It is certainly time to give up trying to explain this basic mathematics to wogoga and just point out to lurkers how bad his understanding is.
Wogoga may have a few valid points in his ramblings, which is why I choose to argue with him. For instance, Wogoga has made a lot of mistakes when 'proving' that the Lorentz transform does not 'reduce' to the Galilean transformation. However, he is repeating an argument made Ralph Baierlein.
I think that Baierlein is making a valid point. So Wogoga in a partly right.
I would like to discuss this statement of Ralph Baierlein that Wogoga cited. I partly agree with Baierlein. However, he is still making a small error.
Quote from Wogoga from Baierlein. Baierlein (RB) says:
'A quote from Two myths about special relativity by RB:
Q. Does the Lorentz transformation reduce to the Galilean transformation when the ratio v/c is small?
A. No.
One argument of the author:
Consider the usual pair of inertial reference frames, the primed frame moving with speed v along the x axis of the unprimed frame. To avoid any spurious dependence on the origins of coordinate systems, consider a pair of physical events. The Lorentz transformation for the time interval between the events takes the form
Δt' = 1/√(1-v2/c2) (Δt - v/c2 Δx)
Let the ratio v/c be as small as desired (but nonzero). Then it is always possible to find an event pair for which Δx is large enough that the term with Δx dominates over the term with Δt. This behavior is entirely different from what the Galilean transformation Δt' = Δt asserts.'
I think that RB is making a slight mistake here. However, it is not nearly as fundamental as the mistake that Wogoga is claiming. RB is not claiming that relativity is wrong.
So I think RB should have said differential instead of infinitesimal. All differential quantities are infinitesimal quantities. Not every infinitesimal is a differential quantity.
In thermodynamics, internal energy can be expressed as a perfect differential. Work can not be expressed as a perfect differential, even when it is an infinitesimal. Heat can not be expressed as a perfect differential, even when it is an infinitesimal.
In the relativity, the proper time ds can be expressed as a perfect differential. Δx and Δt are never differentials, even though they may be infinitesimal. However, v/c can not be treated as a differential either. It does not accumulate.
So I think RB made a slight mistake when using mathematical jargon. He is wrong when he used the word infinitesimal. However, he would have been right had he used the word differential instead of infinitesimal.
Or maybe he shouldn't have used the word 'reduce'. Ralph may think 'reduce' means 'accumulative'. If he used the word accumulative instead of reduce, he would have been unambiguously right.
The formal meaning of the word 'reduce' is critical here. The word 'reduce' is slightly ambiguous, so its meaning must be extracted from the context that is being used. It is probable that RB is using the word reduce a bit differently from most of the posters who reply to Wogoga.
The meaning of the above citation varies with domain of event pairs that the Lorentz transform is applied. A transform takes a domain and maps it on a range. The domain does not have to include the universal set. The remaining issue is what domain we are talking about.
If one |Δx| has a finite upper bound in the domain, then the Lorentz transform reduces to the Galilean transform. Any finite domain. One can use the size of the current universe as an upper bound of |Δx|. Then, Δx' and Δt' can be expanded in Taylor series of Δt as long as |vΔx/c^2|<1.
Although v/c may be treated as an infinitesimal, it can not be treated as differentials unless they are bound in the system being analyzed. The word infinitesimal is slightly different from the word differential. An infinitesimal quantity is a quantity that is smallest than the smallest real number. A differential is an infinitesimal quantity that satisfies a constraint condition.
I would interpret Ralph Baierlein (RP) as follows. Contrary to popular belief, v/c can not be treated as a differential quantity. It does not accumulate. Only Δs, the proper time, can be treated as a differential.
However, this does not show that relativity is wrong. This does not even show that special relativity is wrong. This in no way is a paradox.
If 'reduce' means to be equal after truncation of a Taylor series, then most definitely the Lorentz transform can be reduced to a Galilean transform. That is the way most of the replies have implied. However, RP does not use the word 'reduce' this way. He seems to be using a topological definition of reduce having nothing to do with Taylor series.
I will give Wogoga the benefit of the doubt just to lay my mind to rest. To end this part of the argument, let us assume that Wogoga understood and accepted what RP was saying.
So I will concede Wogoga the following point. If 'reduce' means to use v/c as a differential, then the Lorentz transform does not reduce to the Galilean transform. Basically, one can't assume that v/c is a continuous function of s, the proper time. It is physically possible for the acceleration of an observer to approach infinity. The term, v/c, should never be used as a differential.
However, v/c can sometimes be used as an infinitesimal. This means that one can expand the terms of the Lorentz transform into a Taylor series using v/c. So everyone else on the thread is right, too. One expand the Lorentz transformation in terms of v/c using a Taylor series. If one truncates the series to first order in v/c, one will obtain the Galilean transformation.
RB did not say that this invalidated relativity. If he thought this invalidated relativity, then he would have said so. When Wogoga says that this invalidates relativity, he is wrong. Galilean and Lorentzian relativity are BOTH logically consistent. If RB claimed that relativity is wrong, then Wogoga should cite that section.
I thank Wogoga for quoting that passage from RB. I am reading a book about infinitesimals right now. However, I was a little weak on the difference between infinitesimal and differential. The quotation made me realize that an infinitesimal is different from a differential. So although Wogoga is completely wrong, his errors SOMETIMES provoke thought!
I still recommend that everyone including Wogoga read: 'Infinitesimals:...' by Alexander Amir.