Unless you travel at relativistic speeds every other day, then it's close enough to not make a difference for most people. And I mean most as in 99.9999% of the Earth's population.
We don't. We have to have faith. That's why there's a little known and discredited area of physics known as temporal physics. It's the physics of time travel.
And heck no you do not want to change the past, because once you do, you can't change it back no matter how hard you try. Even being in that point in time changes that moment in time. So, in order to not change the past, you do not go back in time.
About paradoxes: Non-linear time is the answer.
This is my conjecture on time (I call it the Initial Timeline Conjecture).
From zero time (big bang or creation via current theory), one timeline is created that moves at a certain speed (think time dilation). I'd believe it to be the speed of light, but we'd have to create a unit of time-speed to truly measure how fast time is moving.
Anyway, this first timeline is the initial timeline. This timeline has no future; it only has a past. Everyone lives in the present, and all events within space-time contribute to the next "orientation" of everything in space-time at the very next instant. In other words, there is no destiny or fate because the "future" (which really doesn't exist here) is being created by the consequences of the events of the present.
Now, what if a time travel event occurred? Skipping the conjecture on how it would happen, the moment that person arrives in a chosen point in time, a new timeline is created because every event's space-time coordinates are now different. In other words, things have changed. The original timeline goes on, but a new timeline is now created which starts at the exact moment the person arrived back in time. This timeline has a destiny because events will almost match those of the initial timeline, but it won't have a future. Thus, forward time travel is totally impossible. The effect of "destiny" on the new timeline depends on the amount of new events that occurs in the new timeline. The time traveler who created this new timeline will only propagate through the new timeline at the speed of time and not faster.
I created (thought up) this conjecture to solve the familiar "Grandmother Paradox." This is the one where someone goes back in times and kills their parents or grandparents before they were born, preventing them from existing. The confusion then begins.
Well, actually, this is what happens: you don't stop existing when you kill your parents/grandparents/whatever because you're from another timeline in which you did come into existence. When you create the new timeline, you'll only prevent yourself from existing in the new timeline at the same event coordinates as in the old timeline. That's it.
I've since thought of some variations based on temporal theories like Stephen Hawkings "Crono-Protection Conjecture" where if you attempt to change the past, events will occur that will stop you. To me, that's a new timeline that's trying to create events such that it matches the initial timeline. Unfortunately, it can never return to its original state because it has a new event in its past.
So you if you went back in time to yesterday, and lived the day on thru to today, would you HAVE to go back to yesterday?
But then again....why would you want to go back in time? For some horrible moments to undo I can understand, but you are messing with the universe, dont think you want to do that. Like..to stop your parents from dieing in a car crash or something, I could understand, but....isnt life about going forward?
Now if there was a way to go back in time just as a ghost observer and you couldnt interact with anything, that would be cool. I'd go back in time, and watch the D-Day landings, and then come back a week later, having seen the entire first week of the D-day campaign.
Well time's just the concept we tack on to explain rate of change, right? However you measure it, with the vibration of a particle, or the expanding of a spring, you're measuring the change in that object and then appealing to this concept to explain time. If someone asks you what time is you point to something changing and go, 'Look: time!' I mean it runs faster or slower in some areas but it's still rate of change. Like acceleration. What I'm getting at is when you go from 80 miles an hour to 0 you've accelerated. And when you go from 0 to 80 in reverse you've accelerated again. It doesn't really seem possible for time to go backwards any more than acceleration can go backwards.
Can you run events in reverse? That's a different question. That just seems to be a matter of reversing the vectors of all the particles concerned with those specific events until you get to the point where you want to start going forwards again. Once you acknowledge that it's not time you're reversing, any more than acceleration reverses when you put the car into reverse, then most of the contradictions involved in time travel seem to fade away. Physically impossible, perhaps, but it doesn't seem to involve a logical contradiction.
The theory of time travel has been around for a while, and many people have stated their opinions on what the outcome would be. Would anything actually change? Would another Universe be created? Would we ultimately kill ourselves in the process?
Someone has already said here, that if we went back in time and altered something, which would have a consequence on our birth, then we wouldn't have been born, therefore, we'd not be able to go back in time in the first place.
It is possible, that time is fixed, and anyone who attempts to travel through it, ultimately seizes to exist. Think of it as hitting a brick wall; if you decided one day to travel from 2010, back to 1910, you may get there, only because you don't exist there, simply don't arrive at your destination. The minute you attempt to go back in time, your molecules and such burn up.
Then you're got the directions. Would you go back in time, or forward in time? Essentially, you can't go forward in time, because it doesn't exist yet. How would you go somewhere that doesn't exist? Equally, if you were to manage time travel to the past, you'd be stuck in the same situation. In the past, the future (your present) wouldn't exist, so how would you get back there?
It may be possible that once you go 'back in time' you're stuck there, though would you, or would you not alter the future? Even if you did, you'd not know, because there would be no way of getting 'back' to your present.
Anyone confused yet?
Also, if time travel is possible... Nobody has come back to 2009 from 3009 yet have they? I personally believe that time travel isn't possible, and I'd very much hope it isn't. I can only imagine the damage that could be caused by it. The only thing I will say, is that it may (in the future) be possible to 'view' the past.
We know, that if we look into space, we see other planets etc as they were, not as they are. Therefore, if we developed the technology to move to other planets, we may be able to view Earth in its past; heck, we may even be able to develop something that allows us to view things in realtime, such as you'd go to a location on the planet, hit a button on said device, program a time, date etc, and then you'd see (maybe through some special goggles) the past.
All speculation, but something worth discussing I think.
IIRC the present theory is that if you went back and say killed your grandfather you would at that point cause the timeline to split and create a alternate timeline where the two possibilities create two realities and for every difference you just created a split off from the original timeline.
We know, that if we look into space, we see other planets etc as they were, not as they are. Therefore, if we developed the technology to move to other planets, we may be able to view Earth in its past
Not possible. We see space in it's past state because of the limited speed of light and electromagnetic waves (or photons) which carry all of the information about a point in space. To know what's there now, we'd have to instantly go there.
If you leave Earth at the speed of light, and then looked back on it, you would see the Earth in a point in the past history relative to the current time on Earth, but you could not see past when you left. The only way to see the past beyond that is to find and catch the photons carrying that information, all of which are radiating away from their origin at the speed of light. Good luck catching every single photon you need (there are an infinite number that originated from that spot). This applies to looking at the past history of other planets as well.
It could be possible, but it would be a large task. We'd first have to break the speed of light to even start on it.
Actually Newton's first law means we could reconstruct the past, given enough information and processing power. Since every action has an equal and opposite reaction you can take the position of every particle in the universe, it's velocity and direction, and work backwards to find out where they were at any given time. Essentially everything that has happened is the only way things could have happened, because there is no variation in the reaction. It is always equal and opposite, one way or another. Basically the universe is the reaction to the action of the big bang, and can only have happened one way.
Actually Newton's first law means we could reconstruct the past, given enough information and processing power
Afterburner, please read about the Heisenberg Uncertainty Principle.
Also, even if it were possible to specify this sort of thing, to build a computer that could encode all that data you would effectively have a computer the size of the universe; well actually to deal with processing the data, larger than the universe.
This site is part of the Defy Media Gaming network
The best serving of video game culture, since 2001. Whether you're looking for news, reviews, walkthroughs, or the biggest collection of PC gaming files on the planet, Game Front has you covered. We also make no illusions about gaming: it's supposed to be fun. Browse gaming galleries, humor lists, and honest, short-form reporting. Game on!
The Pub 
Re: Time travel? Changing events? 
Although I agree it would make it a lot easier. 
Linear Mode
