Quotation? (time travel's strongest counterargument)

Tue Sep 10 22:51:14 UTC 2013

A news report in Science suggests that a version of the quotation
about future tourists might have appeared in Hawking's paper on the
"Chronology protection conjecture" in 1992 which was published in
Physics Review D, I think. But I cannot download the paper to check.
(See cite further below.)

Alternatively, the quotation appeared in a draft of the paper, or
Hawking may have simply spoken the words.

If someone reading this message is interested and can access the paper
I think it is worth checking.

Note that 1992 is after "Brief History of Time" was first published.

Journal: Science
Date: Apr. 10, 1992
Title: Could a Pair of Cosmic Strings Open a Route Into the Past?
Author: John Travis
Published by: American Association for the Advancement of Science
Datebase: JSTOR
http://www.jstor.org/stable/2876979

[Begin excerpt]
In an effort to prohibit time machines of any design, Hawking  has
just  completed a manuscript, called "The Chronology Protection
Conjecture," arguing that the laws of physics forbid closed timelike
curves. Somewhat tongue-in-cheek, Hawking cites as "strong empirical
evidence" for his conjecture the fact that "we have not been invaded
by hordes of tourists from the future."
[End excerpt]

Here is the cite for the Chronology protection conjecture

Chronology protection conjecture
Phys. Rev. D 46, 603–611 (1992)
http://prd.aps.org/abstract/PRD/v46/i2/p603_1

On Tue, Sep 10, 2013 at 6:17 PM, ADSGarson O'Toole
<adsgarsonotoole at gmail.com> wrote:
> ---------------------- Information from the mail header -----------------------
> Sender:       American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
> Poster:       ADSGarson O'Toole <adsgarsonotoole at GMAIL.COM>
> Subject:      Re: Quotation? (time travel's strongest counterargument)
> -------------------------------------------------------------------------------
>
> Here are some raw GB matches that show a quotation Hawking may have
> written or said. But I haven't found solid evidence yet:
>
> Engineering & Science - Volume 55 - Page 21
> books.google.com/books?id=kylIAQAAIAAJ
> 1991 - Snippet view - More editions
> But the best evidence we have that time travel is not possible and
> never will be, is that we have not been invaded by hordes of tourists
> from the future. means that a tiny change in the initial situation can
> lead to change in the subsequent ...
>
> Nonlinear problems in relativity and cosmology - Page 184
> books.google.com/books?id=HJhFAAAAYAAJ
> J. Robert Buchler, Steven Detweiler, James R. Ipser - 1991 -
> Snippet view - More editions
> ... of physics will always prevent the creation of CTCs.5 He has also
> suggested (half facetiously) that "there is strong experimental
> evidence in favour of this conjecture in the fact we have not been
> invaded by hordes of tourists from the future."
>
> On Tue, Sep 10, 2013 at 5:34 PM, ADSGarson O'Toole
> <adsgarsonotoole at gmail.com> wrote:
>> ---------------------- Information from the mail header -----------------------
>> Sender:       American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
>> Poster:       ADSGarson O'Toole <adsgarsonotoole at GMAIL.COM>
>> Subject:      Re: Quotation? (time travel's strongest counterargument)
>> -------------------------------------------------------------------------------
>>
>> Joel: Here is a preliminary comment. This is an old question/paradox
>> in science fiction. But finding the matching phrasing might be
>> difficult.
>>
>> The quotation is not mentioned on the main Wikiquote page for Hawking
>> (nor the Talk page). However, the excerpt below could be transformed
>> into the quotation.
>>
>> Title: A Brief History of Time
>> Author: Stephen Hawking
>> Date: 1998, First published in 1988
>>
>> http://books.google.com/books?id=oZhagX6UWOMC&q=overrun#v=snippet&
>>
>> [Begin excerpt]
>> This might explain why we have not yet been overrun by tourists from
>> the future, but it would not avoid the problems that would arise if
>> one were able to go back and change history.
>> [End excerpt]
>>
>> Here is an instance where the quotation was attributed to Hawking by 2004
>>
>> Peridocal: Popular Science
>> Date: Feb 2004
>>
>> http://books.google.com/books?id=rdCPa_yGqF0C&q=overrun#v=snippet&
>>
>> [Begin excerpt]
>> His most famous science-fiction-writer-befuddling question: If time
>> travel is possible, why haven't we been overrun by tourists from the
>> future?
>> [End excerpt]
>>
>> Garson
>>
>>
>> On Tue, Sep 10, 2013 at 4:51 PM, Joel S. Berson <Berson at att.net> wrote:
>>> ---------------------- Information from the mail header -----------------------
>>> Sender:       American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
>>> Poster:       "Joel S. Berson" <Berson at ATT.NET>
>>> Subject:      Quotation? (time travel's strongest counterargument)
>>> -------------------------------------------------------------------------------
>>>
>>> I apologize for asking the list -- I don't do quotations, and don't
>>> own the reference books.
>>>
>>> Who first said "if time travel were possible, we would have been
>>> overrun by tourists from the future by now."  Stephen Hawking, or someone else?
>>>
>>> Joel
>>>
>>> ------------------------------------------------------------
>>> The American Dialect Society - http://www.americandialect.org
>>
>> ------------------------------------------------------------
>> The American Dialect Society - http://www.americandialect.org
>
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