Transformation Vs. Physical Law

[GAsahi]

There is really no reason not to either. Reparameterizations are common and well accepted.

You are totally missing (or willfully ignoring) the point: your derivation is not quite right, since the muons move in a cyclotron, $r=R$ so $dr=dz=0$ meaning that $d\tau^2=dt^2-r^2d\theta^2=dt^2(1-R^2 (\frac{d \theta}{dt})^2)$ meaning that $d\tau^2=dt^2 (1-v^2)=(\frac{dt}{\gamma})^2$. So, the correct result is $d\tau = \frac{dt}{\gamma}$.

 

[Dale]

So, the correct result is $d\tau = \frac{dt}{\gamma}$.

That isn't the only correct way to work the problem.

 

[universal_101]

That isn't the only correct way to work the problem.

Let me put it this way, consider the Newtonian mechanics,

Just because we can understand a particular event by using energy conservation(Least action principle), does not mean that there is NO Force involved in the event.

Whereas, you are suggesting, because we can calculate the correct results also by using spacetime metrics, it means that Time Dilation is independent of relative motion, i.e. independent of gamma factor.

 

[Dale]

you are suggesting, because we can calculate the correct results also by using spacetime metrics, it means that Time Dilation is independent of relative motion, i.e. independent of gamma factor.

What I have proven is that the mere fact that gamma shows up does not imply that there was a coordinate transform. I didn't make any claims about the independence of time dilation and relative motion.

Your entire complaint from the OP is that physical effects like muon decay should come from physical laws and not coordinate transforms. I gave the physical law for muon decay. You then complained that simply because gamma pops out of the law that it must be a transform. In fact, you said that the "only way I know of producing gamma factor is using Transformations(Lorentz)". So I showed you that it can be produced directly from the metric without any transform.

So now that you know that gamma can come from other sources than a coordinate transform it should be clear that your complaint is completely resolved.

Do you now accept that the decay of muons can be explained by a law of physics that is not a coordinate transform? If not, then what possible logical reason can you have for not accepting it?

 

[GeorgeDishman]

A Physical effect is that which can be measured independently, that is the to observe the effect we don't need to include any assumptions or the indirect ways, which is done in the MMX experiment and it's extended version, the KT experiment.

That's a difficult definition. If I boil watter in a kettle, does it's temperature rise? I could measure it with a termometer but then I am inferring a rise of temperature indirectly from the expansion of a column of red-dyed fluid. ..

I'm quoting my previous post, which clarifies the above confusion.

The adjective independently was used to reflect the invariant nature of the events. And should not be confused with the dependence on the equipment. ..

OK, then you should note that the null result of the MMX is invariant hence length contraction is a "physical effect" by your definition.

LET cannot be applied to MMX, because it is not falsifiable

That is incorrect, LET predicts a null result for the MMX, if a non-null result was found, LET would be falsified. However, you miss the point, the null result of the MMX is an invariant hence valid by your definition. It is indirect in that it uses a radar-like technique but you say that's not what you meant and such inference is an unavoidable part of most measurements anyway.

And Nobody likes a physics theory based on purely mathematics.

Physics is purely mathematics in which the variables are identified with measurable quantities.

Exactly, I'm suggesting that gamma factor is a physical effect, and there seem to be experimental indication of it. (The paper I quoted earlier)

Well "gamma" is just a mathematical shorthand for a commonly ocurring term, it is part of many "physical" effects. I'm not at all sure what it is that you are arguing about.

 

[universal_101]

Do you now accept that the decay of muons can be explained by a law of physics that is not a coordinate transform? If not, then what possible logical reason can you have for not accepting it?

Do you mean, that Minkowski spacetime or metrics are the physical laws that govern the decay of Muons in motion ?

But then I'm wondering where does this concept of spacetime and the metrics comes from if not from the transformations. Since there must be a physical concept behind any physical law.

Why were these physical laws not discovered on their own !

And how come this physical law can be used to derive the transformations, which it could not if it were an actual physical law !

 

[Mentz114]

Do you mean, that Minkowski spacetime or metrics are the physical laws that govern the decay of Muons in motion ?

But then I'm wondering where does this concept of spacetime and the metrics comes from if not from the transformations. Since there must be a physical concept behind any physical law.

Why were these physical laws not discovered on their own !

And how come this physical law can be used to derive the transformations, which it could not if it were an actual physical law !

In order to do physics with equations we need coordinates and time derivatives of coordinates. This means we implicitly assume some space or spacetime where the coordinates make sense. The physical laws must be written in some such space, although coordinates are themselves not physical.

Relativity demands that we examine the laws in moving frames, and this where transformations of coordinates happen. We demand that physical laws do not change under a relabelling of spacetime points.

Your remarks show a deep lack of understanding of how physics is actually done and makes me wonder why you think you are qualified to make any meaningful remarks about any aspect of physics.

Your last two posts make no sense to me at all.

 

[Muphrid]

I admit, I've not read through the entire thread, but can I give this a shot?

A muon travels on an inertial path from point $A$ to point $B$, separated by some proper time $\tau$, at which point it decays. This trajectory is characterized by four-velocity $v$.

An observer with four-velocity $u$ will measure the elapsed time between events $A$ and $B$ as $\tau v \cdot (-u)$. If it happens that the observer has the same four-velocity as the muon, then this reduces to $\tau$ (in $c=1$ units), but any arbitrary observer will come up with a different result.

There is no transformation of coordinate systems going on here. There is only each observer taking the dot product of their own four-velocity vector and the four-velocity of the muon to find one component of the muon's four-velocity in a particular basis. That, in itself, makes a physical statement about the universe: that we are free to choose any basis we wish because any direction is equivalent to any other. We choose Minkowski spacetime to model the universe because it shares that property of isotropy with what we observe in the real world.

 

[harrylin]

Do you mean, that Minkowski spacetime or metrics are the physical laws that govern the decay of Muons in motion ? [..]

Such things are usually not called laws, as some of us explained much earlier in this thread.

Why were these physical laws not discovered on their own !

Not sure which laws you mean, but physical laws with gamma were largely discovered on their own - see post #236. Physicists solve puzzles of nature by contemplating different types of information.

And how come this physical law can be used to derive the transformations, which it could not if it were an actual physical law !

? The classical physical laws can be used to derive the "Galilean transformations" as I tried to explain many times incl. in post #236. Similarly the Lorentz transformations were first derived from physical laws, deduced from observations. And note that physical laws are always generalisations of ideas that emerged from observations.

 

[Dale]

I noticed that in your response you carefully avoided answering the questions:

Do you now accept that the decay of muons can be explained by a law of physics that is not a coordinate transform? If not, then what possible logical reason can you have for not accepting it?

Do you mean, that Minkowski spacetime or metrics are the physical laws that govern the decay of Muons in motion ?

The metric is the mathematical structure which defines geometry. I.e. it describes distances, durations, angles, and the causal structure. The metric will appear in any law where geometry is important (which is most).

The law that governs the decay of muons (in motion or at rest) is the one I provided >240 posts ago.

But then I'm wondering where does this concept of spacetime and the metrics comes from if not from the transformations. Since there must be a physical concept behind any physical law.

The various geometric concepts don't need coordinates nor coordinate transforms, no matter how much you wish they did. They are physical concepts in and of themselves. Or are you trying to claim that my table leg is perpendicular to my table top only if I perform a coordinate transform?

And how come this physical law can be used to derive the transformations, which it could not if it were an actual physical law !

Nonsense. What possible chain of reasoning could lead you to this absurd comment.

 

[GAsahi]

That isn't the only correct way to work the problem.

True, it is the most direct way of solving the problem. In fact, it is the standard way of solving this problem, there is no need to introduce any notion of "number of laps" (the variable $a$ in your derivation).

 

[Dale]

True, it is the most direct way of solving the problem. In fact, it is the standard way of solving this problem, there is no need to introduce any notion of "number of laps" (the variable $a$ in your derivation).

Agreed.

But again, there is no reason not to introduce a either. Reparameterizations are common and well accepted, no matter if they are needed or not.