At 10:13 AM 29/10/2010, you wrote:
>?> On 29/10/2010 11:44, Ruben J=F6nsson wrote:
> >>
> >> Timetravelling going back in time is never going to be possible -
> >> otherwise we
> >> would have known about it from future visitors by now.
>
>Absence of evidence is not evidence of absence. This is a logical falacy.
>
> >
> >     How can we prove something "is not possible"?
> >
> >     MJ
>
>In the real world you can't prove a negative.

If you can show that the proposition leads to a contradiction,
then you can prove something is impossible.

See, for example, the "halting problem". Or this one:

http://en.wikipedia.org/wiki/Squaring_the_circle

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the rewar=
d"
speff@interlog.com             Info for manufacturers: http://www.trexon.co=
m
Embedded software/hardware/analog  Info for designers:  http://www.speff.co=
m




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