Brent, First thanks for replying however you didn't address the question I'm really interested in.
Of course I understand that the travel is mostly close to the speed of light for most of the trip and that explains the extremity of the effect, but that wasn't my question. My question is this: A is traveling at near light speed most of the trip. That's why B sees A's clock slow because as you pointed out in an earlier post it just takes light a lot further and further, and thus longer and longer, to reach B from A due to A's extreme velocity. No problem there. However from A's POV it is B that is traveling at the exact same near light speed away from A for most of the trip. Therefore A should see B's clock slow by the exact same amount that B sees A's clock slow due to the exact same effect of photons taking longer and longer to reach A from B simply because they have to travel further. So my question is this: Why does A's clock slowing turn out to be ACTUAL (agreed by both A and B) when he stops at the center of the galaxy, and B's slow clock slowing doesn't? If both A and B see each other's clocks slow by the same amount due to the same effect of relative velocity during the trip then why is A's clock slowing real and B's isn't? Thanks, Edgar On Wednesday, January 29, 2014 8:17:11 PM UTC-5, Brent wrote: > > On 1/29/2014 5:19 AM, Edgar L. Owen wrote: > > Brent, > > > > Here's another relativity question I'd like to get your explanation for > if I may... > > > > In Thorne's 'Black Holes and Time Warps' he gives the following example. > > > > Two observers A and B. > > > > A leaves earth orbit to travel to the center of the galaxy, 30,100 light > year away, > > using a constant 1g acceleration to the midpoint and a constant 1g > decelleration on the > > second half of the journey to arrive stationary at the galactic center, > > > > Thorne tells us that the 30,100 light year trip takes 30,102 years on > B's clock back on > > earth but only 20 years on A's clock aboard the spaceship. > > > > Now my question is what causes the extreme slowing of A's clock? > > > > It can't be the acceleration as both A and B experience the exact same > 1g acceleration > > for the duration of the trip. > > > > I can understand that during the trip B will observe A's clock to be > greatly slowed due > > to the extreme relative motion, but since the motion IS relative > wouldn't A also observe > > B's clock to be slowed by the same amount during the trip? > > > > And since the time dilation of relative motion is relative then how does > it actually > > produce a real objective slowing of A's clock that both observers can > agree upon? > > > > You had said yesterday that "geometry doesn't cause clocks to slow" but > other than the > > trivial 1g acceleration isn't all the rest just geometry in this case? > > > > What's the proper way to analyze this to get Thorne's result? > > A rough way to see it is right is to note that c/g = 3e7sec ~ 1year << > 30,000yr. So the > spaceship spends essentially the whole flight at very near c. So the trip > takes 30,100+ > years in the frame of the galaxy. But the proper time for the spaceship is > very small; if > it were actually at speed c, like a photon, its proper time lapse would be > zero. Only, > because it can't quite reach c, the time turns out to be 20 years. To get > the exact values > you have to integrate the differential equations: > > dt/dtau = 1/gamma > dv/dtau = accel/gamma^2 > dx/dtau = v/gamma > > where gamma=sqrt(1-v^2) > > Brent > > > -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
