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An object with mass traveling at lightspeed is perfectly logical. | Facebook
Ok accelerating an object to lightspeed is impossible, but once it's at lightspeed there is no fallacy am i correct?
This is just something i noticed and it's got me interested, i'm no expert.
using the lorentz time transformation
an object with velocity of c has time=0, and if e=hv then energy=0, then mass=0.
If the object has 0 mass then it should move at c, so there is no fallacy.
to the object, the universe has time=∞, so then the universe isn't even relevant.
Does that make any sense to anyone else?
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Charles, there are two types of particles to worry about, those with a rest mass that is non-zero (like an electron) and those with zero rest mass (like a photon).
Particles with zero rest mass move at the speed of light for all observers.
Accelerating a particle with non-zero rest mass to the speed of light is impossible because its inertia keeps increasing without limit as it approaches the speed of light.
The closer it gets to the speed of light the harder and harder it is to speed it up.
You could continuously put all the energy from the rest of the universe into this partlcle and still not get it to the speed of light.
The equations will have a factor of 1/ sqrt( 1 - (v/c)(v/c) ) in them and just replacing v with c will result in infiinity, so you can't just replace v with c and get anything meaningful.
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Yeah i got that that's why i started off by saying accelerating an object to lightspeed is impossible.
You're not telling me anything new here.
i guess what i'm asking is with that kind of breakdown of the laws of physics, then isn't it possible that particles with so called "zero rest mass" actually have mass relative to their own reference frame, but relative to everything not moving light speed they don't?
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Pick a photon (which has zero rest mass) ...
In its own reference frame as an example.
Consider moving with the photon (because you are asking what mass it has in its own reference frame).
The rest of the universe flattens like a pancake in the direction of travel.
Infact the photon sees the location of its creation and its ultimate absorbtion as being in the same place, and indeed at the same time.
It really doesn't exist for any duration ...
As it sees itself.
When you want to know what a photons mass is, it is its resistance to a force, it is inertia.
But from the photons point of view it doesn't exist for any amount of time so the question doesn't make sense.
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Sammuel, are we agreeing or disagreeing?
For a photon with four momentum (p0, p1, p2, p3) where 0 is the time direction and 1,2,3 the space directions, the "length" is p0*p0 - (p1*p1 + p2*p2 + p3*p3) and this sum iis 0 for a photon, it is neither time-like (positive) nor space-like (negative).
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Well that's a very good explanation james.
Thank you.
i'm not understanding though how in it's own reference frame it doesn't exist for an amount of time.
assuming that the photon's life is the difference between leaving it's origin and reaching it's destination and that it exists simultaneously in it's own reference frames at both locations, then one would assume that it doesn't have a life.
But if in it's reference frame everything else has time=∞ then doesn't that mean it's origin and destination exist time=∞ apart?
what i picture happening is the photon just sitting there with the universe crushed to a plane perpendicular to it's travel.
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Charles,
yes in the photons own frame the universe is crushed to a plane perpendicular to it's direction of travel.
Both the point of emission and point of absorbtion are now the same spatial point and the photon spends no time to get from one event to the other.
No time passes for the photon.
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But to the photon it's emission and absorption are an infinite length of time apart, although a zero length of space apart, right?
So then it should just chill at the point of it's emission and absorption indefinitely.
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I think that the emission and absorbtion are not an infinite length of time apart, but rather are at the same moment.
The Lorentz transformation (see http://en.wikipedia.org/wi ki/Lorentz_transformation )
has this:
t' = gamma(v) * ( t - v*x/(c*c) )
The emmission event could be at t=0, x=0 and the absorbtion event would be at x = c T where T is some time later and v = c and this gives:
T' = gamma(c) * ( T - c * (c T)/(c*c)) = 0
Both emmission and absorbtion are at T' = 0
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Hi James, just read your comments on this one.
You explain things from the perspective of a photon very well indeed.
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I see
that's clear enough for me man thanks
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Perfectly logical...but in that case the object has to have an exceptionally small mass mathematically with a fixed amount of energy.
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Adnan, can you define "an exceptionally small mass" ?
Either a particle has zero rest mass, or non-zero.
In the case of non-zero it will never reach light speed.
In the case of zero rest mass it can only move at light speed.
The phrase "exceptionally small mass" would imply that you are taking the limit as the rest mass approaches zero, but in this case it acts like a particle with rest mass as you take the limit.
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An exceptionally small mass was a relative expression for a particle whose rest mass is zero or tends to zero.
For instance, a photon.
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Adnan, the behavior of particles with a rest mass is of one type, and the behavior of particles with zero rest mass is another type of behavior, there is no smooth way of going from one behavior to the other, no way you can take a limit as the rest mass tends to zero.
Imagine a function like this:
f(x) = x/|x| (x over absolute value of x)
as x tends to 0 from the positive side the value is +1 but from the negative side it is -1.
At 0 you can't just substitue x with 0 to get an answer.
So this is a function that has the same value (and I'm implying some physical behavior) for x >
0 and the limit of this function as x tends to zero from the positive side is +1 and yet the value of x=0 is not related to this limit.
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