Time Travel

Don't know about ethical, given the stakes involved, I would ask if it would it be possible to stop it!

 

Depends on the logistics of it - what I mean is, in Back to the Future, Marty goes back to 1955/1895 yet Jennifer is still in 1985, where time has barely moved, so the 1985 world was unchanged...or so it seemed. If that was the case, why not? However, if time changed for eveeeerrryybody then that would mess everything up, like some people might not want to revisit the olden days.

I'd travel back to ancient Greece, they were accepting of the homosexual kind.

 

It depends... if you use said time travel and go back in time and do something as little as kill a bug, would it have a huge impact on the present?

 

Ethical? no.
Fun? YEP.

So worth it.

 

Travel is displacement as a function of time, so "time travel" implies that you're describing a situation where time is a function of time, and that doesn't actually make sense . Instead, physicists call the phenomenon a closed timelike curve (CTC), which could theoretically allow what we commonly call "time travel".

According to the Everett interpretation of quantum mechanics, also known as many-worlds theory, every time you make a choice, the whole universe splits into two parallel ones, where in one you chose one way, and in another you chose the other way. Now, there's a rule in physics called the Novikov self-consistency principle, where the probability of an event occurring that would give rise to a paradox (like killing your grandfather before you were born) is always 0.

However, interpreting that to mean you can't kill your grandfather before you're born is far too simplistic - it's possible, but by doing so, you would have to have traveled through time AND parallel universes - you'd need to be in another universe, a copy of this one running parallel to it, and then you could. This would not prevent your birth, but it would prevent your doppelgänger's birth in the parallel universe you've now travelled to. So there would only be one of you in that world instead of two.

This phenomenon nicely solves the problem of paradoxes, so when (not if, but when) we have a device that can open a hole by bringing two distant points into phase with each other, which would require an absolutely massive amount of energy (10x what the world produces in a year), we'll also be jumping between universes such that our specific worldlines (the path along pace and time that is unique to you) do not cross themselves in such a way that a paradox would be created. Fun, eh? :lol:

 

I know, but I needed that for my point, which I think I may have failed to convey :lol:.

My point was that time travel is ethical because it's impossible to cross worldlines .

 

Travel to the past would be interesting for historical purposes, however being more of a self-described futurist, I'd much rather have a chance to see what humanity is like hundreds or thousands of years from now. Also on a practical level, travel to the future within our own universe is much simpler to attain than AaronMed's well explained many-worlds approach.

Travel to the future can be achieved by exploiting either of Einstein's theories of relativity. For those of you that might not be too familiar, I'll give a quick explanation. In a nutshell, his theories state that "moving clocks run slow" and "clocks also move slower when they are deeper in a gravitational well."

These statements have been verified with extreme precision over the last century and are actually at the backbone of the global positioning system. Without these effects coded into the satellites, the system would completely fail within minutes or hours.

So with these preliminaries out of the way - "travel to the future" would be as simple as hopping on a spaceship and approaching the speed of light. Or, one could just spend some time orbiting a black hole (at a safe distance, don't dare get too close to the event horizon ).

Many have shot down the spaceship idea, saying that it would be impossible to carry enough fuel to propel yourself up to any appreciable fraction of light speed. My favorite solution is the "hydrogen net" approach. Basically, there are hydrogen atoms scattered throughout all of space - typically a few per cubic meter. As the spaceship zips through space it could collect some of these atoms and use them in a nuclear fusion reactor. All the while your ship could be accelerating at 1g (so that handles the artificial gravity problem). Depending on how long you choose to travel like this, anywhere from decades, centuries, or many millennia will have passed on Earth. You may be a decade older on return (assuming you weren't able to go into some form of suspended animation chamber, which may be practical at the time this technology would be implemented.), but you'll have jumped essentially as far into the future as you would like.

To answer the OP's question - is this ethical? I see no reason why it wouldn't be, and I would do it in a heartbeat if I had the opportunity.

 

I'm glad you made your point clear, because I didn't get it from your original post. Would it be possible to return to the original universe?

In any case, I think the ethics would revolve around the intent. Why is the person travelling to a different point?

 

Yay, a fellow physics person! This is going to be fun .

Of course now we're dealing with relativity and time dilation, which requires you to actually travel really far in space at an extremely high speed. Even if the hydrogen net explained below could work (I don't think it can), for the device to be useful, there would have to be passengers. And because passengers breathe, you have to bring along enough oxygen with you, because you won't find any out there. That's a lot of oxygen - so realistically, the only way something like this could work is if you could accomplish suspended animation, i.e. cryonics. I'm going to talk about that, but first I'd like to bring up something else that people often forget: exercise. It seems absurdly ridiculous at first, but it actually is a huge issue and the current reason why we can't send people into space for more than six months.

I once met Dr. Robert Thirsk, a Canadian doctor and astronaut who went into space for six months. It took him two years to prepare his body to a state where he could survive it, and when he came back, he was virtually wasted away - most of his muscles had at least partially atrophied. Upon arriving back on Earth, he was quite wheelchair-bound. It took him three years to recover.

The reason for this is because on Earth, you always have gravity pulling you down at about 9.8 m/s^2. And in order to not become an atrophied puddle, your muscles, even when you're relaxed, always have an existing tone in which they contract and relax over and over so you can stay healthy. In space that doesn't happen, so you need to exercise a lot with special devices that circumvent the necessity for gravity that most Earthly exercised require.

Even with lots of exercise in space, you still get the wasting, just not as fast. But let's make an assumption that you could exercise enough to stay in space for a really long time. That means you need a really big ship to put all your exercise equipment on, and that whole interior space is going to need life support, which will take up a lot of mass. That's important a few paragraphs from now .

I'm actually a member of the Alcor Life Extension Foundation, so I'm pretty well-versed in the science of cryonics (yes, it's quite possible, but that's for another post, haha). To accomplish cryonic suspension in space, you'd need to bring equipment to keep your body at the glass transition temperature for M22 vitrification solution, which mainly contains DMSO (dimethylsulphoxide). More mass, haha. Of course, I suppose you wouldn't need to bring nearly as much oxygen then, so it just might work.

There's a bit of a problem here though - we can't lose sight of the original purpose. Our purpose is to travel into the future. So if we're already suspending someone, that person in suspension won't experience the passage of time because their suprachiasmatic nuclei, along with the rest of their brain, is also suspended. So why not just suspend them and keep them on Earth until the amount of time they wanted to travel through passes, and then just wake them up? From the suspended person's perspective, this would be just as effective .

This is very true, I definitely agree that the theory is sound .

Unfortunately, it was recently discovered that there's not enough hydrogen in space for that purpose. The problem is that in order to have a fusion reaction produce energy, it needs to achieve critical mass - this is the amount of hydrogen that has to be in the reactor for the reaction to be self-sustaining. Critical mass can't be obtained with the amount of hydrogen in our universe .

I totally agree .

No problem .

In theory? Perhaps, but you'd have to know the unique signature of your original universe in order to make it non-random. If you knew something called the grand unified wavefunction of your target, you might be able to find a weak spot on Earth and bring the two into phase with each other. Then you could cross over.

Of course, I've neglected a huge problem: traveling through a wormhole neutralizes electricity. And your heart and brain both run on electricity, so your heart and brain would stop working on the other side. You'd need to be defibrillated with one of these:



And your brain would need to be rebooted chemically. Fun times!

I totally agree .

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Holy shit, that post was long! XD

 

If time travel were possible, id go back in time and kill infamous dictators and leaders who have caused innumerable damage to society and pure evil in general.

 

I'd travel at least as far ahead to see the Mega Millions numbers, then travel back, and buy a few tickets...

And it would be nice to see certain things in the past; I would like to see much of the artwork of Gustav Klimt, before it was destroyed by the Nazis, and things like that. I'd treat it more like a sort of museum, casually observing, and not being overly obtrusive.

 

Well, I think that, if time-travel existed, that the person who went back in time would always have done so. There is no way, in my mind, that they can materialise into the past or future, without that past or future always being destined to have them. (more simply, they always were in that past, so no change is done)

And a note; killing famous dictators wouldn't work, because the moment they are dead, the incentive to kill them (as they were killed) is removed, so they were never assassinated, therefore there is an incentive, and were assassinated, which is a loop where nothing is done. In any case, many dictators have influenced the movements of large populations, making it likely that the time-travelling assassin would never have been born.

Answering the question after my annoyingly pedantic concerns :lol: , I think time travel would be highly unethical, and could result in many problems.

 

Depends what You Do, But according to skinner's Thoery I think, Time Travel would result in total destruction, If you went back in time to stop you're self from doing something stupid and you succeeded there would be an immediate paradox, Because you stopped you're self from doing something you would have no need to go back in time to stop you're self but
so you wouldn't but then you Would do the stupid thing and you would need to go back in time to fix it thus repeating the process, Hope it makes sence

 

May I pose a question. Why do time travel debates always assume that time linear? i.e. that cause always precedes effect.

What if time in non linear? i.e. effect precedes cause.

We know very little about time, and we certainly do not have a model for it. Until we do, I think we have to be open to the possibility of non-linear time. In this case time travel would not only be ethical, it might even be a requirement.

 

As smart as that sounds, it doesn't account for the summary of the "many worlds theory" AaronMed was kind enough to explain. It means you can't do things to yourself; they happened and that's that. You CAN do things to your parallel-self, but it has no bearing on your own universe.

With that said, I would try to be as non-intrusive as possible. I'd be severely tempted to make a game out of messing with the past then seeing the future of an alternate world, but they are real people and I couldn't screw around with their being in good conscience.

 

If you plan on using it to do unethical things I guess it wouldn't be.

You can time travel fractions of a second by leaving the earths atmosphere up to where
satellites are because Earth's gravity no longer slows time down by that tiny amount up there. Though you wouldn't feel it, time goes by a little bit quicker when you aren't near a gravitational mass.

I know nothing about physics but have heard it and read it before, gravity somehow slows time down making time travel to the future possible, and speed also slows time down.

According to our knowledge approaching the speed of light will cause time to be perceived slower in order to "stop" you or the object from actually breaking the speed of light.