Alien conundrum

[slimjim]

Feel free to correct me if my basic understanding of the universe doesn't match current theories. If time is a dimension that can be travelled through, then how come no alien forms from the future have travelled back to visit us. My point being that if they reached a level of intelligence that allows them to travel through time, then they're probably clever enough to find a way of rapidly searching planets for lifeforms. To me, this suggests that the universe is destroyed before any aliens reach such a level of intelligence. And also, if time is a dimension, why have no humans from the future been back to visit us. Do we destro ourselves before we get that clever?

[wildwood]

I don't think time is a dimension that can be travelled through. To my mind it is a perception of how matter exists in relation to the distance from what the observer views due to the speed of light - the sun as we view it is how it was 8.3 minutes ago. From the sun, the Earth is also viewed as it was 8.3 minutes ago.
There is no reason to believe that any life as we know it exists or has done, apart from in our solar system.
In answer to your last question; Yes, we will probably destroy ourselves one way or another!

[TheHitMaker]

There is a theory that if time travel is possible then it would only be possible to travel around after the point that time travel has been invented - therefore no future travellers would be around here/now.

[sft42]

there are a number of possible reasons for time travelling and why it may or may not be possible not the least of them being that if you do travel back in time then any alterations that you make can change the future that you were part of - Read the excellent "A Sound of Thunder by Ray Bradbury" for a vivid demonstration of this effect. and i have to disagree with wildwood that asssertion that there is no reason to believe life exsists anywhere else.....i would say that the sheer weight of numbers of stars up there that even if only 1% have planets and if only 1% of them are inhabitable and then again if only 1% of those has life we are still talking about roughly 1 billion chances for intelligent life, and that sounds like good odds to me.

[lisaj]

Time is a dimension, and is one of the four dimensions of space-time. There is no reason to suppose that this dimension could not be linearly traversed as the standard x/y/z can be, and indeed on a daily basis everything in the universe is moving forwards along this dimension (forward from our perception anyway - it might be backwards from somebody else's). Another (of the very many out there) theory is that whilst manipulation of one's position in space-time may be possible - it probably is, we just don't know how, since in the great scheme of things we're fairly simple beings - interacting with other things at a point in space-time may not be possible. Apparently, it's all about temporal phase - something which I don't understand really, but comes down to a mental image of two sine waves, one of which is being slid back and forth along the x-axis (which represents time): The two go in and out of phase with one another. However, the big crunch is... why would an alien species so advanced necessarily want to communicate with us? sft42 is absolutely correct that the sheer numbers indicate that there probably is life out there, but given the volume of space and their limited resources (everything has limited resources), there might be more attractive options than us!

[Joshua_R]

Cynics answer : Who would waste time , money and effort on travelling back in time to visit a primitive culture when you could travel forwards and reap the technological advances? Just look at our "culture" - what percentage of the global wealth is spent on archeology/anthropology in comparison with that spent on technology?

[TheheftyGeorge]

You will need the TARDIS but for me, a tailcoat is enough.