Physics Time Dilation

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So, have been reading up a little on time dilation (and struggling to wrap my head around it) and from what I can gather it pretty much puts an end to any sort of back and forth space travel between galaxies/planets/future outposts.

If we travel somewhere near the speed of light we can forget about the planet we just left because potentially 1000's of years will have passed even during short trips at speeds approaching the speed of light.

https://www.fourmilab.ch/cship/timedial.html

upload_2017-4-23_3-35-39.png

So if I left Earth and traveled for a day at 0.9 the speed of light 2.29 days will have past on Earth.

If I left Earth and traveled for just 1 day at 0.999999 the speed of light 707 days will have past on Earth.

1 day traveling at 0.99999999 the speed of light and 19.3 years would pass on Earth.

To get anywhere of note in the universe we would need to be traveling at these speeds for years which would mean tens of thousands of years would pass on Earth. Am I reading this wrong? Or has Star Wars lied to me? Seems like this is a fairly big physics barrier for back and forth interspace travel.
 
can't comment on your numbers but what you've inferred from them is generally correct.

(hopefully someone much smarter than me will come along and correct this explanation)

there's another, more glaring issue when it comes to interstellar travel vs physics though- energy. the amount of energy required to get something close to light speed is hugely prohibitive. the closer you get to lightspeed the corresponding increase in mass requires an exponentially-increasing amount of energy to maintain speed/acceleration. this is why the chart only goes to 0.999 etc- because the maths tells us that 1.0 is impossible as you would need an infinite amount of energy to get there.

this is the main reason i don't believe aliens (who surely exist) are likely to ever visit us, and why most theorists talk about interstellar travel with wormholes, rather than super-fast rocketships.
 
boydshow said:
Not quite. You will have experienced more time than Earth did, you will have aged more than people on Earth have
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?

The prime example is that of the two hypothetical twins: One of them stays at home, on Earth. The other journeys into space in an ultra-fast rocket, nearly as fast as the speed of light, before returning home.

Afterwards, when the twins are reunited on Earth, the travelling twin is markedly younger, compared to her stay-at-home sibling.
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http://www.einstein-online.info/spotlights/Twins
 

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Your numbers on time dilation are correct for travel within spacetime, based on Special Relativity.

Interestingly, there has been another type of propulsion proposed that involves travelling within a bubble caused the warping of spacetime called the Alcubierre Drive. This method involves creating a wave-like bubble in the fabric of spacetime, with the spaceship 'riding' that wave while existing in a non-warped flat region of spacetime that would not be time-dilated.

It sounds fanciful, but is taken seriously enough for it to have been studied by NASA. The issues with the method are serious; we don't know how to warp spacetime as yet, we don't know how much energy it would take (probably a great deal), and we don't know how to allow a spaceship to enter/exit the warped region of spacetime.
 
I was wondering whether the earth's movement though space might be a factor in this. We spin round the earth at incredible speed, we orbit the sun, the solar system is whizzing round the galaxy, our galaxy is moving relative to the microwave background radiation. But even at such speeds it is still a tiny fraction of those that are significant for time dilation.
 
volcboy said:
Your numbers on time dilation are correct for travel within spacetime, based on Special Relativity.

Interestingly, there has been another type of propulsion proposed that involves travelling within a bubble caused the warping of spacetime called the Alcubierre Drive. This method involves creating a wave-like bubble in the fabric of spacetime, with the spaceship 'riding' that wave while existing in a non-warped flat region of spacetime that would not be time-dilated.

It sounds fanciful, but is taken seriously enough for it to have been studied by NASA. The issues with the method are serious; we don't know how to warp spacetime as yet, we don't know how much energy it would take (probably a great deal), and we don't know how to allow a spaceship to enter/exit the warped region of spacetime.
Click to expand...
Thanks for the link. Really interesting. On the bolded, on reading the link I was thinking of body-surfing and the push you get from the wave that is over and above your own motion of swimming. I assume this is the simple explanation of the Drive?
 
sorted said:
I was wondering whether the earth's movement though space might be a factor in this. We spin round the earth at incredible speed, we orbit the sun, the solar system is whizzing round the galaxy, our galaxy is moving relative to the microwave background radiation. But even at such speeds it is still a tiny fraction of those that are significant for time dilation.
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But because of those speed our time will still be moving differently relative to other places in the universe. Just for us, it's all constant because we are all experiencing it together.
 
SJ said:
But because of those speed our time will still be moving differently relative to other places in the universe. Just for us, it's all constant because we are all experiencing it together.
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No, it's because we are not moving fast enough for the speeds to be significant for time dilation.
 
sorted said:
No, it's because we are not moving fast enough for the speeds to be significant for time dilation.
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Speed is relative to something else. We would be experiencing time dilation relative to someone on a different planet in a different galaxy.
 
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