[quote]Prove to me that time travel is dangerous.[/quote] The Weeping Angels "are as old as the universe (or very nearly), but no one really knows where they come from." They have been described as "the deadliest, most powerful, most malevolent life-form ever produced." Weeping Angels are unusual as predators in that they neither kill nor directly parasitize their prey. Their usual mode of feeding is to make use of time paradoxes - with a single touch, a Weeping Angel can send a person into the past to a point before his/her own birth, and can then feed off the "potential energy" of the years which that victim would have lived in the present. The Doctor describes the Angels as "the only psychopaths in the universe to kill you nicely" because their victims are otherwise uninjured and may live out their lifespans in the past. Weeping Angels prefer to take their energy from live victims, but if required they can drain other forms such as that from electric lights (as seen in "Blink") or other electronics. In "Blink," the Angels attempted to steal the Doctor's TARDIS after trapping him in the past. The engine of the vehicle contained enough time energy to feed them forever, but The Doctor stated that the possible damage they could cause "could switch off the sun". So, this species is not only drawn to power sources, but are like moths to a flame when it comes to a TT Type 40, Mark 3 of Gallifreyan origin, powered by a harnessed singularity. Their capture of one could devastate a star system and even rip the fabric of spacetime. That's one example of a lifeform that is a danger for any being/technology capable of time travel. Another example are the Reapers, who detect, seek out and destroy paradoxes as well as the existence any time/matter/energy associated with the paradoxical event. A pretty harsh Quality Assurance program if ever I heard of one.

I miss Terra Nova

Op thinks he can time travel when he can't even travel off the couch

You could but you might end up in a tree which would probably hurt a tad bit

My theory is that the past can't even be changed because: Let's say that you want to change something in the past. You change it, ok. But then you never had a reason to time travel, therefore you [i]didn't [/i] time travel and didn't change anything. About how dangerous it is, no one knows what actually happens when you time travel. There may be obstacles of some sort in the dimension(s) between past, present and future. And if you can travel through time safely, you may make some mistakes that leave the world in an entirely different shape than it was before you did it. Like, say, adopting Hitler for whatever reason. Just think how different things would be. [spoiler]To sum it up, I think it's dangerous???[/spoiler]

[u]The Grandfather Paradox[/u] If you go back in time and kill your grandfather before your father was conceived, you will never have been born. If you were never born, you were never born, you could never have time traveled. If you never time traveled, you could never have killed your grandfather and thus you would have been born. If you were born, you would have gone back in time to kill your grandfather before your father was conceived, you will never have been born. If you were never born, you were never born, you could never have time traveled. If you never time traveled, you could never have killed your grandfather and thus you would have been born. If you were born, you would have gone back in time to kill your grandfather before your father was conceived, you will never have been born. If you were never born, you were never born, you could never have time traveled. If you never time traveled, you could never have killed your grandfather and thus you would have been born. If you were born, you would have gone back in time to kill your grandfather before your father was conceived, you will never have been born. If you were never born, you were never born, you could never have time traveled. If you never time traveled, you could never have killed your grandfather and thus you would have been born. If you were born, you would have gone back in time to kill your grandfather before your father was conceived, you will never have been born. If you were never born, you were never born, you could never have time traveled. If you never time traveled, you could never have killed your grandfather and thus you would have been born. If you were born, you would have gone back in time to kill your grandfather before your father was conceived, you will never have been born. If you were never born, you were never born, you could never have time traveled. If you never time traveled, you could never have killed your grandfather and thus you would have been born. [spoiler]You get it?[/spoiler]

It makes you nose bleeds (づಠ╭͜ʖ╮ಠ)づ

Doesn't time travel kinda eliminate free will? If you can go to a pre determined time based on actions of the past wouldn't that mean that the future is already decided and we can't do anything about it?

We don't even know if it's possible, but who knows what those crazy -blam!-s are doing at Aperture.