Implications of time dilation for space travel (1 Viewer)

[chocolatelatte]

If observers in an inertial reference frame in relative motion to rest frame observe time to be longer, then why is it that this time is reduced considerably for astronauts? isn't this contradictory...
i don't understand

 

[Mr_Kap]

If you yourself are travelling at relavistic speeds, time periods become LONGER, meaning 1 second to you is longer than 1 second to someone watching in a different frame of reference.

So you could travel to mars say in 1 year (it feels like to you), but to someone on earth it was like 4 years. (obviosusly made up numbers)

 

[chocolatelatte]

ok, so if one second is longer, then shouldn't time be increased for astronauts? I don't understand
soooo basically I understand length contraction -> because length contracts for astronauts in relative motion to the stat frame, so then going by this principle, except knowing that time dilates, shouldn't astronauts in relative motion take more time?
I'M SOOO CONFUSED.

 

[atargainz]

ok, so if one second is longer, then shouldn't time be increased for astronauts? I don't understand
soooo basically I understand length contraction -> because length contracts for astronauts in relative motion to the stat frame, so then going by this principle, except knowing that time dilates, shouldn't astronauts in relative motion take more time?
I'M SOOO CONFUSED.

Dilation means to expand or lengthen, therefore astronauts in the spaceship will have 'lengthened' time (not correct terminology, but for explanation sake), meaning that their time will feel longer than those on earth. Like Kap explained 1 year to the astronaut becomes elongated in their sense.

 

[chocolatelatte]

Okay I understand that (thanks guys!) but then why is it beneficial for space travel if they experience 'lengthened' time? I don't understand how they would 'age less' and all that jazz written in the textbooks.

 

[atargainz]

Okay I understand that (thanks guys!) but then why is it beneficial for space travel if they experience 'lengthened' time? I don't understand how they would 'age less' and all that jazz written in the textbooks.

time travels slower for them, so a certain space trip can be deemed to take 100 years, but at relativistic speeds it will feel like 10 years for astronauts (astronauts are still young and able to complete the trip, whereas people on earth are old/dead)

 

[godofindolence]

Okay I understand that (thanks guys!) but then why is it beneficial for space travel if they experience 'lengthened' time? I don't understand how they would 'age less' and all that jazz written in the textbooks.

To the astronauts, time pass as normal, because in their inertial frame of reference, the laws of physics is constant. The thing with time dilation is that from an outside frame of reference, time in the spaceship is comparatively slower. This is the same as length contraction. The spaceship itself doesn't get shorter, its just from the outside perspective, because of their relativistic speeds, they appear to shrink.

So therefore, relatively less time passes for an astronaut when they're zooming along really fast, so whilst a 100 light year journey will mean that people on earth will be dead, maybe only like 10 years have passed on the spaceship and they're like nice and healthy

 

[Crisium]

An easy way to remember the implications is to remember that "Moving clocks run slower" (think of the clock in the moving rocket) - I.e. time in the inertial frame of reference (e.g. A rocket travelling at a constant relativistic speed) will see time go by normally as opposed to people in the non-inertial frame of reference (e.g. Aliens on a planet) who will see time go by slowly in the rocket

I hope that makes sense haha

 

[HecticLad]

The observers on earth will perceive events inside the ship to take longer than they actually do for the astronaut, so say an event actually took 1 second on the spaceship, the people on earth will perceive this as taking longer, therefore the astronaut is actually experiencing time quicker than those on earth

 

[chocolatelatte]

haha thanks guys!!!! that makes sense now

 

[InteGrand]

And the astronauts, from their point of view, perceive the time and events on Earth as being slower / taking longer.

 

[TQuadded]

time travels slower for them, so a certain space trip can be deemed to take 100 years, but at relativistic speeds it will feel like 10 years for astronauts (astronauts are still young and able to complete the trip, whereas people on earth are old/dead)

But.. but.. but that hurts my brain. From the day that I was born I was so sure time was relative.