🚀 go-pugleaf

In my big article on relativity and four-vectors, I wrote:

>We then have a very nice-looking
>relation between four-vectors

>       P = mV ,

>where P is the four-momentum, V is the four-velocity, and
                ^^^^^^^^^^^^^
>m is the invariant, unchanging mass. 

Just to be clear: this "four-momentum" P is the same thing as the
"energy-momentum four-vector" P mentioned earlier.

>Four-acceleration A is the derivative of four-velocity with
>respect to time. 
            ^^^^ 
That's *proper* time, not the t coordinate.

I hope you enjoyed the article... boy, am I wasting a lot of time
these days.

-- 
Matt McIrvin   mcirvin@husc.harvard.edu   Long live short .sigs