Fuel Consumption of a Ship Traveling at Near Light Speed

[DaveC426913]

In this article http://www.einsteins-theory-of-relativity-4engineers.com/twin-paradox-2.html

This graph shows what a receding observer sees. Look at the left graph, bottom half. Eartyh stays put (Y-axis/time axis), spaceship moves away to right.

A signal sent out from Earth every year is received on the spaceship every two years. i.e. the spaceship on its 4 year outward journey (2007 to 2011) only receives only 2 yearly greetings from Earth.

(Of course, after it turns around, it receives 7 greetings on its 4 year homeward journey.)

 

[wrongusername]

To both observers (as I'm pretty sure I've mentioned in my previous posts) observe time passing normally.


But, the person on the ship will experience 'less' time passing than the person on the Earth.

This is true, imo, only from the person on Earth's point of view. How much slower time is passing shouldn't be absolute.

Speculatively, what if you have another spaceship, traveling at a fraction of the relativistic speed of the first spaceship? If the first spaceship undergoes 10 years of travel and decelerates to the second spaceship's frame, and the second spaceship's captain says he's been traveling for 50 years, and the first spaceship then decelerates further to be stationary with respect to Earth, would the people on Earth perhaps measure 100 years of time to have passed?

The person on the ship may undergo 10 years of travel and return, to find the Earth has undergone 100 years.

Heck, I've just read the entire wiki article and don't see a problem. From the first line:

You don't see a problem = where's the paradox? :P

Yes, but the traveller in space is changing frames. In one frame, he is traveling at whatever fraction of the speed of light relative to Earth. In 10 years or so in his time, he would change to another frame which is stationary to the person on Earth. Now suddenly the time on Earth doesn't seem to be moving slow anymore, and he finds much more time has passed on Earth somehow. I don't know how this would affect the symmetry between the two frames, but it's the explanation I've been given to the twin paradox.

 

[wrongusername]

In this article http://www.einsteins-theory-of-relativity-4engineers.com/twin-paradox-2.html

This graph shows what a receding observer sees. Look at the left graph, bottom half. Eartyh stays put (Y-axis/time axis), spaceship moves away to right.

A signal sent out from Earth every year is received on the spaceship every two years. i.e. the spaceship on its 4 year outward journey (2007 to 2011) only receives only 2 yearly greetings from Earth.

(Of course, after it turns around, it receives 7 greetings on its 4 year homeward journey.)

Wow, thanks! It makes more sense now

But in the right half of the picture, where Pam sends signals back to earth, is Earth also suddenly seeing Pam's time going really quick (4 signals in 2 years)? If so, why?

 

[DaveC426913]

But in the right half of the picture, where Pam sends signals back to earth, is Earth also suddenly seeing Pam's time going really quick (4 signals in 2 years)? If so, why?

Because she is following very closely behind her own light.