Time Travel Question (Twins Paradox)

[zxlk21e]

" If an astronaut travels into space for six months at a substantial fraction of light speed and takes another six months to return to Earth, he would land in the future.

 

While a year will have elapsed on the astronaut's clock, tens of thousands of years may have gone by on Earth, depending on how close to light speed the astronaut traveled. "

 

How is this? Does our biological clock slow down during high speed? How is speed relative to time and duration?

 

It seems that this may be assuming the existence of Einstein-Rosen bridges (or wormholes). If this is the case, would the speed of the wormhole be congruent to the ratio of Casimir energy to gravity? What, if any ability is created by this mechanism to slow down the duration of time inside of the said space capsule that the astronaut would be traveling in?

[Sayonara]

This is nothing to do with time travel or wormholes - it is due to good old special relativity.

 

Latest thread on the repeatedly debated "Twins Paradox" (basically same scenario as at the start of your question)

http://www.scienceforums.net/forum/showthread.php?t=25400

 

Thread on time dilation due to relativity: http://www.scienceforums.net/forum/showthread.php?t=26728

[someguy]

I like to think of it like this. the faster you move the more ground you take up in space compared to a slower moving object. the faster you move in space also the more ground you make in time. so, while you in your spaceship are not moving compared to other objects in it, and thus not aging at a different rate than those objects, compared to here on earth you are moving much faster and therefore you and everything in your spaceship are making great time in... time. so when you arrive back on earth you will have aged less than everything on earth. i find this way of thinking helps because it helps you think of time not as a linear thing, like we grew up to believe, but more like a 4th axis of the 3 dimensions of space. imagining time slows down for the fast moving spaceship promotes thinking of time in the conventional sense but that it gets warped or changed dependent on your speed which i have come to believe is sort of an imprecise, or misleading, way of looking at it, though it's not really wrong to talk about it in this way. sort of like saying that if the door of plane opens in flight everyone gets sucked out, when technically, they are blown out.

 

if nothing moved at all there would be no time at all right? everything would be on pause. so you can see right away that time and motion are very closely related. in fact, they are co-dependent. this part at least is more obvious as just a natural rule of the way the universe "must" be. when you start thinking about how the faster you move in relation to something else the more different you experience time, it gets more unconventional and weird, but it's the same kind of "must" be.

[zxlk21e]

Thanks for the replies, and the move. I'm all cleared up now. Thanks again!

[Jean Maxwell]

Well, are we not all Time travelers?

 

We all move through time. If in the same inertial frame then at the same rate.

 

If we use more of our movement through space we use less of our movement through time.

 

obviously different than blink- differnt epoch, but still time travel. ; - )

 

Ahh Language

[DZane]

This is my point of view. If you travel faster than light and look behind you things will look like they are going in reverse just because you pass up the light that has already traveled that far. Once you turn around and head back things will look like they are speeding up until they are back to the normal. So you dont travel in time. but you may see light from the past !

[Sayonara]

You can't overtake light. It travels at c in all reference frames.

[DZane]

Faster Than Light Speed

[Sayonara]

Faster Than Light Speed

Trying to write posts in all-caps doesn't make the idea more physically valid.

[swansont]

"Point of view" is irrelevant. This isn't opinion, it's science.

[DZane]

We are standing on earth and the light that we see today from all the stars in the sky are that of "the past". Now we get in our spacecraft now we are going faster than light toward whichever star, would it not seem like time is speeding up?

[swansont]

We are standing on earth and the light that we see today from all the stars in the sky are that of "the past". Now we get in our spacecraft now we are going faster than light toward whichever star, would it not seem like time is speeding up?

 

We are not going faster than light toward the star. If we are in an inertial frame, we will still see the light coming at us at c, though it will be blue-shifted.

[J.C.MacSwell]

We are standing on earth and the light that we see today from all the stars in the sky are that of "the past". Now we get in our spacecraft now we are going faster than light toward whichever star, would it not seem like time is speeding up?

 

If you are using what you are watching, straight ahead, as a reference, then yes, it would seem that way. The "movie" you are watching would have sped up.

[DZane]

Now that we passed all the light that came from Earth or whever your starting point is it should look like the past. Now we get back in and head back faster than light. Now it should look like its speeding up returning to its original position + the time it took for the trip. Right?

[losfomot]

Now that we passed all the light that came from Earth or whever your starting point is it should look like the past.

 

You cannot 'pass' light in the sense that you can outrun it because you CANNOT GO FASTER THAN LIGHT.

 

Now we get back in and head back faster than light.

 

You CANNOT GO FASTER THAN LIGHT

 

Now it should look like its speeding up returning to its original position + the time it took for the trip. Right?

 

What you're describing is the Doppler effect, and it has nothing to do with going faster than light.

[DZane]

You CANNOT GO FASTER THAN LIGHT

 

I still wont believe this till we have the technology that can actaully get us as fast as we can go. At 99.9% of C there may be unforseen things that we just dont see now. Even at 50% of C things could be way different. So you can not say we cant go faster than light till we acutally reach 99.9% of C. The stuff you all know now might just go out the window at those speeds.

[swansont]

I still wont believe this till we have the technology that can actaully get us as fast as we can go. At 99.9% of C there may be unforseen things that we just dont see now. Even at 50% of C things could be way different. So you can not say we cant go faster than light till we acutally reach 99.9% of C. The stuff you all know now might just go out the window at those speeds.

 

Physicists routinely get particles moving >.99c in accelerators. Special relativity has been thoroughly tested. Nature behaves this way; it doesn't care whether you believe or not.

[someguy]

what's 99.9%C? there's no way to know. for all you know we are already moving at 99.9% of C, and compared to something somewhere i guess we must be. the particles accelerated are using earth as rest and then take what's left from earth's speed to light speed and move the particles at 99.9% of that. but even at that 99.9% isn't really very close in terms of trying to reach the speed of light.

 

you can't go the speed of light because the energy required to get you there is way too great because the object increases in mass as you accelerate it. at some point getting 0.0000000000000000000000000001% faster towards the speed of light would require a huuuuge amount of energy. the closer you get to the speed of light the more energy you need to accelerate. even minuscule accelerations guzzle way too much energy. no matter how much energy you put into the object to move it there will still be room left to make it to the speed of light the only difference is you will be using much more energy to get only the tiniest improvement towards your goal. forever.

[Sayonara]

The O/P has been dealt with and this current discussion is a waste of our time.

 

DZane; investigate Special Relativity. Your answer is in there.

[Money]

i dont know very much about special relativity compared to you people

but from reading topics in this forum

you cant ever reach reach C because even if u reached 99.9%C

and u had more energy C would still be C from your point of view

while moving 99.9%C light wouldnt look any different than if you

were looking at it from the speed we are look at it from earth right >???

it doesnt matter how fast you go light still looks the same ???

[RyanJ]

it doesnt matter how fast you go light still looks the same ???

 

Exactly. Light moves at c in all reference frames it therefore looks the same from all reference frames - its a constant.

 

Maybe it would be useful to think of it more like this (not actually sure this is an accurate way of representing it but it works for thought none the less!)

 

Imagine that an objects speed through space and its "speed" through time are added together and must always add up to c.

 

If we start moving through space then we must be moving more slowly through time in order for the total to remain at c as we move faster and faster we take more and more of our speed at which we travel through time in order for c to be maintained as a total.

 

As a result if we move faster through space then we must move slower through time and vice versa.

 

hope that helps

[foodchain]

Exactly. Light moves at c in all reference frames it therefore looks the same from all reference frames - its a constant.

 

Maybe it would be useful to think of it more like this (not actually sure this is an accurate way of representing it but it works for thought none the less!)

 

Imagine that an objects speed through space and its "speed" through time are added together and must always add up to c.

 

If we start moving through space then we must be moving more slowly through time in order for the total to remain at c as we move faster and faster we take more and more of our speed at which we travel through time in order for c to be maintained as a total.

 

As a result if we move faster through space then we must move slower through time and vice versa.

 

hope that helps

 

 

SO basically its that c remains a constant because its time that is shifting and or changing? So I would surmise from that that actions themselves, or then would it be speed or velocity should change time space? How does that equate to just mass, or is that also along with velocity, speed or what not?

[RyanJ]

SO basically its that c remains a constant because its time that is shifting and or changing? So I would surmise from that that actions themselves, or then would it be speed or velocity should change time space? How does that equate to just mass, or is that also along with velocity, speed or what not?

 

time doesn't really change so to speak, its all in terms of different reference frames. time differences are only apparent when observed between different reference frames.

 

I'd say that its the speed that is causing the effect rather than the time, we can easily alter the speed of an object but we cannot so easily do the same for its "speed" through time to it makes more sense (to me anyway) to see the speed as the causal factor.

 

I assume by just mass you mean that the object is completely stationary? Well in that case the object is moving solely through time with no movement through space.

[foodchain]

time doesn't really change so to speak, its all in terms of different reference frames. time differences are only apparent when observed between different reference frames.

 

Right the concept of time dilation I suppose?

 

 

I'd say that its the speed that is causing the effect rather than the time, we can easily alter the speed of an object but we cannot so easily do the same for its "speed" through time to it makes more sense (to me anyway) to see the speed as the causal factor.

 

I know, but if they share a fundamental relationship are we not arbitrarily doing that anyways?

 

I assume by just mass you mean that the object is completely stationary? Well in that case the object is moving solely through time with no movement through space.

 

Well what I mean is gravity if I have my Einstein down is a product of relativity at some scale right? Which also ties into time, but on the course of time space being warped and inducing gravity, then the same would be of events or actions, such as a warp should follow the trail of a comet to some extent, or even me waving my arm up and down on some level, or is this an in bulk phenomena?

[RyanJ]

Right the concept of time dilation I suppose?

 

Exactly.

 

I know, but if they share a fundamental relationship are we not arbitrarily doing that anyways?

 

Well one can be controlled directly the other is indirectly controlled by using the direct effector, in this case the direct effector being speed changes. To me it simply makes more sense to refer to this as the primary effector.

 

 

Well what I mean is gravity if I have my Einstein down is a product of relativity at some scale right? Which also ties into time, but on the course of time space being warped and inducing gravity, then the same would be of events or actions, such as a warp should follow the trail of a comet to some extent, or even me waving my arm up and down on some level, or is this an in bulk phenomena?

 

Gravity is a distortion of space time, seeing as the effects of gravity and accelerated motion are the same (e.g. they both produce a recurrent force, acceleration and gravity create an effect that is identical) then this would act exactly the same way as did the speed but things would get more difficult to imagine as something would then be accelerating in the presence of a gravitational field. As we pass through a gravitational field it has the net effect of decreasing the rate at which time passes as observed from and outside reference frame but if the object is in motion that too would need to be accounted for. I think its simpler to think about it in terms without gravity for simplicity.