20 replies to this topic

[cameron marical]

the faster you move through space the slower you move through time, ok, does this mean that the slower you move through space the faster you move through time? i know its hard to move as fast or remotely near the speed of light, but can we move something "negatively" somehow? so a referance points ages faster than another referance point moving at normal speeds?

[Baby Astronaut]

I wondered the same thing once.

If you can somehow ignore the effects of your frame's gravity, I'd say yeah, time would "speed up" for you because now everyone is going faster than you. However, once you jump back into the galaxy's frame, it'd be a long ways to catch up with them and you'd have to go near light speed to do it, so now time would be slower and because of this you might arrive at the same age regardless -- unless my calculations are totally screwy

[NowThatWeKnow]

Traveling back in time takes advance planning. If you want to come back to 2010 in 2020 you could send Earth on a relativistic trip now and wait on Mars for it's return. As mentioned, you could do the same with gravity. But even if you could ignore the gravity of the Sun and Earth you would only go ahead in time by about 1 minute a year. As Baby Astronaut says, "unless my calculations are totally screwy"

[swansont]

the faster you move through space the slower you move through time, ok, does this mean that the slower you move through space the faster you move through time?

Yes. The length of your velocity 4-vector is c; when you are at rest with respect to an observer that's when the observer will see your time pass at its fastest.

[Pangloss]

(Edit: I re-wrote this post completely, in simpler form.)

Please forgive this if it's way off -- I'm hoping our resident experts can straighten this out more fully.

The OP also seems to be asking whether we can send someone back in time by simply having them move really, really slowly with regard to an observer. The answer to that question would seem to be "no", because (a) these are observed effects, not causal relationships, and (b) in order to observe a "backward" direction you'd have to have a differential greater than the speed of light, which is impossible.

Also, I may be wildly off base here, but this would seem to be related to the old question of what happens when a fast-moving observer turns on a flashlight pointed forward -- does the beam of light travel faster than normal lightspeed? The answer being no, because light always travels at light speed. This seems related to the above question in the sense that it underscores the point about the range of motion really is limited to the set of zero to 186,000 miles per second, no more, no less.

Edited by Pangloss, 9 February 2009 - 04:07 AM.

[Baby Astronaut]

There might not be a way to "slow down" because gravity would keep you going at the minimal speed even against an immobile person. And I'm not sure if you can force yourself to slow down in the same reference frame of our planetary system.

*If* you could press a button and external gravity would instantly stop affecting your body, then the Earth would smash into you or whisk away from you at tremendous speed.

The OP also seems to be asking whether we can send someone back in time by simply having them move really, really slowly with regard to an observer.

NowThatWeKnow also mentioned traveling backwards in time, yet I'm fairly certain the OP didn't ask this.

He probably meant just slowing down. That's it. And would doing so make time go faster. It's the reverse of speeding up, and time would move slower.

[NowThatWeKnow]

He probably meant just slowing down. That's it. And would doing so make time go faster. It's the reverse of speeding up, and time would move slower.

You may be right and I was confused by "but can we move something "negatively" somehow? so a reference points ages faster than another reference point moving at normal speeds?" If so he was sort of answering the question before he asked it.

[Baby Astronaut]

You may be right and I was confused by "but can we move something "negatively" somehow? so a reference points ages faster than another reference point moving at normal speeds?" If so he was sort of answering the question before he asked it.

Well, I'm fluent in most incorrectly-worded terminology

But really, I had the same thought before, realizing you couldn't move slower than a person who's just standing there. And I'm pretty sure "moving negatively" is close to how I originally pictured a solution to it. That's when the idea of gravity tug-along difference hit me.

Edited by Baby Astronaut, 9 February 2009 - 05:09 AM.

[cameron marical]

i ment slowing down to speed up, not the vice versa. moving negatively, i geuss that is kind of badly worded, but that was all i could think of becuase like baby astronaut said, i cant really think of a way to move slower than a person whos just standing there, other than somehow moving "negatively", which i have no idea where to start there.

[Baby Astronaut]

I think moving yourself to a weaker gravity system than our entire planetary, solar, and galaxy's combined reference frames would to do the trick. In other words, move to a system whose cumulative velocities are much slower than ours.

Make sense?

For example, we're going at the speed of human + Earth's orbit around sun + sun's orbit around galaxy + galaxy's orbit around Virgo supercluster, - (minus) the canceled-out speeds from any opposing directions.

In a star within the great voids you can probably find a slow enough system. I doubt those are moving very quickly. But I'm guessing entirely, based on the logic this star would have nothing to orbit around. It's very possible my whole idea is flawed.

[swansont]

The term used in the dilation formula is speed, which is a scalar. It's non-negative. (it gets squared anyway). The 4-vector is squared to find its length. The sign of the velocity components doesn't matter.

[gre]

Doesn't the problem come down to there's no "absolute reference frame" to slow down from?

I believe there is an absolute reference frame WRT mass, time, velocity through space, etc, somewhere in the universe.... A large back hole maybe?

But I don't think physics has an absolute universal reference frame to slow down "against".

[Baby Astronaut]

The term used in the dilation formula is speed, which is a scalar. It's non-negative. (it gets squared anyway). The 4-vector is squared to find its length. The sign of the velocity components doesn't matter.

I looked up "scalar" on Wikipedia and it says the directions are inconsequential. So if I'm reading this correctly, does it mean that if the sun were traveling due east at 100 speed, and the Milky Way traveled west at 200 speed, then our frame of reference would be 300 speed? (math purposely oversimplified)

Doesn't the problem come down to there's no "absolute reference frame" to slow down from?

It's your own frame that you'd be slowing down from. Just enter frame that's going slower than the one you just left.

[Baby Astronaut]

*Bump* to answer last post?

[swansont]

I looked up "scalar" on Wikipedia and it says the directions are inconsequential. So if I'm reading this correctly, does it mean that if the sun were traveling due east at 100 speed, and the Milky Way traveled west at 200 speed, then our frame of reference would be 300 speed? (math purposely oversimplified)

As long as the speeds aren't relativistic (if they are, it's apparent that they don't add linearly), that would be our speed with respect to the Milky Way.

[north]

[QUOTE][quote name='cameron marical']the faster you move through space the slower you move through time, [/QUOTE]

not really

its just about perspective really

what do you base time on in order to come to this conclusion

this is like saying the faster you move through space the slower the galactic spiral arms would be

and the slower you go in space the faster the galactic spiral arms would be

neither would happen

because the speed that the galactic spiral arms would go is completely dependent on the galaxy its self

regardless of your speed

[cameron marical]

what do you base time on in order to come to this conclusion

The measurment of what has happened since a starting point to an ending point.

Im not talking about the any galactic arms, im talking about the persons relative perspective that is traveling at the speed slower compared to everyone elses.

[swansont]

not really

Yes, really. This is the physics section, and we are discussing relativity. Critiques of relativity or alternate proposals belong in the speculations forum.

[phyti]

the faster you move through space the slower you move through time, ok, does this mean that the slower you move through space the faster you move through time? i know its hard to move as fast or remotely near the speed of light, but can we move something "negatively" somehow? so a referance points ages faster than another referance point moving at normal speeds?

1. You don't move through time, you and your clock run at a slower rate.
Eg: you leave earth and return after a trip at .6 light speed. While you are away earth flashes a beacon once a month. You return 6 months later earth time. Your clock records 4.8 months, but your log records 6 flashes. Time did not slow down, the same number of events happen in the world, but your clock just sliced the time into longer intervals.

2. The light clock records the minimum interval between ticks at rest, thus any motion will only lengthen the intervals.

[petebro]

It is something of a paradox and we constantly debate this time slows down in space when earth time seems relative to the effects of gravity or a force field we live in .
we consider light and travel and perhaps we mistake time as being apart of light.
Yet it is clear that time does slow down and is relative to the velocity at which we travel
so we consider lightspeed as a reference for a velocity that is constant , the real questions i ask myself is why does time slow down relative to the time being recorded on earth, ive considered time decay and as aforementioned the is a small difference quoted
as 1 minute a year on a relativistic trip , the difference being that if we know it is possible to travel through time to another I.R.P then it would suggest the time decay factor having only been able to travel back to a certain point that being so then we could continue to travel further through time from that Inertial reference point .
I find another interesting point about the effects of space and time which is the effects
it has on our body , we know that the atomic structure changes on earth i wonder to what effect it would have on atime traveller ?