Time Traveling

[Overnerd]

I meant forward time travel is easy relative to backwards time travel...

 

[Rhazdel]

I recently learned about Wheeler's Delayed Choice experiment. It blew my MIND. Like, dude. Seriously. Wow. Put simply, if you shoot photons through a card with two slits onto a screen, they will form a wave interference pattern, (that is, in some sense it passes both slits). However, detecting the particles between the slits and the screen causes them to lose their wavelike behavior, and the pattern built is one of two bands of light as you would expect for particles.

This is a standerd experiment. But in the Wheeler's Choice varient, instead of placing the detectors between the slit and screen so that the photons are particles when they hit the screen, you put telescopes nearby. In this way, you determine which slit the photon will pass though after it has hit the screen. But here's the wierd thing. When the photon hits the screen, it does so as a particle - no wave pattern. However, at this time, it has not been detected. In fact, it loses is wave property beause it's going to be detected. NO WAY. SERIOUSLY.

In my Quantum Mechanics Must Die varient of the experiment, you set it up so that the screen the photon hits is a LDR, which alters a circuit. The circuit is attatched to the telescopes and activates/deactivates it. When the light is concentrated into two bands, (beacuse it's going to be detected), the telescopes are deactivated and the photon is not detected. However, if the photon is not detected, then it would behave as a wave. But when it is not a particle, the circuit deactivates and reactivates the telescopes, destroying the wave form. In this way, the prediction made invalidates itself, (this is similar to the Laplace's Demon thought experiment, where an infinitely knowledgable being in a determined, determinable universe cannot predict the action of someone who will do the opposite of it's prediction).

Supposedly in quantum mechanics objects can defy the law of excluded middle and possess two conflicting properties. I'd like to know if it can posses neither. Would it then still be light?

Light functions as both a wave and a particle (string theory), and you cannot measure, in quantum physics, position and velocity at the same time. You can tell where the photon is moving to (velocity) by checking it's wave pattern, or you can check the photon's position by checking it's location. By quantifying what you are looking for, the experiments solidify which results you will get. Because it is both a wave and a particle, if you check for a particle, you will see the particle, but no wave (detect position), but if you check for the wave, you will see the wave but no particle (detect velocity).

It's kind going on a roadtrip and mapping Point A and Point B on a map and drawing a line in between them. Can you actually detect where the car is at any given time? What if you took a photo of the car on the road? This would show the position, but not what direction you were travelling. Only when you put the information together can you see both location and direction (ie: visible light).

I don't believe this experiment shows that light "retrogrades" it's state of transmission based on a last-second determination of how it will be recorded, but rather further shows that we cannot detect both waves and particles simultaneously.

It is an interesting experiment, however.

 

[arcthemonkey]

Rhazdel, I think you need to go read about the Double Slit experiment.

It's not a problem of observation alone. It's the fact that observing it changes its behavior. Normally, the particles hit the two slits and leave an interferance pattern on the surfuce they colide with behind them, meaning they were travelling as a wave. However, measuring the particles causes them to imbed in the back surface in an outline of the slits, meaning they were plain old particles.

 

[Rhazdel]

I'm familiar with the Double Slit experiment. But, my point was that when you measure for a wave, you will find a wave, and when you measure for particles you will find particles, because light functions as both (String Theory).

It doesn't prove that light "bends time" to retrograde it's method of transmission based on how it will be perceived (as was indicated), but I think it rather shows the complex nature of light and how much we truly do not know about the subatomic world.

 

[sixtyandaquarter]

me personally, i've always been fond of the idea of a flux capacitor on a delorian traveling at exactly 88 mph...

unless our tourists get really smart in the future, i'm not going to believe in time travel ever actually happening. not that it is or isn't possible, simply never happening. that and i honestly don't get this whole speed of light spacial relativity, which just seems very limited to me - but that's only certain arguments.

Really though, i'm just here since everyone's talking about the double spli experiment, some people might want to see the "delayed choice quantum eraser". it may not add greatly, but it's a fun little thing to look up.

I was planning on spoilering some info, but i opened my mouth before realizing how tired i am - so here's a quick link to wikipedia's article (HERE) but it isn't actually the best article out there on the web about this...
I can't find where I saw it first, but there is a site that will explain this whole thing, as best possible threw various views, in a simple language that anyone (including me) could easily understand. if somebody finds that page, let me know - i'd like to give it to my little cousin.

 

[arcthemonkey]

Hehe, of course, if people will ever be able to travel to the past, don't you think we'd know about it by now?

 

[sixtyandaquarter]

well in truth, if one method of time travel was to set up a locality that manipulated spacetime - in most theories - to an exact need, then we'd be able to travel threw time - perhaps - as long as we were traveling to that exact point, and while that manipulation was active ---or something like that...

though it's not my belief i've seen people swear by it so...

 

[Andy6000]

Hehe, of course, if people will ever be able to travel to the past, don't you think we'd know about it by now?

yeah... Though one could make the assumption that only responsible people would ever time travel? Ever?

Yeah the only 'able to travel backwards' theory that works for me is the 'it just creates an alternate timeline' theory.

Also by all indications going backwards in time just = no by logical fallacy.

 

[Shadow_Strike]

If time is relative to the speed and location of an object. Why couldn't time be changed?

First we have to define Time. You say time is relative.
So is everything else. An apple's relative size to an ant is large, but the same apple's relative size to the human is small. There the apple "changed" size.
We just need to find someway to define time differently.

If someone came up to you and said they're from the future. You'd probably walk on and ignore them. Hell, maybe the people who scry and predict the future events are from the future. You know? They're not really scrying or predicting, because they know. And noone believes them anyway until it happens.

 

[Rhazdel]

If time is relative to the speed and location of an object. Why couldn't time be changed?

First we have to define Time. You say time is relative.
So is everything else. An apple's relative size to an ant is large, but the same apple's relative size to the human is small. There the apple "changed" size.
We just need to find someway to define time differently.

If someone came up to you and said they're from the future. You'd probably walk on and ignore them. Hell, maybe the people who scry and predict the future events are from the future. You know? They're not really scrying or predicting, because they know. And noone believes them anyway until it happens.

The only thing is: Humans cannot alter their location and speed in a significant enough way to affect time. The requirements are beyond our body's physical limitations (not to mention technological limitations). As someone mentioned in here before, as you approach the speed of light, particles begin to heat up. Every particle in the body (and vessel it is travelling in) heats up. There would be no way to dissapate the heat generation, and structure would be compromised.

So, even if it were possible to alter time, you would probably end up in another time, but as a frying pile of goop.

Oh, and Sixtyandaquarter: Excellent Back to the Future reference!

 

[Torik]

I don't believe that it's possible or ever will be.... well maybe it is, but it isn't acquirable by humans. And what if someone did go back in time? What about the problems this might cause? You might screw up ALOT of things. What if since you existed in the past (saying you were going back to do something for yourself) then would there be two of you? Jesus it's just all to confusing and utterly pointless.

 

[PeteD2S]

Well, those paradoxes you talked about are...true? yeah, theorically, because, its obvious if you killed your father before you were born, you wouldn't be born. but, you can't really control time because time isnt, therefore you cant "go back in time".
And about the Deja Vu, it is explained that 1 eye doesn't catch the pictures at the same time the other does, so the brain will think that he passed through that moment before (that is the explanation i heard about), something like that. But does that mean that a person that is blind from 1 eye doesn't go through Deja Vu's sensations?
Also, when i get a sensation of Deja Vu, it isn't as most people describe it. My Deja Vu moments normaly feel like they last 5 seconds, they are first triggered by a milisecond familiar moment, followed by "predictions" of whats going to happen next with a fraction of a second between "predictions" and events and when its finally over i think about how fucking weird it feels.

Offtopic: Getting near a black hole... You would need infinite amounts of energy to even move a little bit at your own will, after you get enough close to it, so dont even think about that. HELL, light isnt able to escape its gravitational force, nothing is.

 

[LightAndMagic]

I kind of liked the Harry Potter theory. That everything already happens. You go back in time, and find out these events had already hapenned, because you go back in time in the future. It's confusing, but I kind of like that idea. That everything essentially still remains on the same path, because time is like a prerecorded event, and you can't change it... Hard to explain...

 

[neomatrixjc]

Time Travel Idea Theory, hmmm, well if it were possible, i think it would be dangerous, considering the very fact that if u mess with the threads of time, you change the course of those threads as well, First of all u better know your geneology at its upmost best, so that way u dont mess with u being born, especially if your the one who created the time machine in the first place, which would make you existant as if someone important in your geneology was to never be born or not exist, The world is better off at having no time machine than to have one, if i remember the last time in history that they even practiced it, would have to be the philadelphia experiment in which if i remember correctly, they fried them selves alive by experimenting.

 

[Torik]

I kind of liked the Harry Potter theory. That everything already happens. You go back in time, and find out these events had already hapenned, because you go back in time in the future. It's confusing, but I kind of like that idea. That everything essentially still remains on the same path, because time is like a prerecorded event, and you can't change it... Hard to explain...

I hate Harry Potter. And some stupid lady wrote a stupid book, and made up the "time theory from Harry Potter" while she was high off of Guatamalan Cocaine.

 

[Reives]

If such things are possible, I'd think they'd be out of our dimensions comprehension such that they do not have to follow our sense of logic. E.g. Theoretically, if we pick up a 2D man Flatty and wave him around in 3D motions, the event would simply not make any sense to him.

Our logic is ultimately based on rules and patterns within our sense of reach. What if three came after one instead of two? It doesn't make sense to us now, but what if it does in another altitude of view?

 

[PeteD2S]

Our usual sequence of counting is ascendent but you can count in infinite other ways.

 

[Reives]

Right, I was just using that as an example. Not a very good one now that I think of it, actually. :|

 

[G-man]

Whoa I had to check this out, since this is the meat of my game.
when I seek info or facts on Timetravel I look at this

http://en.wikipedia.org/wiki/Time_Travel
it's pretty extensive but it gives me the facts I need.

 

[Kraft]

I have a thought...

If Mars is 1/2 a lighthour away (it takes light half an hour to travel from mars to earth) then if you were looking up at mars right now, you would see a mars that is half an hour old.

True?
I mean, if there was a massive explosion on mars, and it took light 30 minutes for the light of it to travel to earth, then it would be 30 minutes after the explosion actually happened before anyone saw it.

Now broaden your view....

With the Hubble telescope, people have seen another galaxy that is near our own. (about 10,000,000 light years away)

If you follow the theory, then if you were to look at that galaxy with the hubble telescope, then essencially you would be gazing 10,000,000 years into the past.

Huh? Pretty interesting.
So if we ever developed a telescope powerful enough to actually view the other planets in that other galaxy, and there happened to be life (such as on this planet) on it, then scientists could basically watch their whole planet evolve! Even though, in actual time, it is 10,000,000 years past what they are viewing.

And then, if the people on that planet were thinking the same thing, and sometime in the future, we traveled there... we could actually see what our planet was like 10,000,000 years ago!

All of that is a theory, I mean, I dont even know if there is other life on planets... but still... You cant help but wonder...

~Kraft