Page 5 of 7

### Re: Time travelling is not posible :(

Posted: Thu Nov 11, 2010 1:58 am
I was watching this video about time travel on youtube once. This dude was talking about all these ways that defend the fact that it is possible. A couple of his theories were:
If the universe is rotating, then if you travel at the opposite direction, around the entire universe, faster than the universe is traveling, then you will arrive on earth before you left.
Another is a loop hole. If you put two dots on separate ends of piece of paper, then fold the paper, the dots are on the same spot. So if you could somehow create a loop hole then you'd be able to be at two times at once. Or something like that.
He had a couple other good theories but i forgot. His argument was that even though time itself was just man-created, it still moves forward. Something is pushing it forward, which makes our days or seconds go by faster. Time wouldn't be able to move itself, so the fabrics of time really would be connected.

### Re: Time travelling is not posible :(

Posted: Thu Nov 11, 2010 3:26 am
I've never understood why people think that moving really fast == time travel. No matter how fast you go, you will never get somewhere before you leave. Consider this:

At normal speed, it takes you 512 minutes to travel 100 miles.
At double speed, it takes you 256 minutes to travel 100 miles.
At double that speed, it takes you 128 minutes to travel 100 miles.
... ... ...
At double that speed, it takes you 4 minutes to travel 100 miles.
At double that speed, it takes you 2 minutes to travel 100 miles.
At double that speed, it takes you 1 minute to travel 100 miles.
At double that speed, it takes you 1 minute to travel 200 miles.
At double that speed, it takes you 1 minute to travel 400 miles.

An increase in speed can either reduce the time it takes to travel a given distance, or increase the distance traveled in a given time. As speed doubles, the time required to travel a given distance is halved. It approaches zero with each doubling, but will never actually reach it. Since it cannot reach zero, it cannot pass it and become negative.

In addition, Einstein showed us that (in a nutshell) it takes a metric fuck-ton of energy to move something at the speed of light. Not going to elaborate too much on that. Google it if you wanna know more.

### Re: Time travelling is not posible :(

Posted: Thu Nov 11, 2010 6:02 am
Goatboy wrote: it takes a metric fuck-ton of energy to move something at the speed of light.

Permission to use this new unit in my Physics paper?

Oh and also...
+1.

### Re: Time travelling is not posible :(

Posted: Thu Nov 11, 2010 11:33 am
Metric Fuck-Ton!!!!!!

fell out of my chair literally...

BTW - Time Travel IS possible.. I wrapped a flannel around my waste this morning and was instantly transported to 1993.

### Re: Time travelling is not posible :(

Posted: Thu Dec 02, 2010 4:55 pm
this subject is for the most part open to me. @goatboy, true, very true, the closest you'll get to time travel with speed is retrograde, or the illusion of time travel. you move away from the object at +c, and it goes backwards.
elaboration:
you don't see things, you see light. if light is moving at c, and you are moving at +c, you are passing light, and seeing old light. therefore, the longer you go +c, away from an object, the more it appears to move backwards in time, but you could never approach this object in its past state, at least with pure speed, because you would have to turn around and pass the light that you have already passed to make it seem like you were traveling through time.

but in the spirit of devils advocate, riddle me this... you wonder why nobody has come back? theoretically, everything has to happen before it's causes can be administered and witnessed, right? who says we aren't one of the leading time paradoxes and possibly all earth matter in existence has only progressed to say... 2150 a.d.? so with this in mind, imagine time travel is invented in 2125, and someone did come back, but they were really careful, and did only displace a rock. when said person returns to the future, sure, technically its different, but over the course of 115 years, how significant of a difference is a displaced rock going to make? possibly not even noticeable, maybe a haircut, maybe the amount of \$\$ in someones pocket is a few bucks higher than it should be, but really what difference does that make? until you get to the point of k's or m's of years, small differences in the past such as a squished bug or a displaced rock wouldn't have quite the paradox effect, if any at all. maybe the bug was squished and no one was to interact with that bug until 2153 a.d.. we'd never know because matter hasnot progressed that far yet.

also, different dimensions do exist, who's to say that one or more are not replicas of this one, but in a different stage of development? if that is possible, with enough force, theoretically, a wormhole could be created between the two dimensions and you could theoretically travel through time, whether it be past or present. and since it's in another dimension, there would be no paradox effect because
a) nothing you do there will affect the future in that dimension because it hasn't happened yet, &
b) (similar to a) nothing you do there will affect the present in our dimension because your not altering it's past.

this makes this subject fairly open to me, although i'm leaning towards the possible side.
of course, if we did discover travel to other replicated dimensions, it would be irresponsible not to test out the paradox theory, and check something that would have little effect. i.e. travel from dimension 1 to dimension 2 (assuming dimension 2 is 12 hours or so behind dimension 1) and bury something underground, travel back and check to see if it's there, if it is, don't travel in time lol, you'll fuck shit up. if not, try recording a day on camera, traveling to dimension 2, burying something, and traveling back to dimension 1 and watching the video. you should see yourself! lol idk if this is 100% feasible, but it sounds good to me.

### Re: Time travelling is not posible :(

Posted: Fri Dec 03, 2010 12:26 am
Has anyone else noticed a sort of butterfly effect fallacy, where people assume that modifying the past in any way is going to vastly impact the future?

Why can't a pebble be thrown and just damn stay there without causing any noticeable changes? (I'm half joking, but it really would be nice to see a movie or book where changing a small detail in the past has a non-noticeable impact on the future).

EDIT: Can someone explain the whole "if you get on an airplane and go fast enough (but not at the speed of light), you'll come back a fraction of a second ahead of time" thing? That's never made any sense to me, although I've never really heard formal scientific reasoning for it. It's usually just "did you know that scientists discovered that..."; a phrase I hate because it's used so often to dodge actual scientific discussion.

### Re: Time travelling is not posible :(

Posted: Fri Dec 03, 2010 4:46 am
sanddbox wrote:Can someone explain the whole "if you get on an airplane and go fast enough (but not at the speed of light), you'll come back a fraction of a second ahead of time" thing? That's never made any sense to me, although I've never really heard formal scientific reasoning for it.

See my last post. Not entirely sure if that's what you're asking, but it sounded that way to me.

Now here's what I wanna know. Assume that you have a personal spacecraft capable of sustaining your life for a year in space. You set two countdown clocks for one year, one on Earth and one in your spacecraft. You launch, and spend the next 365 days happily floating around Earth. When you come back, however, you find that your Earth-clock has passed zero and begun counting up (to signify time since zero) to several months. Your spacecraft clock is at zero.

Apparently this actually happens. Whiskey Tango Foxtrot?

### Re: Time travelling is not posible :(

Posted: Fri Dec 03, 2010 7:02 pm
sanddbox wrote:EDIT: Can someone explain the whole "if you get on an airplane and go fast enough (but not at the speed of light), you'll come back a fraction of a second ahead of time" thing? That's never made any sense to me, although I've never really heard formal scientific reasoning for it. It's usually just "did you know that scientists discovered that..."; a phrase I hate because it's used so often to dodge actual scientific discussion.

I, personally, cannot. This might help you to clear it up though.

http://en.wikipedia.org/wiki/Time_dilation

### Re: Time travelling is not posible :(

Posted: Tue Dec 07, 2010 3:53 pm
ok here is my idea, imagine your traveling in a space craft, with an acurate clock, one on earth as well and they start at the same time.
in order to reach our nearest start which is 4 light years away u have to get thar* gasp*.
now as you go faster time slows down for you.
so if you go at 1/2 the speed of light for example time will slow down by half, therefore you would on board the spacecraft think you are traveling at light speed. (this is an imaginary example to prove a point)
so it will take 8 years to get there but you will only feel 4 years of travel.
time ( i think) slows down more as you speed up and approch the speed of light, (correct me if i'm wrong).
now as you speed up MOAR to for example 75% the speed of light, time is going just 25% speed, so if "feels" as if you are going 2 times light speed. it will take 6 years (reall time) to get there but only 2 years in the spacecraft.
now this is why u can't reach light speed, as you get nearer to light speed, not only will u need MOAR fuel, but you will accellerate slower, as the engine is going slower, for example at 50% light speed, time will be going 50% slower and therefore so will the engines so thats 50% slower accelleration, therefore as we approch light speed, 99.99% of the spped of light, the engine that was ridiculously overpowerd now pales in comparrision to a 1 millivolt battery in realtime, it still accellerates the craft but it gets exponentionally slower as it speeds up, not only that but time will contine to seem to be speeding up outside the fraft from your persective, to you it will seem that you are accellerating at the same pace, but in real time you are not getting much faster, therefore time onboard the spacecraft will start to allmost stand still as you reach nearly the spped of klight, which is impossible beacuse it is a supertask.
because of this it will seem to you that as you reach the speed of light that the universe is speeding up exponentionaly, and becore you know it a "googleplex" years in real time has passed in 1 second (look up a googleplex if youi need to) and the universe along with your craft is destroyed via heat death/ dimensional collapse or whatever.

i think the only reasion particles that travel faster that light can do so is because they may have negative mass (somehow ), and perhaps light is as a particle zero or almost zero mass, which would make light able to travel at almost the top speed making light speed almost the limit in which case light speed is possible but time travel is not.

### Re: Time travelling is not posible :(

Posted: Sat Dec 11, 2010 1:08 pm
1/(1-v^2/c^2)^1/2..aka gamma = let's say &

use it to explain time dialation. T(observer) =&T(proper time)
if you want to understand time dialation and length contraction google cosmic ray muon experiment.

As for why your time differs from the earth's while floating around space. To be observable your speed would have to be huge, since gamma is how u calculate the dialation. and im pretty sure it only works for one dimensional motion, so if you were floating centripetally around earth i think it becomes too complicated. I think for question's like these you need general relativity not special, since calculating accelerations in different reference frames is complicated in special relativity. (The twin paradox only happens due to the acceleration one twin experiences vs. the other).

thats about all I know, so if anyone knows more than that explaining it would really help me for my relativity final on the 15...