system, its total energy content is believed to be finite, not infinite. So not even the cosmos in collective has the energy to accelerate any particle of rest mass to a relative c wrt any other known inertial particle as reference.

    There has been arguments in that particles might exist that travel superluminally, that traveled as such since their creation. Hence, they need not cross that anomaly boundary at v=c. However, we have never detected a superluminal particle in nature. So for now, that's that as they say.

    In the final analysis, no real particle of rest mass can attain a relative rate of c. None have ever been seen to, not even in the supercolliders. There is no good reason to date to believe they have, or ever can. This discussion relates to local spacetime, not the relative rate of particles on grand cosmic scales, where spacetime expansion can cause relative superluminal motions (of sort). That's a different matter.

    Lastly, the LTs of SR use inertial frames of reference. A photon has no rest frame, because it cannot be held at a relative state of rest wrt anything material. Nothing material can accelerate to c, so no rest frame exists at a relative c.

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    Dear Johnzxcv,

    If you want a very different approach & comprehensible replies, please open a thread on the Personal & Alternatives section - because I am not allowed to post anything critical of SR on the main thread.

    TFOLZO
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    Quote Originally Posted by TFOLZO View Post
    Dear Johnzxcv,

    If you want a very different approach & comprehensible replies, please open a thread on the Personal & Alternatives section - because I am not allowed to post anything critical of SR on the main thread.
    Thank the lord almighty

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    Quote Originally Posted by johnzxcv View Post
    When an object is moving , It doesn't incease it's own rest mass, the only things happen is it has more energy in it,Right?
    Correct. It has more and more kinetic energy. The closer to the speed of light the object moves the closer to being infinite the total energy (kinetic energy + rest energy) is.
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    Quote Originally Posted by Physicist View Post
    Correct. It has more and more kinetic energy. The closer to the speed of light the object moves the closer to being infinite the total energy (kinetic energy + rest energy) is.
    Yes. Often, it is said this way as well ... the body's inertia increases as the relative velocity increases, while the rest mass remains invariant.

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  15. #15  
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    Quote Originally Posted by SinceYouAsked View Post
    Yes. Often, it is said this way as well ... the body's inertia increases as the relative velocity increases, while the rest mass remains invariant.
    Correct. Said otherwise, as v -> c, m -> infinity where m is the inertial mass (aka relativistic mass) of the body (never to be confused with total energy just as rest mass should not be confused with rest energy. Their numerical values are proportional but their physical meaning is entirely different).
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