Time travel and saying hello and changing the future.

[flobadob]

If you were to travel to the past and walk up to your grandfather and just say hello, would you then never be born? I was just thinking that say for example, there are 100,000 sperm in every ejaculation and only one gets to make a baby. Obviously these sperm are constantly moving so even a delay of a second would mean a different sperm would fertilise the egg in question. Does it therefore stand that the delay in his life cycle responding to your greeting would have repurcussions resulting in different children being born to him and thus you never being conceived?

[factor-fiction]

These discussions usually go round in circles

[rowanwitch]

But to go back in time you had to have been born so you had no impact

[factor-fiction]

But what if you went back and killed your grandfather....

[rowanwitch]

I wish someone had killed mine

[jackthehat]

Provide I didn't kill him *before* he had created my Mum/Dad.............it wouldn't matter, would it ?

[ChuckFickens]

"These discussions usually go round in circles"

Is that not the idea behind a paradox?

You couldn't stop yourself from being born, because if you had never been born then you could have never have stopped yourself being born.

[wildwood]

You may want to participate in a more realistic pastime.

http://www.informatio...uk/sports.cfm?type=21

[sengas]

whoa !!!!! more please!!!!!!!!!

[flobadob]

I love table tennis.

So can we put to bed any notion whatsoever that time travel to the past is even remotely possible? Can we categorically state it is impossible?

[jackthehat]

I think we can categorically say is that 'presently' it is impossible.

[flobadob]

Though jack when talking about time travel the term "presently" becomes irrelevant as it does not matter if I travel into the past today, tomorrow or in twenty years time the fact is that it has already happened.

[ChuckFickens]

Unless you subscribe to the theory that any time travel would need a "gateway" on either end, so it would never be possible to travel back to a time before the first "gateway" was invented.

[flobadob]

Chuck, even with the gateway scenario, would you still agree with my original post that even something as simple as having a basic discussion of one or two words would drastically alter any further outcomes in those people's lives?

[ChuckFickens]

Of course it could, maybe,

It's basically the butterfly effect, but any discussion about time travel and cause and effect invariably ends up as a unsolvable paradox.

[jackthehat]

I think that whilst it may be possible to pass through 2011 on your way to somewhere else in the past.....it is not presently possible to have 2011 as your starting point.

[jomifl]

If people from the future had ever travelled into the past they would have altered the future so that they didn't travel back in time. So,no obviously !

[squarebear]

Impossible to travel back in time, so any discussions about what you would do are meaningless.

[jake-the-peg]

This paradox is resolved if you believe in multiple Universes.

Going back in time involves returning to a point prior to the seperation of the version of the Universe which you inhabited and proceding down a different time line.

No problem.

Of course the paradox may also be resolved if backwards time travel is impossible

[jackthehat]

Ah, the old 'trousers of time' theory.........?

[murraymints]

eh ????