On Thu, Jan 3, 2019 at 5:59 PM Brent Meeker <[email protected]> wrote:
>>If I travel from event A to event B and use the formula x^2 + y^2 + z^2 >> -(ct)^2 > > > * > You can only travel between A and B if they are timelike, in which > case your formula will yield an negative squared distance.* > So what? The entire point of looking at things from a spacetime perspective is to find a invariant that everybody can agree on, and d provides it. If you don't like imaginary numbers then use d^2, if you don't like negative numbers then use d^4 and get an old fashioned positive Real Number; use whichever one that strikes your fancy it doesn't matter because they're all invariants. >>where x,y,and z are the differences in spatial coordinates I observe and *t >> is the proper time* it took for me to make the trip I will get an >> invariant. > > > * >No.* > Yes. > > *To make that work you have to put in the difference in time > coordinate for t. * > Yes, what else could t mean? In the formula for spacetime distance x^2 + y^2 + z^2 -(ct)^2 t is the difference between what a clock was reading when it started its journey from what it is reading when it ended its journey between the 2 events; and c is the all important speed of light, the only thing that prevents the formula from being Monty Python level silly. > >>The proper time is defined as the time measured by a clock along ANY >> line through spacetime and it doesn't matter a hoot in hell if that line is >> a geodesic or not. > > > *>That's right.* > OK. >>you said "*Proper time is the distance through spacetime*" but every book >> on physics on the planet will tell you that the distance through spacetime >> is an invariant; but proper time is NOT a invariant, different observers >> can have different proper times, > > > >*No. * > No? What the hell do you mean "No"?! > > *Different paths between two events have different proper times between > the same two events.* > Exactly true, and that is exactly why I said "proper time is *NOT* an invariant"! > > *All observers will agree on the length (proper time duration) of > those paths* > No observer agrees on that because no observer knows what the hell meters minus seconds means. But you did agree above that proper time is the time measured by a clock along any line through spacetime, so for my twin that was on a rocket at near light speed and then returned the proper time is one year, but for me who stayed on Earth the proper time was 10 years. Therefore proper time can not be a invariant, therefore the length of the path through spacetime can NOT be the proper time because the length of the path through spacetime *IS *an invariant. > > *You are using the word "observer" as though it referred to a traveler, > but in relativity it usually means someone measuring a physical process > from a different state of motion. * > Proper Time is defined as the amount of change an observer has seen a clock make that is in the same reference frame as the observer. > >> So your ideas are not self consistent but then they had to be, >> spacetime distance and proper time aren't even in the same units. > > > * > You keep a harping on units. * > Yes, apart from confusion of units your ideas are great. And other than that how did you like the play Mrs. Lincoln? > *>That has not more significance than the fact that we measure the length > of highways in miles and widths in feet. * > *Bullshit*. We're not talking about confusing miles and feet we're talking about something far dumber, confusing meters and seconds. The first thing they teach you on day one of high school physics is YOU'VE GOT TO GET THE UNITS RIGHT, otherwise you're talking nonsense. And it doesn't get any more nonsensical than subtracting seconds from meters. The fact that you're STILL defending this ridiculous notion speaks volumes. > * > In practice, all distance measurements are made with clocks. * > Not unless the speed you're moving at is known. > > > *If someone wants the answer in meters they use the conversion factor > 299792458 meter/second.* > And you may be uncertain about how fast you're moving but one thing is absolutely certain, it is *NOT* 299792458 meter/second. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
