Couldn't you use a massive gravitational field to bend your world line backwards and cause your "forward" in time to actually be going back in time compared to everyone else. Though I think I also remember reading that there were some side effects upon leaving that field and that it might undo anything you changed.
One would think that if a time machine were ever developed it would be strictly controlled. It's not like you could just pop down to your local time machine, slot in a coin and go for leisurely stroll through ancient Babylon.... I don't believe that "some jackass" could ever go "joyriding" with it; the technology is without doubt going to be incredibly complicated and require entire legions of scientists and enormous amounts of energy just to operate. Nobody could use it without dozens of people collaborating.
That's even assuming that it wouldn't be immediately dismantled and the technology hidden/destroyed to protect history, and forbidden under pain of immediate death. Time travel has the potential to be extremely dangerous, I imagine that anyone developing it would have the sense to not allow it to be fucked around with.
Anyway, who's to say that time travellers haven't already been here, mucking up history or otherwise? I mean nobody here would ever know the difference. Our entire history could be one giant mess of historical fuckups and we'd never even know.
There could be plenty of secret time travellers around, and even if they did tell people they're from the future, it's not like anyone would believe them.
Last edited by Netherspark; 2014-06-12 at 01:37 AM.
Massive gravitational field only expands event horizon from singularity point, which means you could enter a black hole without being crushed instantaneously. You wouldn't be able to leave it and if you could see inside, you'd see the back of your head while looking forward.
Can you elaborate on this? Right now it seems to me you're mixing two things, space-time curvature as a result of black holes and some sort of alcubierre field. Generating an alcubierre field means you'd "catch" particles in your trajectory and after leaving the field the particles would be released. Ship with such technology could easily obliterate our solar system, which depends on the distance on which it could maintain the field. Even though you'd sail the space in superluminal speeds, the ship or vessel inside the field would only move subluminally, therefore no real time dilation and thus no real time travel would occur.
Last edited by mmoc1c1d6a1668; 2014-06-12 at 10:33 AM.
What if the past already was changed?
Well if traveling backwards in time is possible then the only way it would work is by creating an alternate timeline or universe. Otherwise literally everything will result in a paradox and would violate the basic laws of physics.
You cant just create matter or energy from nothing and time travel would do exactly that. Just think about it. Say you send 1 pound of hydrogen back 1 hour, then in the past start a nuclear reaction and turn it into helium and store the energy. You could basically just double everything with no cost or in other words could just create infinite matter and energy like that. Even if takes a lot of energy to send things back in time, it wouldnt matter at the point of time when the object arrives.. it would just pop into existence.
So what about our universe?
And? It's something that happens all the time. Hawking radiation is a fine example of virtual particles popping into existence, but since the law of conservation of energy still applies, this weakens the black hole itself. Taking matter from one universe to another would not violate this principle.
What about it? If you're suggesting it just popped into existence, I don't believe that... maybe it never had a beginning. We don't know.
No it doesn't, these particles cancel each other out so no new matter or energy is created. If you just send something back in time, you essentially double it.. you have the past version of it in whatever form it is at that time and then the future version. Well I suppose it might be possible if you could send back thought alone, for example transfer someones future state on mind in hes or her past self but that seems even more unlikely, not to mention unethical.And? It's something that happens all the time. Hawking radiation is a fine example of virtual particles popping into existence, but since the law of conservation of energy still applies, this weakens the black hole itself.
Which is what I was trying to say. You can't travel into the past but maybe it might be possible to travel into an alternate version of the past by creating an alternate universe or timeline. Then you could murder your granddaddy just fine without creating a paradox as he wouldnt really be your grandfather, just a copy of him if you will.Taking matter from one universe to another would not violate this principle.
Some like to say there must be an existing destination time machine for it to work, and that's why we haven't seen them. As in, the point at which there is a working device would be the earliest one could go. A bit like having the first telephone - you have no one to call.
Anyway, you'd have to travel at infinite/negative velocity or through a gravity so intense that it curves spacetime back on itself or some other awful thing that wouldn't be terribly comfortable, to put it lightly.
Of course, time travel to the future is definitely a thing. Just not that feasible right now.
Some people keep talking about the theory where you can only travel to the point when first time machine was invented. Can someone please explain how a physical object would be any kind of "block" in going back to earlier times? If time travel is possible, it would have been possible from the beginning of the universe. I can't understand how someone inventing a machine and building it would affect that.
A wormhole with differentiated rotational points could be used as a time machine. Since speed affects time dilation, you can, theoretically, spin one end of a wormhole to move faster than the other. The time would move slower at the faster-rotating point and moving through it to the slower-rotating point would take you back in time.
You could move back in time and use another wormhole to move even further, but each wormhole would represent an obstacle similar to "you can only travel as far as the machine was first turned on." Barring the feedback from virtual particles, that is.
Time travel will never, ever happen; no point debating it.