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I Travelling at the speed of light

  1. Jan 24, 2016 #1
    I don't know if this kind of thought experiment is authorized here, but let's give it a try.

    Let's assume that we had managed to build a spaceship able to travel at the speed of light.

    Since relativity forbids to accelerate until reaching such speed, the spaceship would have to reach it instantaneously, like a photon.

    But this is not the issue.

    The issue is: how could we operate such a spaceship?

    And I am not talking about levers and joysticks, but about establishing a course and reaching a destination safely.

    Because it seems to me that if such a spaceship was pointed towards, say, Mars, it would be impossible to reach this planet without crashing on its surface like a bug hitting a windshield.

    In other words, there would be no way to control the distance travelled.

    The conclusion being that the ability to travel at light speed would be useless.
     
  2. jcsd
  3. Jan 24, 2016 #2

    fresh_42

    Staff: Mentor

    The same procedure to gain instantaneously c and survive it, which is simply not possible, will allow you to lose the speed in reverse order. So your theory lacks at three points.
     
  4. Jan 24, 2016 #3
    I don't have a theory, just a question, and the issue is not about the survival of someone inside...one could assume that it would be entirely robotic.

    The question is: is it possible for an object moving at light speed to stop in any way other than hitting another object at full speed?
     
  5. Jan 24, 2016 #4

    Drakkith

    User Avatar

    Staff: Mentor

    Since relativity forbids objects with mass from traveling at c, we can't answer your question.
     
  6. Jan 24, 2016 #5
    Constructing a ship with zero mass would certainly make you a legend in the history of engineering.
     
  7. Jan 24, 2016 #6
    If, as it seems, mass is not a property of the particles, but is somehow the result of these particles interfering with a so-called Higgs Field, one could find a way to temporarily neutralize the effects of this field, thus freeing an object from its mass and instantly propelling it at light speed.

    Now, I don't know if it has been proven, at least theoretically, whether the Higgs Field can or cannot be neutralized.
     
  8. Jan 24, 2016 #7

    fresh_42

    Staff: Mentor

    Not that we know of. But if you can switch it off, what prevents you from turning it on again to stop?
     
  9. Jan 24, 2016 #8
    Well, that's the problem...what would prevent me, or anyone else, to switch it back on would be a lack of...time!

    Because, as far as I understand the underlying physics, once propelled the speed of light, the distance between the object and its destination would be reduced to zero and time would stand still.

    In other words, the object would reach its destination in no time, leaving no possibility to switch its mass back on and let it decelerate.

    Or am I totally wrong?
     
  10. Jan 24, 2016 #9

    Drakkith

    User Avatar

    Staff: Mentor

    I'm sorry but we don't allow speculation of this nature here at PF. Thread locked.
     
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