Re: Special Relativity - General Consequences


"Pmb" <peter102560_nospam@xxxxxxxxxxx> wrote in message news:RNudnZHCIIxC1A3YnZ2dnUVZ_ruknZ2d@xxxxxxxxxxxxxx

"Dirk Van de moortel" <dirkvandemoortel@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:k%Sjh.255871$QO5.5358660@xxxxxxxxxxxxxxxxxxxxxxxx

"Pmb" <peter102560_nospam@xxxxxxxxxxx> wrote in message news:cp6dnaysnYj2ZRLYnZ2dnUVZ_sapnZ2d@xxxxxxxxxxxxxx
There is a difference in opinion on this newsgroup as to what things are important in relativity. Some take those things which are represented by tensors as those things which are real and thus important. While others, such as myself, take those things which are observable and lend themselves to measurement as being real and thus important. The later are often the components of the former. It is widely held that it is the components that eventually get measured and which are generally used in calculations.

As far as to what I personally believe are important consequences of SR are given in "Gravity from the Ground up," by Bernhard F. Schutz. They are listed on pages 187 to 191. They are

1) Nothing can travel faster than light.
2) Light cannot be made to stand still
3) Clocks run slower when they move
4) The length of an object contracts along the direction of motion
5) There is no universal definition of time and simultaneity
6) The mass of an object increases with speed

Form the recent books and publications I have see, I get the
impression that this one has become old-fashioned.

If so then it was pretty fast since it was published in 2000 which is several years after his well known and admired GR book.

Yes, perhaps in this regard Schutz is a bit old fashioned.
I don't have a problem with that. My sons think of me
as old fashioned in one or two regards as well.
I used to think of my father as old fashioned in hundreds
of regards. But I loved him :-)

[snip]

You'd be surprized at how many crackpots think that kinetic
energy should -at-all-cost- be absolute. Only yesterday I had
to create this entry:

http://users.telenet.be/vdmoortel/dirk/Physics/Fumbles/LuttgensAgain.html
http://users.telenet.be/vdmoortel/dirk/Physics/Fumbles/WhichIsFalse.html

Yipes! I was unaware of this. Thanks.

It's so amazing it almost hurts, actually...


It really doesn't say much to speak of the observer and frame since the observer will always be called "O" and the frame will always be called "S" (or some variant thereof). So one can add these generic terms into the mix. They only time it is warrented to speak of the observer and frame explicitly is when there is more than one. However if you find yourself confused by this lack of explicitly stating observer and frame then please let me know so that I may adjust my posting habits to make myself clear on this point. Thank you all.

We usually have no problem with your implicit assumptions.
No problem.

Can you give me an example of when someone would be speaking about frame dependant quantities which would lead to confusion?

Most of the time it's people speaking about such quantities
which have led those people *themselves* into a state of
bewildered confusion - aka crackpottery.
Examples in abundance.

Tom is so convinced of this that perhaps I need a concrete example to understand what he means.

Just keep an eye open in the threads where Tom engages in
one-way 'conversations' with the known crackpots... Seppala,
Wublee, Tucker, Mike (Eleatis), the standard ether sniffers ....
When you see a lot of <shrugs> from Tom's part, it's usually
bingo ;-)

Dirk Vdm
.

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