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Speed of light problem


destro3979

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I'm just a noob at Physics, even though I love them, so forgive me if I completely mess up.

 

 

 

Does the mass that an accelerated object gains when it's nearing the speed of light come from the energy needed for the acceleration being transformed to mass through E=mc^2? That might finally explain a lot to me. ::'

 

 

 

 

 

The negative mass would mean, in essence, that they would be like boots of lightness or a spottier cape, in RS terms- they would lower your mass. Now, these tachyons probably couldn't lower the mass of matter by combing with baryons, but, these tachyons would interact in strange ways with normal matter, if they do exist.

 

 

 

Wouldn't that be negative weight, not mass?

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Wouldn't that be negative weight, not mass?

 

No, it'd be mass. Weight is just the force exerted based on the effect of gravity. Our weight would change if we were on the moon. Our mass would not.

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Exactly, wouldn't a negative weight mean there is a negative force (applying the standard frame of reference, pointing "upwards") on the object?

 

 

 

[Edit] 5 Ed's are already too much, I won't post until someone else does.

 

The guy above asked what would be the effect of an object with negative mass (which I simply can't understand) accelerated near light speed.

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Exactly, wouldn't a negative weight mean there is a negative force (applying the standard frame of reference, pointing "upwards") on the object?

 

That'd basically be an anti-gravitational force, or a force that causes bodies to push away from each other, not come closer to each other. Which doesn't exist.

 

 

 

Again, what exactly is all this about "negative mass"?

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What I was wondering was what/how would a tachyon be propelled to/beyond light speed.

 

 

 

Someone had the fantastic idea of plugging in a value of v that is greater than c into the Lorentz Transformation equations. You're solution will incorporate complex numbers (square root of negative numbers).

 

 

 

From sr it follows that any massive particle must travel less than c, any particle with zero mass will travel at c, and any particle with imaginary mass (IF they exist) must travel at greater than c.

 

 

 

Also from sr, nothing can be acclerated to c (or faster). So if tachyons exist they must have always been (and always will be) travelling greater than c.

 

 

 

People say tachyons exist because there is nothing in sr that actually says they don't exist (i.e. nothing in sr says that particles cannot travel faster than c). However (imo) tachyons will never be discovered and don't exist, they are just a consequence of playing with the maths and not the physics.

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In response to your previous comments, allow me to quote this tidbit on tachyons:

 

 

 

Tachyons

 

 

 

For a long time people interpreted the material of the previous sub-section to mean that nothing can travel faster than the speed of light. In 1967 Feinberg showed that this is not correct. There is room in the theory for objects whose speed is always greater than c. Feinberg called these hypothetical objects tachyons; the word has the same root as, say, tachometer.

 

 

 

If these objects exist, their properties include:

 

 

 

* It takes infinite energy to slow a tachyon down to the speed of light. Thus c is still a speed limit, but it is a limit from both sides. Ordinary matter always travels at less than the speed of light, light always travels at exactly the speed of light, and tachyons always travel at greater than the speed of light.

 

* If the tachyon has real energy, its rest mass must be imaginary, i.e. have a factor of the square root of minus 1. This is reasonable, since relativity says that there is no reference frame accessible to us in which the tachyon is at rest.

 

* If, say, Lou observes a tachyon produced at point A and then travelling to point B where it it detected, for certain states of motion of Sue relative to Lou she would see the tachyon travelling from B to A. Thus it is uncertain which event created the tachyon and which was its detection. Thus tachyons indicate some difficulty with causality.

 

 

 

Many attempts have been made to observe the existence of tachyons; so far all have failed.

 

 

 

One of the attempts to observe tachyons involves a phenomenon called Cerenkov radiation. In order to understand this, we must first realise that when we say that the speed of light is exactly c with respect to all observers, we are referring to the speed of light in a vacuum. When light travels through a medium such as glass, its speed is less than c; for a typical glass the speed of light in it is only about two-thirds of the speed in a vacuum.

 

 

 

It turns out that when an electrically charged object travels through a medium at a speed greater than the speed of light in that medium, a characteristic electromagnetic radiation is emitted. This is Cerenkov radiation. The radiation is shaped roughly like the bow wave from a speedboat.

 

 

 

For the bow wave of a boat, it similarly arises when the speed of the boat through the water is greater than the speed of a water wave.

 

 

 

Nuclear reactors are sometimes encased in water to protect us from the radiation. Often there is a blue glow emitted by charged objects emitted from the reactor that are travelling through the water at a speed greater than the speed of light in the water. This is an example of Cerenkov radiation.

 

 

 

For an electrically charged tachyon travelling through a vacuum, its speed is greater than the speed of light in the vacuum and thus it should similarly emit Cerenkov radiation. Thus, some attempts to observe tachyons has been to look for anamolous Cerenkov radiation.

 

 

 

Now, sorry for posting all that basic atomic crap before, but it may help other people out if they ever get to read that... Anyway though, antimatter is thought to have positive mass, as if it had a negative mass, it would REPEL its opposite charged counterpart. Thus, many scientists have concluded that antimatter should have positive mass. The tachyons that I am referring to are. in essence, exotic matter.

 

 

 

Now that I did a bit more research on tachyons, they are indeed thought to exist but only under two conditions: if they exist (by Feinberg's analysis) they wouldn't transmit information - but they don't exist anyway (by tachyon condensation). So, these tachyons, if they do exist, won't violate causality, as if it is sent back in time to alter its past, it would be seen as going forward in time as a positive-energy particle. Because of this, these particles probably won't exist, and if they do, serious reforms in our view of the world would have to occur- mainly causality and relativity...

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Hold on a second. You said that it would require an infinite amount of energy to accelerate an object into the speed of light, right? Yet, it wouldn't have an infinite amount of kinetical Energy.

 

How isn't this violating the Energy-conservation law?

 

 

 

Excellent question, but the kinetic energy has two components: mass and velocity. As velocities (speeds) approach the speed of light the mass begins to increase, therefore requiring more energy to continue to accelerate the object. While the speed of light limits the velocity, the mass can increase indefinitely, so the kinetic energy continues to increase.

 

 

 

So if you accelerate an object composed of exotic matter (with negative mass), would its mass decrease to negative infinity, thus propelling it faster, or would its mass, like that of normal matter composed of baryons, increase to infinity? And if the first case is true, then wouldn't exotic matter be shooting around the universe through time, since it would be going faster than the speed of light?

 

 

 

Tachyons are going faster than the speed of light anyway, if they even exist, which I doubt.

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Hold on a second. You said that it would require an infinite amount of energy to accelerate an object into the speed of light, right? Yet, it wouldn't have an infinite amount of kinetical Energy.

 

How isn't this violating the Energy-conservation law?

 

 

 

Excellent question, but the kinetic energy has two components: mass and velocity. As velocities (speeds) approach the speed of light the mass begins to increase, therefore requiring more energy to continue to accelerate the object. While the speed of light limits the velocity, the mass can increase indefinitely, so the kinetic energy continues to increase.

 

 

 

So if you accelerate an object composed of exotic matter (with negative mass), would its mass decrease to negative infinity, thus propelling it faster, or would its mass, like that of normal matter composed of baryons, increase to infinity? And if the first case is true, then wouldn't exotic matter be shooting around the universe through time, since it would be going faster than the speed of light?

 

 

 

Tachyons are going faster than the speed of light anyway, if they even exist, which I doubt.

 

 

 

But if tachyons are going faster than light, wouldn't they be traveling through time? Even though they don't violate causality, wouldn't tachyons be highly unstable? and if the instability was the case, and say, the tachyon was traveling through time at above light speeds, wouldn't it decay into the neutrinos/particles that it is composed of BEFORE it was created?

 

 

 

Also, wouldn't this, in essence, be the creation of energy, as particles/neutrinos 'magically' appeared, and following their creation, a tachyon was created? So wouldn't you get two things for the price of one? (Two tachyons from the energy required to produce one)

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i mean wth no1 cares about that weak noob that was scared of the great almighty lord ZAROS!
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