Time in SR and relativistic mass

In summary: The speed of light is the same for all observers in inertial frames. This is the one that really, really messes up our classical way of thinking. It's also the one that makes relativity work. It is the cornerstone of all of relativity. If you can't explain why the speed of light is the same for all observers, you're not going to be able to come up with a theory of relativity that works.As always, if anyone else disagrees with me, please post so. I know there are people here who have a lot more experience with relativity than I do.
  • #1
exponent137
561
33
Is it possible substitutive explanation of SR: "because of larger relativistic mass everything moves more slowly."

I tried to to get this substitution mathematically, but it not works. I know that lorentz contraction should be included as supposition that things work.

For instance: a = gamma^3 a1.
a=acceleration inside of system which moves very fast.
a1=acceleration seen from not moving observer.
gamma=(1-(v/c)^2)^-1/2
v=velocity
c=speed of light

Or
dW = ma dx gamma3, (2)
when system accelerates and gains additional energy because of acceleration.

One explanation is that m=m0 gamma^3, but this dissagre with
W=W0 gamma and W=mc^2

If Lorentz contraction is included, I get
m=m0 gamma^2, but I wish m=m0 gamma
 
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  • #2
exponent137 said:
Is it possible substitutive explanation of SR: "because of larger relativistic mass everything moves more slowly."

I tried to to get this substitution mathematically, but it not works. I know that lorentz contraction should be included as supposition that things work.

For instance: a = gamma^3 a1.
a=acceleration inside of system which moves very fast.
a1=acceleration seen from not moving observer.
gamma=(1-(v/c)^2)^-1/2
v=velocity
c=speed of light

Or
dW = ma dx gamma3, (2)
when system accelerates and gains additional energy because of acceleration.

One explanation is that m=m0 gamma^3, but this dissagre with
W=W0 gamma and W=mc^2

If Lorentz contraction is included, I get
m=m0 gamma^2, but I wish m=m0 gamma
You don't seem to be using the acceleration transformation correctly. Please see

http://www.geocities.com/physics_world/sr/acceleration_trans.htm

Also, the speed at which something moves has absolutely nothing to do with mass. Only the amount of momentum and the amount of acceleration are functions of speed.

Pete
 
  • #3
I will check forumulae. Speed has nothing with invariant mass, but it has with relativistic mass. This is concept, which is possibility in relativistic physics. Einstein abandoned it. Some physicist did not abandon it.

Maybe it is really uselles. But, maybe it is explanation for slower acceleration, seen from v=0 inertial system. In formula above dW = gamma^3 we should give gamma's to some factors. It is the most natural to give it to acceleration. But, we can suppose that time run is not different as in our system and we can give gamma also to mass and lorentz contraction.
Mathematics do not forbid these alternative possibilities.
The only problem is, that I do not understand this mathematics enough.
Regards
 
  • #4
Special theory of relativity explains relative nature of inertial systems. But, I think that it can also explain, why time in fast rocket runs slower than in our system. (Or explanation of twins paradox) Explanation is simple: when we accelerated rocket, we gave it energy and mass (relativistic mass). So everything in rocket is heavier and moves slowly, so time runs slower.
But, condition that calculations work is, that we suppose Lorentz contraction and formula dE = dm c^2.
It is my intention to find derivation which agree with special relativity. If it is not agree, there is probably one explanation which should say why this time dilatition explanation is not possible.
For instance: known formula for power P given to rocket is:
P = dW/dt = gamma^3 m a v.
m=mass of rocket
v=velocity of rocket
a=acceleration

It is supposed that relativistic mass equals gamma^3 m. But
W=gamma W0, so I suppose that
m=gamma m0.
So other two gammas can be added to a and v, or to dx in them. (t is regarded as absolute.) I addmit this dx is not clear to me, but, if this is true, it is logical explanation, why longitudinal mass is not equall (the only logically) to gamma m.
So formula above can be written
P=gamma^3 m d(dx/dt)/dt dx/dt =
P=gamma m d(gamma dx/dt)/dt (gamma dx)/dt

I think that it is contradition in my formula, but
relativistic energy should be c^2 times relativistic mass.
 
  • #5
exponent137 said:
Special theory of relativity explains relative nature of inertial systems. But, I think that it can also explain, why time in fast rocket runs slower than in our system. (Or explanation of twins paradox) Explanation is simple: when we accelerated rocket, we gave it energy and mass (relativistic mass).

No

So everything in rocket is heavier and moves slowly, so time runs slower.

Also no.

But, condition that calculations work is, that we suppose Lorentz contraction and formula dE = dm c^2.

No logical connection.

It is my intention to find derivation which agree with special relativity. If it is not agree, there is probably one explanation which should say why this time dilatition explanation is not possible.

Good intention but you are on a (very) wrong path. And it cannot be fixed unless you do some serious studying.
 
  • #6
Thanks for answers. I read that Einstein abandoned relativistic mass. But I want to understand why, and why some phsicisics do not abandon it.

But, you will not believe me, I understand ortodox special relativity, their equations and also some general relativity.

But I think above post is important, but nowhere on google I did not find explanation why above "absolute time" and "mass causes time dilatition" do not works.

So I understand ortodox special relativity, therefore I will understand, I someone will explain with formulae, why I am wrong.

If some will write formulae which I do not understand, it is possible to ask for explanation or to find explanation on google.

Is it somewhere something written about why bigger mass causes slowere time run. Or, it is written, why not.
 
Last edited:
  • #7
We have guidelines against talking about new, personal theories in the main forums here on PF forums. The main reason for these guidelines is that people tend to get too attached to their ideas, and the threads bog down into people "defending" their non-standard ideas.

I'm going to bend the rules a bit and give you my opinion on why your idea won't work. The main reason I'm bothering is that you don't yet give the appearance of being overly attached to your own ideas. However, I do encourage you to re-read the PF guidelines on personal theories.

For relativity to work properly, one needs all three of the following elements.

time dilation, length contraction, and the relativity of simultaneity.

Your explanation only addresses one of them. Unless you can explain all three, you're not going to get a theory equivalent to SR.

Note that the 3 elements I listed above are verbal descriptions of the Lorentz transform:

t' = gamma * (t - v x / c^2)

This is how time transforms. The time dilation element is the 'gamma' in the formula. Equally importnat is the '-vx/c^2' term, which represents the relativity of simultaneity. The locus of ponts which satisfied "t=0" is a different set of points than that which satisfies "t'=0". Simultaneity is therefore a concept that depends on the frame of reference in relativity.

x' = gamma ( x - vt)

This is how sapce transforms. It's the familiar gallileant transform (x - vt) except that it gets multiplied by an additional factor, gamma, which is equal to the time dilation factor.

Without length contraction and the relativity of simultaneity, your theory is just not going to be able to be equivalent to SR.

Another way of saying this:

One of the key elements of relativity is that light travels at the same velocity relative to all observers. Mucking around with the "relativistic mass" of particles which do not travel at the speed of light is not going to achieve this property. To achieve this you need the Lorentz transform.
 
  • #8
Well said, as always, pervect! With that commentary, I will close this thread.

exponent137, if you would like to discuss your personal theory, we invite you to submit a post to the Independent Research Forum, subject to the applicable guidelines, found https://www.physicsforums.com/showthread.php?t=82301.
 

Related to Time in SR and relativistic mass

1. What is the theory of Special Relativity (SR)?

Special Relativity is a theory proposed by Albert Einstein in 1905 that describes the relationship between space and time in the absence of gravity. It explains how time and space are relative concepts and how they can be affected by the speed and acceleration of an object.

2. How does Special Relativity affect our understanding of time?

In Special Relativity, time is no longer considered a constant and absolute concept. Instead, it is relative and can be affected by an observer's frame of reference. This means that time can appear to move slower or faster depending on an observer's relative speed to the object or event being observed.

3. What is relativistic mass?

Relativistic mass is a concept that was introduced in Special Relativity to describe the increase in mass of an object as it approaches the speed of light. According to the theory, as an object's velocity increases, its mass also increases, making it more difficult to accelerate.

4. How does time dilation affect relativistic mass?

Time dilation is the phenomenon in which time appears to move slower for an object in motion compared to an object at rest. As an object's velocity increases, time dilation also increases, causing its relativistic mass to increase as well. This means that an object's mass will appear greater to an observer in a different frame of reference due to time dilation.

5. Can relativistic mass exceed the speed of light?

No, according to Special Relativity, the speed of light is the maximum speed at which matter or information can travel. As an object's mass increases, its speed must decrease in order to maintain this limit. Therefore, relativistic mass cannot exceed the speed of light.

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