space: twins parradox (1 Viewer)

[Rahul]

travis is going to travel to a star in a spaceship with velocity 0.8c. his twin andy will be on earth.

why is it not appropriate to consider travis being at rest and andy travelling at 0.8c?

i think that travis is in his inertial frame of reference and so is andy. therefore, two frames of references are moving relative to each other, so you cant say that one(andy) is stationary, as the other(travis) frame of reference will see it as moving.

can someone else comment/try to answer this.

thanks.

 

[CHUDYMASTER]

The idea behind Twin's paradox is that the person who shoots off into space is actually undergoing various accelerations (eg. speeding up to near-light speeds, undergoing centripetal acceleration on turning back, etc.)

Therefore, he's in a NON-INERTIAL frame of reference. Thus, relative to his twin on Earth, he cannot be said to be in a stationary frame, as this would denote an inertial frame of reference.

 

[Rahul]

Originally posted by CHUDYMASTER
Therefore, he's in a NON-INERTIAL frame of reference. Thus, relative to his twin on Earth, he cannot be said to be in a stationary frame, as this would denote an inertial frame of reference.

cheers!
makes a lot of sense.
thanks

 

[jm1234567890]

if you look at it with the general theory of relativity it makes sence

 

[underthesun]

So what happens? Who gets younger and who gets older?

+ another question, what if travis does not always accelerate, as in he went up to 0.8c and stops accelerating, that is, he travels at constant 0.8c? There's gotta be some strange thing happening shouldn't there?

 

[jm1234567890]

going from 0 to 0.8c is accelerating no matter how it happens.

and going form +0.8c to -0.8c is even more acceleration

 

[Ragerunner]

Lets just say when Travis gets back, andy will be dead

Being stationary and travelling at constant velocity would be in an interial frame of reference. but thats assuming you travel in a straight line.

 

[underthesun]

Originally posted by Ragerunner
Being stationary and travelling at constant velocity would be in an interial frame of reference. but thats assuming you travel in a straight line.

Yep, travis accelerates, THEN travels at constant speed in straight line, THEN turns, THEN travels back at constant speed in straight line, THEN decelerates to land on earth.

There you have it. So what happens if it happens like the above condition?

Oh and can someone tell me what happens if what the textbooks are saying is right? Will travis be older or what?

 

[Ragerunner]

According to travis, he would have only aged as normal. But andy would be a heck of a lot older,

Thats according to Travis.

 

[Rahul]

Originally posted by underthesun
So what happens? Who gets younger and who gets older?

when travis comes back, he will have aged less than andy. but like ragerunner said, for travis time would have passed 'normally' and he would have lived 10 years(or however long the trip would take from andy's perspective)

Originally posted by underthesun
Yep, travis accelerates, THEN travels at constant speed in straight line, THEN turns, THEN travels back at constant speed in straight line, THEN decelerates to land on earth.

There you have it. So what happens if it happens like the above condition?

if the acceleration takes place, then travis will be in a non-inertial frame of reference. therefore, general theory of relativity will apply only, NOT SPECIAL THEORY OF RELATIVITY....how would this tie in with general relativity?

Originally posted by underthesun
Oh and can someone tell me what happens if what the textbooks are saying is right? Will travis be older or what?

according to the texts, travis would have aged less relative to andy. that is what andy would say.

but travis would say, "na man, i was on the ship fo' 10 years, bro!". hence the paradox, i think.

 

[Ragerunner]

Imagine that when he tries to come back he finds out the the entire solar system has been destroyed.

I wonder what he will be thinking...

 

[Rahul]

Originally posted by Ragerunner
Imagine that when he tries to come back he finds out the the entire solar system has been destroyed.

ahahha exactly what star is he going to? alpha-veryfaraway?

 

[underthesun]

Originally posted by Rahul
if the acceleration takes place, then travis will be in a non-inertial frame of reference. therefore, general theory of relativity will apply only, NOT SPECIAL THEORY OF RELATIVITY....how would this tie in with general relativity?

I kind-of get it now, after going through paragpraphs of explanation on the net..

Thank god it's not in the syllabus.

rijoys!

edit : is this under the "Einstein's thought experiments" syllabus dot point? If it iz, den fak!

 

[Rahul]

actually it is in the syllabus, not directly stated in the new one, but it wasnt in the older one either.

and this is part of einstein's thought experiments.

excerpt from jacaranda, Einstein himself suggested one of the strangest effects of relativity. His idea was that.....

sorry for the bad news underthesun

 

[Ragerunner]

I sure hope this HSC exam is as easy as the 2002 one.

I looked at the 2003 STANSW physics paper.

I got OWNED.

BADLY.

And i got 82/100 for my CSSA one

I reckon i would of gotten 60/100 for the STANSW

 

[Rahul]

really... i might attempt it tonite.

its on you site rite ragerunner? i think i remember you posting it before.

 

[Ragerunner]

Yeah it is.

It's been added to BOS as well

 

[Rahul]

cool....downloading as we speak
solutions up too....v nice.

 

[Ragerunner]

Should have a crack at it without solutions.

I couldn't do that because i got so pissed at one question i had to take the solutions out then i think "BS, as if i would of ever thought of that answer"

 

[CHUDYMASTER]

UGH!! *unsubscribes to post after getting flooded with reply notifications*